Decoding of a Signal Comprising Encoded Data Symbols

Abstract

A first radio node (108-1,108-2; 110) and a method therein for transmitting a signal comprising encoded data symbols to a second radio node (110; 108-1,108-2). The first and second radio nodes are operating in a wireless communications network (100). The 5 first radio node repeats n times a sequence of data symbols S0,S1, . . . ,Sk1 to be transmitted, wherein k is a multiple of n. The first radio node encodes the n sequences of data symbols S0,S1, . . . ,Sk1 using n orthogonal code sequences, wherein each code sequence comprises n code elements. Further, the first radio node transmits, to the second radio node, a signal comprising the respective encoded sequence of data 10 symbols S0,S1, Sk1 and an optional respective affix for separating two encoded sequences of data symbols S0,S1, . . . ,Sk1.

Claims

1-42 (canceled).

43. A method performed by a first radio node for transmitting a signal comprising encoded data symbols to a second radio node, wherein the first radio node and the second radio node are operating in a wireless communications network, and wherein the method comprises: repeating n times a sequence of data symbols S.sub.0, S.sub.1, . . . , S.sub.k1 to be transmitted, wherein k is a multiple of n; encoding the n sequences of data symbols S.sub.0, S.sub.1, . . . , S.sub.k1 using n orthogonal code sequences, wherein each code sequence comprises n code elements; and transmitting, to the second radio node, a signal comprising the respective encoded sequence of data symbols S.sub.0, S.sub.1, . . . , S.sub.k1 and an optional respective affix for separating two encoded sequences of data symbols S.sub.0, S.sub.1, . . . , S.sub.k1.

44. A method performed by a second radio node for decoding and extracting data symbols from a signal received from a first radio node, wherein the second radio node and the first radio node are operating in a wireless communications network, and wherein the method comprises: receiving a signal from the first radio node; removing an affix from the received signal resulting in n sequences of k received samples; stacking the n sequences of k received samples; decoding the stacked n sequences of k received samples using n orthogonal code sequences, wherein each code sequence comprises n code elements, wherein for each code sequence each of the n sequences of k received samples is multiplied to one out of the n code elements of the code sequence and wherein the multiplied sequences of received samples are subsequently added, and wherein the decoding results in n different decoded sequences of samples of length k each decoded sequence of samples corresponding to one of the n applied code sequences; and extracting a sequence of data symbols S.sub.0, S.sub.1, . . . , S.sub.k1 from the n different decoded sequences of samples.

45. A first radio node for transmitting a signal comprising encoded data symbols to a second radio node, wherein the first radio node and the second radio node are operating in a wireless communications, and wherein the first radio node is configured to: repeat n times a sequence of data symbols S.sub.0, S.sub.1, . . . , S.sub.k1 to be transmitted, wherein k is a multiple of n; encode the n sequences of data symbols S.sub.0, S.sub.1, . . . , S.sub.k1 using n orthogonal code sequences, wherein each code sequence comprises n code elements; and transmit, to the second radio node, a signal comprising the respective encoded sequence of data symbols S.sub.0, S.sub.1, . . . , S.sub.k1 and an optional respective affix for separating two encoded sequences of data symbols S.sub.0, S.sub.1, . . . , S.sub.k1.

46. The first radio node of claim 45, being configured to encode the n sequences of data symbols S.sub.0, S.sub.1, . . . , S.sub.k1 by further being configured to: element-wise multiply one code sequence out of the n orthogonal code sequences to the n times repeated data symbol Si comprised in the n sequences of data symbols S.sub.0, S.sub.1, . . . , S.sub.k1 wherein i [0,1, . . . , k-1].

47. The first radio node of claim 45, being configured to encode the n sequences of data symbols S.sub.0, S.sub.1, . . . , S.sub.k1 by further being configured to: repeatedly use the n orthogonal code sequences for the encoding of the n sequences of data symbols S.sub.0, S.sub.1, . . . , S.sub.k1, wherein the n orthogonal code sequences are used k/n times each for encoding n times repeated symbol S.sub.1 comprised in the n sequences of data symbols S.sub.0, S.sub.1, . . . , S.sub.k1, wherein i [0,1, . . . , k-1].

48. The first radio node of claim 45, being configured to: provide the respective affix before the first data symbol SO of each encoded sequence of data symbols S.sub.0, S.sub.1, . . . , S.sub.k1.

49. The first radio node of claim 48, being configured to provide the respective affix by further being configured to: insert a respective cyclic prefix before the first data symbol So of each encoded sequence of data symbols S.sub.0, S.sub.1, . . . , S.sub.k1, wherein the respective cyclic prefix comprises one or more of the last n1 data symbols of the respective encoded sequence of data symbols S.sub.0, S.sub.1, . . . , S.sub.k1.

50. The first radio node of claim 48, being configured to provide the respective affix by further being configured to: provide a respective guard time period before the first data symbol So of each encoded sequence of data symbols S.sub.0, S.sub.1, . . . , S.sub.k1.

51. The first radio node of claim 45, wherein the data symbols S.sub.0, S.sub.1, . . . , S.sub.k1 are data symbols from a symbol constellation of a linear modulation or a non-linear modulation.

52. The first radio node of claim 51, wherein the linear modulation is one out of: a Phase-Shift Keying, PSK; and a Quadrature Amplitude Modulation, QAM.

53. The first radio node of claim 51, wherein the non-linear modulation is one out of: a Gaussian Minimum Shift Keying, GMSK; a Gaussian Frequency-Shift Keying, GFSK; and a Minimum-Shift Keying, MSK.

54. The first radio node of claim 45, wherein one or more of the data symbols S.sub.0, S.sub.1, . . . , S.sub.k1 are training symbols.

55. The first radio node of claim 45, wherein the n orthogonal code sequences comprise real values.

56. The first radio node of claim 55, wherein the n orthogonal code sequences are comprised in an n by n Hadamard matrix.

57. The first radio node of claim 45, wherein the n orthogonal code sequences comprise complex values.

58. The first radio node of claim 45, being configured to transmit the signal comprising the respective affix and the respective encoded sequence of data symbols S.sub.0, S.sub.1, . . . , S.sub.k1 by further being configured to: transmit the respective affix and the respective encoded sequence of data symbols S.sub.0, S.sub.1, . . . , S.sub.k1 in sequence using a single carrier; or transmit the respective affix and the respective encoded sequence of data symbols S.sub.0, S.sub.1, . . . , S.sub.k1 in parallel using a respective subcarrier in a multicarrier signal.

59. The first radio node of claim 45, wherein the first radio node is configured to repeat n times of the sequence of data symbols S.sub.0, S.sub.1, . . . , S.sub.k1 by being configured to: generate an n by k matrix, wherein each row is a copy of a sequence of data symbols S.sub.0, S.sub.1, . . . , S.sub.k1, wherein n is the number of repetitions of the sequence of data symbols S.sub.0, S.sub.1, . . . , S.sub.k1; wherein the first radio node is configured to encode the n sequences of data symbols S.sub.0, S.sub.1, . . . , S.sub.k1 using n orthogonal code words by being configured to: encode the generated n by k matrix by performing element-wise matrix multiplication using an k/n times repeated n by n orthogonal code matrix comprising the n orthogonal code sequences, wherein the encoding results in an encoded n by k matrix; wherein the first radio node is configured to provide the respective affix by being configured to: insert a cyclic prefix before the encoded n by k matrix, which cyclic prefix comprises one or more of the last n1 columns of the encoded n by k matrix, wherein the inserting results in an n by (x+k) matrix, wherein x is the number of columns of the inserted cyclic prefix, or provide a respective guard time period before the first data symbol So of each encoded sequence of data symbols S.sub.0, S.sub.1, . . . , S.sub.k1; and wherein the first radio node is configured to transmit the respective affix and the respective sequence of data symbols S.sub.0, S.sub.1, . . . , S.sub.k1 by being configured to: transmit row wise the respective affix and the data symbols S.sub.0, S.sub.1, . . . , S.sub.k1 comprised in the n by (x+k) matrix.

60. A second radio node for decoding and extracting data symbols from a received signal, wherein the second radio node and a first radio node are operating in a wireless communications network, and wherein the second radio node is configured to: receive a signal from the first radio node; remove an affix from the received signal resulting in n sequences of k received samples; stack the n sequences of k received samples; decode the stacked n sequences of k received samples using n orthogonal code sequences, wherein each code sequence comprises n code elements, wherein for each code sequence each of the n sequences of k received samples is multiplied to one out of the n code elements of the code sequence and wherein the multiplied sequences of received samples are subsequently added, and wherein the decoding results in n different decoded sequences of samples of length k each decoded sample corresponding to one of the n applied code sequences; and extract a sequence of data symbols S.sub.0, S.sub.1, . . . , S.sub.k1 from the n different decoded sequences of samples.

