Showing papers on "Cellular network published in 1989"

Portable hybrid communication system and methods

Abstract: A laptop device includes a personal computer, a cellular transceiver, a speakerphone, and a hybrid communications control unit. The device has connectors for attaching a headset, cellular control unit, land telephone line, and additional speakers and microphones. The micro-processor-controlled hybrid communications control unit includes a modem, a data access arrangement, and a tone generator as well as digital, analog, and power switches. The hybrid communications control unit switches the communications components and provides, under program control, the proper protocols, level, and impedance matching to connect the modem, speakerphone, headset, speaker/microphone, or cellular control unit to the landline or to the cellular network via the transceiver. Matching and switching operations are automatic and transparent to the user. The unit can also connect two of the terminal devices or connect the cellular and landlines for call relaying. The device is capable of connecting plural calls at the same time. The hybrid communications control unit may be controlled by its internal firmware, by toggle switches, or by commands issued from the personal computer.

Performance analysis of cellular mobile communication systems with dynamic channel assignment

Abstract: The traffic analysis of small-cell mobile networks with dynamic channel assignment is investigated to determine their blocking performance, using a hybrid method of analysis and simulation. The authors particularly focus on the performance problems presented by networks with heterogeneous cell traffic loads, the impact of traffic volatility among the cells, and the impact of multichannel traffic on the channel blocking probabilities. Significant improvement in network performance with dynamic channel assignment is established by numerical results. >

Digital radio transmission system for a cellular network using the spread spectrum technique

Abstract: A base station (BS) and mobile user stations (MS) each with a transmitter (S), a receiver (E) for multipath reception and a control unit (ST) are provided in each cell. Exactly one set of several sequence sets of the auxiliary function used for spectrum spreading is allocated to each cell. Sequences of several sets in pairs have the property that the absolute values of the normalized periodic cross-correlation functions are much smaller than one and for sequences within a set the cross-correlation function in pairs is optimally small around the zero point. Data synchronous generation of the transmission signals takes place in the base station (BS) for all simultaneous connections and the data clock of the received signal is used as data clock of the transmission signal of the user station (MS). Application for digital data transmission in buildings and local areas for the configuration of a so called cordless LAN are considered.

Combining frequency-division and code-division multiplexing in a high-capacity optical network

Abstract: The combination of frequency division and code division multiplexing in a multiaccess network such that the beneficial aspects of each technique mitigate the shortcomings of the other is addressed. The feasibility and expected performance of the resulting hybrid network are examined. CDMA (code-division multiple access) is used to eliminate the need for laser frequency control, which is required for pure FDMA (frequency-division multiaccess) schemes. On the other hand, an FDMA-like mutual avoidance scheme exploits the limited tunability available to keep signals away from one another as much as possible, relieving the need for CDMA to protect against more than the occasional crossover of one interfering signal. This significantly limits the amount of spectral spreading required. The use of the hybrid network for high-bit-rate and low-bit-rate applications is discussed. The power budget for a local network utilizing a star coupler is outlined. >

Factors affecting the bandwidth efficiency of packet reservation multiple access

Abstract: The authors have extended a preliminary study of packet reservation multiple access (PRMA) by examining the influence of a large number of system variables on PRMA performance. The measure of efficiency is eta , the maximum number of conversations per channel that PRMA can support within a given packet-dropping probability constraint of P/sub drop/ >

Idle-signal casting multiple access with data slot reservation (ICMA-DR) for packet radio communications

Abstract: A population of terminals communicating with a central station over a packet-switched multiple access radio channel is investigated with regard to multiple access control schemes. The authors describe the ICMA-DR, which is an advanced idle-signal casting multiple access (ICMA) scheme characterized by data slot reservation. This improved central controlled multiple-access scheme for packet transmission in terrestrial radio communications is evaluated in terms of throughput traffic, throughput delay characteristics, and handling capacity. It is shown that the throughput characteristics of ICMA-DR are superior than those of ICMA or slotted ALOHA when a packet for data slot reservation is relatively short in comparison to that for upward data. Thus, it is shown that ICMA-DR is suitable for the packet radio multiple-access scheme, especially in the case where fading packet error occurs frequently and ordered traffic is heavy. The ICMA-DR scheme has been utilized for the access control channel of NTT's new 800-MHz-band high-capacity land mobile communication system since the Spring of 1988. >

