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IP.com Disclosure Number: IPCOM000005345D
Original Publication Date: 2001-Aug-23
Included in the Prior Art Database: 2001-Aug-23
Document File: 6 page(s) / 166K

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This text was extracted from a WORD97 document.
This is the abbreviated version, containing approximately 27% of the total text.



A Call Admission Control (CAC) scheme is based on the adaptive definition of admission threshold, which allows artificial maximization of the number of simultaneous calls within a given cell.

In order to achieve this, the admission threshold is computed based on the evolution with time of the number of guest users within the cell considered. Prior to the application of the selective admission control, the cell load is checked to be above a specific alert threshold defined and optimized by the network operator. If the alert threshold is exceeded, the CAC algorithm is applied.

The result is a controlled admission of the users favoring users with lowest radio cost rather than users located at the cell edge. When possible, the users whose radio cost is above the admission threshold are handed off to adjacent cell. Otherwise, their requested quality of service is re-negotiated or their call blocked.

Due to a reuse factor of one, interference management is a crucial problem when considering CDMA systems. In order to offer the maximum possible capacity, two main processes have to be settled: an efficient Call Admission Control (CAC) as well as a robust Power Control scheme when the link is established.

One major drawback of CDMA systems is the crucial importance of radio resources partitioning and thus the call admission control. Indeed, within each cell, CDMA systems management can be pictured as a global amount of power to be dispatched between users. Due to their forward transmitted power limitations, base stations (BS) can grant access to a restricted number of users. Furthermore, this number of users likened to the network capacity strongly depends on the radio profile of the users, that is, radio attenuation from their serving base station, local interference levels, requested application(s), velocity ... etc. Indeed, the system capacity will strongly be reduced if most of the users are located at the cell edge compared to the situation where they are a few meters far from it.

For this reason, depending on the network operator policy, it is detrimental to grant radio resources to a costly user (high pathloss and interference level) while several of them close to the BS could enter the system at the same expense.

What is proposed here is a dynamic call admission control, which considers the evolution network load with time to govern the users admission based on their radio profile.

The purpose of this solution is to provide an adaptive principle to help determine the admission criteria of new users in a CDMA cellular network, depending on the system load, its evolution with time and the users profile.

More precisely, the profile of the users to enter the system will highly be defined from the system load status and evolution. Thus, based on the network provider policy, the system capacity can ...