Catálogo de publicaciones - libros

We propose a Modulation and Coding Scheme (MCS) selection algorithm for the collaborative hybrid Automatic-Repeat-reQuest (ARQ) protocol in order to provide high data rates. The collaborative hybrid ARQ protocol is designed to benefit from diversity gain. It exploits not only the broadcast nature of wireless channels, but also spatial diversity by formation of virtual antenna arrays and collaboration between a base station and relay nodes through Space-Time Block Coding (STBC). The proposed algorithm estimates both the effective Signal-to-Noise-Ratio (SNR) and the average throughput of each MCS level, and then selects the MCS level maximizing the average throughput. Simulation results show that the proposed algorithm outperforms conventional MCS selection algorithms in terms of the total throughput and satisfies packet delay constraints.

The IEEE 802.16 mobile multi-hop relay (MMR) task group ’j’ (TGj) has recently introduced the multi-hop relaying concept in the IEEE 802.16 WirelessMAN, wherein a newly introduced is expected to increase the network performance. In this context, we consider the problem of path selection where several RSs might exist between the base station (so called, MR-BS) and the mobile station (MS). We propose a backward compatible signaling mechanism and a path selection algorithm based on the expected link throughput (ELT). To the best of our knowledge, this is the first contribution that presents path selection algorithm in the IEEE 802.16 networks. Performance of the proposed scheme is compared with shortest hop and no-relay schemes and we show our schemes significantly improves the performance in terms of throughput and latency.

We study the connectivity properties of a family of random graphs which closely model the Bluetooth’s device discovery process, where each device tries to connect to other devices within its visibility range in order to establish reliable communication channels yielding a connected topology. Specifically, we provide both analytical and experimental evidence that when the visibility range of each node (i.e., device) is limited to a vanishing function of , the total number of nodes in the system, full connectivity can still be achieved with high probability by letting each node connect only to a “small” number of visible neighbors. Our results extend previous studies, where connectivity properties were analyzed only for the case of a constant visibility range, and provide evidence that Bluetooth can indeed be used for establishing large ad hoc networks.