Topics: Performance, queuing and scaling models for networks; Performance analysis, bounds and optimization; Traffic characterization and traffic models for networks
Authors: Ryan Guerra (Rice University, USA); Narendra Anand (Cisco Systems, Inc); Clayton Shepard and Edward W. Knightly (Rice University, USA)
Presenter bio:
Ryan E. Guerra is a Ph.D. candidate at Rice University for
electrical engineering under Dr. Edward Knightly. He specializes in
next-generation wireless communications system design with a focus on
software-defined radio implementation and experimentation. An expert in
radio architectures and FPGA development, he is also co-founder of
Skylark Wireless, LLC, developer of custom software-defined radio
solutions.
Abstract: Multi-User MIMO (MU-MIMO) linear channel coding can greatly increase
wireless system capacity when Stations (STAs) have fewer antennas than
the Access Point (AP), but it comes at the cost of significant Channel
State Information (CSI) estimation overhead. Previous work has suggested
that 802.11af MU-MIMO systems might benefit from long channel coherence
time, extending the useful duration of CSI. In this paper, we propose
and analyze an opportunistic channel sounding policy that avoids
sounding overhead in wireless channels by gathering implicit CSI
opportunistically. This policy not only avoids CSI overhead, but also
has the potential to enable efficient interoperability of multi-user APs
with legacy single-stream STAs. To investigate the performance of this
new policy, we implement a new mobile channel sounding framework on a
custom 802.11af Software-Defined Radio (SDR) system designed for
UHF-band experimentation and evaluate channel sounding performance in
indoor and outdoor environments under various mobility modes. Additional
protocol analysis shows that in UHF channels with sufficient channel
coherence time, an opportunistic channel sounding policy offers
significant protocol optimization while improving the scalability of
next-generation MU-MIMO systems.
