TRANSMITTING DEVICE AND METHOD THEREOF

Abstract

The present invention relates to a transmitting device. The transmitting device comprises a processor , and a transmitter ; wherein the processor is configured to generate a fractional Orthogonal Frequency Division Multiplexing (OFDM) symbol based on an adjacent OFDM symbol, wherein the fractional OFDM symbol is a cyclic extension of the adjacent OFDM symbol; wherein the transmitter is configured to transmit a multicarrier signal comprising the fractional OFDM symbol and the adjacent OFDM symbol. Furthermore, the present invention also relates to a corresponding method, a multicarrier wireless communication system comprising such a transmitting device, a computer program, and a computer program product.

Claims

1. A transmitting device for a multicarrier wireless communication system, the transmitting device comprising: a processor; and a transmitter; wherein the processor is configured to generate a fractional Orthogonal Frequency Division Multiplexing (OFDM) symbol based on an adjacent OFDM symbol, wherein the fractional OFDM symbol is a cyclic extension of the adjacent OFDM symbol; wherein the transmitter is configured to transmit a multicarrier signal comprising the fractional OFDM symbol and the adjacent OFDM symbol.

2. The transmitting device according to claim 1, wherein, by cyclically extending the adjacent OFDM symbol, the multicarrier signal is continuous at the boundary between the fractional OFDM symbol and the adjacent OFDM symbol.

3. The transmitting device according to claim 2, wherein, by cyclically extending the adjacent OFDM symbol, each subcarrier waveform of the multicarrier signal is continuous at the boundary between the fractional OFDM symbol and the adjacent OFDM symbol.

4. The transmitting device according to claim 3, wherein, by cyclically extending the adjacent OFDM symbol, the modulation symbol of a subcarrier in the fractional OFDM symbol is the same modulation symbol as the modulation symbol of the corresponding subcarrier in the adjacent OFDM symbol.

5. The transmitting device according to claim 1, wherein the symbol duration of the fractional OFDM symbol is shorter than the symbol duration of the adjacent OFDM symbol.

6. The transmitting device according to claim 1, wherein the adjacent OFDM symbol comprises one cyclic prefix.

7. The transmitting device according to claim 1, wherein the fractional OFDM symbol is immediately followed or immediately preceded by the adjacent OFDM symbol.

8. The transmitting device according to claim 1, wherein the transmitter is configured to transmit the fractional OFDM symbol before an OFDM symbol used for data channels or control channels.

9. The transmitting device according to claim 1, wherein the transmitter is configured to transmit the multicarrier signal in an unlicensed spectrum of the multicarrier wireless communication system.

10. A method for a multicarrier wireless communication system, the method comprising: generating, by a transmitting device, a fractional Orthogonal Frequency Division Multiplexing (OFDM) symbol based on an adjacent OFDM symbol, wherein the fractional OFDM symbol is a cyclic extension of the adjacent OFDM symbol; and transmitting, by the transmitting device, a multicarrier signal comprising the fractional OFDM symbol and the adjacent OFDM symbol.

11. The method according to claim 10, wherein, by cyclically extending the adjacent OFDM symbol, the multicarrier signal is continuous at the boundary between the fractional OFDM symbol and the adjacent OFDM symbol.

12. The method according to claim 11, wherein, by cyclically extending the adjacent OFDM symbol, each subcarrier waveform of the multicarrier signal is continuous at the boundary between the fractional OFDM symbol and the adjacent OFDM symbol.

13. The method according to claim 12, wherein, by cyclically extending the adjacent OFDM symbol, the modulation symbol of a subcarrier in the fractional OFDM symbol is the same modulation symbol as the modulation symbol of the corresponding subcarrier in the adjacent OFDM symbol.

14. The method according to claim 10, wherein the symbol duration of the fractional OFDM symbol is shorter than the symbol duration of the adjacent OFDM symbol.

15. The method according to claim 10, wherein the adjacent OFDM symbol comprises one cyclic prefix.

16. The method according to claim 10, wherein the fractional OFDM symbol is immediately followed or immediately preceded by the adjacent OFDM symbol.

17. The method according to claim 10, wherein the fractional OFDM symbol is transmitted before an OFDM symbol used for data channels or control channels.