61. The second radio node of claim 60, being configured to: reorder the n different decoded sequences of samples and possibly moving elements between the n different decoded sequences of samples to obtain n different decoded and reordered sequences of samples.

62. The second radio node of claim 60, being configured to: estimate n channel coefficients h.sub.0, h.sub.1, . . . h.sub.n1 wherein each one of the n different decoded sequences of samples corresponds to the sequence of data symbols S.sub.0, S.sub.1, . . . , S.sub.k1 multiplied by a respective channel coefficient.

63. The second radio node of claim 60, being configured to: combine the n different decoded sequences of samples by performing a Maximum Ratio Combination (MRC), whereby the signal to noise ratio is increased.

64. The second radio node of claim 60, wherein second radio node is configured to stack the n sequences of k received samples by being configured to: stack the n sequences of k received samples into a first n by k matrix; wherein second radio node is configured to decode the stacked sequences of k received samples using n orthogonal code sequences by being configured to: decode the first n by k matrix using an n by n orthogonal code matrix comprising the n orthogonal code sequences, wherein each code sequence comprises n code elements and wherein the decoding results in a second n by k matrix; and wherein second radio node is configured to extract the sequence of data symbols S.sub.0, S.sub.1, . . . , S.sub.k1 from the n different decoded sequences of samples by being configured to extract the sequence of data symbols S.sub.0, S.sub.1, . . . , S.sub.k1 from the second n by k matrix.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0042] Examples of embodiments herein are described in more detail with reference to attached drawings in which:

[0043] FIG. 1 schematically illustrates embodiments of a wireless communications network;

[0044] FIG. 2 is a flowchart schematically illustrating embodiments of a method performed by a first radio node;

[0045] FIG. 3 is a block diagram schematically illustrating embodiments of a first radio node;

[0046] FIG. 4 is a flowchart schematically illustrating embodiments of a method performed by a second radio node;

[0047] FIG. 5 is a block diagram schematically illustrating embodiments of a second radio node;

[0048] FIG. 6 schematically illustrates a vector with data symbols to be transmitted and a code matrix;

[0049] FIG. 7 is a matrix schematically illustrating repeated data symbols;

[0050] FIG. 8 is a matrix schematically illustrating encoded data symbols;

[0051] FIG. 9 is a matrix schematically illustrating a cyclic prefix added to the encoded data symbols;

[0052] FIG. 10 is a vector schematically illustrating the transmitted symbol sequence;

[0053] FIG. 11 schematically illustrates a received signal comprising delayed versions of the transmitted symbol sequence;

[0054] FIG. 12 schematically illustrates the received samples after removal of a cyclic prefix;

[0055] FIG. 13 is a matrix schematically illustrating the stacked received samples;

[0056] FIG. 14A shows a matrix and a vector schematically illustrating the result after decoding with a first code word;

[0057] FIG. 14B shows a matrix and a vector schematically illustrating the result after decoding with a second code word;

[0058] FIG. 14C shows a matrix and a vector schematically illustrating the result after decoding with a third code word;

[0059] FIG. 14D shows a matrix and a vector schematically illustrating the result after decoding with a fourth code word;

[0060] FIG. 15 shows matrices and vectors schematically illustrating the result after sorting of the decoded sequences; and

[0061] FIG. 16 schematically illustrates Maximum Ratio Combining.

DETAILED DESCRIPTION

[0062] According to developments of wireless communications networks improved modulation and equalization methods are needed for improving the performance of the wireless communications network.

[0063] An object of embodiments herein is therefore how to provide an improved performance in a wireless communications network.

[0064] In embodiments disclosed herein, an orthogonal code is applied, by a transmitter, to symbols of a repeated transmission. By the term orthogonal code when used in this disclosure is meant that each code word is orthogonal to all other code words, i.e., that the scalar product between any two code words is zero. Further, different code sequences are applied to different repetitions of the transmission. An affix, e.g. a cyclic prefix, may be added to each repetition and the repetitions are transmitted in sequence. At the receiver side, the code is used when combining the repeated blocks. Different code sequences are used to extract different transmitted symbols. The inter-symbol interference will be resolved in the decoding process and thereby the need for equalization and multi-tap channel estimation is eliminated. From the decoding process one diversity branch for each channel tap in the time-dispersive channel is obtained when assuming that the number of channel taps is not larger than the number of coded repetitions. To combine the diversity branches, a Maximum Ratio Combining (MRC) may be used.

[0065] In this disclosure the channel tap is sometimes referred to as a channel coefficient, and it should be understood that the terms channel tap and channel coefficient may be used interchangeably.

[0066] Note that although terminology from 3GPP LTE is used in this disclosure to exemplify the embodiments herein, this should not be seen as limiting the scope of the embodiments herein to only the aforementioned system. Other wireless systems, such as for example 5G, Wideband Code-Division Multiple Access (WCDMA), Worldwide Interoperability for Microwave Access (WiMax), Ultra-Mobile Broadband (UMB) and GSM, may also benefit from exploiting the ideas covered within this disclosure.

[0067] In this section, the embodiments herein will be illustrated in more detail by a number of exemplary embodiments. It should be noted that these embodiments are not mutually exclusive. Components from one embodiment may be assumed to be present in another embodiment and it will be obvious to a person skilled in the art how those components may be used in the other exemplary embodiments.

[0068] Further, the description frequently refers to wireless transmissions in the downlink, but embodiments herein are equally applicable in the uplink.

[0069] FIG. 1 depicts an example of the wireless communications network 100 in which embodiments herein may be implemented. The wireless communications network 100 is a wireless communication network such as a New radio (NR) network, a 5G network, a GSM EDGE Radio Access Network (GERAN) network, an LTE network, a WCDMA network, a GSM network such as an Extended Coverage (EC) GSM, any 3GPP cellular network, a WiMAX network, a Wireless Local Area Network (WLAN), a Bluetooth communications network such as a Bluetooth Long Range (BLR) communications network, a NB-IoT communications network, or any wireless or cellular network/system.

[0070] The wireless communications network 100 may be a wireless communications network providing extended coverage.

[0071] Some embodiments disclose modulation and demodulation methods for single carrier modulation wireless communications network operating in extended coverage mode. Thus, the wireless communications network 100 may be a wireless 10 communications network operating in extended coverage mode and applying single carrier modulation.

[0072] Some embodiments disclosed herein may be applied to any wireless communications network using single carrier linear or linearizable modulations, such as Gaussian Frequency-Shift Keying (GFSK), Gaussian Minimum Shift Keying (GMSK) or Offset Quadrature Phase-Shift Keying (OQPSK), employed in Bluetooth, DECT, GSM and Zigbee.

[0073] Further, it should be understood that some embodiments may be applied in new and emerging fields of wireless communications networks such as in light communications network. Thus, the wireless communications network 100 may be a light communications network.

[0074] A core network 102 may be comprised in the wireless communications network 100. The core network 102 is a wireless core network such as a NR core network, a 5G core network, GERAN core network, an LTE core network, e.g. an Evolved Packet Core (EPC); a WCDMA core network; a GSM core network; any 3GPP core network; WiMAX core network; or any wireless or cellular core network.

[0075] A core network node 104 may operate in the core network 102. The core network node 104 may be an Evolved Serving Mobile Location Centre (E-SMLC), a Mobile Switching Centre (MSC), a Mobility-Management Entity (MME), an Operation and

[0076] Maintenance (O&M) node, a Serving GateWay (S-GW), a Serving General Packet-Radio Service (GPRS) Node (SGSN), etc.

[0077] A first radio node 108-1, 108-2; 110 and a second radio node 110; 108-1, 108-2 are operating in the wireless communications network 100. In this disclosure the first radio node 108-1, 108-2; 110 is acting as a transmitter, e.g. as a transmitting node, and the second radio node 110; 108-1, 108-2 is acting as a receiver, e.g. as a receiving node. However, it should be understood that the second radio node may be the transmitter and that the first radio node may be the receiver. Thus, both the first and second radio nodes may be configured with functionality to act as both a transmitter and a receiver. In case the first radio node 108-1, 108-2; 110 is a base station, e.g. an eNB, 108-1 or a WLAN AP 108-2, the second radio node 110; 108-1, 108-2 is a wireless device 110, and vice versa.

