Adaptive multicarrier wireless communication system, apparatus and associated methods

• US 20050031047A1
• Filed: 12/16/2003
• Published: 02/10/2005
• Est. Priority Date: 08/08/2003
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Intel Corporation
• Inventors: Maltsev, Alexander A., Rubtsov, Alexey E., Sadri, Ali S., Tiraspolsky, Sergey A.
• Granted Patent: US 7,286,609 B2
• Time in Patent Office: Days
• US Class Current: 375/260
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/0212 of impulse response
• CPC Class Codes: H04L 25/022 of frequency response
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/0042 intra-user or intra-terminal allocation
• CPC Class Codes: H04L 5/0046 Determination of how many bits are transmitted on different sub-channels
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04L 5/006 Quality of the received signal, e.g. BER, SNR, water filling
• CPC Class Codes: H04L 5/0085 when channel conditions change
• CPC Class Codes: H04L 5/0096 Indication of changes in allocation
• 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

Abstract

An adaptive multicarrier wireless communication system, apparatus and associated methods are generally disclosed herein.

Claims

1. A method comprising:

receiving channel state information associated with a multicarrier wireless communication channel having a plurality of subcarriers, wherein the channel is processed to identify active subcarriers and initial power distribution among the subcarriers; and

selecting a bit loading and final power distribution for use in subsequent processing of the subcarriers of the communication channel based, at least in part, on the received channel state information, wherein the bit loading and final power distribution increases channel throughput while guaranteeing a channel quality metric among active subcarriers.

2. A method according to claim 1, wherein identification of active subcarriers and power distribution in the multicarrier wireless communication channel was initially established using a water-filling technique.

3. A method according to claim 2, the water-filling technique comprising:

sorting the subcarriers according to a channel performance metric;

identifying as a threshold among the sorted subcarriers a subcarrier that fails to meet the channel performance metric, wherein the subcarriers above or below the threshold are identified as bad subcarriers;

deactivating the bad subcarriers; and

distributing the available power among active subcarriers of the communication channel.

4. A method according to claim 3, wherein the channel state information is received from a remote device.

5. A method according to claim 4, the channel state information comprising one or more channel processing parameters including bit loading, coding type, modulation type and power allocation, determined by the remote device.

6. A method according to claim 4, wherein the channel state information is representative of one or more of channel performance characteristics and channel quality characteristics.

7. A method according to claim 6, wherein the channel performance characteristics include radio frequency (RF) characteristics comprising one or more of a received signal strength indication (RSSI), a signal to noise ratio (SNR), a signal to interference and noise ratio (SINR), fading characteristic(s), and Doppler characteristics.

8. A method according to claim 6, wherein the channel quality characteristics include one or more of a bit-error rate (BER), a packet-error rate (PER), a symbol-error rate (SER), and a frame error rate (FER).

9. A method according to claim 4, the element of selecting a bit loading and final power distribution comprising:

identifying among the active subcarriers, those which exceed a channel quality performance threshold;

calculating an excess power value by determining how much power could be reduced in the identified subcarriers so that they still meet, but do not exceed, the channel quality performance threshold; and

applying at least a subset of the excess power from higher-rate subsets of subcarriers to subcarriers in lower-rate subsets.

10. A method according to claim 9, wherein applying the excess power value from higher-rate subsets comprises applying the excess power to deactivated subcarriers in lower-rate subsets to increase a number of active subcarriers, and channel throughput.

11. A method according to claim 9, further comprising:

modifying at least a subset of initial power coefficients to reactivate one or more subcarriers which were initially deactivated.

12. A method according to claim 3, wherein the channel state information is received from a local receiver and is representative of an estimate of a channel transfer function.

13. A method according to claim 12, wherein the channel transfer function is one or more of channel transfer function estimate in the frequency domain and a channel transfer function estimate in the time domain based on receipt of a wireless signal transmit from a remote device.

