CONTROL DEVICE, COMMUNICATION NODE AND METHODS THEREOF

Abstract

A control device (100) comprises a processor (101) and a transmitter (103) is provided; wherein the processor (101) is configured to generate a composite beam control signal S which comprises antenna beam control information for communication nodes of a communication path; wherein the transmitter (103) is configured to transmit the composite beam control signal S to at least one communication node. A communication node (300) comprises a processor (301), a transceiver (303), reception antenna elements (305) and transmission antenna elements (307) is provided; the transceiver (303) is configured to receive a composite beam control signal S; the processor (301) is configured to derive antenna beam control information associated with the communication node (300) from the composite beam control signal S; and control the beam of the reception antenna elements (305) or the beam of the transmission antenna elements (307) according to the antenna beam control information.

Claims

1. A control device (100) for a wireless multi-hop communication system (500), the control device (100) comprising: a processor (101); and a transmitter (103); wherein the processor (101) is configured to generate a composite beam control signal S, wherein the composite beam control signal S comprises antenna beam control information for communication nodes of a communication path comprising a source communication node, at least one intermediate communication node and a destination communication node; and wherein the transmitter (103) is configured to transmit the composite beam control signal S to at least one communication node of the communication path.

2. The control device (100) according to claim 1, wherein the composite beam control signal S has the form
S=Σ.sub.i=1.sup.NC.sub.i.Math.φ.sub.i, where φ.sub.i is the beam forming information for communication node i=1, . . . , N, where i=1 is the index for the source communication node and i=N is the index for the destination communication node, and C.sub.i is a communication node identity associated with communication node i.

3. The control device (100) according to claim 2, wherein the communication node identities C.sub.i, i=f1, . . . , N, are orthogonal code sequences.

4. The control device (100) according to claim 2, wherein the beam forming information t is phase information or phase shift information for the antenna elements of communication node i.

5. The control device (100) according to claim 4, wherein the phase shift information is a phase shift difference between neighbouring antenna elements, or a phase shift for each antenna element.

6. The control device (100) according to claim 1, wherein the processor (101) further is configured to generate a composite power level signal, wherein the composite power level signal indicates transmission power levels for the communication nodes; and wherein the transmitter (103) further is configured to transmit the composite power level signal to at least one communication node of the path.

7. A communication node (300) for a multi-hop communication system (500), the communication node (300) comprising: a processor (301); a transceiver (303); reception antenna elements (305); and transmission antenna elements (307); wherein the transceiver (303) is configured to receive a composite beam control signal S, wherein the composite beam control signal S comprises antenna beam control information for communication nodes of a communication path comprising a source communication node, at least one intermediate communication node and a destination communication node; wherein the processor (301) is configured to derive antenna beam control information associated with the communication node (300) from the composite beam control signal S; and control the beam of the reception antenna elements (305) or the beam of the transmission antenna elements (307) according to the antenna beam control information.

8. The communication node (300) according to claim 7, wherein the transceiver (303) further is configured to forward the composite beam control signal S to a next communication node of the communication path.

9. The communication node (300) according to claim 7, wherein the composite beam control signal has the form
S=Σ.sub.i=1.sup.NC.sub.i.Math.φ.sub.i, where φ.sub.i t is the beam forming information for communication node i=1, . . . , N, where i=1 is the index for the source communication node and i=N is the index for the destination communication node, and C.sub.i is a communication node identity associated with communication node i.

10. The communication node (300) according to claim 9, wherein the processor (301) further is configured to derive the beam forming information t for the communication node (300) according to
S.Math.C.sub.i=(Σ.sub.i=1.sup.NC.sub.i.Math.φ.sub.i).Math.C.sub.1=φ.sub.i.

11. The communication node (300) according to claim 9, wherein the beam forming information t is phase information or phase shift information; and wherein the processor (301) further is configured to control the beam of the reception antenna elements (305) or the beam of the transmission antenna elements (307) by phase shifting the reception antenna elements (305) or phase shifting the transmission antenna elements (307) according to the phase shift information.

