Showing papers on "Handover published in 1989"

Handover method for mobile radio system

Abstract: The invention relates to a method in mobile radio systems in which the responsibility for transmitting message information to a mobile station is handed over from a first base station transmitter to a second base station transmitter. In this method, the same radio channel is used, if possible, before and after the handover for transmitting message information to the mobile station. If the same radio channel can be utilized, the handover takes place without the mobile station being informed beforehand of the handover by a special signal or order or the like. In digital mobile ratio systems with digital transmission of message information by digital modulation of the radio signals, the transmission is preferably started from a second base station transmitter before the transmission is terminated from a first base station transmitter. During a certain transmission time substantially the same message information is transmitted to the mobile station from both the first and second base station transmitters.

Strategies for handover and dynamic channel allocation in micro-cellular mobile radio systems

Abstract: Microcellular structures are the central means for increasing the network capacity of mobile radio systems. By examining existing dynamic channel allocation algorithms, the authors identify a class of adaptive algorithms best suited for such microcellular environments. Applicable algorithms of this class require intracell handover and are to a large extent decentralized. One new algorithm of this class is introduced and evaluated by means of simulation. The proposed algorithm (DYNINF) has been evaluated with respect to performance criteria such as blocking probability, interference probability, and number of handovers (stability). It is shown that, based on the capacity improvement achieved by microcells, no relevant further improvement of the capacity can be realized, but that the algorithm is very well suited to cope with the problems of microcells, e.g. discrepancies between the network plan and the real situation and heavy variations of the traffic and interference conditions. >

Cellular radio system

Abstract: A cellular radio system in which a base station (BS1) establishing two way communication with a mobile (10) requests base stations (BS2 to BS7) of a subset of adjacent cells to reserve a channel so that in the event of handover to a base station in one of these cells this can be executed quicker than if the reservation had not been made. In making the request for reservation, the communicating base station (BS1) passes on details of the call-in-progress. Once call has been handed over a new subset of adjacent cells is created.

Properties of a TDMA pico cellular office communication system

Abstract: Properties of a TDMA/TDD (time-division multiple access/time-division duplex) micro or rather pico cellular cordless telephone system using decentralized dynamic channel allocation and handover are presented. The system has 16 or 8 time-division time-duplex channels (slots) per carrier, each occupying 2 MHz or 1MHz. The TDMA frame is 16 ms long and each slot has bits for synchronization, signalling, and data. The data speed is suited for 32 kb/s speech codecs. Procedures have been developed for efficient and quick dynamic channel allocation and handover, using the fact that a single radio can simultaneously monitor or communicate on all 16 or 8 time-slot channels. Simulations for a specific six storey building indicate that 16 channels can provide wireless communications for up to 30% of the telephones, and 32 channels for up to 100% of the telephones. Slot synchronization between adjacent systems is desirable, but not necessary. Tests show that no time dispersion equalizers are needed, and that antenna diversity is effective against fading dips and time dispersion. This system concept has been proposed to CEPT as a base for European Digital Cordless Telecommunications. >

Rural radiotelephone system

Abstract: A remote coverage system extends the effective coverage area of a cellular mobile radiotelecommunications (CMR) master cell. When a mobile unit assigned to the master cell moves from the master cell's coverage area into the coverage area of a satellite cell, the satellite cell sends a signal asking for a handoff of the mobile unit to it. When the handoff occurs, the MTSO exchanges signals with the mobile unit via a relay unit located at the master cell site. The relay unit relays signals between the MTSO and the satellite cell.

The provision of GSM cellular radio environments within passenger aircraft operating over Europe

Abstract: The author describes the findings of a feasibility study into the means of provision of a GSM cellular radio environment inside passenger aircraft. The background and capacity estimates for such a system are discussed prior to the presentation of a description of proposed system architecture. This description includes topics such as network organisation, handover, transmission delay compensation, signalling, the RF link and the aeronautical transponder implementation.

Method of reducing blockages in handing over calls in a mobile, cellular telephone system

Abstract: A method of reducing blockages and call interruption in handling over calls in a cellular mobile radio system. When the signal strength from a base station to a mobile and vice versa falls below a given value the handover shall take place to another base station. In order that the call will not be interrupted, a smaller number of channels are reserved, so-called rescue channels, from the ordinary channels in the system. The rescue channels can be fixed or dynamic for a given base station.

