Showing papers on "Channel allocation schemes published in 1989"
01 May 1989
TL;DR: It is shown that, based on the capacity improvement achieved by microcells, no relevant further improvement of the capacity can be realized, but that the proposed algorithm is very well suited to cope with the problems of microcells.
Abstract: Microcellular structures are the central means for increasing the network capacity of mobile radio systems. By examining existing dynamic channel allocation algorithms, the authors identify a class of adaptive algorithms best suited for such microcellular environments. Applicable algorithms of this class require intracell handover and are to a large extent decentralized. One new algorithm of this class is introduced and evaluated by means of simulation. The proposed algorithm (DYNINF) has been evaluated with respect to performance criteria such as blocking probability, interference probability, and number of handovers (stability). It is shown that, based on the capacity improvement achieved by microcells, no relevant further improvement of the capacity can be realized, but that the algorithm is very well suited to cope with the problems of microcells, e.g. discrepancies between the network plan and the real situation and heavy variations of the traffic and interference conditions. >
162 citations
TL;DR: It is shown that for some test cases the congestion measure is substantially reduced with respect to the values obtained when the embedded topology is kept identical to the backbone topology.
Abstract: The design of a P/S network embedded into a backbone facility network is discussed. The problem is formulated as a network optimization problem where a congestion measure based on the average packet delay is minimized, subject to capacity constraints posed by the underlying facility trunks. The variables in this problem are the routing on the express pipes (i.e. the channels that interconnect the P/S modes) and the allocation of bandwidth to such pipes. An efficient algorithm is presented for the solution of the above problem and it is applied to some representative examples. It is shown that for some test cases the congestion measure is substantially reduced with respect to the values obtained when the embedded topology is kept identical to the backbone topology. Dynamic reconfiguration schemes where the embedded topology is periodically adjusted to track the fluctuations in traffic requirements are discussed. >
132 citations
TL;DR: 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 and shows that a substantial improvement can be achieved.
Abstract: 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. >
131 citations
11 Jun 1989
TL;DR: A load control method and load monitor function are proposed for continuous bit-rate-oriented (CBO) and variable bit- rate (VBR) services in asynchronous transfer mode networks and the need to implement a monitor function to verify the assumptions made by the load control is demonstrated.
Abstract: A load control method and load monitor function are proposed for continuous bit-rate-oriented (CBO) and variable bit-rate (VBR) services in asynchronous transfer mode networks. The allocation algorithm features low complexity and optimizes quality of service and statistical multiplexing gain for variable bit-rate sources. The need to implement a monitor function to verify the assumptions made by the load control is demonstrated. Every single connection is monitored and the negative cumulative distribution of the cell rate compared with an envelope. The load monitor function ensures the proper functioning of the load control mechanisms under all input conditions. >
68 citations
Patent•
12 Jan 1989TL;DR: In this article, a channel allocation controller (CT) operates on request to allocate temporarily an unused channel for transporting signals from a local signal source (SS1, SS2, SS3) to a signal destination receiver (SR1, SR2, SR3).
Abstract: A signal distribution cable network in which a plurality of information channels are defined by respective carrier frequencies and serve a plurality of local signal sources (SS1, SS2, SS3) and signal destination receivers (SR1, SR2, SR3) connected to the network. The network has a channel allocation controller (CT) which operates on request to allocate temporarily an unused channel for transporting signals from a local signal source (SS1, SS2, SS3) to a signal destination receiver (SR1, SR2, SR3). The controller (CT) transmits tuning signals to the local signal source and the signal destination receiver to tune them to the carrier frequency of the allocated channel. The channel allocation excludes channels which normally carry signals from external signal sources.
59 citations
01 May 1989
TL;DR: In this article, the TDMA/TDD (time division multiple access/time division duplex) micro or rather pico cellular cordless telephone system using decentralized dynamic channel allocation and handover is presented.
