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Effect of Soft and Softer Handoffs on CDMA System Capacity

Effect of Soft and Softer Handoffs on CDMA System Capacity
Effect of Soft and Softer Handoffs on CDMA System Capacity
Abstract? The effect of soft and softer handoffs on code-division multiple-access (CDMA) system capacity is evaluated for unsectorized and sectorized hexagonal cells according to an average bit energy-to-interference power spectral density, which corresponds to a bit-error rate (BER) of 10-3. The effect of imperfect sectorization on sectorization efficiency is also considered. On the reverse link, there is no capacity loss as no extra channels are needed to perform soft handoff, while the macrodiversity provided by soft handoff can improve the reverse-link quality and extend the cell coverage. On the forward link, when soft handoff is employed in unsectorized cells, the capacity loss due to two traffic channels assigned to a user in the handoff zone is 0.2% or 1.1% for a voice activity factor of 3/8 or 1/2, respectively. As the forward-link capacity is higher than that of the reverse link, this small capacity loss does not affect the system capacity. For sectorized cells having three sectors per cell, there are overlapping coverage areas between sectors, where mobiles in these areas are subjected to an increase in cochannel iterference. For an overlapping angle of 5°, the sectorization efficiency is 0.96 and 0.7 for the reverse-link and forward-link systems, respectively. When soft and softer handoffs are employed, the forward-link sectorization efficiency is improved to 0.97. We find the application of soft and softer handoff improves not only the forward-link capacity, but also the signal-to-interference ratio (SIR) for mobiles near the cell and sector boundaries. Index Terms?CDMA, macrodiversity, sectorization efficiency, soft handoff, softer handoff.
0018-9545
830-841
Lee, CC
2e9771b8-9f53-45ec-8ab1-2bff99d95fa6
Steele, R
7035a3e5-8a4c-434b-a105-46fe2d63d5c3
Lee, CC
2e9771b8-9f53-45ec-8ab1-2bff99d95fa6
Steele, R
7035a3e5-8a4c-434b-a105-46fe2d63d5c3

Lee, CC and Steele, R (1998) Effect of Soft and Softer Handoffs on CDMA System Capacity. IEEE Transactions on Vehicular Technology, 47 (3), 830-841.

Record type: Article

Abstract

Abstract? The effect of soft and softer handoffs on code-division multiple-access (CDMA) system capacity is evaluated for unsectorized and sectorized hexagonal cells according to an average bit energy-to-interference power spectral density, which corresponds to a bit-error rate (BER) of 10-3. The effect of imperfect sectorization on sectorization efficiency is also considered. On the reverse link, there is no capacity loss as no extra channels are needed to perform soft handoff, while the macrodiversity provided by soft handoff can improve the reverse-link quality and extend the cell coverage. On the forward link, when soft handoff is employed in unsectorized cells, the capacity loss due to two traffic channels assigned to a user in the handoff zone is 0.2% or 1.1% for a voice activity factor of 3/8 or 1/2, respectively. As the forward-link capacity is higher than that of the reverse link, this small capacity loss does not affect the system capacity. For sectorized cells having three sectors per cell, there are overlapping coverage areas between sectors, where mobiles in these areas are subjected to an increase in cochannel iterference. For an overlapping angle of 5°, the sectorization efficiency is 0.96 and 0.7 for the reverse-link and forward-link systems, respectively. When soft and softer handoffs are employed, the forward-link sectorization efficiency is improved to 0.97. We find the application of soft and softer handoff improves not only the forward-link capacity, but also the signal-to-interference ratio (SIR) for mobiles near the cell and sector boundaries. Index Terms?CDMA, macrodiversity, sectorization efficiency, soft handoff, softer handoff.

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Published date: August 1998
Organisations: Electronics & Computer Science

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Local EPrints ID: 253824
URI: http://eprints.soton.ac.uk/id/eprint/253824
ISSN: 0018-9545
PURE UUID: 2d7e5da1-5bdb-4d1a-beb0-21142dc37668

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Date deposited: 20 Apr 2001
Last modified: 16 Dec 2019 20:46

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