Showing papers on "Mobile telephony published in 1971"

Dynamic channel assignment in high-capacity mobile communications systems

Abstract: Computer simulations of high-capacity mobile radio systems using different channel assignment philosophies are described. These simulations initiate call attempts and move vehicles about randomly according to prescribed statistical distributions. Base stations and radio channels are assigned to serve mobiles and system operating statistics are accumulated. Relationships between systems parameters obtained from the simulation are presented. Performance of a dynamic channel assignment system (DYNSYS) which has all channels available at all base stations is compared with performance of a fixed-channel assignment system (FIXSYS) which reserves channel subsets for use at specific base stations. For uniform spatial distributions of call attempts and 40-channel systems with reuse intervals of four base station radio coverage areas, the DYNSYS outperforms the FIXSYS at blocking rates up to 13 percent. For example, at a 3 percent blocking rate the DYNSYS provides 20 percent more calls “on” in the system.

Billing system in mobile communication

Abstract: In a mobile communication system wherein connection is provided between a vehicle and an ordinary telephone network through one of the radio base stations which are installed within a district in which the vehicle passes the radio base station being connected to an exchange station associated with the telephone network, a billing system in mobile communication, wherein an out-band signal is sent from the vehicle to an exchange equipment in the exchange station whereupon a second out-band signal is sent from the exchange equipment to the vehicle so that, only while the second out-band signal is being received, measurement of time and billing are carried out in the vehicle, and wherein a billing classification is discriminated on the basis of a dial signal sent from the vehicle and the result of the discrimination is sent from the exchange equipment to the vehicle in the form of a voice-band multifrequency signal, also serving as a response signal, so that the condition for the billing is set in the vehicle.

Asynchronous Filters and Mobile Radio Communication Based on Walsh Functions

Abstract: It is well known that the usual frequency filters based on sine-cosine functions do not require synchronization. Furthermore, sinusoidal electromagnetic waves of different frequency can be separated in mobile communication without any synchronization between the various transmitters and receivers, It is widely believed that this is a result of certain shift invariant features of sinusoidal functions that do not exist for other functions, The purpose of this paper is to show by means of simple examples that there are infinitely many systems of functions on which one may base asynchronous filters and mobile radio commnuication. The difference in the usefulness of these systems of functions depends only on the state of technology, no system is inherently better than others.