摘要:

An integrated vehicle location system is described which employs an automatic receiver of simple design for the Decca Navigator system, supplemented by an odometer and gymballed flux-gate compass. Data recorded on board the vehicle have been processed offline using a Kalman filter technique. Vehicle tracks are presented which show less than 70 m standard deviation of error over long routes in urban and rural areas.

DOI:10.1049/ip-f-1.1985.0078

出版商:IEE    

年代:1985

数据来源: IET

摘要:

Digital cellular mobile radio systems are described having partially overlapping cells that are based on road configurations, and in which the energy is radiated along the road from approximately street lamp elevations. One proposed system uses propagation frequencies in the vicinity of 900 MHz, employs adaptive differential pulse code modulation at 32 kbit/s and a minimum shift keying modem enabling a channel spacing of 25 kHz. One example of system performance shows that, for clusters of ten cells along a six-lane highway, the signal/interference ratio is 20 dB, the probability of error is 10−3, and the channel SNR is 10.8 dB. Given an allocated mobile radio bandwidth of 20 MHz, the system can support 80 users per cell. If the vehicles are travelling at 88 km/h (55 miles/h) and 10% of the drivers make a telephone call, the cell length is 4.8 km (3 miles), and the cochannel distance is 48 km (30 miles). In our deliberations we made comparisons with conventional analogue FM systems, and showed that they have approximately half the user density capacity of the new system. A digital microcellular mobile radio systems employing 60 GHz is also considered. The bit rate per segment of road was found to be vast, e. g. 100 Mbit/s per 100 m of road. This system is capable of providing portable communications to large numbers of pedestrians and drivers in congested city streets. Because of the configuration of the proposed cell structure, shadow fading is conjectured to have very little impact on system performance.

DOI:10.1049/ip-f-1.1985.0079

出版商:IEE    

年代:1985

数据来源: IET

摘要:

A futuristic mobile communication system is proposed, based on the integration of a high-capacity digital cellular mobile radio system with a packet-switched routing network. Every communication terminal, e. g. a telephone, viewphone or computer, is connected to the fixed part of the local area network (LAN) by short-distance radiocommunication. These terminals are deemed to be ‘mobiles’, irrespective of whether they are in motion. The propagation frequencies advocated are mainly those in the absorption band A1(51.4–66 GHz). Oxygen absorption of radiated energy in this band is 14 dB/km, and this characteristic is utilised to formulated microcellular structures that are tailored to suit specific geographical locations. The small size of the microcells ensures that the radiated power levels are low and that the date capacity per area is high, and, as a consequence, vast numbers of users can be accommodated. Although the microcells are shaped to the environment, the transceivers are standardised. All signals are digitised prior to radio transmission, and the fixed part of the LAN must be able to accommodate the huge mobile data rate, as must the main trunk network. Thus we suggest and optical-fibre LAN and packetised routing network to overlay the existing networks. Also considered briefly are noncommunication services, such as automatic vehicular location, integration of the communication network with an adaptive traffic control system, route guidance and the mobile office. The treatment is qualitative.

DOI:10.1049/ip-f-1.1985.0080

出版商:IEE    

年代:1985

数据来源: IET

摘要:

The regulatory and commercial framework for the introduction of a cellular radio system in the UK is unusual, in that it calls for two competing networks to interwork interchangeably with a range of mobile units. Connection to the fixed telephone network is also required. The Total Access Communication System (TACS) has been defined to meet such conditions. A description is given of the bases for the determination of the overall system parameters, particularly those concerned with the radio paths and end-to-end speech transmission. The definition of the key interfaces to permit interworking without restricting competitive technological development is also outlined.

DOI:10.1049/ip-f-1.1985.0081

出版商:IEE    

年代:1985

数据来源: IET

摘要:

The paper discusses several aspects of cordless telephony which are relevant to systems being discussed for use in the UK in the future. A variety of methods of arriving at traffic estimates are considered, including studies of population density in urban and suburban London. From these estimates it is shown that an allocation of at least forty channels will be needed to satisfy the demand of domestic and small business users. Three analogue and one digital modulation systems are considered, and it is shown that the digital system offers better use of the spectrum than the analogue systems. Additionally, the digital scheme allows convenient implementation of time-division duplex transmission, as well as ongoing call-quality monitoring. The paper looks at the merits of allocating one common channel for signalling purposes and compares these with the advantages of a simpler system, where the signalling information is carried on the speech channels. It is shown that significant extensions of battery life can be achieved by using a common signalling channel. Finally, the paper considers some of the implications of the time-division duplex system on receiver design.

DOI:10.1049/ip-f-1.1985.0082

出版商:IEE    

年代:1985

数据来源: IET

摘要:

The paper first outlines the inherent strengths and weaknesses of mobile and fixed terminals in HF communication systems. Conventional HF system design and operating procedures are then described. The improvement in performance achievable by the use of various forms of diversity combining is quantified, and it is shown how a number of fixed HF terminals can be combined into a geographical diversity network, which can be accessed by mobile terminals. Specific problems of interconnection, data transmission and system control are considered in greater depth.

DOI:10.1049/ip-f-1.1985.0083

出版商:IEE    

年代:1985

数据来源: IET