Showing papers on "Channel allocation schemes published in 1990"

Method for planning radio cells

Abstract: The present invention relates to a method for planning radio cells. The method utilizes an exclusion matrix calculated on the basis of measured field strengths and an iterative allocating algorithm, which allows an adaptation of the cell planning to prevailing traffic demand. The method includes the following steps: the traffic demand is geographically estimated; an acceptable coverage of the traffic demand is produced with the aid of a number of cells with suitable transmitter powers and antenna arrangements; each cell is allocated a number of channels, which corresponds to the estimated traffic demand, having regard to a margin for acceptable blocking; coverage and interference measurements are carried out for the cells, which measurement results are stored in a measurement data base; an exclusion matrix is calculated on the basis of the measurement results, which matrix represents the interaction between the cells in the system; an allocating algorithm is iterated, which algorithm, by utilizing a random technique, provides different collections of channel allocations for the cells; if the channel allocation is not possible with regard to the number of channels in a given frequency band, a new attempt is made and the subsequent steps are repeated; if the number of channels was sufficiently high, a radio cell design is obtained which is acceptable from the point of view of interference and the point of view of blocking. The present invention also provides a method for constructing the exclusion matrix and a method for determining uplink interferences.

On bandwidth allocation to bursty virtual connections in ATM networks

Abstract: The concept of equivalent bandwidth of bursty traffic sources is investigated. The equivalent bandwidth measure depends on the source characteristics, the grade of service, and the interaction with the other type of traffic multiplexed on the same data link. The behavior of the statistical multiplexer is analyzed with inputs consisting of homogeneous bursty sources. The values of the equivalent bandwidth are analyzed for fixed statistical characteristics of the bursty sources and a fixed grade of service, and as a function of a background stream load. By assuming that the peak rate of the sources is sufficiently lower than the link rate (e.g. 1/15) and that the average burst length is greater than the queue length, the equivalent bandwidth independence of the average burst length and of the queue length is shown by simulation. The superposition of two heterogeneous bursty classes is analyzed. >

Adaptive resource allocation in metropolitan area cellular mobile radio systems

Abstract: It is shown that microcellular structures which will be found in future high-density traffic metropolitan areas require the application of adaptive methods for efficiently allocating the radio resource. Different dimensions of adaptation-adaptive base station allocation, dynamic channel allocation, and adaptive power control-are considered in an integrated manner. To answer if and how the proposed methods can work together, a generic algorithm comprising the different adaptive approaches is introduced. This was complemented by the derivation and definition of a comprehensive set of evaluation criteria. For the evaluation a simulation environment is developed, based on a Manhattan-like road grid structure, and comprising corresponding traffic and propagation models. First results indicate that the combined application of the different adaptation approaches yields the best performance. >

Method for determining multiple interference in a mobile radio system

Abstract: The invention relates to a method for determining the total downlink or uplink interference percentage in the coverage area of a designated base station for a mobile radio system with a given channel plan. The invention provides for the need to carry out, after a conventional channel allocation has been carried out, a check of the extent to which total interference requirements are met. The method consists in that field strengths from all base stations are measured on all traffic routes within the geographical area of the mobile radio system. The interference is calculated at each point within the coverage area of a base station for each relevant pair of base stations, preferably base stations which are located in the same channel and base stations which are located in an adjacent channel. The interferences of all the relevant pairs of base stations are added in order to form the total interference at each point. The invention makes it possible to calculate the total interference percentage which constitutes the ratio between the length of road distance with disturbed coverage and the length of total road distance with coverage. The interference percentage is calculated suitably within a contour which limits the coverage area of the base station concerned.

Traffic capacity of cellular mobile communications systems

Abstract: In a cellular mobile communication system, the traffic capacity of the system is an important quantity, and depends on the way that channels are allocated to calls. Many channel allocation algorithms have been proposed, and this paper makes a direct comparison of some of them. Specifically, the operating regimes considered are fixed channel assignment, dynamic channel assignment, directed retry, and directed handoff. The main conclusion is that directed handoff gives a strong gain in traffic capacity and traffic adaptability for these systems. The paper also discusses some of the factors affecting the future development of mobile communication systems.

Method for reducing superfluous channel allocation in a cellular radiotelephone communication system

Abstract: In a communication system which performs radio channel management, there is provided a method and and apparatus for reducing superfluous channel allocation between a plurality of mobile units, making multiple requests, and the communication system comprising the steps of A) receiving a channel request from at least one of the plurality of mobile units, B) determining the processing delays introduced by the communication system in response to the channel request; and C) adjusting the mobile unit retry (retransmit) interval as a function of the processing delay in order to reduce the likelihood that more than one channel will be assigned to a single mobile unit by causing the mobile unit to wait longer between subsequent channel request attempts. An alternative embodiment suggests adjusting the mobile unit retry interval based upon a level of channel request traffic.

