Method and Apparatus for Medium Access Control for a Decentralized Network with Adapted Beamforming and Power Control

• US 20070002734A1
• Filed: 03/14/2006
• Published: 01/04/2007
• Est. Priority Date: 07/01/2005
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Laboratories America Inc (NEC Corporation)
• Inventors: Madihian, Mohammad, Wang, Xiaodong, Kim, Seung-Jun
• Granted Patent: US 7,529,222 B2
• Time in Patent Office: Days
• US Class Current: 370/229
• CPC Class Codes: H04B 7/0408 using two or more beams, i.e. beam diversity
• CPC Class Codes: H04W 28/18 Negotiating wireless communication parameters
• CPC Class Codes: H04W 52/346 distributing total power among users or channels
• CPC Class Codes: H04W 52/42 in systems with time, space, frequency or polarisation diversity
• CPC Class Codes: H04W 74/02 Hybrid access
• CPC Class Codes: H04W 74/08 Non-scheduled access, e.g. ALOHA hybrid access H04W74/02
• CPC Class Codes: H04W 80/00 Wireless network protocols or protocol adaptations to wireless operation
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks

Abstract

A method and apparatus for medium access control in a wireless ad hoc network is disclosed that takes advantage of physical layer properties to jointly and collectively optimize in a distributed fashion transmission parameters such as beam-patterns and transmit powers of all active links in the network. To resolve signal transmission contention, each potential link is associated with a persistence parameter and the persistence parameter is adapted locally, with no central control, to provide medium access for transmissions. Where a node contending for a transmission slot is unable to optimize its transmission parameters due to an invalidity condition or infeasibility condition, the persistence parameter is updated, preferably so as to reduce the probability of such conditions.

Claims

1. A method for medium access control in a distributed communication network, comprising:

associating a persistence parameter with a potential link between a transmitting node and a receiving node in the network;

determining as a function of said persistence parameter whether the transmitting node participates in contention for a transmission slot;

if said transmitting node participates in said contention for said transmission slot, computing adaptive transmission parameters for said transmitting node as a function of an invalidity condition and an infeasibility condition; and

transmitting from said transmitting node in the transmission slot using the computed adaptive transmission parameters if said invalidity condition and said infeasibility condition are met.

2. The method of claim 1 wherein if the invalidity condition is not met, the persistence parameter is updated using a first parameter that is a function of the existence of an invalid link.

3. The method of claim 2 wherein the persistence parameter is updated according to the equation r=r−

β

₁r<sup>α

−

1</sup> where r is the persistence parameter and β

₁ is the first parameter and α

is a parameter greater than 0.

4. The method of claim 1 wherein if the infeasibility condition is not met, the persistence parameter is updated using a second parameter weighting the penalty due to an infeasible link.

5. The method of claim 4 wherein the persistence parameter is updated in accordance with r=r−

β

₂r<sup>α

−

1</sup> where r is the persistence parameter and β

₂ is the second parameter and α

is a parameter greater than 0.

6. The method of claim 1 wherein the persistence parameter is updated if the transmitting node fails to participate in the contention for the transmission slot.

7. The method of claim 1 wherein the persistence parameter represents a probability of the transmitting node participating in the contention for the transmission slot.

8. The method of claim 1 wherein at least one of said transmitting node and said receiving node comprise multiple antennas and wherein the adaptive transmission parameters include parameters for adaptive beamforming.

9. The method of claim 1 wherein at least one of said transmitting node and said receiving node comprise multiple antennas and wherein the adaptive transmission parameters include parameters for power control.

10. The method of claim 1 wherein at least one of said transmitting node and said receiving node compute the adaptive transmission parameters using an iterative mean square error procedure.

11. Apparatus for medium access control in a distributed communication network, comprising:

means for associating a persistence parameter with a potential link between a transmitting node and a receiving node in the network;

means for determining as a function of said persistence parameter whether the transmitting node participates in contention for a transmission slot;

means for computing adaptive transmission parameters for said transmitting node if said transmitting node participates in said contention for said transmission slot, said adaptive transmission parameters computed as a function of an invalidity condition and an infeasibility condition; and

means for transmitting from said transmitting node in the transmission slot using the computed adaptive transmission parameters if said invalidity condition and said infeasibility condition are met.

