Method and system for switching antenna and channel assignments in broadband wireless networks

Abstract

A method and apparatus for antenna switching, grouping, and channel assignments in wireless communication systems. The invention allows multiuser diversity to be exploited with simple antenna operations, therefore increasing the capacity and performance of wireless communications systems. Channel characteristics indicative of signal reception quality for downlink or bi-directional traffic for each channel/antenna resource combination are measured or estimated at a subscriber. Corresponding channel characteristic information is returned to the base station. Channel characteristics information may also be measured or estimated for uplink or bi-directional signals received at each of multiple receive antenna resources. The base station employs channel allocation logic to assign uplink, downlink and/or bi-directional channels for multiple subscribers based on channel characteristics measured and/or estimated for the uplink, downlink and/or bi-directional channels.

What is claimed is: 
     
         1 . A method for assigning a plurality of channels to support communication between at least one subscriber and a base station in a broadband wireless network, the method comprising:
 obtaining, at the base station, at least one channel characteristic for each of the plurality of channels hosted by each of a plurality of antenna resources configured for communication on the plurality of channels, the at least one channel characteristic indicative of reception quality for a corresponding channel; and   assigning, at the base station, at least one of the plurality of channels to the at least one subscriber based on the at least one channel characteristic that is obtained, the obtaining of the at least one channel characteristic being accomplished, at least in part, by ranging operations performed by the at least one subscriber.   
     
     
         2 . The method of  claim 1 , wherein the at least one of the plurality of channels assigned includes one or more downlink channels for use with transmissions sent from the base station to the at least one subscriber. 
     
     
         3 . The method of  claim 1 , wherein the at least one of the plurality of channels assigned includes one or more uplink channels for use with transmissions sent from the at least one subscriber to the base station. 
     
     
         4 . The method of  claim 1 , wherein the at least one of the plurality of channels assigned includes one or more bi-directional link channels employed for both uplink and downlink transmissions between the base station and the at least one subscriber. 
     
     
         5 . The method of  claim 1 , wherein the a east one channel characteristic is measured by performing operations comprising:
 broadcasting a respective beacon signal from each of the plurality of antenna resources at the base station, each of the respective beacon signals including transmissions over the plurality of channels;   measuring channel characteristics indicative of signal quality for each of the plurality of channels at the at least one subscriber; and   sending data corresponding to the channel characteristics indicative of signal quality that are measured from the at least one subscriber to the base station.   
     
     
         6 . The method of  claim 5 , wherein the respective beacon signals that are broadcast from each of the plurality of antenna resources includes orthogonal frequency division multiple access (OFDMA) signals including OFDMA pilot symbols. 
     
     
         7 . The method of  claim 6 , further comprising using, at the at least one subscriber, information from pilot symbol periods and data periods to measure channel and interference information. 
     
     
         8 . The method of  claim 6 , wherein the OFDMA pilot symbols occupy an entire orthogonal frequency division multiplexing (OFDM) frequency bandwidth. 
     
     
         9 . The method of  claim 1 , wherein the plurality of antenna resources includes multiple individual antennas. 
     
     
         10 . The method of  claim 1 , wherein at least one of the plurality of antenna resources includes a set of antennas that are operated collectively to perform at least one of transmit and receive radio frequency transmissions. 
     
     
         11 . The method of  claim 1 , wherein the broadband wireless network supports OFDMA transmissions, and the plurality of channels include combinations of OFDMA subchannels and antenna resources. 
     
     
         12 . The method of  claim 11 , further comprising switching antennas by adjusting inputs to fast Fourier transform (FFT) blocks in an OFDMA transmitter module at a base-band. 
     
     
         13 . The method of  claim 11 , wherein each of the at least one subscriber is assigned to a single OFDMA channel, transmission for the single OFDMA channel being provided by a single antenna resource. 
     
     
         14 . The method of  claim 1 , wherein the assigning of the at least one of the plurality of channels is employed to assign respective channels for downlink and uplink transmissions. 
     
     
         15 . The method of  claim 5 , wherein the at least one channel characteristic measurement includes at least one of signal-to-interference plus noise ratio (SINR), carrier-to-interference plus noise ratio (CINR), and relative-signal strength indicator (RSSI) measurements. 
     
     
         16 . The method of  claim 5 , wherein the at least one channel characteristic measurement includes bit error rate (BER) measurements. 
     
     
         17 . The method of  claim 5 , wherein the at least one channel characteristic measurement includes Quality of Service (QoS) parameters. 
     
     
         18 . The method of  claim 1 , wherein the plurality of channels include at least one of channels and subchannels corresponding to at least one of a frequency division multiple access (FDMA), time division multiple access (TDMA), code division multiple access (CDMA), orthogonal frequency division multiple access (OFDMA), and space division multiple access (SDMA) channel schemes. 
     
