Vincent K. Jones

Multivariate modulation and coding for wireless communication

This paper explores the improvement in information capacity and practical data rate that is possible with adaptive antenna technology applied to wireless-multipath communication channels. Whereas the conventional view is that multipath-signal propagation is an impediment to reliable communication, this paper shows that multipath can actually multiply the achievable data rate for wireless channels provided that the appropriate communication structure is employed. Multivariate discrete multitone (MDMT) combined with multivariate trellis-coded modulation (MTCM) is proposed and analyzed as a practical means of realizing a multiplicative-rate advantage in the case where channel-state information is not available at the transmitter. In Rayleigh fading, these new techniques are shown to simultaneously achieve a multiplicative data-rate advantage and lower error rate as compared to conventional coded orthogonal-frequency division multiplexing. Optimal minimum mean square error (MMSE), adaptive MDMT channel-estimation techniques are derived. The effects of channel-estimation error on MTCM are analyzed.

Adaptive antenna transmission for frequency duplex digital wireless communication

Methods are reported for adaptive phased array transmission of digital wireless communication signals for the purpose of improving network call capacity. Frequency division duplex (FDD), time division multiple access (TDMA) communication channels are considered. The proposed techniques are designed for severe multipath environments with large Doppler, angle and delay spreads. No knowledge of array geometry, propagation path angles or portable feedback is required to adapt the transmission weight vectors. The time or frequency averaged spatial covariance of the received reverse link signal vector is decomposed into desired signal and interference subspaces which are used to form quadratic optimization problems involving matched filter bound cost functions. A dynamic channel allocation algorithm searches for frequency channels in which the adjacent cell portables are spatially compatible with the desired portable. Results of cellular network simulations are provided to illustrate the network call capacity improvements that are possible with the proposed FDD transmission approach.

VOFDM broadband wireless transmission and its advantages over single carrier modulation

In this paper we describe a coding, modulation, and spatial processing technique for fixed broadband wireless Internet access applications and provide examples of its performance. This technique is built on orthogonal frequency division multiplexing (OFDM) and is known as vector OFDM (VOFDM). We compare VOFDM with conventional single carrier modulation (SCM), and show that it provides substantial performance improvements over SCM.