Radio over Fibre (RoF) Distributed Antenna Systems can be deployed in combination with pre-4G and 4G technologies, proposed by the IEEE 802.16 and 3GPP LTE standards, in order to support the increased demand for capacity and coverage for various outdoor, inbuilding and underground scenarios. However, the Physical and Medium Access Control (MAC) protocols have not been designed to account for the additional propagation delay that the optical distribution network inserts. This thesis presents a detailed theoretical analysis of protocol effects in Time Division Duplex (TOO) IEEE 802.16 and 3GPP LTE RoF networks, supported by mathematical analyses. The round trip delays and the timing boundaries of the wireless technologies under investigation might be affected when the optical propagation delay is not taken into account. The analysis indicates that the default durations of the TransmitIReceive Transition Gap (TTG) and the Guard Period, which allow for the downlink-uplink timing synchronisation between the Base Station (BS)Evolved Node B (eNB) and the users, can accommodate fibre lengths up to 14.4 km, 27 km and 69.7 km for legacy IEEE 802.16, IEEE 802.16m and 3GPP TD-LTE systems, respectively. Also, the initial Ranging (IR) slot and the Physical Random Access Channel duration, used for the estimation of the user's distance from the BS/eNE, can accommodate fibre lengths up to 13.2 km, 93 km and 69 Ian for legacy IEEE 802.16, IEEE 802.16m and 3GPP TD-LTE systems, respectively. Furthennore, the OFDM symbol's CP duration has to be chosen based on the maximum difference in fibre lengths between the Remote Antenna Units that needs to be supported in the RoF network. The maximum fibre length differences allowed by the default CP in legacy IEEE 802.16, IEEE 802.l6m and 3GPP TD-LTE systems are equal to 2.2 km, 2.2 km and 1.15 km, respectively. However, it is shown that the system perfonnance deteriorates when these parameters are adapted in order to accommodate longer optical propagation delays and greater fibre length differences. The required protocol and parameter changes for the alleviation of the limitation imposed on the maximum fibre link length are presented. The proposed solutions concern the IR procedure and the MAC management Medium Access Protocol (MAP) messages' timing relevance. The optical propagation delay is compensated and the downlink-uplink timing synchronization between the as and the users is maintained. Thus, the wireless propagation delay estimation (ranging) is successfully carried out, even when the optical propagation delay is greater than what the IR slot and/or the TTG duration can accommodate, and the system's performance is improved, without the need of increased overhead.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:595828 |
| Date | January 2013 |
| Creators | Sklikas, Pavlos |
| Publisher | University of Kent |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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