Cellular Mobile Telephone Research Articles

Distributed traffic adaptive channel allocation

Dynamic channel allocation (DCA) schemes adapt to the time variant demand for channels in cellular mobile telephony systems. In this paper we propose a DCA scheme that smoothly changes the channel allocation by solving the following problem. Given a cell structure, a collection of channels, the frequency reuse distance, an allocation of channels to cells, and the number of active connections per cell, accommodate a new call or a new handover by minimally reconfiguring the established allocation of channels to cells. First, this problem is formulated as 0–1 quadratic programming problem. Next, we present a distributed, heuristic solution to the problem, which is based on the observed behaviour of the optimal algorithm. Finally, we present some simulation results on the performance and the feasibility of the distributed algorithm. © 1997 John Wiley & Sons, Ltd.

Distributed traffic adaptive channel allocation

Dynamic channel allocation (DCA) schemes adapt to the time variant demand for channels in cellular mobile telephony systems. In this paper we propose a DCA scheme that smoothly changes the channel allocation by solving the following problem. Given a cell structure, a collection of channels, the frequency reuse distance, an allocation of channels to cells, and the number of active connections per cell, accommodate a new call or a new handover by minimally reconfiguring the established allocation of channels to cells. First, this problem is formulated as 0–1 quadratic programming problem. Next, we present a distributed, heuristic solution to the problem, which is based on the observed behaviour of the optimal algorithm. Finally, we present some simulation results on the performance and the feasibility of the distributed algorithm. © 1997 John Wiley & Sons, Ltd.

Biological aspects of mobile communication fields

Our knowledge on the biological effects of RF radiation has been increasing for many decades. It has become a focus of attention because of the accelerated use of RF radiation for wireless communication over the past few years. It is fairly well established that at sufficiently high power levels, RF and microwave energy can produce deleterious biological effects. Wireless communication systems use low power modulated forms of RF and microwave radiation that was not investigated extensively in the past. Thresholds and SARs for biological effects both vary widely. Many specific questions must be answered before any consistent, dependable and scientific conclusions can be drawn for the biological effects and safety of wireless mobile communication systems. Nevertheless, available data do not suggest any immediate cause for concern of a impending threat to public health from acute or short term exposure to low level RF and microwave radiation. Investigations to answer some of the questions have already begun. Many of them are designed to study the effects of long term exposure. When considering repeated, low level irradiation, the possibility of cumulative effects have been raised. While there is presently no confirmed evidence for cumulative effect, there is little information to the contrary. Large scale epidemiological investigations should also be undertaken among the two-way mobile communication and cellular telephone users who may be exposed to varying levels of RF radiation over time. Better understanding is needed of the mechanisms of interaction between RF/microwave radiation and biological systems, and of the significance of any observed effects. Enormous progress has been made in the difficult area of dosimetry. However, measurement of energy distribution in and around a subject for exposure assessment remains a challenge, more so for large numbers of people. This type of quantitative information is also required for extrapolation from animal experimentation to human response.

Overall Mortality of Cellular Telephone Customers

Unlike mobile cellular telephones, in which the antenna is not part of the handset, a portable cellular telephone exposes the user's head to radio frequency energy transmitted from the antenna. This exposure has prompted concerns about potential biological effects, including brain cancer. As a first step in a record-based mortality surveillance of cellular telephone customers, we report on overall mortality of a cohort of more than 250,000 portable and mobile telephone customers during 1994. We found age-specific rates to be similar for users of the two types of telephones. For customers with accounts at least 3 years old, the ratio of mortality rates in 1994 for portable telephone users, compared with mobile telephone users, was 0.86 (90% confidence interval = 0.47-1.53).

Optimum frequency reuse in mobile telephony systems

AbstractThe reason why cellular mobile telephony systems exist is that they allow frequency reuse. Dynamic allocation algorithms improve the network efficiency and the service quality. Dynamic allocation is closely related to the following instantaneous allocation problem: given a number of channels (frequencies), a cell structure and the number of calls to be accommodated in each cell, find the optimum allocation of channels to cells subject to restrictions concerning the distance of cells, where the same frequency can be reused. In this paper we formulate and solve this problem by showing that it can be reduced to a 0–1 programming problem. Finally we present results, and draw subsequent conclusions.

Technological discontinuities, competition and firm performance

This article discuss in a tentative way what determines the effect of technological discontinuities on the competitive position. of companies within an industry. Three cases of technological change are anahzed: the change from manual to romputer numericalb controlled metal cutting machine tools, the change from stand-alone machine tools to flexible manufacturing systems; and the change from non-cellular to cellular mobile telephony It is argued that the character of technological discontinuity affects market shares, by altering the barriers to entry and mobility, and by being more or less in accordance with the different firms’ vision about the future, implying variations in the time needed to detect and accept the new threat or opportunity. A technological discontinuity that includes a new threat or opportunig. A technological discontinuip that involues a new generic technology which substitutes for rather than adds to the previous technology base is seen as being most disruptive. The time actualb availa...