12. The communication node (300) according to claim 7, wherein the transceiver (303) further is configured to receive a composite power level signal, wherein the composite power level signal indicates transmission power levels for the communication nodes; wherein the processor (301) further is configured to derive the transmit power level associated with the communication node (300) from the composite power level signal; and wherein the transceiver (303) further is configured to transmit on the transmission antenna elements (307) with the derived power level.

13. The communication node (300) according to claim 7, wherein the processor (301) is a processing circuitry, and wherein the processing circuitry is configured to derive the antenna beam control information by analogue signal processing.

14. A wireless multi-hop communication system (500) comprising: at least one control device; and at least one communication node, wherein the control device comprising a processor (101) and a transmitter (103), the processor (101) is configured to: generate a composite beam control signal S, wherein the composite beam control signal S comprises antenna beam control information for communication nodes of a communication path comprising a source communication node, at least one intermediate communication node and a destination communication node; and wherein the transmitter (103) is configured to transmit the composite beam control signal S to at least one communication node of the communication path; wherein the communication node (300) comprising a processor (301), a transceiver (303), reception antenna elements (305) and transmission antenna elements (307), the transceiver (303) is configured to: receive a composite beam control signal S, wherein the composite beam control signal S comprises antenna beam control information for communication nodes of a communication path comprising a source communication node, at least one intermediate communication node and a destination communication node; wherein the processor (301) is configured to derive antenna beam control information associated with the communication node (300) from the composite beam control signal S; and control the beam of the reception antenna elements (305) or the beam of the transmission antenna elements (307) according to the antenna beam control information.

15. A method for a wireless multi-hop communication system (500); the method comprising: generating (201) a composite beam control signal S, wherein the composite beam control signal S comprises antenna beam control information for communication nodes of a communication path comprising a source communication node, at least one intermediate communication node and a destination communication node; and transmitting (203) the composite beam control signal S to at least one communication node of the communication path.

16. A method for a wireless multi-hop communication system (500); the method comprising: receiving (401) a composite beam control signal S, wherein the composite beam control signal S comprises antenna beam control information for communication nodes of a communication path comprising a source communication node, at least one intermediate communication node and a destination communication node; deriving (403) antenna beam control information associated with the communication node (300) from the composite beam control signal S; and controlling (405) the beam of the reception antenna elements (305) or the beam of the transmission antenna elements (307) according to the antenna beam control information.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0104] The appended drawings are intended to clarify and explain different embodiments of the present invention, in which:

[0105] FIG. 1 shows a control device according to an embodiment of the present invention;

[0106] FIG. 2 shows a flow chart of a method for a multi-hop communication system according to an embodiment of the present invention;

[0107] FIG. 3 shows a communication node device according to an embodiment of the present invention;

[0108] FIG. 4 shows a flow chart of a method for a multi-hop communication system according to an embodiment of the present invention;

[0109] FIG. 5 shows an embodiment of a multi-hop communication system according to the present invention; and

[0110] FIG. 6 illustrates a method in an intermediate communication node according to an embodiment of the present invention.

DETAILED DESCRIPTION

[0111] Current wireless communication systems often comprise multiple communication nodes, or only “node” in short, of different types. The terminology “communication node” or “node” includes but is not limited to a user terminal device (e.g. a User Equipment, UE, in Long Term Evolution terminology) or a network node, or any other type of communication devices capable of operating in a wireless or wire-line communication system. The terminology “network node” includes but is not limited to a base station, a Node-B or eNode-B, an access point, a relay node, a base station controller, an aggregation point or any other type of interfacing communication device of a radio network and/or a wireless communication system.

[0112] In a multi-hop communication system information/data/payload is transferred from a source node (or start node) to a destination node (or end node) via one or more intermediate nodes of a communication path. When mentioned intermediate nodes are working in a wireless manner they are called multi-hop intermediate nodes.

