Methods and apparatus for multi-carrier communication systems with adaptive transmission and feedback

Abstract

An arrangement is disclosed where in a multi-carrier communication system, the modulation scheme, coding attributes, training pilots, and signal power may be adjusted to adapt to channel conditions in order to maximize the overall system capacity and spectral efficiency without wasting radio resources or compromising error probability performance, etc.

What is claimed is: 
     
         1 . A receiving method by a first station served by a second station using one or more subchannels within a channel, the channel comprising a plurality of orthogonal frequency division duplex (OFDM) subcarriers and each subchannel of the one or more subchannels using multiple data OFDM subcarriers from the plurality of OFDM subcarriers of the channel, the method comprising:
 receiving, at the first station, control information from the second station, the control information indicating a first set of transmission parameters to be used for receiving a first transmission; and   receiving, at the first station, the first transmission, the first transmission having a first subchannel, a first modulation and coding scheme (MCS) of a plurality of MCSs, a first pilot pattern of a plurality of pilot patterns, and a first subchannel configuration of a plurality of subchannel configurations, wherein   the first subchannel configuration, the first MCS, and the first pilot pattern are determined based on the first set of transmission parameters; and   the first set of transmission parameters are based at least in part on first channel conditions.   
     
     
         2 . The receiving method of  claim 1 , wherein at least two of: the first subchannel configuration, the first MCS, and the first pilot pattern are determined from a single received transmission parameter. 
     
     
         3 . The receiving method of  claim 1 , wherein a single index value within the first set of transmission parameters indicates a modulation and a code rate of the first MCS. 
     
     
         4 . The receiving method of  claim 1 , wherein the first subchannel is from a plurality of subchannels in the channel, wherein the multiple data OFDM subcarriers of the first subchannel include a plurality of consecutive data OFDM subcarriers. 
     
     
         5 . The receiving method of  claim 1 , wherein the first set of transmission parameters indicates a multiple input multiple output (MIMO) scheme from a set of MIMO schemes. 
     
     
         6 . The receiving method of  claim 1 , further comprising:
 receiving, at the first station, second control information from the second station, the second control information indicating a second set of transmission parameters to be used for receiving a second transmission; and   receiving, at the first station, the second transmission, the second transmission having a plurality of subchannels, a second subchannel configuration, a second MCS, and a second pilot pattern, wherein the second subchannel configuration, the second MCS, and the second pilot pattern are determined based on the second set of transmission parameters, and wherein the second set of transmission parameters are based at least in part on second channel conditions.   
     
     
         7 . The receiving method of  claim 6 , further comprising:
 transmitting a respective channel quality information for each subchannel of the plurality of subchannels.   
     
     
         8 . The receiving method of  claim 6 , wherein a first ratio of pilot OFDM subcarriers to data OFDM subcarriers of the first transmission is different than a second ratio of pilot OFDM subcarriers to data OFDM subcarriers of the second transmission and further wherein the first pilot pattern is based on the first channel conditions and the second pilot pattern is based on the second channel conditions. 
     
     
         9 . The receiving method of  claim 8 , wherein the first ratio of pilot OFDM subcarriers and the second ratio of pilot OFDM subcarriers are based on minimizing pilot overhead. 
     
     
         10 . The receiving method of  claim 6 , wherein the second MCS is the same value as the first MCS. 
     
     
         11 . The receiving method of  claim 6 , wherein the second pilot pattern is applied at a user-based granularity, wherein the second pilot pattern spans multiple subchannels. 
     
     
         12 . The receiving method of  claim 6 , wherein OFDM subcarriers used for the first pilot pattern differ from OFDM subcarriers used for the second pilot pattern. 
     
     
         13 . The receiving method of  claim 6 , wherein the plurality of subchannels includes a first and second data OFDM subcarrier and the second subchannel configuration configures the plurality of subchannels such that the first and second data OFDM subcarrier are separated by multiple OFDM subcarriers in the channel that are not used to send data in the plurality of subchannels. 
     
     
         14 . The receiving method of  claim 1 , further comprising:
 receiving, at the first station, second control information from the second station, the second control information indicating a second set of transmission parameters to be used for receiving a second transmission; and   receiving, at the first station, the second transmission, the second transmission having at least the first subchannel, a second subchannel configuration, a second MCS, and a second pilot pattern, wherein the second subchannel configuration, the second MCS, and the second pilot pattern are determined based on the second set of transmission parameters, and wherein the second set of transmission parameters are based at least in part on second channel conditions.   
     