On the spectral efficiency of CPM systems over real channel in the presence of adjacent channel and cochannel interference: a comparison between partial and full response systems

Abstract: In all the new radio systems to be designed-for example, local radio networks or portable communication systems-a crucial point is determination of the actual spectral efficiency obtainable. To this end, the fundamental role played by adjacent and cochannel interference must be considered. The computer program implemented allows general analysis of continuous phase modulation (CPM) systems with limiter-discriminator detection and symbol-by-symbol regeneration, the combined effects of intersymbol interference, noise, and adjacent channel or cochannel interference have been tested to give the design criteria of the transmission system. To emphasize the role played by interference, an ideal multipath-free channel has been considered: with reference to a binary case, Gaussian minimum-shift keying (GMSK) systems have been investigated and compared with full-response CPM systems to obtain a suitable tradeoff between spectral efficiency (connected to channel spacing at radio frequency) and signal-to-noise ratio with fixed bit-error probability. The numerical results presented emphasize the performance obtainable with full- and partial-response techniques for varying system parameters such as phase deviation index, receiver filter bandwidth, and spectral efficiency. >

A multi-carrier switching TDMA-TDD microcell telecommunications system

Abstract: A multicarrier switching time division multiple access-time domain duplex (TDMA-TDD) radio access suitable for the next generation of digital microcellular telecommunications systems is described. In an interference limited environment improved coexistence between slot asynchronous TDMA systems can be effectively achieved by dynamically allocating TDMA slots and carrier frequencies. Signaling channel allocation is focused on the carrier frequency, which gives the advantage of making possible mobile-controlled hand-over and advanced radio channel control for multicarrier TDMA systems. A traffic rate of 16 kbit/s per channel with a frame length of 1 ms is suitable for diversified applications, such as 32 kbit/s to 8 kbit/s codecs and ISDN services. >

Channel allocation mechanism

Abstract: A channel allocation mechanism especially useful in a trunked communication system that can accommodate both voice and data signals, and that operates in true trunked manner to efficiently utilize spectral resources.

An integrated access terminal for wideband packet networking: Design and performance overview

Abstract: In order to provide for more eficient means of handling the changing nee& of voice, data, and image trafic, ATdT has introduced the Integrated Access and Cross-connect System (IACS). This paper will focus on the design and performance of a component of the UCS. the Integrated Access Terminal (IAT) which performs the integration and packet multiplexing @nctions, and also provides circuit and packet cross-connect capabilities. Based on packet switching, proven digital signal pmcesn'ng techniques, and standard protocols, the U T extends packet switching of data to voice and to image, and provides a variety of techniques to optimize the use of bandwidth and the quality of service. Congestion control and bandwidth allocation are critical issues in the integration of diflerent troffic types. One of the congestion control schemes used in the U T is block dmpping on voice packets. The IATalso usesa dynamic bandwidth allocation scheme which efficiently integrates packetized voice and data traffic. This allocation scheme guarantees a certain bandwidth to both voice and data queues, and at the same time allows each queue to use any bandwidth momentarily unused in the other queue. We present results k e d on modeling and subjective listening tests of voice quality when subjected to block dropping in a network. The results show that excellent performance is achiewd in the IATfor both voice anddata. We demonsrate that packetized voice is technologically ideal for integration of services, and one can expect (at better than 4:1 compression ratios) a voice quality virtually indistinguishable from that of the best circuits in an existing digital network

Improved call set-up in a radio communication system with dynamic channel allocation

Abstract: IMPROVED CALL SET-UP IN A RADIO COMMUNICATION SYSTEM WITH DYNAMIC CHANNEL ALLOCATION Abstract of the Disclosure The call set-up technique of this invention is characterized by the use of channel information from both base station and subscriber terminal in determining the radio traffic channel upon which to set-up a new call.Communication between the base station and subscriber terminal is carried out on a signalling channel until the traffic channel is chosen. Calls are set-up so that they proceed on the radio channel which, of a set of channels under consideration by the subscriber terminal, contains the least amount of interference as measured at the subscriber terminal. The set of channels under consideration by the subscriber terminal is a subset of the entire set of channels allocated to the service. This subset is comprised of those channels having little interference, as measured by the base station. The call set-up technique thereby assures that calls proceed on channels containing little interference from the viewpoints of both base station and subscriber terminal.

A multiservice high-performance packet switch for broad-band networks

Abstract: An input queued packet switch for broadband networks that supports data link connections and whose capacity is not constrained by the capacity of a single packet channel is described The switch bandwidth is allocated at two different times At connection setup time, an output data link (a channel group) is selected on which some bandwidth is reserved for the new call At transmission time, specific channels within the data link are optimally allocated, slot by slot, to the packets addressed to that link, solving the output channel contention at the same time The interconnection network of the switching is basically a Batcher-banyan network including the additional networks required to handle channel groups and to allocate bandwidth fairly at transmission time Packet sequence integrity can be guaranteed for jitter-sensitive services, as the emulation of a circuit connection It is shown that the channel group capability of the switch greatly improves the performance of standard input queued packet switches, so that input queuing with suitable data link capacities and output queueing give comparable performances >