[0078] The first radio node 108-1, 108-2 may serve the second radio node 110 when located within an area, e.g. a first serving area 108a-1, 108a-2. The first radio node 108-1, 108-2 may be a transmission and reception point e.g. a radio access network node such as a Wireless Local Area Network (WLAN) access point or an Access Point Station (AP STA), an access controller, a base station, e.g. a radio base station such as a NodeB, an evolved Node B (eNB, eNode B), a base transceiver station, a radio remote unit, an Access Point Base Station, a base station router, a transmission arrangement of a radio base station, a stand-alone access point or any other network unit capable of communicating with a wireless device within the service area served by the access point depending e.g. on the first radio access technology and terminology used. The first radio node 108 may be referred to as a serving radio network node and communicates with a wireless device with Downlink (DL) transmissions to the wireless device and Uplink (UL) transmissions from the wireless device. Other examples of the first radio node 108 are Multi-Standard Radio (MSR) nodes such as MSR BS, network controllers, Radio Network Controllers (RNCs), Base Station Controllers (BSCs), relays, donor nodes controlling relay, Base Transceiver Stations (BTSs), Access Points (APs), transmission points, ransmission nodes, Remote Radio Units (RRUs), Remote Radio Heads (RRHs), nodes in Distributed Antenna System (DAS), etc. In case of Device-to-Device communication, the first radio node may be a wireless device.

[0079] The second radio node 110 may be a wireless device, such as a mobile station, a non-Access Point (non-AP) STA, a STA, a user equipment (UE) and/or a wireless terminals, communicate via one or more Access Networks (AN), e.g. RAN, to one or more Core Networks (CN).

[0080] It should be understood by the skilled in the art that wireless device is a non-limiting term which means any terminal, communications device, wireless communication terminal, user equipment, Machine-Type Communication (MTC) device, Device-to-Device (D2D) terminal, or node e.g. smart phone, laptop, mobile phone, sensor, relay, mobile tablets, an Internet-of-Things (IoT) device, e.g. a Cellular IoT (CIoT) device or even a small base station communicating within a service area.

[0081] In this disclosure the terms communications device, terminal, wireless device and UE are used interchangeably. Please note the term user equipment used in this document also covers other wireless devices such as Machine-to-Machine (M2M) devices, even though they do not have any user.

[0082] Methods e.g. for transmitting a signal comprising encoded data symbols in the 10 wireless communications network 100, is performed by the first radio node 108-1, 108-2; 110. Further, methods e.g. for decoding and extracting data symbols from a signal received from the first radio node 108-1, 108-2; 110 is performed by the second radio node 110;108-1, 108-2. As an alternative, a Distributed Node (DN) and functionality, e.g. comprised in a cloud 106 as shown in FIG. 1 may be used for performing or partly performing the methods.

[0083] Examples of methods performed by the first radio node 108-1, 108-2; 110 for transmitting a signal comprising encoded data symbols to the second radio node 110; 108-1, 108-2 will now be described with reference to flowchart depicted in FIG. 2. As 20 previously mentioned, the first radio node 108-1, 108-2; 110 and the second radio node 110; 108-1, 108-2 are operating in the wireless communications network 100. Thus, the first radio node 108-1, 108-2; 110 is acting as a transmitter and the second radio node 110; 108-1, 108-2 is acting as a receiver. However, it should be understood that the second radio node may be the transmitter and that the first radio node may be the 25 receiver. In case the first radio node is a base station e.g. an eNB, 108-1 or a WLAN AP 108-2, the second radio node is a wireless device 110, and vice versa.

[0084] Action 201 The first radio node 108-1, 108-2; 110 repeats n times a sequence of data symbols So,S1, . . . ,Sk1 to be transmitted, wherein k is a multiple of n. The repetition is done in order to obtain extended coverage by transmitting the sequence of data symbols So,S1, . . . ,Sk1 several times, i.e. n times. k should be a multiple of n in order to ensure that the inter-symbol interference from the cyclic prefix is orthogonal to the transmitted sequence of data.

[0085] The data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1 may be data symbols from a symbol constellation of a linear modulation or a non-linear modulation.

[0086] The linear modulation may be a Phase-Shift Keying (PSK), such as Binary PSK (BPSK), Quadrature PSK (QPSK) or 8 PSK, or a Quadrature Amplitude Modulation (QAM) such as 16 QAM, 32 QAM, or 64 QAM, just to give some examples.

[0087] The non-linear modulation may be one out of a Gaussian Minimum Shift Keying (GMSK), a Gaussian Frequency-Shift Keying (GFSK), and a Minimum-Shift Keying (MSK), just to give some examples.

[0088] In some embodiments, one or more of the data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1 are 10 training symbols. For example, this may be the case when a phase/amplitude reference is needed, relative to which the information bearing data symbols are interpreted (demodulated), and thereby coherent demodulation is achieved.

[0089] Embodiments described herein may be realized using matrices. In such embodiments, the first radio node 108-1, 108-2; 110, when repeating n times the sequence of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1, generates an n by k matrix, wherein each row is a copy of a sequence of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1, wherein n is the number of repetitions of the sequence of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1.

[0090] FIG. 6 schematically illustrates a vector with data symbols S.sub.0,S.sub.1, . . . ,S.sub.7, to be transmitted and a code matrix. FIG. 6 will be described in more detail below.

[0091] FIG. 7 is a matrix schematically illustrating n=4 times repeated data symbols S.sub.0,S.sub.1, . . . ,S.sub.7. FIG. 7 will be described in more detail below.

Action 202

[0092] The first radio node 108-1, 108-2; 110 encodes the n sequences of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1 using n orthogonal code sequences, wherein each code sequence comprises n code elements.

[0093] In some embodiments, the first radio node 108-1, 108-2; 110 encodes the n sequences of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1 by element-wise multiplying one code sequence out of the n orthogonal code sequences to the n times repeated data symbol S.sub.i comprised in the n sequences of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1, wherein i [0,1, k-1].

[0094] In some embodiments, the first radio node 108-1, 108-2; 110 encodes the n sequences of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1 by repeatedly using the n orthogonal code sequences for the encoding of the n sequences of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1, wherein the n orthogonal code sequences are used k/n times each for encoding (each) n times repeated symbol S.sub.i comprised in the n sequences of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1, wherein i [0,1, . . . , k1].

[0095] The n orthogonal code sequences may comprise real values. In some embodiments, the n orthogonal code sequences are comprised in an n by n Hadamard matrix. Alternatively, the n orthogonal code sequences comprise complex values.

[0096] In embodiments realized using the matrices, the the first radio node 108-1, 108-2; 110 encodes then sequences of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1 using n orthogonal code words by encoding the generated n by k matrix by performing element-wise matrix multiplication using a k/n times repeated n by n orthogonal code matrix comprising the n orthogonal code sequences, wherein the encoding results in an encoded n by k matrix.

[0097] FIG. 8 is a matrix schematically illustrating encoded data symbols. In this example, the data symbols have been encoded using the code matrix of FIG. 6. FIG. 8 will be described in more detail below.

Action 203

[0098] The first radio node 108-1, 108-2; 110 may provide the respective affix before the first data symbol So of each encoded sequence of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1.

[0099] In some embodiments, the first radio node 108-1, 108-2; 110 provides the respective affix by inserting a respective cyclic prefix before the first data symbol So of each encoded sequence of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1, wherein the respective cyclic prefix comprises one or more of the last n1 data symbols of the respective encoded sequence of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1.

[0100] In some alternative embodiments, the first radio node 108-1, 108-2; 110 provides the respective affix by providing a respective guard time period before the first data symbol So of each encoded sequence of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1.

[0101] In embodiments realized using the matrices, the the first radio node 108-1, 108-2; 110 provides the respective affix by inserting a cyclic prefix before the encoded n by k matrix, which cyclic prefix comprises one or more of the last n1 columns of the encoded n by k matrix, wherein the inserting results in an n by (x+k) matrix, wherein x is the number of columns of the inserted cyclic prefix. Alternatively, the the first radio node 108-1, 108-2; 110 provides the respective affix by providing a respective guard time period before the first data symbol So of each encoded sequence of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1.

[0102] FIG. 9 is a matrix schematically illustrating a cyclic prefix added to the encoded data symbols. In this example, the cyclic prefix corresponds to the last n1 (n=4)=3 columns of the matrix shown in FIG. 8. FIG. 9 will be described in more detail below.

Action 204

[0103] The first radio node 108-1, 108-2; 110 transmits, to the second radio node 110; 108-1, 108-2, a signal comprising the respective encoded sequence of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1 and an optional respective affix for separating two encoded sequences of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1.

[0104] In some alternative embodiments, the first radio node 108-1, 108-2; 110 transmits the respective affix and the respective encoded sequence of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1in sequence using a single carrier. Alternatively, the first radio node 108-1, 108-2; 110 transmits the respective affix and the respective encoded sequence of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1 in parallel using a respective subcarrier in a multicarrier signal.

