Abstract:
In past few years, rate adaptation for wireless multimedia applications has been a subject of wide
research. Rate adaptation can be achieved at MAC/PHY layer by making the accurate decision to
choose available data rates. The motivation to adapt suitable data rates of 802.11 wireless LANs
explores the synchronized cooperation of application and MAC/PHY layer. At application layer,
adjustments for deciding quality of multimedia entirely depend upon sound transmission
conditions of the channel. Therefore, precise assessment of channel condition is an issue of
significant consideration. In recent research, estimations for condition of channels are based on
following approaches (i) use physical layer parameters (e.g. SNR, RSSI, SINR, PSNR) (ii) use
the statistics of transmitted data (e.g. no of retransmissions, throughput, PER).
Our research evaluates that depending upon one approach entirely while ignoring other can lead
to loss of valuable information about adaptation of rate to send data. This in turn can highly
degrade throughput.
In view of this, the proposed scheme, RBSRA, defines channel assessment as the function of
combining PHY layer parameter with statistical metrics. RBSRA estimates accurate assessment
of fluctuating channel conditions, so it leads to the substitution of data rates to yield higher
throughput. RBSRA uses the PHY layer parameter RSSI in cooperation with the statistical
metric that is number of received ACKs. In our scheme RSSI is being used to assess the
variations of the channel conditions, which has been incorporated with the statistics of received
ACKs to decide the data rate for the stream. So, RBSRA avoids unnecessary fluctuations in data
rates and provides more realistic selection amongst the available link speeds. Performance of
RBSRA depicts that the data rate selection has been precisely synchronized with ups and downs
of the channel conditions along with statistics of transmitted stream. Results show that the
proposed scheme increases the overall throughput.
