Can I add a VoIP call?

Author

Garg, Sachin ; Kappes, Martin

Author_Institution

Ayaya Labs., Basking Ridge, NJ, USA

Volume

2

fYear

2003

fDate

11-15 May 2003

Firstpage

779

Abstract

In this paper, we study the inherent limitations of the 802.11 (a/b) distributed coordination function (DCF) in supporting VoIP calls over a wireless LAN. Specifically, we evaluate the upper bound on the number of simultaneous VoIP calls that can be placed in a single cell of an 802.11 (a/b) network. Making one additional VoIP call in that cell would degrade the quality of all VoIP call. The upper bound is calculated as a function of the choice of VoIP codec and the length of the audio payload. As an example, when a G711 codec with 20 millisecond audio payload is used, an 802.11b cell can support only 3 to 12 simultaneous VoIP calls. The actual number depends on the effective transmission rate of the wireless station, which for 802.11b can be 1 Mbps, 5.5 Mbps and 11 Mbps. We also study the effect of spatial distribution of the wireless stations on the upper bound which is the dominant factor in determining the effective transmission rate of a station.

Keywords

Internet telephony; data communication; quality of service; speech codecs; transport protocols; wireless LAN; IEEE 802.11 protocol; Internet protocol; VoIP call; VoIP codec; audio payload; call quality; distributed coordination function; effective transmission rate; voice over IP; wireless LAN; wireless local area network; Codecs; Degradation; IP networks; Internet telephony; Jitter; Payloads; Propagation losses; Quality of service; Upper bound; Wireless LAN;

fLanguage

English

Publisher

ieee

Conference_Titel

Communications, 2003. ICC '03. IEEE International Conference on

Print_ISBN

0-7803-7802-4

Type

conf

DOI

10.1109/ICC.2003.1204432

Filename

1204432