Reducing Handover Scanning Time in Next-Generation Communication Systems with Multi-Carrier Operations
Date Issued
2011
Date
2011
Author(s)
Shu, Che-Hao
Abstract
Multi-carrier operation has been lately adopted by next-generation communication systems, such as IEEE 802.16m, as a promising technology to improve the system performance. However, a new issue arises when mobile stations need to scan the neighboring cells operating with multiple carrier. The handover decision might be delayed when the scanning time increases dramatically by the large amount of candidate carriers. A delayed handover decision would interrupt existing connections and incur serious damage to the system performance, such as throughput. To address this
problem, this thesis focuses on how to reduce the scanning time while still maintaining a good handover quality. We reduce the scanning time from two aspects: the first one gives priority to the carriers of the neighboring cells, and the other reduces the unnecessary time if more effort may not increase the scanning performance. Based on the two concepts, the algorithm for prioritized scanning and expedited scanning are proposed accordingly. Prioritized scanning estimates the carrier qualities from the historical reports in the neighboring area. According to the estimated carrier qualities, a high priority is assigned to a carrier with better carrier quality. On the
other hand, expedited scanning also estimates the carrier quality, but it jointly considers carrier correlations and spatial correlations. A dynamic estimation method is proposed to further enhance the estimation accuracy. Based on simulation results, the proposed algorithms can provide an average gain between 50% to 75% compared to the default scanning method when the neighbor distance is between 10 and 50 meters.
Subjects
Scanning
Multi-Carrier
Type
thesis
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