18. The method according to claim 10, wherein the multicarrier signal is transmitted in an unlicensed spectrum of the multicarrier wireless communication system.

19. A non-transitory computer-readable memory having processor-executable instructions stored thereon for a multicarrier wireless communication system, the processor-executable instructions, when executed, facilitating performance of the following: generating a fractional Orthogonal Frequency Division Multiplexing (OFDM) symbol based on an adjacent OFDM symbol, wherein the fractional OFDM symbol is a cyclic extension of the adjacent OFDM symbol; and transmitting a multicarrier signal comprising the fractional OFDM symbol and the adjacent OFDM symbol.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0063] The appended drawings are intended to clarify and explain different embodiments of the present invention, in which:

[0064] FIG. 1 shows a transmitting device according to an embodiment of the present invention;

[0065] FIG. 2 shows a method according to an embodiment of the present invention;

[0066] FIG. 3 shows the PSD for OFDM symbols of different duration showing that the OOB emissions decrease for fractional OFDM symbols being generated as cyclic extensions of a subsequent OFDM symbol;

[0067] FIG. 4 illustrates the generation of the fractional OFDM symbol in a way that the fractional OFDM symbol is a cyclic extension of the subsequent OFDM symbol;

[0068] FIG. 5 illustrates the generation of the fractional OFDM symbol in a way that the fractional OFDM symbol is a cyclic extension of the subsequent OFDM symbol;

[0069] FIG. 6 illustrates the generation of the fractional OFDM symbol in a way that the fractional OFDM symbol is a cyclic extension of the previous OFDM symbol; and

[0070] FIG. 7 illustrates a multicarrier wireless communication system according to an embodiment of the present invention.

DETAILED DESCRIPTION

[0071] FIG. 1 shows a transmitting device 100 according to an embodiment of the present invention. The transmitting device 100 comprises a processor 102 and a transmitter 104 (e.g. part of a transceiver device). The processor 102 is communicably coupled with the transmitter 104 with communication means (illustrated with the dashed arrow) known in the art. The transmitter 104 is further coupled to an antenna device 106 configured for wireless communications in the multicarrier wireless communication system 500 which is illustrated with dashed lines in FIG. 1. The wireless communications may be according to suitable communication standards, such as e.g. 3GPP standards.

[0072] The processor 102 of the transmitting device 100 is configured to generate a fractional OFDM signal based on an adjacent OFDM symbol, such that the fractional OFDM symbol is a cyclic extension of the adjacent OFDM symbol. Hence, the fractional OFDM symbol is immediately followed or immediately preceded by the adjacent OFDM symbol according to an embodiment of the present invention. The generated fractional OFDM symbol is forwarded to the transmitter 104 after being generated. The transmitter 104 is configured to receive the fractional OFDM symbol from the processor 102 and further configured to transmit a multicarrier signal S.sub.MC comprising the fractional OFDM symbol and the adjacent OFDM symbol in the multicarrier wireless communication system 500. The multicarrier signal S.sub.MC is in the example in FIG. 1 transmitted via the antenna device 106 of the transmitting device 100.

[0073] The transmitting device 100 can be any suitable communication device having the capabilities and being configured to transmit multicarrier signals in a wireless communication system 500. It should is noted that the transmitting device 100 also comprises other means, units, elements, devices, etc., such that the transmitting device 100 has the mentioned capabilities. Examples of such means, units, elements, and devices are given in the following description. Further, examples of such communication devices are radio network nodes and user devices.

[0074] A radio network node, such as a base station, e.g. a Radio Base Station (RBS), which in some networks may be referred to as transmitter, “eNB”, “eNodeB”, “NodeB” or “B node”, depending on the technology and terminology used. The radio network nodes may be of different classes such as e.g. macro eNodeB, home eNodeB or pico base station, based on transmission power and thereby also cell size. The radio network node can be a station (STA), which is any device that contains an IEEE 802.11-conformant media access control (MAC) and physical layer (PHY) interface to the wireless medium (WM).

