Showing papers on "Mobile telephony published in 1984"

High density cellular mobile radio communications

Abstract: In a cellular mobile telecommunication system, a method and apparatus for controlling the process of locating a mobile unit from the cell sites. When a mobile unit goes beyond the radio range of its associated controlling cell site, that cell site sends a message to nearby cell sites to measure and report the strength of the received signal from that mobile on each of their directional antennas and to report radio channel availability. These reports are returned to the controlling cell site which compares the received signal strength mesurements against stored thresholds. The controlling cell site generates and transmits to the mobile telecommunications switching office (MTSO) a hand-off request message including a list of candidate hand-off cell sites and directional antennas. The MTSO then selects an available channel associated with one of the candidate cell sites and antennas and generates a sequence of messages to hand-off communications control from the controlling cell site to a candidate cell site.

Control of telecommunication switching systems

Abstract: A method and apparatus for controlling a cellular mobile telecommunication system. A switch (153) and a telecommunication control complex (101, 164, 163, 142, 144, 143, 145) cooperate to set up connection between a telecommunication network, such as the common carrier public telephone network, and a plurality of mobile units (165). The switch sets up connections between trunks to the telephone network (157, 158) and communication links (149, 150, 160, 161) connected to the cell sites (I, N) of the mobile telecommunication system. The telecommunication control complex, including a mobile telecommunication controller (101) and a cell site controllers (164), controls the radio connections between these communication links and the mobile units.

Outage Probability in Mobile Telephony with Directive Antennas and Macrodiversity

Abstract: Signal-to-interference ratio statistics for mobile telephony systems with hexagonal coverage areas, multiple interferers, and threecorner base stations are investigated. Corner base stations simultaneously reduce total interference (because of antenna directivity) and provide macrodiversity against shadow fading. Our results indicate that for 3 or 7 channel sets, with 2 tiers of interferers and typical system parameters (propagation exponent of 3.7 and lognormal spread of 8 dB), the improvement is on the order of 11 dB over a baseline arrangement which employs centrally located omnibase stations without macrodiversity. Additional considerations of blocking probabilities and average voice activity indicate possible further improvements.

Outage probability in mobile telephony with directive antennas and macrodiversity

Abstract: Signal-to-interference ratio statistics for mobile telephony systems with hexagonal coverage areas, multiple interferers, and three-corner base stations are investigated. Corner base stations simultaneously reduce total interference (because of antenna directivity) and provide macrodiversity against shadow fading. Our results indicate that for 3 or 7 channel sets, with 2 tiers of interferers and typical system parameters (propagation exponent of 3.7 and lognormal spread of 8 dB), the improvement is on the order of 11 dB over a baseline arrangement which employs centrally located omnibase stations without macrodiversity. Additional considerations of blocking probabilities and average voice activity indicate possible further improvements.

Traffic characterization and classification of users of land mobile communications channels

Abstract: An analysis of traffic parameters for different types of users of land mobile radio (LMR) communications channels is presented. Based on audio monitoring of voice traffic, this analysis provides valuable information concerning efficiency of channel utilization by users; such information corroborates results already obtained through RF carrier monitoring. In addition, a user classification strategy, based on their message characteristics, is proposed and different procedures are suggested for estimating user message length when only base station information is available. Finally, the effects of grouping two users on the same channel are discussed from both channel allocation and grade of service points of view.

Traffic Characterization And Classification Of Users Of Land Mobile Communications Channels.

Abstract: An analysis of traffic parameters for different types of users of land mobile radio (LMR) communications channels is presented. Based on audio monitoring of voice traffic, this analysis provides valuable information concerning efficiency of channel utilization by users; such information corroborates results already obtained through RF carrier monitoring. In addition, a user classification strategy, based on their message characteristics, is proposed and different procedures are suggested for estimating user message length when only base station information is available. Finally, the effects of grouping two users on the same channel are discussed from both channel allocation and grade of service points of view.

High performance digital communications in mobile channels

Abstract: Random amplitude and phase modulations experienced in mobile channels result in a number of system limitations and link impairments. In this paper, a novel approach named "tone calibrated technique" which mitigates multipath fading induced distortions in a digital link is presented. It is shown that a low power pilot tone can be used to continuously calibrate a mobile link against time varying impairments. Coherent demodulation of data is possible by means of the pilot tone without using a conventional tracking loop. Since very little power is consumed by the pilot tone, the performance of the tone calibrated technique is only marginally below BPSK in an unfaded environment.

