Method, apparatus and computer program product providing randomized relay network
View Patent ↗A relay node is provided for being interposed between at least one source node and at least one destination node. The relay node includes a receiver, a transmitter and a control unit. A transmission signal transmitted by the at least one source node is received by the relay node and modified by the control unit in a substantially pseudo-random manner to generate a time-varying signal that is transmitted by the relay node to the at least one destination node.
1. A relay node for being interposed between at least one source node and at least one destination node, comprising:
a data processor; and
a memory storing computer program code, the memory and the computer program code being configured to, with the data processor, cause the relay node at least to perform:
receive a transmission signal from the at least one source node; and
modify the received transmission signal in a substantially pseudo-random manner to generate a time-varying signal that is to be transmitted by the relay node to the at least one destination node, wherein a complex channel h 23 between the relay node (node 2 ) and the at least one destination node (node 3 ) is modified at a time slot t to:
{tilde over (h)} 23 [t ]=√{square root over ( p 2 [t ])} w 2 [t]h 23
where p 2 [t] is a transmit power of the relay node and w 2 [t] is a unit-power complex-valued coefficient applied at the relay node.
2. The relay node of claim 1 , wherein the relay node comprises an in-band relay node.
3. The relay node of claim 1 ,
wherein the relay node is a first relay node (node 2 ),
wherein the time-varying signal is a first time-varying signal,
wherein a second relay node (node 4 ) comprising a receiver, a transmitter and a control unit receives the transmission signal transmitted by the at least one source node,
wherein the control unit of the second relay node modifies the received transmission signal in a substantially pseudo-random manner to generate a second time-varying signal that is transmitted by the second relay node to the at least one destination node, and
wherein a complex channel h 43 between the second relay node (node 4 ) and the at least one destination node (node 3 ) is modified at a time slot t to:
{tilde over (h)} 43 [t ]=√{square root over ( p 4 [t ])} w 4 [t]h 43
where p 4 [t] is a transmit power of the second relay node and w 4 [t] is a unit-power complex-valued coefficient applied at the relay node.
4. The relay node of claim 3 , wherein p 2 [t]≠ p 4 [t].
5. The relay node of claim 4 , wherein w 2 [t]≠ w 4 [t].
6. The relay node of claim 3 , wherein w 2 [t]≠ w 4 [t].
7. The relay node of claim 1 , wherein there is a plurality of relay nodes, wherein a k th relay node modifies the transmission signal at slot/symbol t with a k,t th element of a matrix W, wherein each relay node of the plurality of relay nodes has knowledge of its corresponding row in the matrix.
8. The relay node of claim 7 , wherein at least two matrix elements of the matrix W are different for at least two subcarriers.
9. The relay node of claim 1 , wherein the relay node comprises a plurality of transmit antennas.
10. The relay node of claim 1 , wherein a relay input signal and a relay output signal are in substantially orthogonal channels.
11. The relay node of claim 1 , wherein the transmission signal is modified by the control unit in the substantially pseudo-random manner in accordance with a pattern.
12. The relay node of claim 11 , wherein the pattern is controlled by an external agency.
13. The relay node of claim 1 , wherein the substantially pseudo-random manner comprises time-varying a transmission power at the at least one relay node.
14. The relay node of claim 13 , wherein the substantially pseudo-random manner further comprises time-varying a phase of the transmitted signal.
15. The relay node of claim 1 , wherein the transmission signal is varied in a cyclostationary manner.
16. The relay node of claim 1 , wherein the relay node comprises a transceiver that operates in a relay mode when not fully occupied with other tasks.
17. The relay node of claim 1 , wherein the relay node operates half duplex using at least two time slots.
18. The relay node of claim 1 , wherein the relay node operates half duplex using at least two frequency bands.
19. The relay node of claim 1 , wherein at least one frequency offset is utilized at the relay node.
20. The relay node of claim 19 ,
wherein the relay node is a first relay node,
wherein the time-varying signal is a first time-varying signal,
wherein the at least one frequency offset is a first frequency offset,
wherein a second relay node comprising a receiver, a transmitter and a control unit receives the transmission signal transmitted by the at least one source node,
wherein the control unit of the second relay node modifies the received transmission signal in a substantially pseudo-random manner to generate a second time-varying signal that is transmitted by the second relay node to the at least one destination node,
wherein a second frequency offset is utilized at the second relay node, and
wherein the first frequency offset is different from the second frequency offset.
21. The relay node of claim 1 , wherein power selection is controlled by an external agency.
22. The relay node of claim 1 , wherein node selection is controlled by an external agency.
23. The relay node of claim 1 , wherein at least one transmission channel parameter is determined by a scheduling unit.
24. The relay node of claim 1 , wherein at least one scheduling criterion is utilized to schedule the transmission of the transmission signal.
25. The relay node of claim 24 , wherein the scheduling of the transmission signal comprises temporal scheduling.
26. The relay node of claim 25 , wherein the scheduling of the transmission signal further comprises frequency scheduling.
27. The relay node of claim 24 , wherein the scheduling of the transmission signal comprises frequency scheduling.
28. The relay node of claim 1 , wherein proportionally fair scheduling is employed.
29. The relay node of claim 1 , wherein delay-differentiated scheduling is employed.
30. The relay node of claim 1 , wherein an assignment algorithm is employed.
31. The relay node of claim 1 , wherein at least one transmission channel parameter is signaled to the at least one source node from the at least one destination node.
