Slow adaptation of modulation and coding for packet transmission
Systems and methods for performing MCS adaptation are provided. In some cases, the network performs MCS adaptation based on received NACKs. In other cases, the mobile station determines an MCS based on channel quality measurements, and feeds back the MCS adaptation decision to the network. In either case, NACK-only feedback may be implemented to reduce interference.
1. A method comprising:
transmitting packets to a receiver using an MCS (modulation and coding scheme);
receiving NACKs (negative acknowledgement) in respect of packets transmitted to the receiver;
determining an updated MCS (modulation and encoding scheme) used to transmit subsequent packets to the receiver as a function of the received NACKs, wherein adapting an MCS (modulation and encoding scheme) used to transmit the sequence of packets as a function of the received negative acknowledgements comprises:
counting a number of NACKs received over a time period, wherein updating an MCS (modulation and encoding scheme) used to transmit the sequence of packets as a function of the received negative acknowledgements further comprises:
moving to a less aggressive MCS if the number of NACKs received over the time period exceeds a first threshold;
moving to a more aggressive MCS if the number of NACKs received over the time period is less than a second threshold.
2. A method comprising:
transmitting packets to a receiver using an MCS (modulation and coding scheme);
receiving NACKs (negative acknowledgement) in respect of packets transmitted to the receiver;
determining an updated MCS (modulation and encoding scheme) used to transmit subsequent packets to the receiver as a function of the received NACKs, wherein adapting an MCS (modulation and encoding scheme) used to transmit the sequence of packets as a function of the received negative acknowledgements comprises:
counting a number of NACKs received over a time period, wherein the time period is at least 400 ms or comprises a sliding window.
3. A method comprising:
a receiver receiving packets sent to the receiver over a wireless channel;
the receiver making a channel quality measurement in respect of the wireless channel;
the receiver making an MCS adaptation decision based on the channel quality measurement;
the receiver feeding back a first signal to indicate that a more aggressive MCS should be used when the channel quality measurement is above a first threshold; and the receiver feeding back a second signal to indicate that a less aggressive MCS should be used when the channel quality measurement is below a second threshold, wherein the receiver feeding back the MCS adaptation decision is performed at least every 400 ms.