A proposed architecture for a mobile telephone system utilizing multi-beam satellite coverage

Abstract: Recent work toward direct-to-satellite mobile telephony has been pursued under the Canadian MSAT study. This paper outlines a system design utilizing a multi-beam coverage plan to meet the broad design objectives of efficient channel usage and flexible system configuration. Call routing, sharing of traffic loads amongst beams, interconnection, billing issues, and management of mobile units are discussed. Access to any voice channel from any geographic location allows a variety of call switching options and powerful loadsharing properties.

Adaptive mobile access protocol (AMAP) for the message service of a land mobile satellite experiment (MSAT-X)

Abstract: This paper describes a feasibility study of the adaptive mobile access protocol (AMAP) for MSAT-X, a proposed experimental mobile satellite communication network. The mobiles are dispersed over a wide geographical area and the channel data rate is limited due to the size and cost limitations of mobile antennas. AMAP is a reservation based multiple-access scheme. The available bandwidth is divided into subchannels, which are divided into reservation and message channels. The ALOHA multiple-access scheme is employed in the reservation channels, while the message channels are demand assigned. AMAP adaptively reallocates the reservation and message channels to optimize system performance. It has been shown that if messages are generated at a rate of one message per hour, AMAP can support approximately 2000 active users per 2400 bit/s channel with an average delay of 1.4 s.

Mobile communication system of unrestricted area for separate charging of incoming and outgoing call

Abstract: PURPOSE:To increase the capacity for subscriber numbers and to eliminate troublesome callback operation by dialing a telephone number of a mobile device to be called by a caller whereever the mobile device to be called exists so as to connect the caller and the mobile device to be called and applying charging separately to the caller and the called party. CONSTITUTION:When a subscriber 1 dials number 030 (car telephone identification code) + CDEFGHJ (subscriber number), a toll center 2 prepares for charging the same as the existing system (since it is not necessary to designate any area, 7 digits are used as the subscriber number capacity). Its home AMC is identified by assigning a CD code or the like for each AMC. The charge from the subscriber 1 to a home AMC14 of a mobile communication exchange station having subscriber information of the mobile device 10 to be called is imposed on the subscriber 1. A district center 11 or a regional center 12 is connected to a mobile communication exchange station AMC13 nearby, the AMC13 identifies the home AMC14 by the CD code or the like, inquires the location of the mobile device 10 to be called for the AMC14 through a common line 16 and is connected to its incoming AMC15. Further, the subscriber 1 is connected to the mobile device 10 to be called by the subscriber number CDEFGHJ, and the share of the movement of the mobile device 10 to be connected is charged to the mobile device 10 depending on the distance between the AMC14 and the incoming AMC15 and the duration of the call.

Design consideration in the MSAT mobile telephone system setup channel

Abstract: MSAT is a mobile communication satellite intended to offer mobile radio and mobile telephone service (MTS) in the 800 MHz band. Although the MTS, in particular, is very similar in organization to terrestrial cellular system, there are unavoidable differences in both the signal and traffic environments. This paper examines the effect of the mobile satellite environment on the performance of the MTS call setup channel. In addition the paper presents new results on the effect of random FM on a Manchester coded data signal, and on the performance of a cellular-like data format in the presence of Rice fading.

Mobile communication system for unrestricted area with position guide talkie

Abstract: PURPOSE:To know a caller recognize position information of a mobile device to be called prior to the setting of a talking line by the constitution that an outgoing exchange receiving a calling dial informs the acquired position information from a talkie device to an outgoing subscriber before the connection control is started. CONSTITUTION:When a mobile communication identification number, e.g. 30, and the number X of a mobile device 2 are dialed from a telephone set 1, a central controller CC42 of a relay exchange 4 retrieves a mobile communication exchange 5, transmits the number X to the exchange 5 via a common line signal path 4 and requests the position information. A CC52 of the exchange 5 accesses a memory 53 based on the number X and extracts the position information. This information is an identification number of a mobile communication exchange 6 relating to a position registration area to which the mobile device 2 belongs and is, e.g. 40. This information is transmitted from the CC52 to the CC42. The CC42 controls a channel 41 based on this information before the connection control, connects the talkie device 45 and informs the position of the mobile device 2 to the telephone set 1.