Current Research Topics
- Satellite based navigation receiver design
- 5G and Beyond Wireless Communication Networks
- Rate, reliability and complexity limits in MIMO communications
- Communication protocols for RF energy harvesting based systems
Satellite based navigation receiver design
GNSS receivers compute the user position, velocity, and precise time (PVT) by processing any combination of signals broadcasted by navigation satellite systems. Currently five autonomous systems namely GPS, GLONASS, Galileo, IRNSS and BeiDou are broadcasting navigation messages. GNSS receiver are specifically useful in urban areas with high rise buildings where elevation angle masks are to be increased to get favorable propagation conditions for the navigation signals. GNSS receivers allow for an improved availability and continuity. This research focuses on reducing time-to-first-fix and improving measurement accuracy in the presence of signal multipaths, interference and spoofing. Severe signal attenuation and multipath fading in urban canyons and indoor environments pose a big challenge for satellite based robust and accurate positioning in all environments. Obtaining ubiquitous positioning solutions requires development of hybrid positioning technique that utilizes multiple positioning techniques to derive the navigation solution.
5G and Beyond Wireless Communication Networks
The development of communications has vastly relied on theories and models, from information theory to channel modelling. These traditional approaches are showing serious limitations, especially in view of the increased complexity of communication networks. The advent of 5G is introducing new challenges for mobile communications service providers, and integrating signal processing and learning based techniques into networks is one way the industry is addressing these complexities. The research here will focus on use of learning based methods to address challenges of 5G and beyond communication networks specifically issues with respect to the ultra reliable and low latency communication (uRLLC). In terms of physical layer technologies to address challenges of uRLLC, the work here focuses on advanced channel code designs. The channel code design for uRLLC need to consider short block length codes, antenna and feedback diversity, the decoding complexity and processing time.
Rate, reliability and complexity limits in MIMO communications
This research focuses on establishing fundamental rate, reliability and complexity limits in general outage-limited multiple-input multiple-output (MIMO) communications, and its related point-to-point, multiuser, cooperative, two-directional, and feedback-aided scenarios. In particular, the ongoing research provides analytical insights into the following pertinent questions
- What are the computational reserves required to achieve a vanishing gap to ML or (regularized) lattice decoding performance of MIMO, multiuser and cooperative communications?
- What is the role of feedback in reducing decoding complexity?
- What policies can regulate complexity at a limited performance loss?
- How should users behave in the presence of complexity constraints for multiuser communications?
Mathematically rigorous answers to the aforementioned questions require proper honing of advanced mathematical tools from information theory, large deviations theory, matrix theory and linear algebra to provide a never before attempted unified exposition of performance and complexity. The ultimate goal of the proposed research is to provide for theoretical breakthroughs as well as practical solutions (novel transceiver design) that can be smoothly integrated into the existing infrastructure, leading to an energy-efficient green communications technology.
Communication protocols for RF energy harvesting based systems
This research focuses on establishing opportunistic signaling based communication protocols, appropriate for sensor data with laxer latency requirements. The proposed communication protocols can exploit channel fluctuations to achieve higher long-term throughput by transmitting information only when and where the channel is strong, along with optimal power and rate allocation for multiple access fading channels. In environments with little scattering and strict latency requirements, channels where the dynamic range of the channel fluctuations is small and the peaks are close to the average, the opportunistic beamforming techniques can be employed to induce large and fast channel fluctuations achieving higher energy efficiency for sensing data communication even in the absence of channel state information at the transmitter.