[0105] The first radio node 108-1, 108-2; 110 transmits the respective sequence of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1 by further performing one or more out of: pulse shaping; digital to analog conversion; up-conversion to radio frequency; and power amplification.

[0106] In embodiments realized using the matrices, the the first radio node 108-1, 108-2; 110 transmits the respective affix and the respective sequence of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1 by transmitting row wise the respective affix and the data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1 comprised in the n by (x+k) matrix.

[0107] FIG. 10 is a vector schematically illustrating an example of a transmitted symbol sequence. The underlined symbols correspond to symbols of the cyclic prefix. FIG. 10 will be described in more detail below.

[0108] To perform the method for transmitting a signal comprising encoded data symbols to the second radio node 110; 108-1, 108-2, the first radio node 108-1, 108-2; 30 110 may comprise an arrangement depicted in FIG. 3. As previously mentioned, the first radio node 108-1, 108-2; 110 and the second radio node 110; 108-1, 108-2 are configured to operate in the wireless communications network 100. Thus, the first radio node 108-1, 108-2; 110 is acting as a transmitter and the second radio node 110;108-1, 108-2 is acting as a receiver. However, it should be understood that the second radio node may be the transmitter and that the first radio node may be the receiver. In case the first radio node is a base station e.g. an eNB, 108-1 or a WLAN AP 108-2, the second radio node is a wireless device 110, and vice versa.

[0109] In some embodiments, the first radio node 108-1, 108-2; 110 via an input and output interface 300 is configured to communicate with one or more second radio node 110; 108-1, 108-2. The input and output interface 300 may comprise a wireless receiver (not shown) and a wireless transmitter (not shown).

[0110] The first radio node 108-1, 108-2; 110 is configured to receive, e.g. by means of a receiving module 301 configured to receive, transmissions from one or more second radio nodes 110; 108-1, 108-2. The receiving module 301 may be implemented by or arranged in communication with a processor 307 of the first radio node 108-1, 108-2; 110. The processor 307 will be described in more detail below.

[0111] The first radio node 108-1, 108-2; 110 is configured to transmit, e.g. by means of a transmitting module 302 configured to transmit, transmit, to the second radio node 110; 108-1, 108-2, a signal comprising a respective encoded sequence of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1 and an optional respective affix for separating two encoded sequences of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1. The transmitting module 302 may be implemented by or arranged in communication with the processor 307 of the first radio node 108-1, 108-2; 110.

[0112] As previously mentioned, the data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1 may be data symbols from a symbol constellation of a linear modulation or a non-linear modulation.

[0113] The linear modulation may be a PSK, such as BPSK, PSK, a QPSK or an 8PSK, or a QAM such as 16 QAM, 32 QAM, or 64 QAM, just to give some examples.

[0114] The non-linear modulation may be one out of a GMSK, a GFSK, and a MSK, just to give some examples.

[0115] In some embodiments, one or more of the data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1 are training symbols.

[0116] In some embodiments, the first radio node 108-1, 108-2; 110 is configured to transmit the signal comprising the respective affix and the respective encoded sequence of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1 by further being configured to transmit the respective affix and the respective encoded sequence of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1 in sequence using a single carrier; or to transmit the respective affix and the respective encoded sequence of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1 in parallel using a respective subcarrier in a multicarrier signal. The first radio node 108-1, 108-2; 110 may further be configured to transmit to the respective sequence of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1 by further being configured to perform one or more out of: pulse shaping; digital to analog conversion; up-conversion to radio frequency; and power amplification.

[0117] In embodiments realized using the matrices, the first radio node 108-1, 108-2; 110 is configured to transmit the respective affix and the respective sequence of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1 by being configured to transmit row wise the respective affix and the data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1 comprised in the n by (x+k) matrix.

[0118] The first radio node 108-1, 108-2; 110 is configured to repeat, e.g. by means of a repeating module 303 configured to repeat, n times a sequence of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1 to be transmitted, wherein k is a multiple of n. The repeating module 303 may be implemented by or arranged in communication with the processor 307 of the first radio node 108-1, 108-2; 110.

[0119] In embodiments realized using the matrices, the first radio node 108-1, 108-2; 20 110 is configured to repeat n times of the sequence of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1 by being configured to generate an n by k matrix, wherein each row is a copy of a sequence of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1, wherein n is the number of repetitions of the sequence of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1.

[0120] The first radio node 108-1, 108-2; 110 is configured to encode, e.g. by means of an encoding module 304 configured to encode, the n sequences of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1 using n orthogonal code sequences, wherein each code sequence comprises n code elements. The encoding module 304 may be implemented by or arranged in communication with the processor 507 of the first radio node 108-1, 108-2; 30 110.

[0121] In some embodiments, the first radio node 108-1, 108-2; 110 is configured to encode the n sequences of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1 by further being configured to element-wise multiply one code sequence out of the n orthogonal code sequences to the n times repeated data symbol S.sub.i comprised in the n sequences of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1, wherein i [0,1, . . . , k-1].

[0122] In some embodiments, the first radio node 108-1, 108-2; 110 is configured to encode the n sequences of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1 by further being configured to repeatedly use the n orthogonal code sequences for the encoding of the n sequences of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1, wherein the n orthogonal code sequences are used k/n times each for encoding (each) n times repeated symbol S.sub.i comprised in the n sequences of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1, wherein i [0,1, . . . , k1].

[0123] As previously mentioned, the n orthogonal code sequences may comprise real values. In some embodiments, the n orthogonal code sequences are comprised in an n by n Hadamard matrix. Alternatively, the n orthogonal code sequences comprise complex values.

[0124] In embodiments realized using the matrices, the first radio node 108-1, 108-2; 110 is configured to encode then sequences of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1 using n orthogonal code words by encoding the generated n by k matrix by performing element-wise matrix multiplication using a k/n times repeated n by n orthogonal code matrix comprising the n orthogonal code sequences, wherein the encoding results in an encoded n by k matrix.

[0125] The first radio node 108-1, 108-2; 110 may be configured to provide, e.g. by means of a providing module 305 configured to provide, the respective affix before the first data symbol So of each encoded sequence of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1. The providing module 305 may be implemented by or arranged in communication with the processor 507 of the first radio node 108-1, 108-2; 110.

[0126] In some embodiments, the first radio node 108-1, 108-2; 110 is configured to provide the respective affix by further being configured to insert a respective cyclic prefix before the first data symbol So of each encoded sequence of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1, wherein the respective cyclic prefix comprises one or more of the last n1 data symbols of the respective encoded sequence of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1.

[0127] In some alternative embodiments, the first radio node 108-1, 108-2; 110 is configured to provide the respective affix by further being configured to provide a respective guard time period before the first data symbol So of each encoded sequence of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1.

[0128] In embodiments realized using the matrices, the first radio node 108-1, 108-2; 110 is configured to provide the respective affix by being configured to insert a cyclic prefix before the encoded n by k matrix, which cyclic prefix comprises one or more of the last n1 columns of the encoded n by k matrix, wherein the inserting results in an n by (x+k) matrix, wherein x is the number of columns of the inserted cyclic prefix. Alternatively, the first radio node 108-1, 108-2; 110 may be configured to provide the respective affix by being configured to provide a respective guard time period before the first data symbol So of each encoded sequence of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1.

[0129] The first radio node 108-1, 108-2; 110 may also comprise means for storing data. In some embodiments, the first radio node 108-1, 108-2; 110 comprises a memory 306 configured to store the data. The data may be processed or non-processed data and/or information relating thereto. The memory 306 may comprise one or more memory units.

[0130] Further, the memory 306 may be a computer data storage or a semiconductor memory such as a computer memory, a read-only memory, a volatile memory or a non-volatile memory. The memory is arranged to be used to store obtained information, data, configurations, scheduling decisions, and applications, etc. to perform the methods herein when being executed in the first radio node 108-1, 108-2; 110.

[0131] Embodiments herein for transmitting a signal comprising encoded data symbols to the second radio node 110; 108-1, 108-2 may be implemented through one or more processors, such as the processor 307 in the arrangement depicted in FIG. 3, together with computer program code for performing the functions and/or method actions of embodiments herein. The program code mentioned above may also be provided as a computer program product, for instance in the form of a data carrier carrying computer program code for performing the embodiments herein when being loaded into the first radio node 108-1, 108-2; 110. One such carrier may be in the form of an electronic signal, an optical signal, a radio signal or a computer-readable storage medium. The computer-readable storage medium may be a CD ROM disc or a memory stick.

