Medium access control for orthogonal frequency-division multiple-access (OFDMA) cellular networks

DC CAFC

US 7,072,315 B1
Filed: 10/10/2000
Issued: 07/04/2006
Est. Priority Date: 10/10/2000
Status: Expired due to Fees

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1. A cellular network comprising:

a plurality of subscribers each of said subscribers communicating with one base station of a plurality of base stations using orthogonal frequency division multiple access (OFDMA);

each of said base stations having logic to coordinate multiple-access and information exchange between the base station and the plurality of subscribers, the logic selecting a set of OFDMA traffic channels from a plurality of candidate OFDMA traffic channels, based on feedback OFDMA channel information collected from the plurality of subscribers and OFDMA channel information collected from at least one of the other base stations, and in collaboration with said at least one other base station to provide joint OFDMA channel allocation to multiple ones of said plurality of subscribers.

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Abstract

A method and apparatus for controlling OFDMA cellular networks is described. In one embodiment, the method comprises receiving channel characteristics and noise-plus-interference information measured at spatially distributed subscribers and assigning traffic channels for an orthogonal frequency-division multiple-access (OFDMA) network.

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35 Claims

1. A cellular network comprising:
- a plurality of subscribers each of said subscribers communicating with one base station of a plurality of base stations using orthogonal frequency division multiple access (OFDMA);
  
  each of said base stations having logic to coordinate multiple-access and information exchange between the base station and the plurality of subscribers, the logic selecting a set of OFDMA traffic channels from a plurality of candidate OFDMA traffic channels, based on feedback OFDMA channel information collected from the plurality of subscribers and OFDMA channel information collected from at least one of the other base stations, and in collaboration with said at least one other base station to provide joint OFDMA channel allocation to multiple ones of said plurality of subscribers.
- View Dependent Claims (2, 3, 4, 5, 6)
- - 2. The network defined in claim 1 wherein the logic calculates spatial gains of uplink and downlink channels based on responses of spatially separated receivers at the base station.
  - 3. The network defined in claim 1 wherein the feedback information comprises channel fading information and noise and interference levels for each of the plurality of candidate OFDMA traffic channels.
  - 4. The network defined in claim 1 wherein the plurality of subscribers send the feedback information in response to a sounding signal from each of one or more of the base stations.
  - 5. The network defined in claim 1 wherein said logic selects a combination of modulation and coding schemes based on the SINR of the selected traffic channel for each accessing subscriber.
  - 6. The network defined in claim 1 wherein the logic comprises medium access control (MAC) logic.

7. A method comprising:
- sending sounding signals to a plurality of subscribers from a plurality of base stations;
  
  receiving, at each base station, channel condition information for a plurality of OFDMA traffic channels from at least one of said subscribers and at least one other base station; and
  
  performing OFDMA multi-user traffic channel assignment to assign OFDMA traffic channels from the plurality of OFDMA traffic channels to the plurality of subscribers, based on the OFDMA channel condition information received from at least one of said subscribers and at least one other of said base stations and estimated spatial gains for the uplink and downlink signals for the plurality of subscribers, and in collaboration with said at least one other of said base stations to provide joint OFDMA channel allocation to multiple ones of said plurality of subscribers.
- View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
- - 8. The method defined in claim 7 wherein the channel condition information comprises information regarding estimated channel gains and channel interference for the plurality of OFDMA traffic channels.
  - 9. The method defined in claim 7 wherein performing traffic channel assignment is based on channel conditions between one or more antennas at a base station and one or more antennas at subscriber locations.
  - 10. The method defined in claim 7 further comprising estimating spatial gains for uplink and downlink signals.
  - 11. The method defined in claim 10 further comprising estimating signal-to-noise-plus-interference rates (SINRs) for the uplink and downlink signals, and wherein performing channel assignment is based on the SINRs for the uplink and downlink signals.
  - 12. The method defined in claim 11 wherein estimating SINRs for the uplink and downlink signals is performed on all OFDMA traffic channels for all active and accessing subscribers.
  - 13. The method defined in claim 11 wherein performing channel assignment is based on quality of service (QoS) requirements.
  - 14. The method defined in claim 13 wherein the QoS requirements include one or more of the following:
    - data rate, time-out, bit error rate, and writing time.
  - 15. The method defined in claim 13 wherein performing channel assignment is based on priority.
  - 16. The method defined in claim 7 further comprising determining a combination of coding and modulation schemes when performing channel assignments.
  - 17. The method defined in claim 7 wherein performing traffic channel assignments comprises said plurality of base stations coordinating to perform the traffic channel assignment.
  - 18. The method defined in claim 17 wherein each of the plurality of base stations is within a cell and estimates SINRs for uplink and downlink signals across all OFDMA traffic channels for accessing subscribers.
  - 19. The method defined in claim 18 when the plurality of base stations perform estimates for active and accessing subscribers.
  - 20. The method defined in claim 7 wherein the sounding signal is omni-directional.
  - 21. The method defined in claim 7 wherein estimating spatial gains for uplink and downlink signals comprises:
    - estimating broadband spatial channels across the plurality of OFDMA traffic channels for each accessing subscriber;
      
      determining the spatial processing gains for uplink and downlink signals on each of the plurality of OFDMA traffic channels;
      
      predicting signal-to-noise-plus-interference ratio (SINR) for uplink and downlink transmission with spatial processing over each of available OFDMA traffic channels by adding the spatial processing gain to downlink signal strength feedback from one or more subscribers.