32. The relay node of claim 31 , wherein the relay node is enabled to decode the signaled at least one transmission channel parameter and wherein the relay node is enabled to modulate a transmit power of the relay node in response to the decoded signaled at least one transmission channel parameter.
33. The relay node of claim 1 , wherein at least one control signal is utilized to determine an activity value of the relay node.
34. A relay node for being interposed between at least one source node and at least one destination node, comprising:
a data processor; and
a memory storing computer program code, the memory and the computer program code being configured to, with the data processor, cause the relay node at least to perform:
receive a transmission signal transmitted from the at least one source node; and
modify the received transmission signal to generate a time-varying signal that is to be transmitted by the relay node to the at least one destination node,
wherein a complex channel h 23 between the relay node (node 2 ) and the at least one destination node (node 3 ) is modified at a time slot t to:
{tilde over (h)} 23 [t ]=√{square root over ( p 2 [t ])} w 2 [t]h 23
where p 2 [t] is a transmit power of the relay node and w 2 [t] is a unit-power complex-valued coefficient applied at the relay node, and
wherein factors √{square root over (p 2 [t])}w 2 [t] are selected such that a received signal power is made to combine coherently at the at least one destination node and a received noise power is made to combine incoherently at the at least one destination node.
35. A relay device comprising: control means coupled to receiver means and transmitter means, said control means for modifying a received signal in a substantially pseudo-random manner to generate a time-varying signal that is to be transmitted by the transmitter means, wherein a complex channel h 23 between the relay device (node 2 ) and at least one destination node (node 3 ) is modified at a time slot t to:
{tilde over (h)} 23 [t ]=√{square root over ( p 2 [t ])} w 2 [t]h 23
where p 2 [t] is a transmit power of the relay device and w 2 [t] is a unit-power complex-valued coefficient applied at the relay device.
36. The relay node of claim 35 , wherein factors √{square root over (p 2 [t])}w 2 [t] are selected such that a received signal power is made to combine coherently at the at least one destination node and a received noise power is made to combine incoherently at the at least one destination node.
37. A wireless communication system comprising a plurality of relay nodes interposed between at least one source node and at least one destination node, wherein each relay node of the plurality of relay nodes comprises a data processor and a memory storing computer program code, the memory and the computer program code being configured to, with the data processor, cause the relay node at least to perform:
receive a transmission signal; and
modify the received transmission signal in a substantially pseudo-random manner to generate a time-varying signal that is to be transmitted by the relay node performing the modification, wherein the relay node comprises an in-band relay node, wherein a complex channel h 23 between the relay node (node 2 ) and the at least one destination node (node 3 ) is modified at a time slot t to:
{tilde over (h)} 23 [t ]=√{square root over ( p 2 [t ])} w 2 [t]h 23
where p 2 [t] is a transmit power of the relay node and w 2 [t] is a unit-power complex-valued coefficient applied at the relay node.
38. The wireless communication system of claim 37 , wherein a relay input signal and a relay output signal are in substantially orthogonal channels.
39. A method for relaying a signal comprising:
receiving, by a relay node, a transmission signal from at least one source node, wherein the relay node is interposed between the at least one source node and at least one destination node; and
modifying, by the relay node, the received transmission signal in a substantially pseudo-random manner to generate a time-varying signal that is to be transmitted by the relay node to the at least one destination node, wherein a complex channel h 23 between the relay node (node 2 ) and the at least one destination node (node 3 ) is modified at a time slot t to:
{tilde over (h)} 23 [t ]=√{square root over ( p 2 [t ])} w 2 [t]h 23
where p 2 [t] is a transmit power of the relay node and w 2 [t] is a unit-power complex-valued coefficient applied at the relay node.
40. The method of claim 39 , wherein the received transmission signal is modified in a substantially pseudo-random manner in accordance with a pattern.
41. The method of claim 39 , wherein the received transmission signal is modified in a cyclostationary manner.
42. The method of claim 39 , further comprising: transmitting the time-varying signal.
43. The method of claim 42 , wherein the transmission signal and the transmitted time-varying signal are in substantially orthogonal channels.
44. A non-transitory computer-readable medium storing program instructions, execution of the program instructions by a relay node resulting in operations comprising:
receiving a transmission signal from at least one source node, wherein the relay node is interposed between the at least one source node and at least one destination node; and
modifying the received transmission signal in a pseudo-random manner to generate a time-varying signal that is to be transmitted by the relay node to the at least one destination node, wherein a complex channel h 23 between the relay node (node 2 ) and the at least one destination node (node 3 ) is modified at a time slot t to:
{tilde over (h)} 23 [t ]=√{square root over ( p 2 [t ])} w 2 [t]h 23
where p 2 [t] is a transmit power of the relay node and w 2 [t] is a unit-power complex-valued coefficient applied at the relay node.
45. The computer-readable medium of claim 43 , wherein the received transmission signal is modified in a cyclostationary manner.
46. The computer-readable medium of claim 43 , execution of the program instructions resulting in operations further comprising: transmitting the time-varying signal.
47. The computer-readable medium of claim 46 , wherein the transmission signal and the transmitted time-varying signal are in substantially orthogonal channels.