A common air interface between wide‐area cordless telephone and urban cellular radio: Frequency channel doubly‐reused cellular systems

AbstractThis paper proposes a new system [1] in which the frequency channel of the wide‐area cordless telephone is reused doubly by the frequency channel employed in the urban cellular mobile telephone with a weak power. A condition is imposed whereby the two systems can operate with equal telephone qualities when cochannel interferences exist between two systems.The radius of the microcell and the weak power are analyzed and completed. According to the analysis, the theoretical limit of the spectrum efficiency of the new system is doubled compared to the system where the frequency bands of the two systems are placed independently in adjacent bands (AB) [2, 3]. To realize the cooperation between the wide‐area cordless telephone and the urban cellular mobile telephone on the equally coexistent condition, an autonomous spectrum distributed management system is proposed in principle [3] which can maintain in a simple way the cochannel interference sharing.

On the chip rate of CDMA systems with doubly selective fading and rake reception

The bit error probability for a direct-sequence code division multiple access (CDMA) system is determined as a function of the chip rate for communications over doubly selective fading channels. The effect the chip rate has on the performance of a CDMA system is considered for both a correlation receiver and a rake receiver. Several selective fading channels are employed as examples to illustrate that the choice of the best chip rate depends upon the characteristics of the channel and the number of taps in the rake receiver. The tradeoff between the number of taps and the bit error probability is investigated for different chip rates. Additionally, the effects of the Doppler spread on the performance of the system and the choice of chip rate are considered. The purpose of this paper is to examine some of the fundamental issues that influence performance of CDMA systems when employed for mobile cellular telephony and personal communication systems on channels with doubly selective fading.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A design of AM/FM mobile telephone triband antenna

In vehicles, antennas for AM/FM broadcasting (BC) and cellular mobile telephone (MT) are usually mounted on the car's body. However, a triband antenna which can be used for both AM/FM BC and MT is more desirable to decrease the number of antennas. An outline of the general design for the AM/FM MT triband antenna with coils is described. Next, the design of a new triband antenna with double sleeves instead of coils is presented. The double sleeves consist of two coaxial lines connected in series. It is shown that the triband antenna with double sleeves has good characteristics, including radiation patterns and voltage standing-wave ratio (VSWR). >

Market failure in ‘open’ telecommunications networks: Defining the new ‘natural monopoly’

This paper is a response to ‘Public policy for a multiproduct firm: tearing down the “Berlin Wall” in telecommunications’, by Edward C. Beauvais and Virginia K. Sheffield of GTE. 1 It refutes these authors' portrayal of the demise of the telecommunications monopoly by exploring the formation of market power in highly interconnected, high-capacity telecommunications networks, and in so doing it identifies the limitations of effective competition in nominally ‘open’ network environments. The paper will argue that efforts to prescribe ‘unnatural’ industry structures are doomed to failure, and that ‘natural’, often highly concentrated markets will evolve in network-based industries despite efforts to legislate balkanization. Examples are drawn from the cellular mobile telephone industry, the airline industry, and the interexchange (long-distance) telephone common carrier markets. Drawing on this experience, the paper will demonstrate that current regulatory reform initiatives of the dominant local telephone monopolies that are either predicated upon or portrayed as leading to the development of effective competition at the local exchange constitute little more than a ‘regulatory gaming’ strategy that is more likely to impede the development of competition than affirmatively to promote it.

CDMA mobile station modem ASIC

An implementation of a complete modulator/demodulator (modem) for use in portable and mobile cellular telephones implementing code-division multiple-access (CDMA) digital technology is described. Key features are high circuit density and complexity, a short design cycle, flexibility, testability, and low power consumption. A universal microprocessor interface allows for efficient control, data transfer, and testability of the ASIC. The chip is fabricated in double-metal 0.8 mu m CMOS technology and implements a mixture of custom and synthesized design approaches. The power consumption is less than 350 mW at 5 V. >

KISS-16V2: a one-chip ASIC DSP solution for GSM

Outlines the requirements for the various digital signal processing functions of the pan-European digital mobile cellular telephone system in terms of computational power and RAM and ROM capacities, and describes a digital signal processor (DSP) solution which is able to integrate all of these digital baseband functions for a hand-held terminal onto one VLSI chip. The KISS-16V2 processor, a low-power CMOS 16-b DSP, is optimized for digital telecommunications, especially for Groupe Speciale Mobile (GSM). A power-down mode together with the capability of memory and multiplier standby operation make this DSP well suited for handheld devices. A design strategy based on the extensive use of cell compilers and synthesis tools reduces the design of further DSP derivations to a minimum. >

Should a ‘Natural Monopolist‘ Be Subject to Competition?: With Special Reference to Cellular Mobile Telephone Services in Australia

