UC San Diego

This dissertation focuses on the topic of interference management in wireless networks with multiple-antenna nodes. Two network paradigms are considered, namely, time- division duplexing (TDD)/code-division multiple-access (CDMA) cellular and ad hoc. In TDD/CDMA cellular networks with asymmetric data traffic, dynamic channel allocation (DCA) enhances resource utilization compared to fixed channel allocation (FCA); however, it induces base-to-base and mobile-to-mobile crossed-slot intercell interference that can severely degrade network performance. To deal with this problem, a decentralized scheme is proposed, which combines an interference-aware DCA algorithm with space-time linear minimum-mean-square-error (LMMSE) joint detection at the base and mobile stations. The former assigns active links to timeslots in a way that crossed- slot interference is mitigated, while the latter suppresses the remaining intercell interference (along with intersymbol and intracell interference) by exploiting its spatio-temporal autocorrelation statistics. The performance of this scheme is evaluated in terms of SINR outage and average throughput via analytical approximations and Monte Carlo simulations, and it is compared with that of benchmark random DCA (RDCA) and FCA schemes. The cases of single- and dual-antenna reception with perfect and imperfect channel state information are examined. It is shown that the proposed scheme achieves higher average throughput than FCA (particularly for dual- antenna reception) as well as RDCA (for heavy traffic loads). These throughput gains are more significant in uplink than in downlink. In ad hoc networks, interference management via collision-avoidance medium access schemes results in poor spatial reuse and, thus, restricts network throughput. To address this shortcoming, two physical- medium-access-control cross-layer protocols are proposed. The first increases spatial reuse by integrating medium access, power control, and optimum receive beamforming in a distributed manner, and it is named progressive back-off algorithm with optimum receive beamforming (PBOA-ORB). The second additionally incorporates transmit beamforming, on the premise of centralized control, and it is named progressive back-off algorithm with transmit and optimum receive beamforming (PBOA-TORB). The performance of both protocols is evaluated in terms of aggregate throughput and energy efficiency via simulations over a single-hop network. It is shown that the throughput of PBOA-ORB increases linearly with the number of antennas per node thanks to interference suppression provided by optimum receive beamforming. PBOA-TORB achieves only an incremental throughput gain over PBOA-ORB despite its centralized nature. However, it is significantly more energy efficient than PBOA-ORB thanks to extra array gain provided by transmit beamforming. The research for this dissertation was conducted at the UCSD Center for Wireless Communication, under the "MIMO Wireless Communication Systems" project (CoRe research grant com04-10176) and the ̀̀Multiuser MIMO Systems'' project (CoRe research grant com07-10241)