[0113] As the conditions of the wireless communication system changes, there is a need to change the communication path for information/data/payload to be transmitted from the source node to the destination node. Those conditions include but are not limited to the addition of the new node, or the removal of one node in the communication path.

[0114] The addition/removal of the nodes in a communication path can be arranged e.g. in the manner of sleeping or waking up nodes in order to save energy. That is to put one node into sleep mode when there is no data traffic and to wake up the node when there is data traffic to be passed through this particular node. The connection from one node to another node may have to be modified due to the mobility of certain nodes, for example of user terminal equipments or mobile stations.

[0115] The change of the connection of nodes can be implemented as the change of beam direction of transmitter antennas or beam direction of receiver antennas of the nodes. For example, normally an antenna beam of a transmitter antenna is used to aim towards the intended receiver and an antenna beam of a receiver antenna is used to aim towards the intended transmitter in order to increase the reception quality. The antenna of the transmitter and/or the receiver often comprise multiple antenna elements and antenna beams are created or steered by imposing different signals to those multiple antenna elements.

[0116] In conventional implementation of beamforming of multi-hop networks, the direction from node A to node B is often stored in a memory device of node A. When needed, for example demanded by a controller, node A will take out the direction information and then steer its antenna beam towards node B according to the direction information. This memory-processor based processing may cause latency within each node and the overall latency of the multi-hop network may become intolerable for certain wireless communication architectures or applications.

[0117] In a Cloud type wireless communication architecture, most of the signalling processing is done in a central node, i.e. in the Cloud. After signal processing, the resulting radio signal is sent to the receiving destination node. Sometimes the processing of the central node will depend on the feedback information from the receiving destination node. This means higher requirements on the overall latency of the network.

[0118] According to embodiments of the present invention, in order to control the beam of antennas of nodes of a communication path, a control device will send/transmit/transfer a single composite beam control signal including antenna beam control information to nodes of the communication path. The beam control information can include control information for transmission antenna and/or reception antenna elements for the nodes.

[0119] FIG. 1 shows an embodiment of a control device 100 according to an embodiment of the present invention. The control device 100 comprises a processor 101 communicably coupled to a transmitter 103. The processor 101 is configured to generate a composite beam control signal S and the transmitter 103 is configured to transmit the composite beam control signal S to at least one communication node in a communication path comprising a source communication node, at least one intermediate communication node and a destination communication node.

[0120] In FIG. 1 two different ways of sending or transmitting the composite beam control signal to the at least one communication node is illustrated. The composite control signal can be sent by means of a wireless communication link (illustrated by the antenna) or by means of a wired communication link (illustrated with the arrow from the transmitter 103). Also the combination of wireless and wired link to the at least one communication node can be used.

[0121] Generally, the present control device 100 can be located or integrated in the source communication node or be located somewhere else in the multi-hop communication system. In the first case the composite beam control signal S is transmitted by the source communication node to the first intermediate communication node of the communication path. In the latter case the composite beam control signal S is transmitted to the source communication node which forwards/relays the composite beam control signal to the first intermediate communication node, which in turn forwards the composite beam control signal to the second intermediate communication node, and so on such that the composite beam control signal reaches the destination communication node by propagating through the multi-hop communication system.

[0122] FIG. 2 shows a corresponding method for a multi-hop communication system. As disclosed the method comprises the steps of generating 201 a composite beam control signal S, wherein the composite beam control signal S comprises antenna beam control information for communication nodes of a communication path comprising a source communication node, at least one intermediate communication node and a destination communication node. The method further comprises the step of transmitting 203 the composite beam control signal S to at least one communication node of the communication path. The method may e.g. be executed by a control device 100 according to an embodiment of the present invention.

[0123] The control device 100 may be a central control device in a centralised network configuration. However, the control device may also be part of a distributed network configuration in which two or more control device are responsible for different parts of the network. The present control device 100 has the functions and capabilities for controlling the beam forming of the antennas of the communication nodes of the communication path. For example, the control device may be a network management server, a network element manager, an operations support server or a network optimization server. It may further be part of a network management system, an Operations Administration and Management (OAM) system or a network control element. The purpose of controlling the antenna direction of the nodes may be to establish a wireless multi-hop connection from the source node to the destination node (the information sink) in order to transmit payload data.