[0075] A user device, such as a user equipment (UE), mobile station, wireless terminal and/or mobile terminal is enabled to communicate wirelessly in a wireless communication system, sometimes also referred to as a cellular radio system. The user equipment may further be referred to as mobile telephones, cellular telephones, computer tablets or laptops with wireless capability. The user equipments in the present context may be, for example, portable, pocket-storable, hand-held, computer-comprised, or vehicle-mounted mobile devices, enabled to communicate voice and/or data, via the radio access network, with another entity, such as another receiver or a server. The user equipment can be a station (STA), which is any device that contains an IEEE 802.11-conformant media access control (MAC) and physical layer (PHY) interface to the wireless medium (WM).

[0076] The disclosed solution is applicable to all coded modulation transmission systems sending information to multiple users, possibly combined with OFDM and Multiple Input Multiple Output (MIMO) transmissions. For example, 3GPP LAA systems can take advantage of the present solution. Therefore, according to an embodiment of the present invention the multicarrier signal S.sub.MC is transmitted in unlicensed spectrum of the multicarrier wireless communication system 500.

[0077] FIG. 2 shows a general flow chart of a method 200 according to an embodiment of the present invention. The method 200 may be executed in a transmitting device 200, such as the one shown in FIG. 1. The method 200 comprises the first step of generating 202 a fractional OFDM symbol based on an adjacent OFDM symbol. The fractional OFDM symbol is, as described above, a cyclic extension of the adjacent OFDM symbol. The method 200 further comprises the second step of transmitting 204 a multicarrier signal S.sub.MC comprising the fractional OFDM symbol and the adjacent OFDM symbol.

[0078] The generated fractional OFDM symbol has no fixed duration and may be adjacent with an OFDM symbol containing preamble, or an OFDM symbol containing data and/or control information according to embodiments of the present invention.

[0079] The length of the fractional OFDM symbol is not fixed and may change for each time the transmitting device 100 (such as a LAA eNodeB) transmits the multicarrier signal S.sub.MC. This is because the transmitting device 100 may start transmission once it measures the channel as clear and it can be at any time during a subframe.

[0080] Embodiments of the present invention disclose to generate the fractional OFDM symbol from the adjacent OFDM symbol in a way comprising at least one of the following: the fractional OFDM symbol is a cyclic extension of the subsequent OFDM symbol; or the fractional OFDM symbol is a cyclic extension of the previous OFDM symbol.

[0081] A cyclic extension implies that the signal is continuous between the fractional OFDM symbol and the subsequent/previous OFDM symbol. One way of cyclic extension is to assure that each subcarrier waveform is continuous between the fractional OFDM symbol and the subsequent/previous OFDM symbol, which can be achieved by, for each subcarrier, use the same modulation symbol in the fractional OFDM symbol and the subsequent/previous OFDM symbol.

[0082] Therefore, embodiments of the present invention consider two consecutive OFDM symbols, i.e. the fractional OFDM symbol and the adjacent OFDM symbol. The adjacent OFDM symbol could be an OFDM symbol containing preamble, or an OFDM symbol containing data and/or control information.

[0083] The adjacent OFDM symbol could comprise a cyclic prefix. Moreover, typically an OFDM symbol has a duration of its useful part, T.sub.U, such that each subcarrier produces an integer number of periods during T.sub.U, where the number of periods depend on the subcarrier frequency. Embodiments of the present invention are applicable to where the duration of the useful part of the adjacent OFDM symbol is such that each subcarrier produces an integer number of periods during the useful period. A skilled person in the art will also be able to apply the present solution by performing a cyclic extension for cases where the duration of the useful part of the adjacent OFDM symbol is such that each subcarrier does not produce an integer number of periods during the useful period.

[0084] In the following description LTE terminology and systems are considered for exemplifying embodiments of the present invention. It should however be noted that the present solutions are not limited hereto.