On the impact of traffic burst on performances of high capacity cellular systems

Abstract: The effect of unpredictable traffic oscillations (due to traffic jams or accidents for example) occurring in urban areas with heavy road traffic and resulting in unacceptable performances of mobile radio systems are studied. The main goal is to determine whether an improvement in counteracting traffic bursts can be accomplished by means of dynamic channel allocation (DCA), with respect to fixed schemes. The control and management procedures used in the analysis do not represent a proposal for the architecture of the final system. They are very simple, and should be intended only as tools for illustrating the capabilities of DCA strategies. A description of a methodology suitable for evaluating system performances is given. The performance of fixed and dynamic schemes, with uniform spatial traffic distribution by means of a computer simulation program, are compared. A cellular layout based on a hexagonal grid where cell radius is equal to one kilometer is considered. >

Channel allocation strategies in dual mode digital cellular networks

Abstract: Two considerably different control strategies for dual-mode digital cellular networks are examined and compared. In one strategy, a number of channels is allocated to each type of traffic; in the other strategy, a threshold is placed on the number of available channels before an analog call request is served. It is shown that a no-control strategy is clearly not desirable from a performance point of view. At low to moderate fractions of analog traffic, the improvement in the probability of blocking is significant if one of the two strategies discussed is employed. Some what surprisingly, it is found that both control strategies resulted in approximately the same performance, implying that either strategy could be used with the same resulting performance. Thus, from a practical point of view, one would use the strategy that has implementational advantages. Another implication is that there may be other strategies that perform even between. >

Multiple channel architecture

Abstract: A parallel processing architecture based on multiple-channel optical communication is described. A large number of independent, selectable channels (or virtual buses) are available using a single optical fiber. Arbitrary interconnection patterns, as well as machine partitions, can be emulated by using appropriate channel assignments. Hierarchies of parallel architectures and simultaneous execution of parallel tasks are also possible. Recent technological advances in semiconductor laser technology that make such a parallel architecture possible, a basic system overview, various channel allocation strategies, and a summary of advantages compared with traditional interconnection techniques are presented. >

Spectrum efficiency of multi-carrier switching TDMA microcellular communication systems

Abstract: The spectrum efficiency of microcellular digital systems under high-density traffic and indoor propagation environments is described. The number of necessary channels is evaluated for given traffic densities and several indoor propagation models related to room size. It is shown that more than one hundred channels are required for one system under heavy traffic density conditions, for example 20000 erl/km/sup 2/. Multicarrier switching time-division multiple access (TDMA) radio access, which shares carriers and timing as slots, is effective in interference limited conditions. The improved channel efficiency of carrier-switching TDMA, about double that of conventional TDMA, is confirmed by computer simulation. >

Signal distribution network

Abstract: PURPOSE: To advantageously allocate information channels by temporarily allocating unused channels to local, signal sources and signal destination receivers to transmit information signals and sending signals tuned in the carrier frequency of the channels. CONSTITUTION: A signal distribution cable circuit network regulating plural information channels by respective carrier frequency bands and allowed to be used for plural local signal sources SS1 to SS3 and signal destination receivers SR1 to SR3 connected to the circuit network is provided with a channel allocation controller CT. The controller CT temporarily allocates unused channels for transmitting signals from the signal sources SS1 to SS3 to the receivers SR1 to SR3 based on requests, transmits tuning signals to the signal sources SS1 to SS3 and the receivers SR1 to SR3 to tune these elements SS1 to SS3 and SR1 to SR3 in the the carrier frequency of the allocated channels. Consequently all available dead channels are allocated as local channels and the allocation of information channels can be advantageously executed.

Discrete channel assignment with message priority for packet-switched networks

Abstract: Optimal channel allocation with message priority is formulated as a mathematical programming problem, and it is shown that the exact solution is computationally impractical because of the combinatorial nature of the problem. A heuristic algorithm that is computationally very efficient is then developed to determine the optimal number of channels allocated to each link and the maximum user input rates with message priority for packetized traffic. Message priority is considered in the input rate flow control strategy, and a discrete number of channels is used in the optimization process. >

Satellite channel allocation system

Abstract: PURPOSE:To suppress the influence of a noise on a channel to be used at minimum by selecting and allocating the channel in which the increment of a noise quantity on an existing channel and that on its own channel based on a noise distribution pattern stored in advance. CONSTITUTION:A control information storage unit 5 stores the frequency of the channel in current use, the satellite input level of the frequency, the patterns of an inter-different polarization interference noise quantity and an inter-another satellite interference noise quantity, and general noise distribution including a cross modulation noise quantity found from the pattern. When channel allocation information is inputted, the frequency to be allocated next is selected based on the information stored in the control information storage unit 5 so as to minimize a general S/N for its own channel and the channel in current use, and a channel allocation signal is sent to a transmission equipment 7. In such a way, it is possible to select the channel possible to minimize the influence of the noise quantity on the channel to be set, and to set the channel with quality higher than ever.