Speech recognition system for electronic switches in a cellular telephone or personal communication network

The personal networks of listeners and nonlisteners to an entertainment-education radio soap opera in Tanzania are examined to determine the effects of interpersonal discussion of the soap opera's educational themes of family planning and HIV prevention. Listeners are more likely to discuss these two educational issues in their personal communication networks and are also more likely to have other listeners to the radio program in their personal communication networks. Respondents demonstrate a relatively high degree of homophily with their network partners and are more likely to discuss matters arising from the radio program with their network partners who are of similar tribal membership, religious affiliation, and gender, and those who are equally or more highly educated than themselves.

This paper presents a discussion of system design issues related to the development of next-generation multimedia personal communication networks (PCN). It is proposed that the baseline definition of emerging PCN systems be broadened to provide multimedia transport capabilities qualitatively similar to those offered by BISDN/ATM. A number of system-level design and technology selection issues are discussed. Specific topics considered include: multimedia PCN traffic handling requirements, service cost targets, system design criteria, choice of packet switching vs. circuit switching, strategies for ATM compatibility, media access control (MAC) selection, etc. The presentation is concluded with an outline of a dynamic TDMA based multimedia PCN system architecture consistent with the preceding discussion. Simulation based performance evaluation results are also given for such a dynamic TDMA PCN channel operating in example mixed voice/data traffic scenarios.

Personal communication networks (PCN) have recently been put into operation in the UK. The PCN/DCS1800 is expected to be a very high capacity system because smaller cells are intended to be used. The data rate of 270 kbits/sec exceeds the reciprocal of the decay spread often measured in mobile radio environments. Hence PCN can be regarded as a wideband transmission system and therefore the frequency-selective fading behaviour of the radio channel cannot be ignored. This paper shows possible improvements that can be obtained if PCN systems employ 2-branch selection or equal gain diversity techniques. The diversity schemes implemented in this study are totally based on the received signal strength. The results show that, at a BER of 0.01, 2-branch selection diversity can provide a gain of 5-6 dB for the various channels specified for the DCS1800 system. A further 1 dB improvement can be obtained using equal-gain combining. >

Personal Communication Networks (PCNs) have become an important filed of activity and they are expected to play a fundamental role in next-generation telecommunication systems. In particular, the emerging personal communication services, such as portable computing, paging, personal e-mail, etc. have led to the need of an efficient integration of voice and data traffic in a same PCN by means of a suitable multiple-access scheme. This paper considers stability and optimization issues for the Packet Reservation Multiple Access (PRMA) protocol used for integrating voice and burst data traffic in a PCN. An important result here devised is that the optimized PRMA protocol permits to be achieved good performance even under heavy traffic load conditions.

A novel approximate technique is proposed for the estimation of call blocking probabilities in cellular mobile telephone networks where call blocking triggers customer retrials. The approximate analysis technique is based on Markovian models with state spaces whose cardinalities are proportional to the maximum number of calls that can be simultaneously in progress within cells. The accuracy of the approximate technique is assessed by comparison against results of detailed simulation experiments. Numerical results show that the proposed approximate technique is very accurate, in spite of the remarkably small state spaces of the Markovian models.

Error correcting codes are used in various processing systems such as computers, control systems, optical disks, audio recordings, space communications and particularly land mobile radio communications. A unique feature of the mobile radio communication system is the fact that the received signal envelope varies constantly due to the motion of the vehicle and the multipath propagation. In addition, the demand for services such as cellular telephone, paging, personal communication network, and automatic vehicle location systems, etc., is rapidly increased. As a result, these disturbances cause transmission imparities in both random and burst errors and result in degradation of system performance, i.e. increase of system bit error rate (BER) [1].

We propose an efficient location management algorithm for broadband personal communication networks (PCNs) which reduces the complexity of network signaling and delay due to database access when locating a portable station (PS). Previous works on updating and search algorithms for personal communications have concentrated on the access delay due to signaling network traffic only. But, with the advances in fiber optic technology, it will be possible to provide the capacity of signaling network on the order of several Mbps in broadband PCNs. Thus it may be more important to simplify the signaling procedure and reduce the number of database accesses for mobility management at the cost of some increase of signaling traffic. In the proposed algorithm, we first remove all visitor location registers (VLRs) in order to achieve the simplicity of signaling procedure. Thus, only home databases for mobility management are distributed in a global network, and each database keeps only the current locations of PSs initially registered in its management area. It can solve the problem of requiring an impractically large database in a centralized database structure by distributing home location registers (HLRs) while maintaining the simplicity of mobility management and reducing database loads. This algorithm has a simple signaling procedure, and reduces database operations when compared to hierarchical algorithms as network switching hierarchy increases or relocation and calling rate increase.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

This paper is concerned with the development of a backbone network for a high capacity personal communication network (PCN). It is expected that some of the 1st generation PCNs will be implemented on the DCS1800, which is a GSM based standard. The present backbone network of the GSM system is based on a conventional centralised structure. The paper examines the efficiency of the current GSM backbone network using circuit switched input traffic for both full rate and half rate speech coders. Finally the paper proposes an ATM LAN/MAN based backbone network which removes some of the inefficiencies of the existing GSM backbone network and can efficiently handle new services.

