Mythili Vutukuru, Hari Balakrishnan, Kyle Jamieson
ACM SIGCOMM, Barcelona, Spain, August 2009
This paper presents SoftRate, a wireless bit rate adaptation protocol
that is responsive to rapidly varying channel conditions. Unlike
previous work that uses either frame receptions or signal-to-noise
ratio (SNR) estimates to select bit rates, SoftRate uses confidence
information calculated by the physical layer and exported to higher
layers via the SoftPHY interface to estimate the prevailing channel
bit error rate (BER). Senders use this BER estimate, calculated over
each received packet (even when the packet has no bit errors), to pick
good bit rates. SoftRate's novel BER computation works across
different wireless environments and hardware without requiring any
retraining. SoftRate also uses abrupt changes in the BER estimate to
identify interference, enabling it to reduce the bit rate only in
response to channel errors caused by attenuation or fading. Our
experiments conducted using a software radio prototype show that
SoftRate achieves 2X higher throughput than popular frame-level
protocols such as SampleRate and RRAA. It also achieves 20% more
throughput than an SNR-based protocol trained on the operating
environment, and up to 4X higher throughput than an untrained
SNR-based protocol. The throughput gains using SoftRate stem from its
ability to react to channel variations within a single packet-time and
its robustness to collision losses.
[PDF (853KB)]
Bibtex Entry:
@inproceedings{vutukuru2009cross-layer, author = "Mythili Vutukuru and Hari Balakrishnan and Kyle Jamieson", title = "{Cross-Layer Wireless Bit Rate Adaptation}", booktitle = {ACM SIGCOMM}, year = {2009}, month = {August}, address = {Barcelona, Spain} }