Purushotham Kamath

Research

Current research

Performance analysis of wireless networks.

Dissertation research

My dissertation research proposed Interference Avoidance, a contention media access control protocol for optical Code Division Multiple Access (CDMA) Local Area Networks (LANs). Interference Avoidance extended the Carrier Sensing media access control protocol to high speed, shared medium, optical LANs.

Optical CDMA is a direct sequence spread spectrum based technology for multiplexing transmissions on an optical fiber. Although it can be used as the physical layer of a high speed, all optical, shared medium LAN, the throughput of such a network collapses at high offered load due to multi-user interference. By exploiting the properties of optical CDMA, Interference Avoidance reduces packet loss due to interference and prevents throughput collapse. It consists of state estimation and transmission scheduling. My work proposes algorithms for state estimation and transmission scheduling. The algorithms are evaluated through a combination of analysis, simulation and empirical measurements. Analysis and simulation show that they stabilize network throughput at high offered load when used with large length, low weight codesets while the throughput without media access control tends to zero. The throughput performance of the algorithms is within 20% of corresponding optimal estimation and scheduling algorithms. Measurements from a laboratory testbed demonstrate that transmission scheduling reduces the bit error rate in the presence of severe physical layer noise. More information may be found here.

Past projects

Network architecture for optical CDMA LANs: This project explored the design and analysis of network protocols for networks built on an optical CDMA physical layer. The project focussed on the interactions between the network architecture, codeset design and device design.

Protocols for packets over wavelengths: This project explored the design and analysis of signalling protocols for the dynamic allocation of wavelength paths for all optical switching in Internet backbone networks.