     
         19 . The method of  claim 1 , further comprising:
 obtaining, periodically, updated channel characteristics for the at least one subscriber; and   reassigning at least one other channel for the at least one subscriber in view of the updated channel characteristics.   
     
     
         20 . A method for assigning a plurality of channels in a broadband wireless network, the method comprising:
 obtaining at least one channel characteristic for each of the plurality of channels hosted by at least one antenna resource of a plurality of antenna resources configured for communication, the at least one antenna resource being located at a base station, and the at least one channel characteristic being indicative of reception quality of at least one subscriber;   determining, at the base station, an available channel with the highest gain among the plurality of antenna resources, the determining of the available channel being based at least on one of the at least one channel characteristic and a plurality of available channels of the at least one antenna resource of the plurality of antenna resources; and   assigning, at the base station, at least one channel to the at least one subscriber, the assigning of the at least one channel being based at least on the determining of the available channel.   
     
     
         21 . The method of  claim 20 , wherein obtaining of the at east one channel characteristic comprises:
 measuring, at the at least one subscriber, the at least one channel characteristic; and   reporting the at least one channel characteristic measured at the at least one subscriber to the base station.   
     
     
         22 . The method of  claim 20 , wherein the obtaining of the at least one channel characteristic comprises:
 measuring, at the base station, the at least one channel characteristic.   
     
     
         23 . The method of  claim 22 , further comprising:
 receiving, at the base station, test data for one or more uplink channels from the at least one subscriber.   
     
     
         24 . The method of  claim 20 , wherein the determining of the available channel is performed for each of the at least one subscriber in the assigning of the at least one channel. 
     
     
         25 . The method of  claim 20 , further comprising:
 storing the obtained at least one channel characteristic, the at least one channel characteristic being updated on an ongoing basis; and   maintaining and updating the plurality of available channels of the at least one antenna resource on an ongoing basis to provide current channel allocation information.   
     
     
         26 . The method of  claim 20 , wherein the determining of the available channel comprises:
 selecting a channel of the plurality of available channels with the highest gain for each of the plurality of antenna resources;   determining whether the selected channel is available;   selecting another channel of the plurality of available channels with the next highest gain for each of the plurality of antenna resources if the selected channel is not available;   comparing the gains of the selected channel and the selected another channel; and   selecting one of the selected channel and the selected another channel with the highest gain for assignment to the at least one subscriber in response to the comparing of the gains of the selected channel and the selected another channel.   
     
     
         27 . A base station comprising:
 at least one antenna resource of a plurality of antenna resources for communication over a wireless communication system;   a transmission module configured to generate signals to transmit data over one of a downlink channel and a bi-directional channel via the at least one antenna resource to at least one subscriber;   a reception module configured to:
 receive data from signals at the at least one antenna resource; and 
 extract the data from the signals received at the at least one antenna resource over one of an uplink channel and the bi-directional channel from the at least one subscriber; and 
   channel allocation logic configured to:
 determine an available channel associated with a highest gain among the plurality of antenna resources, determination of the available channel being based on at least a plurality of available channels of the at least one antenna resource and at least one channel characteristic indicative of reception quality for a corresponding channel obtained at the base station; and 
 assign at least one of the uplink channel, the downlink channel, and the bi-directional channel to the at least one subscriber, assignment of the at least one of the uplink channel, the downlink channel, and the bi-directional channel being based on at least the determination of the available channel. 
   
     
     
         28 . The base station of  claim 27 , wherein the reception module is further configured to receive the at least one channel characteristic indicative of reception quality from the at least one subscriber, the at least one subscriber being configured to measure the at least one channel characteristic indicative of reception quality. 
     
     
         29 . The base station of  claim 27 , wherein the channel allocation logic is further configured to measure the at least one channel characteristic indicative of reception quality. 
     
     
         30 . The base station of  claim 29 , wherein the reception module is further configured to receive test data for the at least one uplink channel from the at least one subscriber. 
     
     
         31 . The base station of  claim 27 , further comprising:
 a channel profile register configured to store the at least one channel characteristics indicative of reception quality, the at least one channel characteristics indicative of reception quality being updated on an ongoing basis; and   a channel assignment register configured to maintain and update the plurality of available channels of the at least one antenna resource on an ongoing basis to provide current channel allocation information.   
     
     
         32 . The base station of  claim 27 , wherein assignment of the least one of the uplink channel, the downlink channel, and the bi-directional channel to the at least one subscriber includes:
 selection of a channel of the plurality of available channels with the highest gain for each of the plurality of antenna resources;   determination of whether the selected channel is available;   selection of another channel of the plurality of available channels with the next highest gain for each of the plurality of antenna resources if the selected channel is not available;   comparison of the gains of the selected channel and the selected another channel; and   selection of one of the selected channel and the selected another channel with the highest gain for assignment to the at least one subscriber in response to the comparison of the gains of the selected channel and the selected another channel.