[0085] In the LTE system, the time-continuous signal s.sub.l.sup.(p)(t) on antenna port p in OFDM symbol l in a downlink slot is defined by

[00003] $s_{l}^{(p)} (t) = {.Math.}_{k = - .Math. N_{RB}^{DL} .Math. N_{sc}^{RB} / 2 .Math.}^{- 1} .Math. .Math. a_{k^{(-)}, l}^{(p)} .Math. e^{j .Math. .Math. 2 .Math. .Math. π .Math. .Math. k .Math. .Math. Δ .Math. .Math. f (t - N_{CP, l} .Math. T_{s})} + {.Math.}_{k = 1}^{.Math. N_{RB}^{DL} .Math. N_{sc}^{RB} / 2 .Math.} .Math. .Math. a_{k^{(+)}, l}^{(p)} .Math. e^{j .Math. .Math. 2 .Math. .Math. π .Math. .Math. k .Math. .Math. Δ .Math. .Math. f (t - N_{CP, l} .Math. T_{s})}$

for 0≦t<(N.sub.CP,l+N)×T.sub.s where k.sup.(−)=k+└N.sub.RB.sup.DLN.sub.sc.sup.RB/2┘ and k.sup.(+)=k└N.sub.RB.sup.LDN.sub.sc.sup.RB/2┘−1, resource element (k,l) on antenna port p corresponds to the complex value α.sub.k,l.sup.(p), T.sub.s=1/(15000*2048) second N.sub.sc.sup.RB=12 and N.sub.RB.sup.DL is related to the system bandwidth, e.g. it assumes the value 100 for 20 MHz bandwidth.

[0086] The variable N equals 2048 for Δf=15 kHz subcarrier spacing and 4096 for Δf=7.5 kHz subcarrier spacing. The OFDM symbols in a slot shall be transmitted in increasing order of l, starting with l=0, where OFDM symbol l>0 starts at time Σ.sub.r=0.sup.l−1(N.sub.CP,l+N)T.sub.s within the slot. The value of N.sub.CP,l is given in Table 1 below for LTE.

TABLE-US-00001 TABLE 1 OFDM signal parameters in LTE Configuration Cyclic prefix length N.sub.CP, l Normal cyclic prefix Δf = 15 kHz 160 for l = 0 144 for l = 1, 2, . . . , 6 Extended cyclic prefix Δf = 15 kHz 512 for l = 0, 1, . . . , 5 Δf = 7.5 kHz 1024 for l = 0, 1, 2

[0087] In embodiments of the present invention, the fractional OFDM symbol l′ followed by the OFDM symbol l can be generated as

[00004] $s_{l^{'}}^{(p)} (t) = {.Math.}_{k = - .Math. N_{RB}^{DL} .Math. N_{sc}^{RB} / 2 .Math.}^{- 1} .Math. .Math. a_{k^{(-)}, l}^{(p)} .Math. e^{j .Math. .Math. 2 .Math. .Math. π .Math. .Math. k .Math. .Math. Δ .Math. .Math. f (t - N_{CP, l} .Math. T_{s} - T_{0 .Math._.Math. F})} + {.Math.}_{k = 1}^{.Math. N_{RB}^{DL} .Math. N_{sc}^{RB} / 2 .Math.} .Math. .Math. a_{k^{(+)}, l}^{(p)} .Math. e^{j .Math. .Math. 2 .Math. .Math. π .Math. .Math. k .Math. .Math. Δ .Math. .Math. f (t - N_{CP, l} .Math. T_{s} - T_{0 .Math._.Math. F})}$

for 0≦t<T.sub.0.sub._.sub.F. It can be observed each subcarrier waveform is continuous between the fractional OFDM symbol l′ and the subsequent OFDM symbol l because

[00005] $\lim_{t .fwdarw. T_{0 .Math._.Math. F}} .Math. s_{k, l^{'}}^{(p)} (t) = a_{k, l}^{(p)} .Math. e^{j .Math. .Math. 2 .Math. .Math. π .Math. .Math. k .Math. .Math. Δ .Math. .Math. f (t - N_{CP, l} .Math. T_{s})} = s_{k, l}^{(p)} (0),$

where k is the subcarrier index.

