Throughput in multi-rate wireless networks using variable-length packets and other techniques
In a wireless communication network having a plurality of devices operating at different data rates that contend for access to the network, a method is provided that assigns network access parameters to one or more of the devices so as to control throughput on the network. Examples of network access control parameters are the maximum data packet size and the contention window size. Generally, the network access control parameter for slower data rate users is configured so that they do not occupy the network a disproportionate amount of time compared to faster data rate users.
1. A method for a wireless communication wherein a plurality of devices are contending for access to a network and the plurality of devices include devices that operate at different data rates when transmitting data on the network, the method comprising: dynamically assigning network access parameters to one or more of the devices so as to control throughput on the network, the parameters including a contention window network access control parameter by which a longer contention window interval is assigned for low data rate devices and a shorter contention window interval is assigned for high data rate devices, whereby the contention window interval is a maximum duration for a back-off counter that is decremented each idle time slot until reaching zero at which time the device attains access to the network and transmits a data packet.
2. The method as in claim 1 , further comprising an access point in the network detecting increased access times for the devices and determining an unacceptable average throughput of the network, whereby the access point sends messages to the devices to adjust the network access parameter for a longer contention window size.
3. The method as in claim 2 , further comprising the access point detecting decreased access times for the devices and determining an acceptable average throughput of the network, whereby the access point sends messages to the devices to adjust the network access parameter to return to a normal contention window size.
4. The method of claim 1 , and further comprising the step of detecting when a device goes on or off the network, and in response thereto, modifying the network access parameters of one or more devices.
5. A wireless station (STA), comprising a processor configured to process:
a logical link control (LLC) Driver configured to receive a message from an access point directing an update to a maximum transmit packet size parameter and to compare an intended transmit packet size to the maximum transmit packet size parameter; and
a network layer configured to send a data transmission request primitive indicative of the intended transmit packet size to the LLC Driver and to receive data transmission response primitive from the LLC Driver indicative of whether the intended transmit packet size is smaller than or greater than the maximum transmit packet size parameter; whereby on a condition that the intended transmit packet size is greater than the maximum transmit packet size parameter, the size of the transmit packet is reduced to a size less than the maximum packet data size parameter.
6. The STA as in claim 5 , further comprising a memory to store the maximum transmit packet size parameter.
7. The STA as in claim 5 , further comprising a timer that is set once the message is received from the access point to reduce the maximum transmit packet size parameter, whereby upon expiration of the timer after a fixed duration, the network layer changes the intended transmit packet size back to an initial value that is greater than the reduced transmit packet.