Abstract: Properties of a TDMA/TDD (time-division multiple access/time-division duplex) micro or rather pico cellular cordless telephone system using decentralized dynamic channel allocation and handover are presented. The system has 16 or 8 time-division time-duplex channels (slots) per carrier, each occupying 2 MHz or 1MHz. The TDMA frame is 16 ms long and each slot has bits for synchronization, signalling, and data. The data speed is suited for 32 kb/s speech codecs. Procedures have been developed for efficient and quick dynamic channel allocation and handover, using the fact that a single radio can simultaneously monitor or communicate on all 16 or 8 time-slot channels. Simulations for a specific six storey building indicate that 16 channels can provide wireless communications for up to 30% of the telephones, and 32 channels for up to 100% of the telephones. Slot synchronization between adjacent systems is desirable, but not necessary. Tests show that no time dispersion equalizers are needed, and that antenna diversity is effective against fading dips and time dispersion. This system concept has been proposed to CEPT as a base for European Digital Cordless Telecommunications. >
56 citations
TL;DR: A discrete-time priority queuing system is introduced and investigated, and message-delay distributions are obtained for priority and ordinary messages in a two-class system model, under each service discipline.
Abstract: A multiplexing communications channel is considered. The network stations share the channel on a time-division multiple-access (TDMA) basis or by using a slotted frequency-division multiple-access (FDMA) scheme. Messages are categorized by their differing priorities. Two service disciplines are considered: nonpreemptive and preemptive-resume. A discrete-time priority queuing system is introduced and investigated. Message-delay distributions are obtained for priority and ordinary messages in a two-class system model, under each service discipline. Next, delay analysis for a p-class model is carried out. The results are then applied to general, slotted, priority FDMA and TDMA schemes. >
43 citations
11 Jun 1989
TL;DR: The flexible reuse strategy in dynamically assigning radio channels, in which radio channels are reused at short distances according to their states and those of mobile stations, can effectively improve the spectrum efficiency, especially for users of portable units.
Abstract: Strategies for assigning radio channels and their effects on cellular system capacity are described. A new strategy, flexible reuse in dynamically assigning radio channels, in which radio channels are reused at short distances according to their states and those of mobile stations, is proposed. The effect of this strategy on the increase in spectrum efficiency is clarified. Performance evaluation is carried out for both vehicle-mounted and portable mobile stations. The flexible reuse strategy can effectively improve the spectrum efficiency, especially for users of portable units. >
41 citations
TL;DR: An efficient, fully-distributed protocol for integrated voice/data traffic in a local-area, random-access broadcast network is described in which time frames are dynamically partitioned between voice and data according to the traffic load.
Abstract: An efficient, fully-distributed protocol for integrated voice/data traffic in a local-area, random-access broadcast network is described in which time frames are dynamically partitioned between voice and data according to the traffic load. The protocol introduces a movable voice-data boundary to framed TDMA/CSMA and eliminates the requirement of system-wide synchronized clocks. The movable boundary is a major advantage in any system where fluctuations in voice and data loads are expected because assignment of idle capacity from one traffic class to the other increases the utilization of the channel. The protoco; provides collision-free virtual circuits for voice and periods of non-persistent CSMA/CD for data traffic and call establishment, and can support multi-party calls as well as two-way conversations. The protocol supports variable-size voice packets with very low overhead, and variable-size data packets that may be much longer than voice packets. This is of significant practical advantage over previous work, which has required fixed-size voice and/or data packets, or voice packets with significantly higher overhead, or severe restrictions on data-packet length. The behavior of framed TDMA/CSMA in general, and movable-boundary framed TDMA/CSMA in particular, is investigated via simulation and analysis. A method of dynamically controlling the movable boundary to balance the voice and data traffic is also proposed; this provides for maximum voice utilization consistent with user-defined constraints on data delay.
22 citations
11 Jun 1989
TL;DR: A Batcher-banyan interconnection network and a three-phase algorithm to resolve the output channel contention are discussed and two alternative solutions that aim at providing a fair access to the output channels independent of the specific switch input port requesting the transmission bandwidth are proposed.