A satellite mobile system integrated with the terrestrial cellular network

Abstract: The structure and performance of an integrated system for all mobile communications, based on the Pan European digital cellular network standard, are presented. The system architecture and protocols are discussed. A performance analysis of the satellite access procedure is given. Also, the performance of a satellite system integrated with the terrestrial network is considered, referring to the present bandwidth allocation for a land mobile satellite system. The results suggest that some the proposals are feasible solutions for the integration of a satellite system with the terrestrial network for mobile communications. >

Evaluation of overall outage probability in cellular systems

Abstract: A novel method for the evaluation of the overall outage probability in cellular mobile radio is proposed. This method involves both links, i.e., M to B (mobile-to-base) and B to M (base-to-mobile), taking into account the joint effects of co-channel and adjacent channel interferences, the net filter discrimination, the radiation patterns of the base station antennas, the power control characteristic, the traffic distribution, and some typical propagation phenomena of the mobile radio environment, such as shadowing effects. The overall outage probability is assessed for some coverages of practical interest for a pan-European cellular TDMA (time division multiple access) digital land mobile radio system currently under study. Cellular coverages with centrally located omnidirectional antennas and with sectoral antennas are considered. For each coverage, frequency plans avoiding strong adjacent channel interferences are presented. The results are given in terms of cumulative distributions of the overall outage probability. >

Signaling protocol architecture for digital mobile system

Abstract: The authors consider a signaling protocol architecture for future digital mobile user-network interfaces which can support a wide range of services similar to the ones defined in ISDN (integrated services digital network). This architecture is based on the Open Systems Interconnection (OSI) Reference Model. The interfaces proposed support ISDN functions and public land mobile network (PLMN) functions, and have the capability of guaranteeing their independence. The authors propose a novel link access procedure with multiple access control at the mobile station to base station interface (radio interface), called LAPF (link access procedure on the free-access control channel), and specify its management procedures. >

An integrated voice/data system for mobile indoor radio networks using multiple transmission rate

Abstract: A centralized, integrated voice/data radio network for indoor fading multipath radio channels is proposed and analyzed. It can operate as a stand-alone system or as a cell in a cellular network. The packets of voice and data in the uplink are integrated through a movable-boundary framed-polling protocol to optimize the throughput of the data traffic for a given number of voice terminals. The down link is a simple TDM (time division multiplexing) system. The system dynamically switches between two transmission rates and uses multiple antennas to maximize the throughput in the fading multipath indoor channel. Using three different techniques, the throughput and delay characteristic of the system are analyzed. A simple equation is given to provide an approximate relation between the number of voice users, the data traffic with less than 10-ms delay, and the average transmission rate of the system. The results are compared with those of Monte Carlo computer simulations. >

Effect of Cochannel Interference on Handover in Microcellular Mobile Radio

Abstract: The effect of cochannel interference on a fast handover algorithm for microcellular mobile radio systems is described. The presence of cochannel interference had only a marginal effect on the handover point when the microcell base stations were spaced by 300m. Increasing the mobile speed increased the effective cell length.

