Dual-Branch MRC Receivers under Spatial Interference Correlation and Nakagami Fading

Despite being ubiquitous in practice, the performance of maximal-ratio combining (MRC) in the presence of interference is not well understood. Because the interference received at each antenna originates from the same set of interferers, but partially de-correlates over the fading channel, it possesses a complex correlation structure. This work develops a realistic analytic model that accurately accounts for the interference correlation using stochastic geometry. Modeling interference by a Poisson shot noise process with independent Nakagami fading, we derive the link success probability for dual-branch interference-aware MRC. Using this result, we show that the common assumption that all receive antennas experience equal interference power underestimates the true performance, although this gap rapidly decays with increasing the Nakagami parameter $m_{\text{I}}$ of the interfering links. In contrast, ignoring interference correlation leads to a highly optimistic performance estimate for MRC, especially for large $m_{\text{I}}$. In the low outage probability regime, our success probability expression can be considerably simplified. Observations following from the analysis include: (i) for small path loss exponents, MRC and minimum mean square error combining exhibit similar performance, and (ii) the gains of MRC over selection combining are smaller in the interference-limited case than in the well-studied noise-limited case.Comment: to appear in IEEE Transactions on Communication

A New Analysis of the DS-CDMA Cellular Uplink Under Spatial Constraints

A new analysis is presented for the direct-sequence code-division multiple access (DS-CDMA) cellular uplink. For a given network topology, closed-form expressions are found for the outage probability and rate of each uplink in the presence of path-dependent Nakagami fading and log-normal shadowing. The topology may be arbitrary or modeled by a random spatial distribution for a fixed number of base stations and mobiles placed over a finite area with the separations among them constrained to exceed a minimum distance. The analysis is more detailed and accurate than existing ones and facilitates the resolution of network design issues, including the influence of the minimum base-station separation, the role of the spreading factor, and the impact of various power-control and rate-control policies. It is shown that once power control is established, the rate can be allocated according to a fixed-rate or variable-rate policy with the objective of either meeting an outage constraint or maximizing throughput. An advantage of the variable-rate policy is that it allows an outage constraint to be enforced on every uplink, whereas the fixed-rate policy can only meet an average outage constraint.Comment: 6 pages, 6 figures, to appear at International Conference on Communications (ICC) 201

Performance analysis of diversity techniques in wireless communication systems: Cooperative systems with CCI and MIMO-OFDM systems

This Dissertation analyzes the performance of ecient digital commu- nication systems, the performance analysis includes the bit error rate (BER) of dier- ent binary and M-ary modulation schemes, and the average channel capacity (ACC) under dierent adaptive transmission protocols, namely, the simultaneous power and rate adaptation protocol (OPRA), the optimal rate with xed power protocol (ORA), the channel inversion with xed rate protocol (CIFR), and the truncated channel in- version with xed transmit power protocol (CTIFR). In this dissertation, BER and ACC performance of interference-limited dual-hop decode-and-forward (DF) relay- ing cooperative systems with co-channel interference (CCI) at both the relay and destination nodes is analyzed in small-scale multipath Nakagami-m fading channels with arbitrary (integer as well as non-integer) values of m. This channel condition is assumed for both the desired signal as well as co-channel interfering signals. In addition, the practical case of unequal average fading powers between the two hops is assumed in the analysis. The analysis assumes an arbitrary number of indepen- dent and non-identically distributed (i.n.i.d.) interfering signals at both relay (R) and destination (D) nodes. Also, the work extended to the case when the receiver employs the maximum ratio combining (MRC) and the equal gain combining (EGC) schemes to exploit the diversity gain

Energy harvesting AF relaying in the presence of interference and Nakagami-m fading

Energy-harvesting relaying is a promising solution to the extra energy requirement at the relay. It can transfer energy from the source to the relay. This will encourage more idle nodes to be involved in relaying. In this paper, the outage probability and the throughput of an amplify-and-forward relaying system using energy harvesting are analyzed. Both time switching and power-splitting harvesting schemes are considered. The analysis takes into account both the Nakagami-$m$ fading caused by signal propagation and the interference caused by other transmitters. Numerical results show that time switching is more sensitive to system parameters than power splitting. Also, the system performance is more sensitive to the transmission rate requirement, the signal-to-interference-plus-noise ratio in the first hop and the relaying method