AbstractThe argument against competition based on natural monopoly is questioned. A true natural monopolist needs no protection. Rapid product innovation and technical advance render the telecommunications industry not a natural monopolist.Telephones may involve two sources of external benefits: benefits to callers and benefits to receivers. Neither source justifies treating country areas more favourably since the access externality also applies, probably with larger magnitudes, to metropolitan areas.The Cellular Mobile Telephone Service (CMTS) involves the use of parts of the radio frequency spectrum. The spectrum should be treated as a scarce resource. Competitive bidding is probably the most efficient method of allocation if the whole spectrum is to be reallocated. However, with only a small band allocated to CMTS, auctioning need not be the most efficient outcome though it is better than maintaining its monopolised usage.Even if competition results in a higher cost initially, the gain in dynamic efficiency can offset this initial loss. A minimum estimate of the benefits to the public of introducing competition in CMTS gives a present value of $2.4 billion.

Evolution of wireless information networks

Consumer and business demands for cellular mobile telephones and residential cordless phones are growing rapidly throughout the world. Both are relatively new and still function with their original, first generation technologies. In response to various pressures second generation systems and services are scheduled for introduction over the next three years. Meanwhile researches are formulating a vision of the third generation, when cordless, cellular, and other wireless networks will merge in a unified means of wireless access to advanced information services. This paper traces the evolution of wireless information networks by examining goals, network architecture, transmission technologies, and control channels. In each instance, we describe, in a general way, first generation systems. We then discuss details of four different second generation systems: Pan-European Digital Cellular (GSM), North American Digital Cellular (IS-54), Second Generation Cordless Telecommunications (CT2), and Digital European Cordless Telecommunications (DECT). Finally, we provide a glimpse into the future by presenting work in progress on third generation technology, based on packet transmission and switching.

A low-cost approach to cellular mobile telephones

A chip-set has been developed which substantially reduces the complexity and cost of cellular mobile phones. The architecture adopted allows the maximum use of VLSI to reduce total component count and minimize power consumption. This architecture is partitioned into five main blocks: an RF subsystem containing the receiver, tuning system, and transmitter; a continuous-time data processing block to handle the cellular data/control channel streams; an analog audio processing block to handle the baseband telephony audio functions; a system control unit to handle the cellular switching protocols and to control the system hardware; and a user interface. >

Technologies on the horizon-deploying personal communication networks

Present plans for personal communication networks (PCNs) in Great Britain are described. These are networks that allow mass communications between users who are generally mobile. They represent a significant extension of the capabilities of today's cellular mobile telephone networks with much smaller cells and far lower station power requirements. The relationship between PCNs and current cellular networks is examined. Technical approaches that will promote widespread PCN availability are explored.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A cellular mobile telephone system with load sharing-an enhancement of directed retry

A load sharing facility, which enables subscribers in a mobile telephone system to look for free radio channels in more than one cell, is investigated with respect to blocking probability and channel utilization. Results show that a substantial improvement, compared to other channel allocation techniques, can be achieved. The positive effects are especially notable for an asymmetric traffic situation. The improvement is accomplished at the expense of an increased risk of cochannel interference between mobiles. >

Comparisons of channel-assignment strategies in cellular mobile telephone systems

Two novel channel-assignment strategies are proposed: the locally optimized dynamic assignment (LODA) strategy and the borrowing with directional channel-locking (BDCL) strategy. Their performance is compared with the fixed-assignment (FA) strategy (currently used on certain systems) and the borrowing with channel ordering (BCO) strategy (the strategy that has given the lowest blocking probability in previous research). Computer simulations on a 49-cell network for both uniform and nonuniform traffic showed that the average call-blocking probability of the BDCL strategy is always the lowest. The LODA performance is comparable with that of BCO under nonuniform traffic conditions but is inferior under uniform traffic conditions.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Channel Utilization and Blocking Probability in a Cellular Mobile Telephone System with Directed Retry

A directed retry facility, which enables subscribers in a mobile telephone system to look for free radio channels in more than one cell, is investigated with respect to blocking probability and channel utilization. An iterative procedure is devised, by which the dependencies among cells can be illustrated. This procedure makes use of theories developed for overflow systems in classical telephony, and proves to be very accurate for the situations under study. Analytical results are compared with simulations and good agreement is observed. Results show that a substantial improvement, compared with systems without a directed retry facility, can be achieved as far as carried traffic is concerned. The improvement is accomplished at the expense of those subscribers who cannot make use of the directed retry facility due to variations in radio coverage.

Cellular Mobile Telephone Environment

Cellular mobile telephone systems are rapidly going into service throughout the Continental United States. They are being installed in a large variety of vehicles both of domestic and of foreign manufacture. In this paper we discuss the physical, climatic, and electronic environments which cellular telephones may expect to encounter in nationwide service. We also discuss procedures used to evaluate the ability of a cellular phone to operate without failure in these environments and to avoid interfering with the increasingly complex vehicular electronic systems.