[0132] The computer program code may furthermore be provided as program code stored on a server and downloaded to the first radio node 108-1, 108-2; 110.

[0133] Those skilled in the art will also appreciate that the input/output interface 300, the receiving module 301, the transmitting module 302, the repeating module 303, and the encoding module 304, and the providing module 305 above may refer to a combination of analog and digital circuits, and/or one or more processors configured with software and/or firmware, e.g. stored in the memory 306, that when executed by the one or more processors such as the processors in the first radio node 108-1, 108-2; 110 perform as described above. One or more of these processors, as well as the other digital hardware, may be included in a single Application-Specific Integrated Circuitry (ASIC), or several processors and various digital hardware may be distributed among several separate components, whether individually packaged or assembled into a System-on-a-Chip (SoC).

[0134] Examples of methods performed by the second radio node 110; 108-1, 108-2 for decoding and extracting data symbols from a signal received from the first radio node 108-1, 108-2; 110 will now be described with reference to flowchart depicted in FIG. 4. As previously mentioned, the first radio node 108-1, 108-2; 110 and the second radio node 110; 108-1, 108-2 are operating in the wireless communications network 100. Thus, the first radio node 108-1, 108-2; 110 is acting as a transmitter and the second radio node 110; 108-1, 108-2 is acting as a receiver. However, it should be understood that the second radio node may be the transmitter and that the first radio node may be the receiver. In case the first radio node is a base station e.g. an eNB, 108-1 or a WLAN AP 108-2, the second radio node is a wireless device 110, and vice versa.

[0135] The methods comprise one or more of the following actions. Thus one or more of the actions may be optional. It should be understood that the actions may be taken in any suitable order and that some actions may be combined.

Action 401

[0136] The second radio node 110; 108-1, 108-2 receives a signal from the first radio node 108-1, 108-2; 110. The signal may be a weighted sum of delayed versions of a signal transmitted from the first radio node 108-1, 108-2; 110.

[0137] On the received signal, the second radio node 110; 108-1, 108-2 may perform signal processing such as one or more out of: analog filtering, down-conversion to baseband, analog to digital conversion, and digital filtering.

[0138] FIG. 11 schematically illustrates an example of a received signal comprising delayed versions of the transmitted symbol sequence. FIG. 11 will be described in more detail below.

Action 402

[0139] The second radio node 110; 108-1, 108-2 removes a possible affix from the received signal resulting in n sequences of k received samples. As previously mentioned, the affix is optional and thus the received signal may not comprise an affix and consequently the second radio node 110; 108-1, 108-2 does not have to remove an affix. If the received signal comprises an affix, the affix is used to separate the sequences of received samples and is not part of the sequences of received samples that should be decoded, and therefore the affix should be removed.

[0140] Each received sample is a weighted sum of several data symbols due to ISI plus possible noise and interference.

[0141] FIG. 12 schematically illustrates an example of the received samples after removal of a cyclic prefix. FIG. 12 will be described in more detail below.

Action 403

[0142] The second radio node 110; 108-1, 108-2 stacks the n sequences of k received samples. The reason for stacking the n sequences of k received samples is to align received samples corresponding to the same transmitted symbols, thereby simplifying subsequent processing performed per symbol position (the subsequent adding which will be described in Action 404 below).

[0143] As previously mentioned, embodiments described herein may be realized using matrices. In such embodiments, the second radio node 110; 108-1, 108-2 stacks the n sequences of k received samples by stacking the n sequences of k received samples into a first n by k matrix.

[0144] FIG. 13 is a matrix schematically illustrating an example of the stacked received samples. FIG. 13 will be described in more detail below.

Action 404

[0145] The second radio node 110; 108-1, 108-2 decodes the stacked n sequences of k received samples using n orthogonal code sequences, wherein each code sequence comprises n code elements. Further, for each code sequence each of the n sequences of k received samples is multiplied to one out of the n code elements of the code sequence and the multiplied sequences of received samples are subsequently added. Thereby, the decoding results in n different decoded sequences of samples of length k, wherein each decoded sequence of samples corresponds to one of the n applied code sequences.

[0146] In embodiments realized using the matrices, the second radio node 110; 108-1, 108-2 decodes the stacked sequences of k received samples using n orthogonal code sequences by decoding the first n by k matrix using an n by n orthogonal code matrix comprising the n orthogonal code sequences, wherein each code sequence comprises n code elements. The decoding results in a second n by k matrix. FIGS. 14A-14D shows matrices and vectors schematically illustrating the result after decoding with a first code word, a second code word, a third code word and a fourth code word, respectively. FIGS. 14A-14D will be described in more detail below.

Action 405

[0147] In some embodiments, the second radio node 110; 108-1, 108-2 reorders the n different decoded sequences of samples and possibly moving elements between the n different decoded sequences of samples to obtain n different decoded and reordered sequences of samples.

[0148] FIG. 15 shows matrices and vectors schematically illustrating the result after sorting of the decoded sequences. FIG. 15 will be described in more detail below.

[0149] Action 406 The second radio node 110; 108-1, 108-2 extracts a sequence of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1 from the n different decoded sequences of samples. The extracted sequence of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1 are the same sequence of data symbols as the one that was to be transmitted by the first radio node 108-1, 108-2; 110 in Action 201 above. Thus, the signal received by the second radio node 110; 108-1, 108-2 has been successfully decoded and the correct sequence of data symbols extracted.

[0150] In embodiments realized using the matrices, the second radio node 110; 108-1, 108-2 extracts the sequence of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1 from the n different decoded sequences of samples by extracting the sequence of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1 from the second n by k matrix.

Action 407

[0151] In some embodiments, the second radio node 110; 108-1, 108-2 estimates n channel coefficients h.sub.0, h.sub.1, . . . h.sub.n1, wherein each one of then different decoded sequences of samples corresponds to the sequence of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1 multiplied by a respective channel coefficient.

[0152] Each channel coefficient is a complex number corresponding to an amplification and a phase shift for one of the delayed versions of the transmitted symbol sequence (as illustrated in FIG. 11). The channel coefficients may be estimated if one or a few of the data symbols are training symbols. The use of training symbols and their positions would typically be a predetermined part of the used transmission scheme. The alternative to using training symbols would be to use a differential modulation. Differential modulation means that the relative phase (and possibly amplitude) changes between consecutive transmitted symbols is determined by the information bits to be communicated, thereby making an absolute phase/amplitude reference unnecessary.

Action 408

[0153] In some embodiments, the second radio node 110; 108-1, 108-2 combines the n different decoded sequences of samples by performing a Maximum Ratio Combination, MRC, whereby the signal to noise ratio is increased. By the term signal when used here is meant the n reordered sequences, i.e. the rows of the matrix in the middle part of FIG. 15. Thus, by performing a MRC the ratio between the signal strength of the n reordered sequences and noise is increased.

[0154] FIG. 16 schematically illustrates Maximum Ratio Combining. FIG. 16 will be described in more detail below.

[0155] Actions 407 and 408 described above may in some embodiments be seen as one possible way of performing Action 406 previously described. Thus, the extracting of the sequence of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1 from the n different decoded sequences of samples may be performed by MRC combining the rows of the matrix. However, it should be understood that other possible ways may exist, such as just selecting one row and extracting the symbols from that row (estimating only the channel coefficient corresponding to that row).

[0156] To perform the method for decoding and extracting data symbols from a received signal, the second radio node 110; 108-1, 108-2 may comprise an arrangement depicted in FIG. 5. As previously mentioned, the first radio node 108-1, 108-2; 110 and the second radio node 110; 108-1, 108-2 are configured to operate in the wireless communications network 100. Thus, the first radio node 108-1, 108-2; 110 is acting as a transmitter and the second radio node 110; 108-1, 108-2 is acting as a receiver. However, it should be understood that the second radio node may be the transmitter and that the first radio node may be the receiver. In case the first radio node is a base station e.g. an eNB, 108-1 or a WLAN AP 108-2, the second radio node is a wireless device 110, and vice versa.

[0157] In some embodiments, the second radio node 110; 108-1, 108-2 via an input and output interface 500 is configured to communicate with one or more first radio nodes 108-1, 108-2; 110. The input and output interface 500 may comprise a wireless receiver (not shown) and a wireless transmitter (not shown).

[0158] The second radio node 110; 108-1, 108-2 is configured to receive, e.g. by means of a receiving module 501 configured to receive, transmissions from the first radio node 108-1, 108-2; 110. The receiving module 501 may be implemented by or arranged in communication with a processor 511 of the second radio node 110; 108-1, 108-2. The processor 511 will be described in more detail below.