Handover criteria and control in cellular and microcellular systems

Abstract: Cellular system operation relies on frequency reuse, with cell sizes and reuse distances governed by receiver tolerance to cochannel interference. It is possible for a mobile unit to move away from the initial base station during communication, so the facility to handover the link to adjacent base stations is a necessary feature of the network. The complexity of the problem renders it difficult to quantitatively compare handover algorithms in a system design; hence a computer simulation tool has been developed to expedite this comparison. This has been used for handover criteria performance assessment within the model. A first order estimate of typical signalling loads anticipated in microcell based systems has been obtained. Simulation illustrates the excessive handover numbers compared with the number of cell boundary crossings, whenever the criteria chosen exhibit statistically indeterminate behaviour. However, the performance can approach that of a deterministically controlled system if the handover algorithm is modified. More sophisticated handover algorithms could magnify this effect.

Effect of Cochannel Interference on Handover in Microcellular Mobile Radio

Abstract: The effect of cochannel interference on a fast handover algorithm for microcellular mobile radio systems is described. The presence of cochannel interference had only a marginal effect on the handover point when the microcell base stations were spaced by 300m. Increasing the mobile speed increased the effective cell length.

Handoff in a cellular commuinication system

Abstract: A method of handoff for use at base sites (110) of a cellular telephone system for handing off from one of the base sites to another one of the base sites at least one of a plurality of cellular telephones (102) each transceiving data packets and sharing a cellular radio channel of the cellular telephone system, which channel may be packet-switched or digital. A handoff message is sent to one of the active ones of the plurality of cellular telephones in response to determined system loading or signal characteristic, as exemplified in FIG. 7.

Efficient handoff policy without guard channels for mobile radio telephone systems

Abstract: Presented in this letter is a prioritised pushout handoff policy without guard channels for increasing the total grade of service (GOS) in a mobile radio telephone system. Blocking probability and waiting time distribution for each call are obtained, and a boundary for two handoff policies between with and without guard channels is found. >

Method of operating a mobile radio system

Abstract: of EP0535714The method transfers the responsibility for transmitting message information to a mobile station from one base station transmitter (Bma, Bmb) to a second base station transmitter (Bna, Bnb). The transmission of the message information to the mobile from the second base transmitter (Bna) is started before the transmission of the message information to the mobile from the first base transmitter (Bma) has been terminated. During the transition period, the same message information is transmitted to the mobile station from both the two transmitters. Before the handover takes place, testing is carried out in the stationary part of the system to see whether the second base transmitter can use the same radio channel after the handover, as the radio channel the first base transmitter used before handover. When the radio transmission conditions and remaining communication in the system permit, the same radio channel is used before and after handover.

Handover without notice

Abstract: The invention relates to a method in mobile radio systems in which the responsibility for transmitting message information to a mobile station (MS1, MS2) is handed over from at least a first base station transmitter (Bma,Bmb) to at least a second base station transmitter (Bna,Bnb). In accordance with the invention, the same radio channel is used, if possible, before and after the handover for transmitting message information to the mobile station. If the same radio channel can be utilised, the handover takes place without the mobile station being informed beforehand of the handover by a special signal or order or the like. In digital mobile radio systems with digital transmission of message information by digital modulation of the radio signals, the transmission is preferably started from a second base station transmitter before the transmission is terminated from a first base station transmitter. During a transmission time substantially the same message information is transmitted to the mobile station from both at least one first and one second base station transmitter.

Narrow-band FM transmission in land mobile radio

Abstract: The authors describe the narrow-band mobile radio transmission technologies used in NTT's High-Capacity Land Mobile Communications System. These include 12.5 kHz-band analog FM transmission for voice; 2400 b/s data transmission for access and paging control; 100 b/s data transmission for channel associated control; and enhanced cellular technologies such as diversity reception, adaptive transmitter power control, interference evasive intrazone handoff, excess level detection/interzone handoff, and error control schemes in common control channels. Field trial data on power control and handoff are also presented. >