This research examines a two-way relay network consisting of two transceivers and
multiple parallel relays, which are equipped with single antennas and operate in a halfduplex
mode. In this system, the two transceivers prefer to exchange their information via
relays. It is assumed that the relays have the full instantaneous channel state information
(CSI) and relay the signals using the amplify-and-forward (AF) method.
The performance of two AF bi-directional network beamforming schemes, namely
multiple access broadcast channel (MABC) strategy and time division broadcast channel
(TDBC) protocol, under joint optimal power control and beamforming design are
studied and compared. To do so, we first design a TDBC-based bi-directional network
beamformers, through minimization of the total power consumed in the whole network
subject to quality of service (QoS) constraints, for the case with a direct link between
the two transceivers. The corresponding power minimization problem is carried out over
the transceiver transmit powers as well as relay beamforming weights, thus resulting in a
jointly optimal power allocation and beamforming approach. We devise optimal secondorder
cone programming based solutions as well as fast gradient-based solutions to these
problems.
Then these solutions are exploited to compare the performance of the underlying
TDBC-based approach to that of the MABC-based technique developed in [1]. This
comparison is important because the TDBC approach appears to have certain advantages
which can be exploited towards improving the performance of two-way network
beamforming. These advantages include the additional degree of freedom as well as the
possibility of benefitting from the availability of a direct link between the two transceivers.
Interestingly, in the absence of a direct link between the two transceivers, we show that
when the QoS constraints are imposed to meet certain given probabilities of un-coded error
(or, equivalently, to meet certain signal-to-noise ratio constraints), these two schemes
perform closely in terms of the minimum total transmit power. However, when the QoS
iv
constraints are used to guarantee certain given rates, the MABC-based scheme outperforms
the TDBC counterpart. In the case when a direct link exists between the two
transceivers, the TDBC-based approach can outperform the MABC-based method provided
that the direct link is strong enough. / UOIT
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:OOSHDU.10155/219 |
| Date | 01 October 2011 |
| Creators | Zaeri Amirani, Mohammad |
| Contributors | ShahbazPanahi, Shahram |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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