[0159] The second radio node 110; 108-1, 108-2 is configured to receive a signal from the first radio node 108-1, 108-2; 110. As previously mentioned, the signal may be a weighted sum of delayed versions of a signal transmitted from the first radio node 108-1,108-2; 110.

[0160] The second radio node 110; 108-1, 108-2 may be configured to receive the signal by further being configured to perform signal processing such as one or more out of analog filtering, down-conversion to baseband, analog to digital conversion, and digital filtering.

[0161] The second radio node 110; 108-1, 108-2 is configured to transmit, e.g. by means of a transmitting module 502 configured to transmit, a transmission to the first radio node 108-1, 108-2; 110. The transmitting module 502 may be implemented by or arranged in communication with the processor 511 of the second radio node 110; 108-1, 108-2.

[0162] The second radio node 110; 108-1, 108-2 is configured to remove, e.g. by means of a removing module 503 configured to remove, a possible affix from the received signal resulting in n sequences of k received samples. The removing module 503 may be implemented by or arranged in communication with the processor 511 of the second radio node 110; 108-1, 108-2.

[0163] As previously mentioned, each received sample is a weighted sum of several data symbols (due to ISI) plus possible noise and interference.

[0164] The second radio node 110; 108-1, 108-2 is configured to stack, e.g. by means of a stacking module 504 configured to stack, the n sequences of k received samples;. The stacking module 504 may be implemented by or arranged in communication with the processor 511 of the second radio node 110; 108-1, 108-2.

[0165] Embodiments described herein may be realized using matrices. In such embodiments, the second radio node 110; 108-1, 108-2 is configured to to stack the n sequences of k received samples by being configured to stack the n sequences of k received samples into a first n by k matrix.

[0166] The second radio node 110; 108-1, 108-2 is configured to decode, e.g. by means of a decoding module 505 configured to decode, sequences of received samples. The decoding module 505 may be implemented by or arranged in communication with the processor 511 of the second radio node 110; 108-1, 108-2.

[0167] The second radio node 110; 108-1, 108-2 is configured to decode the stacked n sequences of k received samples using n orthogonal code sequences, wherein each code sequence comprises n code elements. Further, for each code sequence each of the n sequences of k received samples is multiplied to one out of the n code elements of the code sequence. The multiplied sequences of received samples are subsequently added, and the decoding results in n different decoded sequences of samples of length k each decoded sample corresponding to one of the n applied code sequences.

[0168] In embodiments realized using the matrices, the second radio node 110; 108-1, 108-2 is configured to decode the stacked sequences of k received samples using n orthogonal code sequences by being configured to decode the first n by k matrix using an n by n orthogonal code matrix comprising the n orthogonal code sequences, wherein each code sequence comprises n code elements. The decoding results in a second n by k matrix.

[0169] The second radio node 110; 108-1, 108-2 may be configured to reorder, e.g. by means of a reordering module 506 configured to reorder, decoded sequences of samples. The reordering module 506 may be implemented by or arranged in communication with the processor 511 of the second radio node 110; 108-1, 108-2.

[0170] The second radio node 110; 108-1, 108-2 may be configured to reorder the n different decoded sequences of samples and possibly moving elements between the n different decoded sequences of samples to obtain n different decoded and reordered sequences of samples.

[0171] The second radio node 110; 108-1, 108-2 is configured to extract, e.g. by means of an extracting module 507 configured to extract, a sequence of data symbols. The extracting module 507 may be implemented by or arranged in communication with the processor 511 of the second radio node 110; 108-1, 108-2.

[0172] The second radio node 110; 108-1, 108-2 is configured to extract a sequence of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1 from the n different decoded sequences of samples.

[0173] In embodiments realized using the matrices, the second radio node 110; 108-1, 108-2 is configured to extract the sequence of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1 from the n different decoded sequences of samples by being configured to extract the sequence of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1 from the second n by k matrix.

[0174] The second radio node 110; 108-1, 108-2 may be configured to estimate, e.g. by means of an estimating module 508 configured to estimate, one or more channel coefficients. The estimating module 508 may be implemented by or arranged in communication with the processor 511 of the second radio node 110; 108-1, 108-2.

[0175] The second radio node 110; 108-1, 108-2 may be configured to estimate n channel coefficients , wherein each one of then different decoded sequences of samples corresponds to the sequence of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1 multiplied by a respective channel coefficient.

[0176] As previously mentioned, each channel coefficient is a complex number corresponding to an amplification and a phase shift for one of the delayed versions of the transmitted symbol sequence (as illustrated in FIG. 11). The channel coefficients may be estimated if one or a few of the data symbols are training symbols. The use of training symbols and their positions would typically be a predetermined part of the used transmission scheme. As mentioned above, an alternative to using training symbols would be to use a differential modulation.

[0177] The second radio node 110; 108-1, 108-2 may be configured to combine, e.g. by means of a combining module 509 configured to combine, decoded sequences of samples. The combining module 509 may be implemented by or arranged in communication with the processor 511 of the second radio node 110; 108-1, 108-2.

[0178] The second radio node 110; 108-1, 108-2 may be configured to combine the n different decoded sequences of samples by performing a Maximum Ratio Combination, MRC, whereby the signal to noise ratio is increased.

[0179] The second radio node 110; 108-1, 108-2 may also comprise means for storing data. In some embodiments, the second radio node 110; 108-1, 108-2 comprises a memory 510 configured to store the data. The data may be processed or non-processed data and/or information relating thereto. The memory 510 may comprise one or more memory units. Further, the memory 510 may be a computer data storage or a semiconductor memory such as a computer memory, a read-only memory, a volatile memory or a non-volatile memory. The memory is arranged to be used to store obtained information, data, configurations, scheduling decisions, and applications, etc. to perform the methods herein when being executed in the second radio node 110; 108-1, 108-2.

[0180] Embodiments herein for decoding and extracting data symbols from a received signal may be implemented through one or more processors, such as the processor 511 in the arrangement depicted in FIG. 5, together with computer program code for performing the functions and/or method actions of embodiments herein. The program code mentioned above may also be provided as a computer program product, for instance in the form of a data carrier carrying computer program code for performing the embodiments herein when being loaded into the second radio node 110; 108-1, 108-2. One such carrier may be in the form of an electronic signal, an optical signal, a radio signal or a computer-readable storage medium. The computer-readable storage medium may be a CD ROM disc or a memory stick.

[0181] The computer program code may furthermore be provided as program code stored on a server and downloaded to the second radio node 110; 108-1, 108-2.

[0182] Those skilled in the art will also appreciate that the input/output interface 500, the receiving module 501, the transmitting module 502, the removing module 503, the stacking module 504, the decoding module 505, the reordering module 506, the extracting module 507, the estimating module 508, and the combining module 509 above may refer to a combination of analog and digital circuits, and/or one or more processors configured with software and/or firmware, e.g. stored in the memory 510, that when executed by the one or more processors such as the processors in the second radio node 110; 108-1, 108-2 perform as described above. One or more of these processors, as well as the other digital hardware, may be included in a single Application-Specific Integrated Circuitry (ASIC), or several processors and various digital hardware may be distributed among several separate components, whether individually packaged or assembled into a System-on-a-Chip (SoC).

EXAMPLIFYING EMBODIMENT

[0183] In this section a step-by-step description of one embodiment of the coded repetition scheme is described and illustrated.

Introduction

[0184] A sequence of data symbols to be transmitted is illustrated in FIG. 6. Also, a code matrix is given in FIG. 6. In FIG. 6 the grey shades are used to illustrate the four code words, e.g. rows, of the code matrix. In the example, the code matrix is a 44 Hadamard matrix, but any n by n orthogonal real- or complex valued code may be used.

[0185] The size n of the code matrix shall be equal to the number of coded repetitions to be transmitted. The code words (rows) of the code matrix have been given different grey shades for illustrative purposes The number of data symbols is arbitrarily chosen to be k=8 but may be any multiple of n. The data symbols may be taken from the symbol constellation of any linear modulation. Non-linear modulations such as GFSK and GMSK may also be used but the description below assumes a linear modulation for simplicity. Non-linear modulations will be discussed in more detail below. Some of the data symbols may be training symbols.

[0186] One or more actions relating to repetition, encoding, cyclic prefix, and transmission mentioned below are performed by the first radio node 108-1, 108-2; 110 acting as a transmitter.

Repetition The data symbols are repeated n=4 times. This is illustrated as four rows in the matrix of FIG. 7.

[0187] This relates to Action 201 previously described.

