Wideband Code Division Multiple Access (WCDMA) is one of the technologies for third generation systems. In a CDMA system, all users interfere with each others, therefore the CDMA system is interference limited. The users, who suffer from a strong shadow effect or that are far away from the BS, need more power to reach it. In this case, the users may transmit at their maximum allowed power without satisfying their Quality of Service. Therefore, this would leave some mobiles in outage and also create too much interference to the neighboring cells. One-way to counter this problem and therefore to improve the capacity is to increase the number of BSs. But this solution cannot be efficient as it significantly increases the network infrastructure cost. Alternative techniques that involve less planning and are quick to deploy appear to be more advantageous. Relaying is one of these techniques and is growing in importance for future wireless systems. In this thesis, a new radio access network based on combinations of multi-hop and star-topology architectures is proposed. The main objective of this thesis is to demonstrate achievable capacity gains under various relaying criteria compared with no-relaying (conventional) cellular architecture. In this new architecture, some intermediate nodes (mobile or fixed) located between the originating terminal and the BSs are used for the purpose of retransmitting the original packets. We show that under specific criteria and conditions the multihop concept indeed yields capacity gains. A number of different scenarios are defined and their relative performances are fully evaluated using an accurate dynamic system-level simulator. The capacity gains are compared to the case of no relaying/hopping. To demonstrate the achievable capacity gains, we use UMTS FDD and TDD modes. The proposed concepts and criteria for relaying are generic enough to be used with current and future radio access technologies. The results show that under certain conditions an uplink capacity gain of 30-40% is readily achievable with the multihop architecture.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:433306 |
| Date | January 2006 |
| Creators | Nourizadeh, Hamed |
| Publisher | University of Surrey |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://epubs.surrey.ac.uk/844065/ |
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