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Title: Resource allocation for the Long Term Evolution (LTE) of 3G
Author: Beh, Kian Chung
ISNI:       0000 0004 2691 3238
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2009
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Long Term Evolution (LTE) is the next major step in mobile radio communications and is currently introduced as Release 8 in the 3rd Generation Partnership Project (3GPP). The new evolution aims to reduce delay, improve spectrum flexibility and further reduce the cost for operators and end users. In order to fulfil the target of achieving high throughput, LTE employs Orthogonal Frequency Division Multiplexing (OFDM) as the physical layer transmission technique in the downlink. OFDM is suitable for high data rate transmission in wideband wireless systems due to its spectral efficiency and good immunity to multipath fading. LTE enables multiple user access through an Orthogonal Frequency Division Multiple Access (OFDMA) scheme. In OFDMA, multiple user access is enabled by sharing the subcarriers among different users. The division of the system bandwidth between multiple users opens up an additional dimension in the frequency domain which can be exploited for diversity purposes. In addition to that, two MIMO techniques are adopted in LTE, namely space frequency block coding (SFBC) and Spatial Multiplexing (SM). The adaptation of the spatial multiplexing technique in LTE creates additional freedom in the resource allocation in the downlink. By employing a transmit precoding technique, spatial layers can be scheduled to different users and an additional layer of diversity in the space domain can be achieved. The additional layer of diversity can further increase the diversity gain that be achieved in the frequency and time domains. This thesis mainly addresses the gain that can be achieved by resource allocation in the time, frequency and spatial domains in LTE. A detailed performance analysis on the physical layer of LTE downlink will be presented for both SISO and MIMO scenarios. A unitary precoding technique is also considered. Some well known and commonly used scheduling and resource allocations algorithms are investigated and presented. In addition to that, several novel scheduling and resource allocation algorithms are proposed and presented. Simulation results have shown that considerable improvement in terms of throughput performance or complexity can be observed. In particular, a diversity gain of up to 10dB can be achieved in the downlink when resource allocation algorithms are employed for a MU-MIMO scenario. In short, this thesis aims to give a detailed analysis on the diversity gain that can be achieved in the OFDMA system and the possible tradeoff between the diversity gain in three dimensions as well as the signalling overhead.
Supervisor: Doufexi, Angela ; Armour, Simon Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available