Encoding

[0188] The Hadamard code matrix of FIG. 6 is applied symbol-wise, repeatedly. Each column, i.e. repeated symbol, in the matrix is multiplied (element-wise) by a code word, e.g. a row, of the code matrix. The grey shades in FIG. 8 schematically illustrate the code words used for each column.

[0189] This relates to Action 202 previously described.

[0190] Cyclic prefix

[0191] As previously mentioned an optional affix may be added to separate two encoded sequences of data symbols S.sub.0,S.sub.1, . . . ,S.sub.k1. In this example, a cyclic prefix is added. The last n1 columns of the matrix in FIG. 8 are added before the matrix, as schematically illustrated in FIG. 9. Since n=4 in this example, the three last columns of the matrix in FIG. 9 is added.

[0192] This relates to Action 203 previously described.

Transmission

[0193] The symbols are transmitted sequentially, row by row in the matrix, as schematically illustrated in FIG. 10. The transmission may involve pulse shaping and one or more other regular transmitter functions.

[0194] This relates to Action 204 previously described.

[0195] One or more actions relating to reception, encoding, cyclic prefix removal, stacking, decoding, sorting and MRC mentioned below are performed by the second radio node 110; 108-1, 108-2 acting as a receiver.

Reception

[0196] As previously mentioned, due to inter-symbol interference in filters, e.g. in the transmitter filter and/or in the receiver filter, and due to inter-symbol interference in the channel, the received signal will be a weighted sum of delayed versions of the signal, as schematically illustrated in FIG. 11. The weights are the complex valued channel taps h.sub.i. Here it is assumed that the total channel length is n. In addition, there will be noise added (not illustrated).

[0197] This relates to Action 501 previously described.

Cyclic Prefix Removal

[0198] The cyclic prefix is removed and n sequences of received samples are extracted.

[0199] The blocks in the lower end of FIG. 12 schematically illustrate n=4 sequences of k=8 samples each. As mentioned above, each sample is a sum of delayed versions of the signal due to ISI.

[0200] This relates to Action 502 previously described.

Stacking

[0201] The n sequences of k received samples are stacked into a matrix. This is schematically illustrated in FIG. 13, which figure illustrates a 48 matrix.

[0202] This relates to Action 503 previously described.

Decoding

[0203] The code words are applied row-wise and the rows are added. FIG. 14A schematically illustrates the result when the first code word +1,+1,+1,+1 has been applied. The rows are multiplied by +1, +1, +1, +1, respectively, and added. The sum is shown in the lower part of FIG. 14A. Only symbols originally coded with the first code word are present while others have been cancelled. Note that the ISI is removed or rather resolved, since each ISI tap of the channel is represented by a different sample.

[0204] Similarly, the second, third and fourth code words are applied to extract the remaining data symbols, as illustrated in FIGS. 14B-14D.

[0205] This relates to Action 504 previously described.

Sorting

[0206] The n=4 different decoded sequences illustrated on the upper part in FIG. 15 are sorted into a matrix as shown in the middle part of FIG. 14. The n=4 times repeated signal transmitted over a channel with ISI of four symbols has been transformed into n=4 ISI-free signals as schematically illustrated in the lower part of FIG. 15, each with n=4 times processing gain.

[0207] This relates to Action 505 previously described.

Extracting

[0208] The data symbols S.sub.0,S.sub.1, . . . ,S.sub.7 is extracted from the ISI-free signal schematically illustrated in the lower part of FIG. 15.

[0209] This relates to Action 506 previously described.

Maximum Ratio Combining (MRC)

[0210] In presence of Additive White Gaussian Noise (AWGN), the SNR of the combined signal is maximized if the n signals are combined using the MRC. This means that the signals should be coherently combined after each have been scaled with the square root of the SNR of the individual signal. Since the noise energy is the same in all n signals, this is equivalent to multiplication by the conjugate of the channel coefficient h.sub.i of each signal. This is schematically illustrated in FIG. 16. Channel coefficients may be estimated if one or a few of the data symbols are training symbols. Since the ISI has been removed, the channel estimation is straightforward.

[0211] This relates to Actions 507 and 508 previously described.

Other Aspects

[0212] The scheme is applicable for any linear modulation, such as BPSK, 8 PSK, 16 QAM, etc. Since differentially encoded GMSK, GFSK, or MSK, may be approximately or exactly described as a linear modulation, the scheme may be applied to these modulations as well. Multiplications with the code (+1, 1) is then replaced by XORing of bits. It is straightforward to add Rx antenna diversity to the scheme. The Rx branches are processed separately in the receiver and combined using MRC. The MRC between Rx branches is done in the same way as the MRC between diversity branches created by the coded repetition scheme. Coded repetition may be combined with conventional blind transmissions and I/Q combining.

Exemplifying Formal Description of Some Embodiments

[0213] Below, the following notation is used:

[0214] a.sup.T denotes the transpose of vector (or matrix) a.

[0215] a.sup.H denotes the conjugate transpose of vector (or matrix) a.

[0216] a* denotes the (element-wise) conjugate of vector (or matrix) a.

Actions of the First Radio Node 108-1, 108-2; 110, e.g. the Transmitter

[0217] Given k data symbols =[s.sub.0 . . . s.sub.k1], and an nn code matrix

[00001]$C=\left[{\stackrel{.Math.}{c}}_0^T.Math..Math.\mathrm{.Math.}.Math..Math.{\stackrel{.Math.}{c}}_{n-1}^T\right]=\left[\begin{array}{ccc}{c}_{0,0}& \mathrm{.Math.}& c_{0,n-1}\\ \mathrm{.Math.}& & \mathrm{.Math.}\\ c_{n-1,0}& \mathrm{.Math.}& c_{n-1,n-1}\end{array}\right]$

with orthogonal columns, where k is an integer multiple of n, the transmitter performs the following steps:

[0218] Generate an nk matrix R in which each row is a copy of

[00002]$R=\left[\begin{array}{ccc}{r}_{0,0}& \mathrm{.Math.}& r_{0,k-1}\\ \mathrm{.Math.}& & \mathrm{.Math.}\\ r_{n-1,0}& \mathrm{.Math.}& r_{n-1,k-1}\end{array}\right]=\left[\begin{array}{ccc}{s}_0& \mathrm{.Math.}& s_{k-1}\\ \mathrm{.Math.}& \mathrm{.Math.}& \mathrm{.Math.}\\ s_0& \mathrm{.Math.}& s_{k-1}\end{array}\right]$

[0219] This relates to Action 201 previously described.

Encoding

[0220] Generate an nk matrix

[00003]$E=\left[\begin{array}{c}{\stackrel{.Math.}{e}}_0\\ \mathrm{.Math.}\\ {\stackrel{.Math.}{e}}_{n-1}\end{array}\right]=\left[\begin{array}{ccc}{e}_{0,0}& \mathrm{.Math.}& e_{0,k-1}\\ \mathrm{.Math.}& & \mathrm{.Math.}\\ e_{n-1,0}& \mathrm{.Math.}& e_{n-1,k-1}\end{array}\right]$

[0221] where e.sub.i,j=r.sub.i,jc.sub.i,j mod n, i.e., R is multiplied element-wise with a repeated version of the code matrix C. E can also be written as

[0222] E=

[[s.sub.0.sub.0.sup.T] . . . s.sub.n1.sub.n1.sup.T] [s.sub.n.sub.0.sup.T . . . s.sub.2n1.sub.n1.sup.T] . . . [s.sub.kn.sub.0.sup.T . . . [s.sub.k1.sub.n1.sup.T]].

[0223] This relates to Action 202 previously described.

[0224] Cyclic prefix: Generate an n(k+n1) matrix

[00004]$P=\left[\begin{array}{ccc}{e}_{0,k-n+1}& \mathrm{.Math.}& e_{0,k-1}\\ \mathrm{.Math.}& & \mathrm{.Math.}\\ e_{n-1,k-n+1}& \mathrm{.Math.}& e_{n-1,k-1}\end{array}\begin{array}{ccc}{e}_{0,0}& \mathrm{.Math.}& e_{0,k-1}\\ \mathrm{.Math.}& & \mathrm{.Math.}\\ e_{n-1,0}& \mathrm{.Math.}& e_{n-1,k-1}\end{array}\right]$

[0225] I.e., the n1 last columns of E are concatenated with E.

[0226] This relates to Action 203 previously described.

Transmission

[0227] Transmit the symbols of P row-wise, as a sequence of n(k+n1) symbols, using regular transmitter functions (pulse shaping, digital to analog conversion, up-conversion to radio frequency, power amplification, etc.)

[0228] This relates to Action 204 previously described.

