Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
2001-08-10
2004-08-10
Maung, Nay (Department: 2684)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S063100, C455S067130, C455S561000, C455S226100
Reexamination Certificate
active
06775544
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an automatic diagnostic application for use in wireless communication systems.
Wireless communication systems are well-known. They typically involve transmission of modulated information signals from a central base station to mobile subscriber terminals and back over wireless channels. Over the years, because of the intense commercial success of such systems, several alternate architectures have been deployed for wireless communication systems. Thus, wireless communication systems may vary by access technique and carrier modulation techniques, among other things. For example, cellular systems have been deployed according to frequency division multiple access, time division multiple access and code division multiple access. Further, these cellular systems have employed both analog modulation techniques, such as frequency modulation, and digital modulation techniques, such a frequency shift keying, amplitude shift keying, phase shift keying or combinations thereof.
The various communication systems, however, share at least one thing in common—when extraneous energy is received by a base station in traffic channels, it interferes with the reception of information signals that are supposed to be received in those channels. Accordingly, to maintain high signal quality in a system, it is desirable to identify and either suppress or avoid strong interference signals in the system.
Interference typically is created from either a ‘rogue’ interference source or from intra-system interference. A rogue interferer may be a broadcasting agent from another wireless communication system. While different co-located wireless communication systems typically are allocated mutually exclusive segments of radio spectrum, it is not uncommon for equipment malfunction or some high power broadcast event in a first system to generate interference energy in reception channels of a second system. Intra-system interference refers to broadcast energy from a first element in a wireless system that is received inadvertently by a second element of the same system.
Interferers may be transient. A rogue interferer may be active only intermittently, for a short period of time. Thus, while a cell site may experience severe interference effects when the rogue is active, it may not suffer performance degradation continuously. Similarly, intra-system interference may occur randomly for reasons that are well-known. For maintenance personnel of the wireless communications, the random nature of interference may make it very difficult to identify cell sites that are candidates for remediation. To identify cell sites that experience interference, it had been necessary in the past for maintenance personnel to travel to the cell site and perform interference measurements manually. This manual search process increases the time and expense involved in identifying and remediating interference in a wireless system.
Accordingly, there is a need in the art for an automatic diagnostic method for wireless communication systems that identify and report periods of severe interference in the system.
SUMMARY
Embodiments of the present invention provide an automated diagnostic method for identifying interference events at a receiver of a wireless communication system. According to the method, the receiver is queried for energy measurement data. From the energy measurement data, a probability distribution of the energy is calculated. An interference event may be identified at the receiver if the calculated probability distribution for the receiver exceeds an average probability distribution for a larger set of receivers in the system. In an embodiment, the energy measurement data may represent the noise floor at the receiver and, optionally, may include channel quality metrics.
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AT&T Wireless Services Inc.
Kenyon & Kenyon
Maung Nay
Sobutka Philip J.
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