Distributed cooperative MIMO in beyond 2020 wireless networks.

Abstract

Mobile communication systems are currently being developed with the aim of providing peak data rates up to 20 times higher to those of Long Term Evolution (LTE)-Advanced Release 10. However, this performance improvement is often far from being the experimented performance by all users, especially, for those users who are far from the base station. In this sense, there exists a consensus within the international scientific community on the fact that the best way to achieve the same quality for all users is with the use of heterogeneous networks composed of macrocells, microcells, femtocells, and relays.This dissertation addresses the use of mobile relays to provide service to users who are out-of-coverage or undergo low data rates as they are located at the cell-edge. Mobile relaying is a natural extension of the fixed relay in which users who are in the idle state could retransmit signals received from other transmitters to enhance signal quality and consequently data rates. The use of mobile relaying could make the data boost required by the future Fifth Generation (5G) affordable.Our investigations employ a simulation platform that includes link-level and system-level simulations. This dissertation focuses on proposing and evaluating new techniques that manage the use of the mobile relay in the new generation cellular networks. In particular, the dissertation studies mobile relaying from two complementary points of view.The first point of view investigates the mobile relay management at the network level through a signaling protocol known as Media Independent Handover (MIH). The main idea of the proposed mechanism is to use this signaling to connect the base station and the user in one of the following two manners. In the former, both entities are connected directly through the xG (x= 2, 3, 4, 5) wireless network. In the latter, there exists an xG connection between the base station and the mobile relay and another one between the mobile relay and the user through an IEEE 802.11 local wireless network. The investigations in this Thesis aim at finding a trade-off between using multiple mobile relays and reducing signaling overhead. i ABSTRACTThe second point of view deals with mobile relying integration at the air interface level. It consists in detecting, proposing, and evaluating new transmission techniques that solve the drawbacks derived from coherent detection. As with point-to-point systems, employing multiple antennas in a cooperative system can significantly improve the spectral efficiency of the systems with only one transmit antenna assuming that the channel state information is available at the receiver. However, performing a coherent detection in a network assisted by relays consumes much more resources than a point-to-point network since the coherent detection requires the channel estimation of source-relay, relaydestination, and source-destination links. In this Thesis, the proposed solution is to use transmission techniques that do not need the channel knowledge to perform the detection. ...