Telefonaktiebolaget Lm Ericsson (Publ)

Michel Desgagne

Arne Simonsson

Patrik Torgny Karlsson

Angelo Cuffaro

Sylvain Labonte

Pat Minichiello

Matthieu Lachance

Gopichand Kongara

Mairead Nagle

The present invention is directed to method and apparatus for detecting base station (BS) transceivers malfunctions in a cellular telecommunications system. A Transceiver Malfunction Detector (TMD) receives and stores information related to the service performance of the BS transceivers and sorts the information on a per transceiver basis, for generating a service quality value for each transceiver. The TMD computes a service quality threshold value proportional to the average performance of the BS transceivers, and compares the service quality value of each monitored transceiver with the threshold, for determining the acceptability of the transceiver performance. The TMD also detects the cause of a malfunction in a transceiver, by assigning the frequencies used by an adequate transceiver to a transceiver suspected to be malfunctioning and by further monitoring the activity of the initially malfunctioning transceiver. When the transceiver persists malfunctioning after the frequency change, it is concluded that the malfunction is due to a hardware or software problem in the transceiver, while if the transceiver performance improves after the frequency change, it is concluded that the malfunction is due to a frequency interference.

Method and apparatus for detecting base station transceivers malfunctions

Cellular telephone systems may have to handle high rate data calls that utilize multiple full rate channels within a frequency. It is important to increase the availability of the system for these high rate data calls while maintaining the quality of the radio links within the cellular radio network. A first sort is performed to find full rate channels that meet a requested call service type below the operator allowed cost threshold related to the radio conditions. Using the previously sorted FR channels, a second sort is performed to find the multi-full rate channel combinations that meet a requested call service rate. The call is then assigned to the found channel combination with the lowest cost. Otherwise, the system reduces the requested service rate of the call and attempts to place the call into a multi-full rate channel combination channel again. If the call has reached the minimum acceptable service rate, the system reduces an existing high rate call, and attempts to place the call into a multi-full rate channel combination. Additional functionality allows the system to perform intra-cell or intra-frequency hand-offs.

Multi-full rate channel assignment for a cellular telephone system

A cellular communications network includes a plurality of cells whose base stations have both sector and smart antenna capabilities. While engaged in a call, mobile station downlink signal strength measurements are made on its own serving traffic channel and the control channels of neighboring cells. These measurements are then adjusted by one or more factors which take into account the operational and physical differences between sector antenna and smart antenna. For example, the signal strength measurements may be appropriately adjusted by measured differences in gain between the smart antenna and sector antenna, output power backoff values associated with smart antenna and sector antenna support of the traffic channels in comparison to the control channels, and power control attenuation applied to the traffic channels. The resulting adjusted downlink signal strength measurements may then be compared against each other (as off-set by any imposed hysteresis value) to more precisely locate the mobile station and uniformly, predictably and accurately identify when it is appropriate to authorize a hand-off.

Preservation of cell borders at hand-off within a smart antenna cellular system

A method of reducing co-channel interference in a cellular telecommunication system having a congested serving cell, a plurality of neighbor cells controlled by a mobile switching center (MSC), and an accessing mobile station attempting to access the cellular system in the serving cell. The MSC fetches signal strength information from mobile stations camped on the serving cell's digital control channel (DCCH). The signal strength information includes received signal strengths at the camped mobile stations from the serving cell and the neighbor cells. The MSC then fetches signal strength information from busy mobile stations involved in on-going calls in the serving cell. For each busy and camped mobile station, the expected downlink signal strength from each neighbor cell is subtracted from the maximum downlink signal strength from the serving cell. The mobile station/neighbor cell combination with the numerically least difference causes the least co-channel interference when the identified mobile station is moved into the identified neighbor cell. If the identified mobile station is the accessing mobile station, the MSC redirects the accessing mobile station to access the cellular system in the identified neighbor cell. If the identified mobile station is a busy mobile station involved in a call, the MSC forces a handoff of the identified mobile station to the identified neighbor cell.

Method of selectively directing a mobile station to retry system access

A method of selecting a voice channel in a radio telecommunications network. The method begins by seizing a first digital traffic channel (DTC) having a carrier signal strength (C) and an interference strength (I), and calculating an expected ratio of the carrier signal strength to the interference strength (C/I) on the first DTC. From this calculation, it is determined whether the first DTC is disturbed. This is followed by utilizing the first DTC for a call upon determining that the first DTC is not disturbed, and seizing a second voice channel upon determining that the first DTC is disturbed. The second voice channel may be a second DTC or may be an analog voice channel (AVC). If a second DTC is seized, the C/I is determined for the second DTC, and the DTC with the higher C/I is retained. If the second DTC is also disturbed, another reselection and comparison may be performed. Reselections continue until a channel with good C/I is found, or a maximum number of reselections is performed.

Method of selecting a voice channel in a radio telecommunications network

Each base station in a cellular telephone system includes a signal strength measurement device operable to tune to and make signal strength measurements on not only the frequencies allocated to other cells, but also on its own allocated frequencies. Measurements are made by the device on those of its own frequencies having idle traffic channels to obtain an indication of injected uplink interference. An interference penalty is then assessed against the measured uplink interference for those frequencies having more than a threshold number of idle traffic channels. The adjusted measurements for the frequencies allocated to the cell are then sorted in relative order of idle traffic channel (adjusted) measured uplink interference from a least (adjusted) interfered frequency to a most (adjusted) interfered frequency. An idle traffic channel is then selected for assignment at either call set-up or hand-off from the least (adjusted) interfered frequency.

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St-Hubert, Canada

Michel Desgagne