Ravi Palanki

Preamble Design in Ultra Mobile Broadband Communication Systems

The preamble design for a highly flexible wireless communication system can be challenging. This paper describes a preamble design for ultra mobile broadband (UMB) communication systems that allows flexible deployment, such as flexible bandwidth allocation, synchronous/asynchronous modes, FDD/TDD, full/half duplex, and configurable cyclic prefix duration, etc. The UMB preamble design facilitates the flexibility and yet has low overhead, low acquisition latency, and low complexity.

Scalable and accurate indoor positioning on mobile devices

Location-based services (LBS) are an integral part of the mobile ecosystem today, relying on the Global Positioning System (GPS) and other technologies. However, while these technologies have been highly successful at positioning outdoors, they either fail to obtain a fix or do not provide the necessary accuracy indoors. In this paper, we will describe a low-cost high-accuracy indoor positioning system that can run on mobile devices. The system has high-accuracy because it combines several sources of information, thus improving accuracy over using any one of them alone. The cost is low because the sources of information used by the system such as WiFi measurements, inertial sensor data and building maps are readily available for use on a mobile device.

Iterative Decoding of Multiple-Step Majority Logic Decodable Codes

We investigate the performance of iterative decoding algorithms for multistep majority logic decodable (MSMLD) codes of intermediate length. We introduce a new bit-flipping algorithm that is able to decode these codes nearly as well as a maximum-likelihood decoder on the binary-symmetric channel. We show that MSMLD codes decoded using bit-flipping algorithms can outperform comparable Bose-Chaudhuri-Hocquenghem (BCH) codes decoded using standard algebraic decoding algorithms, at least for high bit-flip rates (or low and moderate signal-to-noise ratios (SNRs)).

Beacon signaling and its application to inter-frequency handoff in OFDMA cellular communications

This paper introduces a beacon coding and signaling technique and its application to handoff in OFDMA cellular communication networks. Beacon signaling provides an efficient alternative to the conventional tune-away approach for inter-carrier/frequency handoff. The proposed handoff technique transmits beacon pilots in other carrier frequencies in the network allowing for easy and early detection of neighboring cells, and fast and seamless handoffs in a multi-carrier synchronous or asynchronous deployment. The proposed technique thereby minimizes the call drop rate and interference due to delayed handoff.