[0088] In addition, the signal between the fractional OFDM symbol l′ and the subsequent OFDM symbol l is also continuous because

[00006] $\lim_{t .fwdarw. T_{0 .Math._.Math. F}} .Math. s_{l^{'}}^{(p)} (t) = {.Math.}_{k = - .Math. N_{RB}^{DL} .Math. N_{sc}^{RB} / 2 .Math.}^{- 1} .Math. .Math. a_{k^{(-)}, l}^{(p)} .Math. e^{j .Math. .Math. 2 .Math. .Math. π .Math. .Math. k .Math. .Math. Δ .Math. .Math. f (- N_{CP, l} .Math. T_{s})} + {.Math.}_{k = 1}^{.Math. N_{RB}^{DL} .Math. N_{sc}^{RB} / 2 .Math.} .Math. .Math. a_{k^{(+)}, l}^{(p)} .Math. e^{j .Math. .Math. 2 .Math. .Math. π .Math. .Math. k .Math. .Math. Δ .Math. .Math. f (- N_{CP, l} .Math. T_{s})} = s_{l}^{(p)} (0)$

[0089] In this way the fractional OFDM symbol l′ is a cyclic extension of the subsequent OFDM symbol, where the following condition is fulfilled

s.sub.l′.sup.(p)(t)=s.sub.l.sup.(p)(NT.sub.s−T.sub.0.sub._.sub.F+t).

[0090] Without loss of generality, the cyclic extension of the subsequent OFDM symbol can also be expressed by

F.sup.p(t)=S.sup.(p)(T.sub.u−T.sub.0.sub._.sub.F+t) or F.sup.p(t)=S.sup.(p)((T.sub.u−T.sub.0.sub._.sub.F+t)mod(T.sub.u+T.sub.G)),

where F.sup.p(t) is the fractional OFDM symbol on antenna port p in the time domain with symbol duration T.sub.o.sub._.sub.F; mod is modulo operation; and S.sup.(p)(t) is the subsequent OFDM symbol on antenna port p with a positive information symbol duration T.sub.uand a non-negative cyclic prefix duration T.sub.CP.

[0091] By generating the fractional OFDM symbol as a cyclic extension of the subsequent OFDM symbol, the OFDM symbol duration is prolonged compared with the concerned fractional OFDM symbol, and also the subsequent OFDM symbol, resulting in reduced power emission, as shown in FIG. 3 where the x-axis shows the frequency offset and the y-axis shows the PSD.

[0092] In one other embodiment of the present invention, the fractional OFDM symbol is generated from the previous OFDM symbol. The fractional OFDM symbol l′ following the OFDM symbol l can be generated as:

[00007] $s_{l^{'}}^{(p)} (t) = {.Math.}_{k = - .Math. N_{RB}^{DL} .Math. N_{sc}^{RB} / 2 .Math.}^{- 1} .Math. .Math. a_{k^{(-)}, l}^{(p)} .Math. e^{j .Math. .Math. 2 .Math. .Math. π .Math. .Math. k .Math. .Math. Δ .Math. .Math. ft} + {.Math.}_{k = 1}^{.Math. N_{RB}^{DL} .Math. N_{sc}^{RB} / 2 .Math.} .Math. .Math. a_{k^{(+)}, l}^{(p)} .Math. e^{j .Math. .Math. 2 .Math. .Math. π .Math. .Math. k .Math. .Math. Δ .Math. .Math. ft}$

for 0≦t<T.sub.0.sub._.sub.F. It can be observed each subcarrier waveform is continuous between the fractional OFDM symbol l′ and the previous OFDM symbol l because

s.sub.k,l′.sup.(p)(0)=α.sub.k,l.sup.(p)=lim.sub.t.fwdarw.(N.sub.CP,l.sub.+N)×T,s.sub.k,l.sup.(p)(t),

where k is the subcarrier index.

[0093] In addition, the signal between the fractional OFDM symbol l′ and the previous OFDM symbol l is also continuous because

[00008] $\lim_{t .fwdarw. (N_{CP, l} + N) \times T_{s}} .Math. s_{l}^{(p)} (t) = {.Math.}_{k = - .Math. N_{RB}^{DL} .Math. N_{sc}^{RB} / 2 .Math.}^{- 1} .Math. a_{k^{(-)}, l}^{(p)} + {.Math.}_{k = 1}^{.Math. N_{RB}^{DL} .Math. N_{sc}^{RB} / 2 .Math.} .Math. .Math. a_{k^{(+)}, l}^{(p)} = s_{l^{'}}^{(p)} (0) .$

[0094] In this way the fractional OFDM symbol l′ is a cyclic extension of the previous OFDM symbol, where the subcarrier spacing concerning the fractional OFDM symbol is the same as the subcarrier spacing concerning the previous OFDM symbol l, and the following condition is fulfilled

s.sub.l′.sup.(p)(t)=s.sub.l.sup.(p)(N.sub.CP,lT.sub.s+t).