     
         15 . The receiving method of  claim 14 , wherein the channel includes a first OFDM subcarrier, the first OFDM subcarrier is used by the first subchannel to receive data in the first transmission using the first subchannel configuration; and the first OFDM subcarrier is not used by the first subchannel to receive data in the second transmission using the second subchannel configuration. 
     
     
         16 . The receiving method of  claim 14 , wherein OFDM subcarriers used for the first pilot pattern are the same as OFDM subcarriers used for the second pilot pattern and at least one OFDM subcarrier used for both the first and second pilot patterns has different amplitude and phase values as between the first and second pilot patterns. 
     
     
         17 . The receiving method of  claim 1 , wherein the first MCS is determined from a received index value of a set of index values, and wherein a first index value of the set of index values indicates a first MCS that uses QPSK and ½ code rate, a second index value of the set of index values indicates a second MCS that uses 16 QAM and ½ code rate, a third index value of the set of index values indicates a third MCS that uses 16 QAM and ¾ code rate, a fourth index value of the set of index values indicates a fourth MCS that uses 64 QAM and ⅔ code rate, and a fifth index value of the set of index values indicates a fifth MCS that uses 64 QAM and ⅚ code rate. 
     
     
         18 . The receiving method of  claim 1 , wherein the first channel conditions are detected at both the first station and the second station. 
     
     
         19 . The receiving method of  claim 1 , further comprising:
 transmitting channel quality information to the second station prior to receiving the control information, wherein the channel quality information is determined based on a probing sequence transmission.   
     
     
         20 . The receiving method of  claim 1 , further comprising:
 transmitting channel quality information to the second station prior to receiving the control information, wherein the channel quality information is explicitly transmitted from the first station to the second station and the channel quality information is a function of a signal level and a noise level.   
     
     
         21 . The receiving method of  claim 1 , further comprising:
 transmitting channel quality information to the second station prior to receiving the control information, wherein the channel quality information indicates information used to request transmission parameters and the first set of transmission parameters at least in part override the requested transmission parameters.   
     
     
         22 . The receiving method of  claim 1 , wherein the first transmission uses one of a plurality of available multiple antenna techniques, the available multiple antenna techniques including transmission diversity and multiple-input multiple-output (MIMO) and the multiple antenna technique used by the first transmission is determined based on the first set of transmission parameters. 
     
     
         23 . The receiving method of  claim 1 , wherein a single index determines the first pilot pattern, the first MCS, and the first subchannel configuration. 
     
     
         24 . The receiving method of  claim 1 , wherein the first set of transmission parameters are received on a separate control channel from the first transmission and the first set of transmission parameters has stronger error protection than the first transmission. 
     
     
         25 . The receiving method of  claim 1 , further comprising performing user-based power control that is determined based on user-specific power control information. 
     
     
         26 . The receiving method of  claim 1 , wherein the first subchannel configuration is based on the first channel conditions and a user profile. 
     
     
         27 . The receiving method of  claim 1 , wherein the first subchannel configuration determines an arrangement of the multiple data OFDM subcarriers of the first subchannel among OFDM subcarriers in the channel that are not used to send data in the first subchannel. 
     
     
         28 . The receiving method of  claim 27 , wherein a plurality of subchannel configurations includes the first subchannel configuration and a second subchannel configuration, the first subchannel configuration characterized by the arrangement of the multiple data OFDM subcarriers of the first subchannel such that the multiple data OFDM subcarriers of the first subchannel are adjacent within the channel and the second subchannel configuration characterized by an arrangement of the multiple data OFDM subcarriers of the first subchannel such that the multiple data OFDM subcarriers of the first subchannel are not adjacent within the channel. 
     
     
         29 . The receiving method of  claim 1 , wherein the plurality of OFDM subcarriers of the channel comprise at least one silent OFDM subcarrier and the OFDM subcarriers in the channel that are not used to send data in the first subchannel include the at least one silent OFDM subcarrier. 
     
     
         30 . The receiving method of  claim 29 , wherein the first subchannel configuration configures the multiple data OFDM subcarriers of the first subchannel such that a first and second data OFDM subcarrier within the first subchannel are separated by a single silent OFDM subcarrier within the channel.