Suman Das

On MIMO decoding algorithms for UMTS

With the understanding of the channel capacity in wireless systems that allows much higher data rates in high scattering environments, transmission over multiple antenna systems has become an attractive option. In this paper we present candidate algorithms for decoding multiple-input-multiple-output (MIMO) systems and study their behavior and implementation for a 4-by-4 antenna system in a UMTS environment.

Rapid prototyping design of a 4/spl times/4 BLAST-over-UMTS system

BLAST techniques to increase the utilized bandwidth in commercial systems are currently feasible. This paper describes the design of a UMTS prototype, supporting four transmit and four receive antennas, achieving almost four times the capacity of a conventional system. Various parts of the transmitter and receiver are mapped on FPGAs and fast DSPs communicating via a specially designed communication link. The system was entirely designed using C code, embedded in SIMULINK S-functions for simulation, and, after validation, automatically mapped onto the hardware platform.

Interference Mitigation Through Interference Avoidance

Wireless cellular systems are inherently interference limited, however a fixed frequency reuse scheme to reduce interference is not optimal for all users. While users close to the base station (BS) see minimal interference and can benefit from using the entire bandwidth available to the system, users at the cell edge can benefit tremendously from interference avoidance through frequency planning. Our goal is to design a cellular system that can autonomously and in a distributed fashion achieve dynamic frequency reuse plan. We also show how various QoS criteria can be met in such a system.

EV-DO revision C: Evolution of the CDMA2000 ∗ data optimized system to higher spectral efficiencies and enhanced services

Wireless packet data services are poised to be a major growth area, as wireless voice services have reached a fair level of maturity. An effort by the 3rd Generation Partnership Project 2 (3GPP2) standards body to continue to develop the successful data-optimized 1x EV-DO high rate packet data (HRPD) 3G system is under way. Alcatel-Lucent along with partners is proposing several novel techniques beyond the state of the art. Some of the key technologies are orthogonal frequency code division multiple access (OFCDMA), multi-carrier as well as wideband transmission, both frequency division duplex (FDD) and time division duplex (TDD) modes, multiple antenna techniques such as space division multiple access (SDMA) and multiple input multiple output (MIMO), interference mitigation techniques, and frequency domain interference cancellation. These are described in detail along with the resulting benefits. The design goals are to provide flexibility, backward compatibility (both loose and strict), a boost in the spectral efficiency and peak rates, a reduction in latency for real-time services, and a reduction in complexity in the base stations (BS) and mobile stations (MS). In this paper, we describe the underlying design philosophy and the associated technologies of 1x EV-DO Revision C with a focus on Alcatel-Lucents contribution and provide associated performance results. The standard is expected to be completed in 2Q 2007.