[0095] Without loss of generality, the cyclic extension of the previous OFDM symbol can also be expressed by

F.sup.p(t)=S.sup.(p)((T.sub.CP+t)mod(T.sub.u+T.sub.CP)),

where F.sup.p(t) is the fractional OFDM symbol on antenna port p in the time domain; mod is the modulo operation; and S.sup.(p)(t) is the previous OFDM symbol on antenna port p with a positive information symbol duration T.sub.u and a non-negative cyclic prefix duration T.sub.CP.

[0096] In another example of the present invention, the adjacent OFDM symbol is an OFDM symbol with at least one subcarrier not having an integer number of periods. The time-continuous signal s.sub.l.sup.(p)(t) on antenna port p in the adjacent OFDM symbol l in a downlink slot is defined by

[00009] $s_{l}^{(p)} (t) = {.Math.}_{k = - .Math. N_{RB}^{DL} .Math. N_{sc}^{RB} / 2 .Math.}^{- 1} .Math. a_{k^{(-)}, l}^{(p)} .Math. e^{j .Math. .Math. 2 .Math. .Math. π .Math. .Math. k .Math. .Math. Δ .Math. .Math. f (t - N_{CP, l} .Math. T_{s})} + {.Math.}_{k = 1}^{.Math. N_{RB}^{DL} .Math. N_{sc}^{RB} / 2 .Math.} .Math. a_{k^{(+)}, l}^{(p)} .Math. e^{j .Math. .Math. 2 .Math. .Math. π .Math. .Math. k .Math. .Math. Δ .Math. .Math. f (t - N_{CP, l} .Math. T_{s})}$

for T.sub.start≦t<T.sub.end, where T.sub.end−T.sub.start<NT.sub.s. Subcarrier k has a period of 1/(kΔf) and since NT.sub.s=1/Δf, then there is an integer number of periods within the duration of NT.sub.s. Therefore if T.sub.end−T.sub.start<NT.sub.s, then there is at least one subcarrier not having an integer number of periods.

[0097] In one embodiment of the present invention, the fractional OFDM symbol is generated from the following/subsequent OFDM symbol in a way that the fractional OFDM symbol is the cyclic extension of the subsequent OFDM symbol. One example assuming the subsequent OFDM symbol is an OFDM symbol containing cyclic prefix and useful OFDM symbol is illustrated in FIG. 4. It should be noted that the x-axis in FIGS. 4-6 represent time T.

[0098] As shown in FIG. 4 the fractional OFDM symbol with duration T.sub.0.sub._.sub.F is a cyclic extension of the subsequent OFDM symbol. The subsequent OFDM symbol is in this particular example an OFDM symbol comprising cyclic prefix with duration T.sub.G and useful information with duration T.sub.U.

[0099] In another embodiment of the present invention, the subsequent OFDM symbol is an OFDM symbol without cyclic prefix as illustrated in FIG. 5. This may be used for many purposes, e.g. for purpose of reducing the overhead. In FIG. 5 the fractional OFDM symbol with duration T.sub.0.sub._.sub.F is a cyclic extension of the subsequent OFDM symbol without cyclic prefix. Generating the fractional OFDM symbol as a cyclic extension of the subsequent OFDM symbol still provides the advantages of simple implementation and prolonged symbol duration to reduce out-of-band power emissions.

[0100] In a further embodiment of the present invention, the fractional OFDM symbol is generated from the subsequent OFDM symbol in a way that the multicarrier signal S.sub.MC is continuous at the boundary between the fractional OFDM symbol and the subsequent OFDM symbol. One example of generating continuous symbols is by means of N-continuous OFDM.

