Method and apparatus for rate adaptation in a wireless communication system

A method for selection of a Modulation and Coding Selection (MCS) from a plurality of available MCS in a wireless communications system, the method having the steps:

• obtaining a derived signal to noise ratio (SNR_d);
• establishing threshold values SNR_high, SNR_low;
• if SNR_d>SNR_high, selecting the highest MCS;
• if SNR_d<SNR_low, selecting the lowest MCS;
• if SNR_high>SNR_d>SNR_low, selecting MCS based on:
• obtaining a table of the product of f(MCS) and f_m corresponding to each MCS, where f(MCS) is an estimate of throughput in the absence of collisions or interference, and f_m is a correction factor for the effects of collisions or interference;
• selecting the MCS that maximizes said product of f(MCS) and f_m;
• and where said method of selection repeats when a change in SNR_d is detected.

A method for the selection of a particular Modulation and Coding Selection (MCS) from a plurality of available MCS in a wireless communications system, the method having the steps:

• obtaining a derived signal to noise ratio (SNR_d);
• establishing threshold values SNR_high, SNR_low;
• if SNR_d>SNR_high, selecting the highest MCS;
• if SNR_d<SNR_low, selecting the lowest MCS;
• if SNR_high>SNR_d>SNR_low, selecting MCS based on:
• obtaining a table of the product of f(MCS) and f_m corresponding to each MCS, where f(MCS) is an estimate of throughput in the absence of collisions or interference, and f_m is a correction factor for the effects of collisions or interference;
• selecting the MCS that maximizes said product of f(MCS) and f_m;
• said plurality of MCS including at least a modulation type and a coding rate where
• f
• ⁡
• (
• MCS
• )
• =
• 1
• -
• PER
• ⁡
• (
• length
• packet
• ,
• MCS
• ,
• H
• hat
• ,
• nosie
• power
• )
• length_packet
• ⁢
• (
• packet
• size
• ,
• MCS
• )
• where f(MCS) is an estimated throughput for a particular MCS in the absence of collisions or interference and where:
• PER is a packet error rate;
• length_packet is the length of the packet;
• MCS is a particular Modulation and Coding Selection;
• H_hat is an estimate of channel matrix H;
• Noise power is an estimated noise level in the absence of collisions or interference.

A method for the selection of a particular Modulation and Coding Selection (MCS) from a plurality of available MCS in a wireless communications system, the method having the steps:

• obtaining a derived signal to noise ratio (SNR_d);
• establishing threshold values SNR_high, SNR_low;
• if SNR_d>SNR_high, selecting the highest MCS;
• if SNR_d<SNR_low, selecting the lowest MCS;
• if SNR_high>SNR_d>SNR_low, selecting MCS based on:
• obtaining a table of the product of f(MCS) and f_m corresponding to each MCS, where f(MCS) is an estimate of throughput in the absence of collisions or interference, and f_m is a correction factor for the effects of collisions or interference;
• selecting the MCS that maximizes said product of f(MCS) and f_m;
• said plurality of MCS including at least a modulation type and a coding rate;
• where SNR_d, SNR_high, SNR_low are derived from receive signal strength indication (RSSI)
• where SNR_high is selected such that
• PER(length_packet, MCS_highest, SNR_high)=PER_thresh, where:
• PER is the packet error rate of the communications channel and excludes the effect of collisions, and said PER is a function of said length_packet which is the time duration of a packet, said MCS_highest is an MCS corresponding to the highest data rate, and said PER_thresh is less than or equal to 1%.

A method for the selection of a particular Modulation and Coding Selection (MCS) from a plurality of available MCS in a wireless communications system, the method having the steps:

• obtaining a derived signal to noise ratio (SNR_d);
• establishing threshold values SNR_high, SNR_low;
• if SNR_d>SNR_high, selecting the highest MCS;
• if SNR_d<SNR_low, selecting the lowest MCS;
• if SNR_high>SNR_d>SNR_low, selecting MCS based on:
• obtaining a table of the product of f(MCS) and f_m corresponding to each MCS, where f(MCS) is an estimate of throughput in the absence of collisions or interference, and f_m is a correction factor for the effects of collisions or interference;
• selecting the MCS that maximizes said product of f(MCS) and f_m;
• said plurality of MCS including at least a modulation type and a coding rate;
• where SNR_d, SNR_high, SNR_low are derived from receive signal strength indication (RSSI)
• where SNR_low is selected such that
• PER(length_packet, MCS_lowest, SNR_low)=PER_thresh, where:
• PER is the packet error rate of the communications channel and excludes the effect of collisions, and said PER is a function of said length_packet which is the time duration of a packet, said MCS_lowest is an MCS corresponding to the lowest data rate, and said PER_thresh is less than or equal to 1%.