Performance of a digital cellular experimental testbed

Abstract: A digital cellular radio experimental system has been developed for the North American market. It has been demonstrated for CTIA in Los Angeles in December 1988. After describing the experiment TDMA (time-division multiple access) system, the authors present field-test results. From the demonstration it was concluded that the speech quality of the digital system was at least as good as for the analog reference under all conditions. During the time of implementation of the testbed, work was done on an 8.7 kb/s speech codec, resulting in quality as good as for the 13 kb/s codec. This means a three-times direct capacity improvement in a 3-split TDMA system. >

Adaptive forwarding and routing in frequency-hop spread-spectrum packet radio networks with partial-band jamming

Abstract: The authors consider adaptive protocols for routing around localized partial-band jamming in a frequency-hop (FH) packet radio network. With such protocols, a radio is permitted to modify its normal routing procedures according to local information. A computer program has been developed to simulate an FH packet radio network with partial-band jamming and interference due to other FH and narrowband radios. The network uses time-slotted, receiver-directed, FH spread-spectrum signaling. Results on throughput are presented, and comparisons between different protocols are obtained for a static network topology with both static and mobile network jamming. The authors also introduce least-resistance routing, a routing algorithm that accounts for multiple-access interference, jamming, and other partial-band interference. >

Bounded delay routing for real-time communication in tactical radio networks

Abstract: To deal with the need for availability and real time response, military communication has employed protocols with deterministic service such as that found in SS/TDMA (spread-spectrum/time-division multiple-access) control of satellite links, or T1, T2, or T3 ground relay optic fibers. The author addresses the problem of providing network layer communication with deterministic service in multihop radio networks. First, he investigates the complexity of the problem of minimizing delay in routing algorithms, showing that its complexity is high. He then presents a simple, efficient, and fully distributed control policy for packet-switched networks that guarantees bounded time-delay packet switching for any static or mobile network topology and any loop-free routing protocol. The proposed control thus provides deterministic packet delivery service in multihop radio networks without the significant overhead associated with circuit switching. >

Random access systems: ALOHA's progeny

Abstract: Random access algorithms allow a large number of bursty data sources to share a common transmission medium. Such algorithms are essentially refinements of the distributed algorithm first introduced in the ALOHA system. Unlike techniques such as time division multiple access (TDMA), frequency division multiple access (FDMA) and polling, the performance of random access algorithms is insensitive to the number of stations in the system. The weakness of early random access systems is extreme sensitivity to traffic, resulting in instability. Later implementations of the technique have improved throughput, eliminating instability. This paper discusses the three forms of random access techniques: stable backoff algorithms, tree search algorithms and carrier sensing techniques. Forms of the last of these have been used in an optical-fibre local area network. The particular application of random access techniques to satellite communication systems is also considered.

Supervision and control in cellular systems

Abstract: The necessity for a novel cellular supervision and control system is described from two points of view. The first view is that increasing service complexity and customer demands are forcing the creation of a supervision and control system that will apply a common database and a unified approach to network management. The other point of view is that a supervision and control system should have improved automatic and remote functions, and should provide the operator with simplified interfaces. The system function structure, which is hierarchical, will permit extensive and sophisticated cellular network operations to effect the required total network operations. The appropriate design objectives are described, and methods for their implementations are discussed. >

A comparison of CDMA and NPCSMA for an indoor data network

Abstract: An indoor communication system using direct-sequence spread-spectrum signaling is considered. CDMA (code-division multiple-access) and NPCSMA (nonpersistent carrier-sense multiple-access) are considered as multiple-access alternatives and are compared based on their throughput and delay characteristics. The advantage of multipath diversity is illustrated. For NPCSMA and CDMA, delay and code length, respectively, restrict the number of simultaneous accesses allowable. A hybrid scheme, NPCSMA-CDMA, based on code sharing by contention, is examined. This scheme offers high capacity, without requiring very long codes or exhibiting excessive delays. Throughputs that approach that of NPCSMA are observed. >

Congestion based routing in packet radio networks

Abstract: The authors develop a routing procedure that is sensitive to the performance of each link in the presence of multiuser interference. They consider a multihop network using code division multiple access (CDMA) and assume an inverse fourth power law for radio signal propagation. They measure link congestion by the mean number of schedulings per successful packet transmitted on the link. The routing algorithm selects the best links from any specified candidate set, and routes end-to-end traffic over the least congested paths. It is possible to have all links in the network as potential candidates. Even if a set of routing links is specified with a uniform routing range, the algorithm performs better than a minimum-hop routing. >