[0124] The present composite beam control signal S may be transmitted together with the payload data so as to reduce signalling overhead. However, the signal S can also be sent as a separate independent signal in the system.

[0125] Moreover, FIG. 3 shows an embodiment of a communication node 300f according to an embodiment of the present invention. The communication node 300 comprises a processor 301 and a transceiver 303, wherein the processor 301 and the transceiver 303 are communicably coupled to each other. The communication node 300 also comprises, in this case, reception antenna elements 305 and transmission antenna elements 307 coupled to the transceiver 303. The transceiver 303 is configured to receive a composite beam control signal S, e.g. from a control device 100 or from a previous communication node of a communication path, via the reception antenna elements 305. Further, the processor 301 is configured to derive antenna beam control information associated with the communication node 300 from the composite beam control signal S. Finally, the processor 301 is configured to control the beam of the reception antenna elements 305 and/or the beam of the transmission antenna elements 307 according to the derived antenna beam control information.

[0126] It is also shown in FIG. 3 how the composite beam control signal S is transmitted by the transceiver 303 via the transmission antenna elements 307 to the next node in the communication path according to an embodiment of the present invention.

[0127] FIG. 4 shows a corresponding method for a multi-hop communication system. The method comprises the step of receiving 401 a composite beam control signal S. Further, the method comprises the step of deriving 403antenna beam control information associated with the communication node from the composite beam control signal S. Finally, the method comprises the step of controlling 405 the beam of the reception antenna elements or the beam of the transmission antenna elements according to the antenna beam control information. The method may e.g. be executed in a communication node 300 of a multi-hop communication system.

[0128] According to an embodiment of the present invention, the composite beam control signal S can be described as:

S=Σ.sub.i=1.sup.NC.sub.i.Math.φ.sub.i,   (1)

[0129] where φ.sub.i is the beam forming information for communication node i=1, . . . , N, wherein i=1 is the index for the source communication node and i=N is the index for the destination communication node, and C.sub.i is a communication node identity associated with communication node i.

[0130] C.sub.i is node specific information so that node i will be able to only receive its own beam-forming information φ.sub.i and ignore beam-forming information which is intended for other nodes of the communication path. Therefore, C.sub.i can be an orthogonal code sequence and when node i receives the composite beam-forming signal, it can derive its own beam-forming information φ.sub.i by using the expression:

S.Math.C.sub.i=(Σ.sub.i=1.sup.NC.sub.i.Math.φ.sub.i).Math.C.sub.i=φ.sub.i   (2)

[0131] where φ.sub.i is the beam forming information for communication node i=1, . . . , N, wherein i=1 is the index for the source communication node and i=N is the index for the destination communication node, and C.sub.i is a communication node identity associated with communication node i.

[0132] FIG. 5 illustrates a multi-hop communication system 500 according to an embodiment of the present invention. In FIG. 5 the leftmost device is the control device 100 and there is a communication path from the source node to the destination node in the multi-hop communication system. In this particular example the control device 100 is a part of the source node. The control device 100 determines and generates beam-forming information for nodes of the communication path. In order to generate beam-forming information for the nodes of the communication path, the control device 100 needs knowledge of for example the position of the communication node, as well as the properties of the transmission antennas and/or the reception antennas. The control device 100 uses node specific spreading codes C.sub.i to spread the beam-forming information of node i. By summing up the beam-forming information after spreading the beam-forming information for the nodes of the communication path, the control device 100 generates the composite beam-forming signal S and sends it to the first intermediate node i=2 in this case since the control device 100 is part of the source node. On receiving the composite beam-forming signal S, the first intermediate node i=2 de-spreads the composite signal S with its own spreading code C.sub.2 and takes out the beam-forming information which is intended for itself, i.e. the first intermediate node. Therefore, according to an embodiment of the present invention, the communication node 300 identities C.sub.i, i=1, . . . , N, are orthogonal code sequences, i.e. they are all orthogonal to each other.

