Effectiveness of UBR VC Approach in AAL2 Networks and Its Application to IMT-2000

Hiroshi SAITO  

IEICE TRANSACTIONS on Communications   Vol.E83-B   No.11   pp.2486-2493
Publication Date: 2000/11/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Switching
AAL2,  IMT-2000,  VTOA,  bandwidth management,  

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This paper investigates the effectiveness of a network that uses unspecified bit rate (UBR) for a virtual channel (VC) accommodating AAL2 connections. AAL2 is a new ATM adaptation layer that has recently been standardized. Since it is designed to carry low-bit-rate voice signals efficiently, it should be used in the ATM backbone for mobile networks, especially in the IMT-2000 network (International Mobile Telecommunication in the Year 2000 network). Normally, constant-bit-rate (CBR) VCs or variable-bit-rate (VBR) VCs are used to accommodate AAL2 connections. In our previous work, however, we showed that using UBR VCs (equivalent to no VC-level bandwidth management) to accommodate AAL2 connections needs much less VP bandwidth than using CBR or VBR VCs. In this paper, the previous results are extended to the network and the network bandwidth reduction is shown to be larger than that of the virtual path. In addition, the bandwidth reduction achieved by using UBR VCs is comparable with that achieved by introducing AAL2 switching nodes. Based on these results, the core network of the IMT-2000 is discussed.