[0101] In further embodiments of the present invention, the fractional OFDM symbol is generated from the previous OFDM symbol in a way that the fractional OFDM symbol is a cyclic extension of the previous OFDM symbol.

[0102] In one example the fractional OFDM symbol with duration T.sub.0.sub._.sub.F starts not at the OFDM symbol boundary and could be used to at least reserve the channel until the downlink transmission carrying other useful information happens, e.g. downlink transmission for control information or data. The fractional OFDM symbol starts immediately after the previous OFDM symbol and ends at the OFDM subframe boundary. In this case the fractional OFDM symbol is a cyclic extension of the previous OFDM symbol. The previous OFDM symbol may start immediately when the transmitting device 100 measures the channel as clear.

[0103] In a further embodiment of the present invention, the fractional OFDM symbol is generated from the subsequent/previous OFDM symbol by means of manipulation of the subsequent/previous OFDM symbol. The manipulation includes but is not limited to manipulations, such as multiplication of the subsequent OFDM symbol by a real or complex value, the shifts or cyclic shifts of the subsequent OFDM symbol, truncation, puncturing, using different parameters defining the subsequent OFDM symbol (e.g., root indices, initialization values of shift registers, etc.), other linear transformations and any other means using the subsequent OFDM symbol.

[0104] FIG. 7 illustrates a multicarrier wireless communication system 500 according to an embodiment of the present invention. The transmitting device 100 is in this example a LAA eNodeB configured to transmit downlink signals in a cellular multicarrier communication system. In FIG. 7 also two exemplary User Devices (UDs) UD1 and UD2 are shown. The UDs may be any mobile station or corresponding devices known in the art, such as user equipments. The transmitting device 100 transmits one or more multicarrier signals S.sub.MC in the downlink. UD1 and UD2 are configured to receive the multicarrier signal(s) S.sub.MC from the transmitting device 100. UD1 and UD2 get synchronized to the LAA eNodeB based on the aperiodically transmitted preamble and are able to demodulate data immediately after the preamble. The preamble may contain a fractional OFDM symbol and at least one complete OFDM symbol, or may contain fractional OFDM symbol only, or may contain complete OFDM symbols only.

[0105] Furthermore, any method according to the present invention may be implemented in a computer program, having a program code, which when runs by processing means causes the processing means to execute the steps of the method. The computer program is included in a computer readable medium of a computer program product. The computer readable medium may comprises of essentially any memory, such as a ROM (read-only memory), a PROM (programmable read-only memory), an EPROM (erasable PROM), a Flash memory, an EEPROM (electrically erasable PROM), or a hard disk drive.

[0106] Moreover, it is realized by the skilled person that the present transmitting device 100 comprises communication capabilities in the form of e.g., functions, means, units, elements, etc., for performing the present solution. Examples of other such means, units, elements and functions are: processors, memory, buffers, control logic, encoders, decoders, rate matchers, de-rate matchers, mapping units, multipliers, decision units, selecting units, switches, interleavers, de-interleavers, modulators, demodulators, inputs, outputs, antennas, amplifiers, receiver units, transmitter units, digital signal processors (DSPs), MSDs, trellis-coded modulation (TCM) encoder, TCM decoder, power supply units, power feeders, communication interfaces, communication protocols, etc. which are suitably arranged together for performing the present solution.

[0107] Especially, the processors of the present devices may comprise, e.g., one or more instances of a central processing unit (CPU), a processing unit, a processing circuit, a processor, processing mean, an application-specific integrated circuit (ASIC), a microprocessor, or other processing logic that may interpret and execute instructions. The expression “processor” may thus represent a processing circuitry comprising a plurality of processing circuits, such as, e.g., any, some or all of the ones mentioned above. The processing circuitry may further perform data processing functions for inputting, outputting, and processing of data comprising data buffering and device control functions, such as call processing control, user interface control, or the like.

[0108] Finally, it should be understood that the present invention is not limited to the embodiments described above, but also relates to and incorporates all embodiments within the scope of the appended independent claims.

[0109] Additionally, statements made herein characterizing the invention refer to an embodiment of the invention and not necessarily all embodiments.

TRANSMITTING DEVICE AND METHOD THEREOF

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Abstract

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Description