[0133] The processor 301 (or dedicated beam-forming circuitry) of the first intermediate node, based on the beam-forming information derived from the composite beam control signal S, tunes its transmission antenna beam accordingly towards the second intermediate node C.sub.3. In a similar manner, the first intermediate node can tune its reception antenna beam towards the previous node, i.e. the source node in this case.

[0134] The composite beam control signal S will be forwarded by the first intermediate node C.sub.2 to the second intermediate node C.sub.3, e.g. together with payload data which is to be transferred from the source node C.sub.1 to the destination node C.sub.N. The next intermediate node C.sub.i, upon receiving the composite beam control signal S, will execute the same dispreading operation as described above, and tune its antenna beam direction and forward the composite beam control signal S and the payload data as well to the next node in the communication path, and so on.

[0135] Hence, upon receiving the composite beam control signal S, each node will take out its own beamforming information and change its antenna beam direction accordingly by controlling the antenna elements, and forward/transmit the composite beam control signal S to the next node of the communication path in a receiving-forwarding manner. If necessary, the composite beam control signal S may be amplified when transmitted to the next node of the communication path.

[0136] The operation of taking out its own beam-forming information, performing its own beam-forming and of receiving-amplifying-forwarding signal S can be implemented such that only hardware circuitry is involved and therefore no need for digital processing involving processor, memory and software is needed. The hardware oriented implementation according to this embodiment can make the overall latency minimal since no latency of memory access and digital processing have to occur. Therefore, the processor 301 in this embodiment is a dedicated processing circuitry, and the antenna beam control information is derived by pure analogue signal processing instead of digital signal processing.

[0137] According to another embodiment of the present invention, the beam forming information t is phase information or phase shift information for the antenna elements of communication node i. According to yet another embodiment of the present invention, the phase shift information is a phase shift difference between neighbouring antenna elements, or a phase shift for each antenna element.

[0138] According to the above described embodiments beamforming for node i can be implemented as in the below example of Table 1. In this example there are four antenna elements for the transmission antenna of node i, and each antenna element can be assign one of eight possible phases and, e.g. φ.sub.i={000;001;010;011} will specify phases for the four antenna elements of node i as {0; π/8; π/4; 3π/8} according to Table 1.

TABLE-US-00001 TABLE 1 0 0 0 0 0 0 1  π/8 0 1 0  π/4 0 1 1 3π/8 1 0 0  π/2 1 0 1 5π/8 1 1 0 3π/4 1 1 1 7π/8

[0139] However, the beamforming information (or configuration) can instead be signalled as phase shift difference between neighbouring antenna elements rather than the phase shifts for each antenna element as described above. This is particular applicable when the antenna element placement is regular and the phase shift pattern is also regular such that only one base phase value and one (or a small number of) phase shift values are needed to control such regular structured antenna elements. It is in this case sufficient to signal one value for each dimension of the antenna array. For example, in a two dimensional antenna array the signal could comprise {π/8; 3π/4} to indicate that the phase shift between neighbouring elements in the x-dimension should be π/8 and the difference between neighbouring elements in the y-dimension should be 3π/4. This embodiment has the advantage that the amount of information in the configuration signal is independent of the number of antenna elements.

[0140] Furthermore, the operation of equations (1) and (2) above can be performed with conventional spreading and de-spreading operations with orthogonal code as in CDMA or WCDMA systems. Each node 300 in the communication path is assigned one unique orthogonal code, such that, after de-spreading, node i will only take out the beamforming information intended for itself, i.e. φ.sub.i. Further φ.sub.i is used to tune the antenna beam direction which is illustrated in FIG. 6.