In an earlier paper, we proposed a new approach for mobility management and wireless call control in ATM-based PCNs (personal communication networks). In this paper, we focus on the procedures used for mobile tracking and mobile location for call delivery. We describe a discrete-event simulation of our approach to measure the time delay for mobile location. The simulation includes procedures for registrations, call/connection setups (with mobile location), handoffs and call/connection releases. Our results show that the delay for mobile location during call delivery is half that of the delay incurred for mobile location using the current cellular network approach to mobility management.

Star 16QAM is a modulation method that transmits 4 bits per symbol and has the advantage that it may be differentially encoded and detected. It is very robust to fast multiplicative Rayleigh fading and is suitable for mobile telephone systems and personal communication networks. The main contribution of this paper is the derivation and bit error probability simulation of the maximum likelihood differential detector using phase differences and amplitude ratios from L diversity branches for bit decisions. As a comparison, much simpler previously known post detection combining techniques are generalized for star 16QAM and optimized. The bit error probability is simulated for both diversity detectors on a multiplicative Rayleigh fading channel with additive white Gaussian noise. It is found that the bit error probability of the ML detector may also be obtained by the simple combining detector. This is also true for the error floor due to the maximum Doppler frequency. The diversity gain is almost 8 dB, measured in signal to noise ratio per diversity branch, at a bit error probability of 1 percent. The diversity detector can sustain an almost 3 times larger Doppler frequency again at a bit error probability of 1 percent. We also show that star 16QAM offers, at most, 3 subchannels with different bit error probabilities. >

Wireless random access channels can provide communications from many terminals to a single hub station. Examples of such channels occur in cellular networks, personal communication networks (PCN’s), packet radio networks, local area networks (LAN’s) and very small aperture terminal (VSAT) satellite networks.

The complexity, image quality, bandwidth efficiency, and robustness issues of a mobile video telephone scheme for personal communications networks (PCNs) are addressed. The motion-compensated 55 kb/s subband codec using seven nonuniformly spaced active bands with bandspecific scanning and runlength coding achieves image peak signal-to-noise ratios (SNR) of around 38 dB, associated with good communications quality for monochrome common intermediate format images sampled at 10 frames per second. The motion dependent bitrate fluctuations are smoothed out by buffering with adaptive quantizer control feedback. The video bits are then sorted into two sensitivity classes and error protected by a twin-class binary BCH scheme. The separately BCH-encoded more significant bits (MSB) and less significant bits (LSB) are transmitted via separate subchannels of the 16-level quadrature amplitude modulator (16-QAM), having different integrity. The overall signaling rate becomes 22 kBd. No equalizer has to be used yet unimpaired image quality is achieved for channel SNR in excess of 20 dB. >

Understanding the Design of Mobile Social Networking

An ubiquitous network for multimedia personal communications (Personal Communications Network (PCN)) with small, individual low-cost terminals is one of the most ambitious worldwide projects for the 21st century that are being pursued nowadays. In the development of such PCN, Geostationary, Medium, and Low Earth Orbiting (GEO, MEO, LEO) satellite constellations will play a fundamental role to provide worldwide coverage for most services required by the end-user. The characteristics of efficiency and flexibility inherently required by that scenario suggest, amidst other possibilities, to take into special consideration a radio interface based on code division multiple access (CDMA) to ensure, in addition to the features mentioned above, a sufficient grade of power and spectral efficiency of the relevant satellite radio link. The aim of this paper is a review of the current status of those issues in the field of satellite CDMA transmission systems design that, in our opinion, appear fundamental to the successful operation of an efficient PCN. In particular, we survey the techniques for multiplexing, coding and transmission of direct-sequence spread spectrum (DS/SS) signals, and we touch upon the techniques for the minimization of the self-noise effect, and the related topics of power-control and multiuser detection. We also shortly address in this respect some technological aspects related to an efficient modem design via digital signal processing techniques. The final part of the paper deals more specifically with some typical issues of satellite transmission, namely the minimization of the detrimental effects of the nonlinear satellite transponder and of multipath propagation; the applicability of diversity reception to a multisatellite network is also addressed as possible means of performance boost.

Digital signal processors (DSPs) play a major role in personal communications networks (PCNs). The benefits of making DSPs the ideal processing element for digital PCN systems are considered. DSPs affect not only the new digital networks but also analog systems. This results from the advantages of digital integrated circuit process technology, of manipulating signals in the digital domain, and of programmable solutions over hard-wired solutions. These advantages are discussed, along with examples. >