22. A method comprising:
- receiving, at one of a plurality of base stations, OFDMA channel characteristics and noise-plus-interference information measured at spatially distributed subscribers;
  
  receiving OFDMA channel characteristics information for at least one other base station; and
  
  assigning OFDMA traffic channels for an OFDMA network, based on received OFDMA channel characteristics and noise-plus-interference information measured at the spatially distributed subscribers and the OFDMA channel characteristics information from the at least one other base station, and in collaboration with at least said one other base station to provide joint OFDMA channel allocation to multiple ones of said subscribers.
- View Dependent Claims (23)
- - 23. The method defined in claim 22 wherein assigning traffic channels is performed for the OFDMA network that uses spatial multiplexing.

24. A method comprising:
- each of a plurality of subscribers estimating channel gains and noise-plus-interference levels of a set of OFDMA traffic channels in response to a sounding signal;
  
  the plurality of subscribers transmitting to a first base station measured OFDMA channel and noise-plus-interference information;
  
  receiving, by one of said subscribers, an allocation of one or more OFDMA traffic channels allocated, in response to the measured channel and noise-plus-interference information and OFDMA channel information from a plurality of base stations including a second base station other than the first base station, and in collaboration with at least said second base station to provide joint OFDMA channel allocation to multiple ones of said plurality of subscribers;
  
  at least one of the plurality of subscribers transmitting packets using one or more allocated OFDMA traffic channels.
- View Dependent Claims (25, 26)
- - 25. The method defined in claim 24 wherein the plurality of subscribers transmit the measured channel and noise-plus-interference information on pre-allocated channels.
  - 26. The method defined in claim 24 wherein the plurality of subscribers transmits the measured channel and noise-plus-interference information when paged or when one or more of the plurality of subscribers have a packet to transmit to the first base station.

27. An apparatus comprising:
- an OFDMA channel and noise-plus-interference estimator;
  
  an access signal generator coupled to the estimator;
  
  an OFDM modem coupled to the generator; and
  
  a radio frequency transmitter to transmit information on OFDMA traffic channels jointly allocated to a plurality of subscribers through a collaborative OFDMA channel assignment among multiple base stations.
- View Dependent Claims (28, 29, 30, 31)
- - 28. The apparatus defined in claim 27 wherein the estimator estimates channel gains and noise-plus-interference levels in a pre-determined set of traffic channels.
  - 29. The apparatus defined in claim 28 wherein the generator encodes channel and noise-plus-interference information to form an access signal.
  - 30. The apparatus defined in claim 29 wherein the OFDM modem modulates the access signal and transmits a modulated version of the access signal through an access channel.
  - 31. The apparatus defined in claim 30 wherein the access channel comprises at least a subset of all traffic channels during and access time slot.

32. An apparatus comprising:
- at least one spatially separated transceiver;
  
  an access signal detector and demodulator coupled to the at least one spatially separated transceivers;
  
  a spatial channel and spatial gain estimator;
  
  an uplink and downlink signal-to-noise-plus-interference estimator;
  
  a multi-user traffic channel allocator coupled to said estimators to determine OFDMA channel assignment based on broadband spatial channel estimates and measured OFDMA channel and noise-plus-interference information feedback from subscribers and from at least two base stations to provide joint OFDM channel allocation to multiple subscribers; and
  
  an OFDM modem coupled to the allocator.
- View Dependent Claims (33, 34)
- - 33. The apparatus defined in claim 32 wherein the allocator determines traffic channel assignment and a code and modulation combination for each accessing subscriber, and the OFDM modem modulates the traffic channel assignment and transmits a modulated version of the traffic channel assignment to at least one subscriber.
  - 34. The apparatus defined in claim 32 wherein the broadband spatial channel estimates comprise the broadband spatial channel between a base station and each accessing subscriber.

35. The apparatus defined in 32 wherein the access signal detector and demodulator detects access signals transmitted by subscribers and demodulates the measured channel and noise-plus-interference information feedback from subscribers.

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Current Assignee
Adaptix, Inc. (Acacia Research Corporation)
Original Assignee
Adaptix, Inc. (Acacia Research Corporation)
Inventors
Liu, Hui, Li, Xiaodong, Mu, Fuqi
Primary Examiner(s)
NGUYEN, STEVEN H D

Application Number

US09/685,977
Time in Patent Office

2,093 Days
Field of Search

370203-210, 370/329, 370/341, 370/348, 370/332, 375/147, 375/148, 375/260, 375/264, 375/346, 375/348, 455449-4522, 455463-464, 455/561, 455/69, 455/63.1, 455/67.13, 455/509, 455/512, 455/513
US Class Current

370/329
CPC Class Codes

H04L 1/0003   by switching between differ...

H04L 1/0009   by adapting the channel cod...

H04L 1/0026   Transmission of channel qua...

H04L 5/0007   the frequencies being ortho...

H04L 5/0023   Time-frequency-space

H04L 5/0037   Inter-user or inter-termina...

H04L 5/0046   Determination of how many b...

H04L 5/006   Quality of the received sig...

H04L 5/0064   Rate requirement of the dat...

H04W 48/16   Discovering, processing acc...

H04W 72/02   Selection of wireless resou...

H04W 72/0453   Resources in frequency doma...

H04W 72/541   using the level of interfer...

Medium access control for orthogonal frequency-division multiple-access (OFDMA) cellular networks

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35 Claims

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Medium access control for orthogonal frequency-division multiple-access (OFDMA) cellular networks

First Claim

11 Assignments

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Abstract

275 Citations

35 Claims

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