[0141] FIG. 6 shows the method in an intermediate node i (300) of the communication path. Node i receives the composite beam-forming signal S, and the received composite beam-forming signal S is de-spread with spread code C.sub.i and the beam-forming information for node i (φ.sub.i) will be derived. As described above, the beamforming information may be phase information for each antenna element of the transmission antenna of node i. The beam direction of the node i transmission antenna will be tuned as to aim at the next intermediate node C.sub.1+1. Also the composite beamforming signal S will be relayed from node C.sub.i to node C.sub.i+1f through the communication path.

[0142] In an embodiment of the present invention, only the transmitting antenna of the node is regulated by the composite beam-forming signal and the receiving antenna of the node always assume omni-directional antenna beam or a wide antenna beam such that it can always receive signal from different direction. Since the reception quality of one radio link is impacted by both the transmission antenna and reception antenna, if the transmission antenna gain is high enough, omni-directional antenna can be used. One benefit of such arrangement is to have lower chance of miss-alignment of the transmission beam and reception beam. That is, with omni-directional reception antenna, only the transmission antenna beam direction needs to be optimized.

[0143] In another embodiment of the present invention, the receiver antenna of a node 300 switches to a configuration where it can receive from more than one direction, for example omni-directionally, when it is not receiving any transmission. This reception mode can be used both to initially detect a transmission and in case of failures where a new communication path has to be found. With the less directionally sensitive configuration of the receive antenna it is simpler for the receiving node to detect the antenna configuration signal.

[0144] In yet another embodiment of the present invention, the composite beam control signal S can be transmitted with different power levels for different nodes i of the communication path. If the control device knows beforehand that node i+1 will have a lower receiving antenna gain when receiving the composite beam control signal transmitted from node i, the control device can set the transmission power value higher for intermediate node i such that the transmission from node i to node i+1 will be successful. The transmission power values for intermediate nodes are pre-set by the control device 100 in the similar manner as for controlling the beam direction by the use of the composite beam control signal S. Therefore, according to this embodiment a single composite power level signal is generated by the control device 100 and transmitted to at least one node in the communication path. In one example the composite power level signal may be part of the composite beam control signal S. In another example the composite power level signal could be transmitted as a separate signal in the communication path depending on the application.

[0145] In an embodiment of the present invention, two nodes 300 can use the same code for spreading and de-spreading if these two nodes can be distinguished by the control node, e.g. by their geographic positions. This allows a geographical reuse of the codes which reduces the need for a very large code space. The constraint that is imposed on the positions is that no nodes with the same code should be on the same communication path. In network topologies where the communication paths are not very long this will be relatively simple to ensure by having a certain geographic distance between nodes with the same code. In networks where the possible topologies are quite simple, e.g. tree topology, it is also relatively simple to plan the code assignment so that there is no reuse of the same code on a single communication path.

[0146] A useful application of embodiments of the present invention is in the backhaul of a wireless network. It would typically be used on high frequency spectrum bands as it is in general more effective to implement beamforming on high frequency spectrum band, however the disclosed solution is not limited to any specific spectrum bands. With an increasing number of base stations in radio networks the backhaul is becoming more important and costly. Wireless backhaul is practical since it is in general cheaper to deploy than wired backhaul. With the present invention it is also possible to reconfigure the topology of the backhaul, which is an advantage in radio networks with a dense deployment of base stations where base stations may be powered on and off depending on variations in the traffic load.

[0147] Furthermore, any method according to the present invention may be implemented in a computer program, having code means, which when run 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.

[0148] It should however be remembered that some of the methods according to the present invention may be executed in hardware in the form of dedicated processing circuitry for reduced latency.

[0149] Moreover, it is realized by the skilled person that the present control device and communication node comprises the necessary 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, DSPs, MSDs, TCM encoder, TCM decoder, power supply units, power feeders, communication interfaces, communication protocols, etc. which are suitably arranged together for performing the present solution.

[0150] Especially, the processors of the present scheduler, sender, receiver and network nodes, may comprise, e.g., one or more instances of a Central Processing Unit (CPU), a processing unit, a processing circuit, a processor, 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.

[0151] 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.