An Integrated Services Management Protocol for a Short-Range Mobile Radio Network Using Multiple Access

Abstract: Future pan-european road-traffic communication networks will use high capacity short-range radio networks with a large number of mobiles. There, many different communication demands arise, especially if we assume a many-services network, where continuous, bursty and/or priorized communication has to be supported. We define an Integrated Services MAnagement Protocol (ISMA-protocol) using multiple access, designed for an efficient use of the limited channel capacity available. The protocol comprises capacity management of direction of movement oriented decoupling of channels via the Decentral Channel Assignment Protocol (DCAP), a packet radio facility using S-ALOHA, handling of priorized emergency warning and in addition provides high capacity channel of 100 kbit/s.

Integrated voice and data transmission in packet radio network

Abstract: A multiaccess scheme, that is a variation of movable slot time-division multiplexing and p-persistent carrier-sense multiple-access is proposed for voice only or integrated voice and data transmission in a packet radio network. Simulations are performed to examine the performance characteristics of the proposed scheme under various system parameter values. Three different sets of parameters are selected for voice transmission, and a particular set of parameters is used for integrated voice and data transmission. >

Why is CDMA the solution for mobile satellite communication

Abstract: It is demonstrated that spread spectrum Code Division Multiple Access (CDMA) systems provide an economically superior solution to satellite mobile communications by increasing the system maximum capacity with respect to single channel per carrier Frequency Division Multiple Access (FDMA) systems Following the comparative analysis of CDMA and FDMA systems, the design of a model that was developed to test the feasibility of the approach and the performance of a spread spectrum system in a mobile environment Results of extensive computer simulations as well as laboratory and field tests results are presented

Wireless digital access

Abstract: It is expected that the advent of digital radiotelephony with its attendant capability to provide multichannel per carrier service will significantly expand the capacity of the scarce spectrum. Two new concepts which are emerging in telecommunications, and the resultant synergy between those concepts are discussed. The first concept is the radio carrier serving area (RCSA), and the second is wireless digital access (WDA). The concept of the RCSA is evolving from the work of those telephone companies that have been pioneering in the development and implementation of basic exchange telecommunications radio service (BETRS). The RCSA, based on radio area coverage, is a logical extension of the CSA application for digital loop carriers which was introduced to the network in the early 1980s. WDA represents the future intersection of BETRS, digital cellular, and personal communications research. It is expected that digital radio loop and digital cellular will merge in the 1990s to provide WDA to the network. IMM's Ultraphone system (RELP, DSPK, 4:1 CKTS/carrier) is discussed as a forerunner of these developments. >

Queueing analysis on a CSMA/CD packet switched mobile network with capture

Abstract: The capture effect on a CSMA/CD protocol for a mobile radio-telephone network, without hidden users and fading effects is analysed and discussed Various system parameters, like packet length, time recovering from collisions resulting in no successful transmission, attempt rate and the signal-to-noise ratio are studied in detail A Markov model is constructed based on the regenerated time instants between successful transmissions, and the slot property of the channel It is shown that such a system exhibits stable operation, and that for moderate values of the system parameters a considerably better performance in the throughput delay trade off than the conventional delta -CSMA/CD schemes can be achieved >

Indoor Radio Communication

Abstract: Multiple access techniques for indoor radio communication are studied. The system model used speciftes a distributed an- tenna connected to a central controller. The data traffic is as- sumed to be composed of both voice and data. A time division multiple access scheme using frames and a movable boundary slot allocation is presented. Analysis using a continuous model with a matrix geometric solution to the data queueing is given. An example of this analysis is given. Direct-sequence code- division multiple access is then discussed, although an analysis of this case is not given. Comments on the two multiple access techniques are given at the end of the paper.