12. The apparatus of claim 11 further comprising means for updating said persistence parameter using a first parameter that is a function of the existence of an invalid link if the invalidity condition is not met.

13. The apparatus of claim 12 further comprising means for updating said persistence parameter according to the equation r=r−

β

₁r<sup>α

−

1</sup> where r is the persistence parameter and β

₁ is the first parameter and α

is a parameter greater than 0.

14. The apparatus of claim 11 further comprising means for updating said persistence parameter using a second parameter weighting the penalty due to an infeasible link if the infeasibility condition is not met.

15. The apparatus of claim 14 further comprising means for updating said persistence parameter according to r=r−

β

₂r<sup>α

−

1</sup> where r is the persistence parameter and β

₂ is the second parameter and α

is a parameter greater than 0.

16. The apparatus of claim 11 further comprising means for updating said persistence parameter if the transmitting node fails to participate in the contention for the transmission slot.

17. The apparatus of claim 11 wherein the persistence parameter represents a probability of the transmitting node participating in the contention for the transmission slot.

18. The apparatus of claim 11 wherein at least one of said transmitting node and said receiving node comprise multiple antennas and wherein the adaptive transmission parameters include parameters for adaptive beamforming.

19. The apparatus of claim 11 wherein at least one of said transmitting node and said receiving node comprise multiple antennas and wherein the adaptive transmission parameters include parameters for power control.

20. The apparatus of claim 11 wherein at least one of said transmitting node and said receiving node compute the adaptive transmission parameters using an iterative mean square error procedure.

21. A computer readable medium storing computer program instructions which, when executed on a processor, define the steps of:

associating a persistence parameter with a potential link between a transmitting node and a receiving node in the network;

determining as a function of said persistence parameter whether the transmitting node participates in contention for a transmission slot;

if said transmitting node participates in said contention for said transmission slot, computing adaptive transmission parameters for said transmitting node as a function of an invalidity condition and an infeasibility condition; and

transmitting from said transmitting node in the transmission slot using the computed adaptive transmission parameters if said invalidity condition and said infeasibility condition are met.

22. The computer readable medium of claim 21 further comprising program instructions which, when executed on a processor, define the step of:

if the invalidity condition is not met, updating said persistence parameter using a first parameter that is a function of the existence of an invalid link.

23. The computer readable medium of claim 22 wherein the persistence parameter is updated according to the equation r=r−

β

₁r<sup>α

−

1</sup> where r is the persistence parameter and β

₁ is the first parameter and α

is a parameter greater than 0.

24. The computer readable medium of claim 21 further comprising program instructions which, when executed on a processor, define the step of:

if the infeasibility condition is not met, updating the persistence parameter using a second parameter weighting the penalty due to an infeasible link.

25. The computer readable medium of claim 24 wherein the persistence parameter is updated in accordance with r=r−

β

₂r<sup>α

−

1</sup> where r is the persistence parameter and β

₂ is the second parameter and α

is a parameter greater than 0.

26. The computer readable medium of claim 21 further comprising program instructions which, when executed on a processor, define the step of:

updating said persistence parameter if the transmitting node fails to participate in the contention for the transmission slot.

27. The computer readable medium of claim 21 wherein the persistence parameter represents a probability of the transmitting node participating in the contention for the transmission slot.

28. The computer readable medium of claim 21 wherein at least one of said transmitting node and said receiving node comprise multiple antennas and wherein the adaptive transmission parameters include parameters for adaptive beamforming.

29. The computer readable medium of claim 21 wherein at least one of said transmitting node and said receiving node comprise multiple antennas and wherein the adaptive transmission parameters include parameters for power control.

30. The computer readable medium of claim 21 wherein at least one of said transmitting node and said receiving node compute the adaptive transmission parameters using an iterative mean square error procedure.