Actions of the Second Radio Node 110; 108-1, 108-2, e.g. the Receiver

Reception

[0229] After regular receiver functions (analog filtering, down-conversion to baseband, analog to digital conversion, digital filtering, etc.), the received signal is represented by n(k+n)1 symbol-spaced complex samples =[v.sub.0 . . . v.sub.n(k+n)2]. Here it is assumed that the combined effect of filtering in the transmitter, time dispersion on the channel and filtering in the receiver can be expressed as =*+, where =[h.sub.0, . . . h.sub.n1] are the channel taps and n is a vector with noise samples.

[0230] This relates to Action 501 previously described.

[0231] Stacking (including removal of possible cyclic prefix)

[0232] Stack subsequences of into an nk matrix

[00005]$F=\left[\begin{array}{c}{\stackrel{.Math.}{f}}_0\\ \mathrm{.Math.}\\ {\stackrel{.Math.}{f}}_{n-1}\end{array}\right]=\left[\begin{array}{ccc}{f}_{0,0}& \mathrm{.Math.}& f_{0,k-1}\\ \mathrm{.Math.}& & \mathrm{.Math.}\\ f_{n-1,0}& \mathrm{.Math.}& f_{n-1,k-1}\end{array}\right]=\left[\begin{array}{ccc}{v}_{n-1}& \mathrm{.Math.}& v_{n+k-2}\\ v_{2.Math.\left(n-1\right)+k}& \mathrm{.Math.}& v_{2.Math.\left(n+k\right)-3}\\ \mathrm{.Math.}& & \mathrm{.Math.}\\ v_{n\left(n-1\right)+\left(n-1\right).Math.k}& \mathrm{.Math.}& v_{n\left(n+k\right)-n-1}\end{array}\right]$

[0233] I.e., n sequences of k samples are put in the rows of F, skipping the n1 first samples, the n1 last samples and n1 samples between every stored subsequence of . Note that due to the cyclic prefix, F=*E+N, where is the channel, E are the encoded symbols, N is a matrix of AWGN samples with variance .sup.2 and * denotes row-wise cyclic convolution.

[0234] This relates to Actions 502 and 503 previously described.

Decoding

[0235] Multiply F with the transpose of the code matrix C from left, giving the nk matrix

[00006]$D=C^T.Math.F=C^T\left(\stackrel{.Math.}{h}*E+N\right)=C^T\left(\stackrel{.Math.}{h}*\left[\left[s_0.Math.{\stackrel{.Math.}{c}}_0^T.Math..Math.\mathrm{.Math.}.Math..Math.s_{n-1}.Math.{\stackrel{.Math.}{c}}_{n-1}^T\right]\left[s_n.Math.{\stackrel{.Math.}{c}}_0^T.Math..Math.\mathrm{.Math.}.Math..Math.s_{2.Math.n-1}.Math.{\stackrel{.Math.}{c}}_{n-1}^T\right].Math..Math.\mathrm{.Math.}.Math.\left[s_{k-n}.Math.{\stackrel{.Math.}{c}}_0^T.Math..Math.\mathrm{.Math.}.Math..Math.s_{k-1}.Math.{\stackrel{.Math.}{c}}_{n-1}^T\right]\right]\right)+C^T.Math.N=\stackrel{.Math.}{h}*\left[C^T\left[s_0.Math.{\stackrel{.Math.}{c}}_0^T.Math..Math.\mathrm{.Math.}.Math..Math.s_{n-1}.Math.{\stackrel{.Math.}{c}}_{n-1}^T\right].Math.C^T\left[s_n.Math.{\stackrel{.Math.}{c}}_0^T.Math..Math.\mathrm{.Math.}.Math..Math.s_{2.Math.n-1}.Math.{\stackrel{.Math.}{c}}_{n-1}^T\right].Math..Math.\mathrm{.Math.}.Math..Math.C^T\left[s_{k-n}.Math.{\stackrel{.Math.}{c}}_0^T.Math..Math.\mathrm{.Math.}.Math..Math.s_{k-1}.Math.{\stackrel{.Math.}{c}}_{n-1}^T\right]\right]+C^T.Math.N=n.Math.\stackrel{.Math.}{h}*\left[\left[\begin{array}{ccc}{s}_0& & \\ & & \\ & & s_{n-1}\end{array}\right].Math.\left[\begin{array}{ccc}{s}_n& & \\ & & \\ & & s_{2.Math.n-1}\end{array}\right].Math..Math.\mathrm{.Math.}.Math.\left[\begin{array}{ccc}{s}_{k-n}& & \\ & & \\ & & s_{k-1}\end{array}\right]\right]+C^T.Math.N=n[.Math.\begin{array}{cccccccccc}[h_0.Math.s_0& \mathrm{.Math.}& h_{n-1}.Math.s_0]& [h_0.Math.s_n& \mathrm{.Math.}& h_{n-1}.Math.s_n]& \mathrm{.Math.}& [h_0.Math.s_{k-n}& \mathrm{.Math.}& h_{n-1}.Math.s_{k-n}]\\ h_{n-1}.Math.s_{k-n+1}]& [h_0.Math.s_1& \mathrm{.Math.}& h_{n-1}.Math.s_1]& [h_0.Math.s_{n+1}& \mathrm{.Math.}& h_{n-1}.Math.s_{n+1}]& \mathrm{.Math.}& [h_0.Math.s_{k-n+1}& \mathrm{.Math.}\\ \mathrm{.Math.}& \mathrm{.Math.}& \mathrm{.Math.}& \mathrm{.Math.}& \mathrm{.Math.}& \mathrm{.Math.}& \mathrm{.Math.}& \mathrm{.Math.}& \mathrm{.Math.}& \mathrm{.Math.}\\ \mathrm{.Math.}& h_{n-1}.Math.s_{k-1}]& [h_0.Math.s_{n-1}& \mathrm{.Math.}& h_{n-1}.Math.s_{n-1}]& [h_0.Math.s_{2.Math.n-1}& \mathrm{.Math.}& h_{n-1}.Math.s_{2.Math.n-1}]& \mathrm{.Math.}& [h_0.Math.s_{k-1}\end{array}]+.Math.N^{}$

[0236] where N is a matrix of AWGN samples with variance no.sup.2.

[0237] This relates to Action 504 previously described.

Reordering

[0238] Generate a nk matrix X by reordering the elements in D

[00007]$X=n\left[\begin{array}{ccc}{h}_0.Math.s_0& \mathrm{.Math.}& h_0.Math.s_{k-1}\\ \mathrm{.Math.}& & \mathrm{.Math.}\\ h_{n-1}.Math.s_0& \mathrm{.Math.}& h_{n-1}.Math.s_{k-1}\end{array}\right]+N^{}=n.Math.{\stackrel{.Math.}{h}}^T.Math.\stackrel{.Math.}{s}+N^{}$

[0239] where N is the reordered version of N.

[0240] It can be noted that the signal received on the time dispersive channel has been separated into n ISI-free signals (represented by the rows in X).

[0241] Thereafter, the sequence of data symbols may be extracted. One possible way of doing the extraction is explained by the MRC combining action, which requires the channel coefficients from a Channel estimation action.

[0242] This relates to Actions 505 and 506 previously described.

Channel Estimation

[0243] Estimate the channel vector . Since each channel tap impacts only one of the n signals, the channel estimation is straightforward. Using the weights * implies that the n signals will be coherently combined, i.e., they are added constructively. Further, the magnitude of the weights will maximize the SNR of the combined signal. The channel coefficients can be estimated if one or a few of the data symbols are training symbols.

[0244] This relates to Action 507 previously described.

[0245] MRC combining

[0246] Calculate

=X=n*.sup.T+*N=n||.sup.2+

where is a vector of AWGN samples with variance n||.sup.2.sup.2. Note that the derived signal is the vector of transmitted symbols , plus noise. Assuming that has unit energy, the signal-to-noise ratio is

[00008]$\frac{n.Math.{.Math.\stackrel{.Math.}{h}.Math.}^2}{{}^2},$

i.e., n times the signal-to-noise ratio of the received signal. A processing gain of n times has been achieved.

[0247] This relates to Action 508 previously described.

ABBREVIATIONS

[0248] AWGN Additive White Gaussian Noise [0249] ISI Inter-Symbol Interference [0250] MRC Maximum Ratio Combining [0251] SNR Signal to Noise Ratio

[0252] When using the word comprise or comprising it shall be interpreted as non-limiting, i.e. meaning consist at least of.

[0253] Modifications and other variants of the described embodiment(s) will come to mind to one skilled in the art having the benefit of teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the embodiment(s) herein is/are not be limited to the specific examples disclosed and that modifications and other variants are intended to be included within the scope of this disclosure. Although specific terms may be employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.