Low-Latency MAC-Layer Handoff for a High Altitude Platform delivering Broadband Communications

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This paper presents a low-latency handoff algorithm that exploits the unique characteristics of a high-altitude platform (HAP) multi-cell system payload to signifi cantly reduce the need for payload stabilization. The handoff algorithm incorporates a novel time reuse Time-Division Multiplex/Time-Division Multiple Access (TDM/TDMA) frame structure, similar to that available with IEEE
802.16. Single- and multiple-frequency variants have been developed, with the intention of keeping the handoff process transparent to the user. The multiple-frequency variant is designed to increase system capacity by using a sequence
of frequencies in different parts of the frame. Performance of the single-frequency-band handoff scheme is assessed using a generic pitch model. It has been shown to perform robustly, offering low-latency handoff, even with very
short cell dwell times. Using a number of developed HAP mobility models – such as bounce, random walk, and rotation – the worst-case handoff performance is also quantified for a distribution of fi xed users within a coverage area. It is shown that local user traffi c hotspots are the dominant
factor affecting performance, but that mitigation strategies are available.
Original languageUndefined/Unknown
Pages (from-to)39-49
JournalURSI Radio Science Bulletin
Issue number332
Publication statusPublished - Mar 2010

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