14. A method according to claim 1, the element of selecting a bit loading and final power distribution comprising:

identifying among the active subcarriers, those which exceed a channel quality performance threshold;

calculating an excess power value by determining how much power could be reduced in the identified subcarriers so that they still meet, but do not exceed, the channel quality performance threshold; and

applying at least a subset of the excess power from higher-rate subsets of subcarriers to subcarriers in lower-rate subsets.

15. A method according to claim 14, wherein applying the excess power value from higher-rate subsets comprises applying the excess power to deactivated subcarriers in lower-rate subsets to increase a number of active subcarriers, and channel throughput.

16. A method according to claim 14, further comprising:

modifying at least a subset of a plurality of power coefficients applied to the subcarriers to reactivate one or more subcarriers which were initially deactivated.

17. A method according to claim 1, further comprising:

modifying at least a subset of power coefficients applied to a plurality of subcarriers comprising the multicarrier communication channel in support of the bit loading and final power distribution reactive at least a subset of subcarriers that were initially deactivated.

18. A method according to claim 1, further comprising:

issuing a message to a remote transmitter to apply the bit loading and final power distribution to subsequent processing of the multicarrier communication channel.

19. A storage medium comprising content which, when executed by an accessing device, causes the device to implement a method according to claim 1.

20. An apparatus comprising:

a transceiver, to establish a multicarrier communication channel with a remote transceiver; and

a subcarrier management agent (SMA), coupled with the transceiver, to receive channel state information associated with a multicarrier wireless communication channel having a plurality of subcarriers, wherein the channel is processed to identify active subcarriers and initial power distribution among the subcarriers, and to select a bit loading and final power distribution for use in subsequent processing of the subcarriers of the communication channel based, at least in part, on the received channel state information, wherein the bit loading and final power distribution increases channel throughput while guaranteeing a channel quality metric among active subcarriers.

21. An apparatus according to claim 20, wherein the SMA employs a water-filling technique to identify active subcarriers and power distribution in the multicarrier wireless communication channel.

22. An apparatus according to claim 21, wherein the SMA sorts the subcarriers according to a channel performance metric, identifies as a threshold among the sorted subcarriers a subcarrier that fails to meet the channel performance metric, wherein the subcarriers above or below the threshold are identified as bad subcarriers, deactivates the identified bad subcarriers, and distributes the available power among active subcarriers of the communication channel.

23. An apparatus according to claim 22, the channel state information comprising one or more channel processing parameters including bit loading, coding type, modulation type and power allocation, determined by the remote device.

24. An apparatus according to claim 22, wherein the channel state information is representative of one or more of channel performance characteristics and channel quality characteristics.

25. An apparatus according to claim 24, wherein the channel performance characteristics include radio frequency (RF) characteristics comprising one or more of a received signal strength indication (RSSI), a signal to noise ratio (SNR), a signal to interference and noise ratio (SINR), fading characteristic(s), and Doppler characteristics.

26. An apparatus according to claim 24, wherein the channel quality characteristics include one or more of a bit-error rate (BER), a packet-error rate (PER), a symbol-error rate (SER), and a frame error rate (FER).

27. An apparatus according to claim 22, wherein the SMA identifies, among the active subcarriers, those which exceed a channel quality performance threshold, calculates how much power could be reduced in the identified subcarriers so that they still meet, but do not exceed, the channel quality performance threshold to identify an excess power level, and applies at least a subset of the excess power from higher-rate subsets of subcarriers to subcarriers in lower-rate subsets.

28. An apparatus according to claim 27, wherein the SMA selectively applies at least a subset of the excess power value identified in one or more higher-rate subsets to deactivated subcarriers in lower-rate subsets to increase a number of active subcarriers, and channel throughput.

29. An apparatus according to claim 28, wherein the SMA dynamically generates updated power coefficients to replace at least a subset of initial power coefficients, and selectively applies the updated coefficients to a weighting element of the transmitter.

30. An apparatus according to claim 20, wherein the SMA identifies, among the active subcarriers, those which exceed a channel quality performance threshold, calculates how much power could be reduced in the identified subcarriers so that they still meet, but do not exceed, the channel quality performance threshold to identify an excess power level, and applies at least a subset of the excess power from higher-rate subsets of subcarriers to subcarriers in lower-rate subsets.

31. An apparatus according to claim 30, wherein the SMA dynamically generates control content comprising one or more of a bit distribution mask, a coding type, a modulation and power allocation coefficients for application to one or more elements of the transceiver.

32. An apparatus according to claim 30, wherein the SMA selectively applies at least a subset of the excess power value identified in one or more higher-rate subsets to deactivated subcarriers in lower-rate subsets to increase a number of active subcarriers, and channel throughput.

33. A system comprising:

one or more dipole antenna(e);

a transceiver, selectively coupled to one or more of the antenna(e), to establish a multicarrier communication channel with a remote transceiver; and

a subcarrier management agent (SMA), coupled with the transceiver, to receive channel state information associated with a multicarrier wireless communication channel having a plurality of subcarriers, wherein the channel is processed to identify active subcarriers and initial power distribution among the subcarriers, and to select a bit loading and final power distribution for use in subsequent processing of the subcarriers of the communication channel based, at least in part, on the received channel state information, wherein the bit loading and final power distribution increases channel throughput while guaranteeing a channel quality metric among active subcarriers.

34. A system according to claim 33, wherein the SMA employs a water-filling technique to identify active subcarriers and power distribution in the multicarrier wireless communication channel.

35. A system according to claim 33, the channel state information comprising one or more channel processing parameters including bit loading, coding type, modulation type and power allocation, determined by the remote device.

36. A system according to claim 33, wherein the channel state information is representative of one or more of channel performance characteristics and channel quality characteristics.

37. A system according to claim 36, wherein the channel performance characteristics include radio frequency (RF) characteristics comprising one or more of a received signal strength indication (RSSI), a signal to noise ratio (SNR), a signal to interference and noise ratio (SINR), fading characteristic(s), and Doppler characteristics.

38. A system according to claim 36, wherein the channel quality characteristics include one or more of a bit-error rate (BER), a packet-error rate (PER), a symbol-error rate (SER), and a frame error rate (FER).

39. A system according to claim 33, wherein the SMA identifies, among the active subcarriers, those which exceed a channel quality performance threshold, calculates how much power could be reduced in the identified subcarriers so that they still meet, but do not exceed, the channel quality performance threshold to identify an excess power level, and applies at least a subset of the excess power from higher-rate subsets of subcarriers to subcarriers in lower-rate subsets.

40. A system according to claim 39, wherein the SMA selectively applies at least a subset of the excess power value identified in one or more higher-rate subsets to deactivated subcarriers in lower-rate subsets to increase a number of active subcarriers, and channel throughput.

41. A storage medium comprising content which, when executed by an accessing device, enables the device to selectively receive channel state information associated with a multicarrier wireless communication channel having a plurality of subcarriers, wherein the channel is processed to identify active subcarriers and initial power distribution among the subcarriers, and to select a bit loading and final power distribution for use in subsequent processing of the subcarriers of the communication channel based, at least in part, on the received channel state information, wherein the bit loading and final power distribution increases channel throughput while guaranteeing a channel quality metric among active subcarriers.

42. A storage medium according to claim 41, further comprising content which, when executed causes the accessing device to implement a water-filling technique to identify active subcarriers and initial power distribution in the multicarrier wireless communication channel.

43. A storage medium according to claim 41, the element of selecting a bit loading and final power distribution comprising:

identifying among the active subcarriers, those which exceed a channel quality performance threshold;

calculating an excess power value by determining how much power could be reduced in the identified subcarriers so that they still meet, but do not exceed, the channel quality performance threshold; and

applying at least a subset of the excess power from higher-rate subsets of subcarriers to subcarriers in lower-rate subsets.

44. A storage medium according to claim 43, wherein applying the excess power value from higher-rate subsets comprises applying the excess power to deactivated subcarriers in lower-rate subsets to increase a number of active subcarriers, and channel throughput.