Abstract: A Batcher-banyan interconnection network and a three-phase algorithm to resolve the output channel contention are discussed. For the implementation of the sorting network the author proposes two alternative solutions that aim at providing a fair access to the output channels independent of the specific switch input port requesting the transmission bandwidth. The first uses two complementary Batcher networks. The second adopts a preprocessing of the jobs entering the interconnection network, so that each input port is cyclically served first within the set of input ports requesting the same output channel with the same priority. The general architecture of the interconnection network is described, and implementation guidelines are discussed. >
11 citations
27 Nov 1989
TL;DR: Simulation shows that the traffic carrying capacity in the system can be increased by about 10% with the use of this channel allocation algorithm and that this gain is additive to the improvement obtained from the channel borrowing strategies.
Abstract: An algorithm for allocating nominal channels according to the traffic distribution is designed. The algorithm attempts to minimize the average blocking probability as nominal channels are allocated one at a time. Simulation shows that the traffic carrying capacity in the system can be increased by about 10% with the use of this channel allocation algorithm and that this gain is additive to the improvement obtained from the channel borrowing strategies. If shadow blocking is used in the channel assignment strategies, only a very small increase in the traffic carrying capacity is observed. >
22 Mar 1989
TL;DR: Two distributed channel allocation algorithms are presented for a reconfigurable communication network with a multiple-channel link architecture that can dynamically allocate transmitters and receivers among links to match traffic fluctuations and hence improve the average delay and throughput performance over that of a fixed-link architecture.
Abstract: Two distributed channel allocation algorithms are presented for a reconfigurable communication network with a multiple-channel link architecture. In this architecture, every switching node can dynamically allocate transmitters and receivers among links to match traffic fluctuations and hence improve the average delay and throughput performance over that of a fixed-link architecture. The authors show that the first algorithm always converges to an optimum configuration while assuming that link may never be saturated and requiring global information on channel allocation. The second algorithm needs local information only and poses no limitation on link capacity but may terminate at suboptimum configurations. The conditions under which the local search algorithm may fail to converge to an optimum configuration is also discussed. >
Patent•
17 Jan 1989TL;DR: In this article, a channel allocation controller (CT) operates on request to allocate temporarily an unused channel for transporting signals from a local signal source (SS1, SS2, SS3) to a signal destination receiver (SR1, SR2, SR3).
Abstract: A signal distribution cable network in which a plurality of
information channels are defined by respective carrier
frequencies and serve a plurality of local signal sources (SS1,
SS2, SS3) and signal destination receivers (SR1, SR2, SR3)
connected to the network. The network has a channel allocation
controller (CT) which operates on request to allocate temporarily
an unused channel for transporting signals from a local signal
source (SS1, SS2, SS3) to a signal destination receiver (SR1,
SR2, SR3). The controller (CT) transmits tuning signals to the
local signal source and the signal destination receiver to tune
them to the carrier frequency of the allocated channel. The
channel allocation excludes channels which normally carry signals
from external signal sources.
01 May 1989
TL;DR: A comparison of spectrum efficiency between TDMA and FDMA in digital cellular systems was made and several effects are found to make TDMA inferior to FDMA for mobile-unit reception.
Abstract: A comparison of spectrum efficiency between TDMA (time-division multiple access) and FDMA (frequency-division multiple access) in digital cellular systems was made. In theory, these two schemes do not differ in terms of spectrum efficiency. However, in a practical application, due to the actual signal reception of the mobile units in a mobile radio environment, several effects are found to make TDMA inferior to FDMA for mobile-unit reception. When the received signal becomes weaker, i.e. at a lower value of the carrier-to-interference ratio, the FDMA degrades gracefully but the TDMA degrades more rapidly. >
11 Jun 1989
TL;DR: The authors analyze and compare two possible access schemes to be used in satellite networks with a large number of small users, spread-spectrum multiple access and frequency-division multiple access, and find spread FDMA shows higher efficiency than SSMA for the nonlinear channel.
Abstract: The authors analyze and compare two possible access schemes, spread-spectrum multiple access (SSMA) and frequency-division multiple access (FDMA) to be used in satellite networks with a large number of small users. For FDMA, it is assumed that individual carriers are also spread, to the extent that the available bandwidth is always fully occupied. Spectral efficiencies are computed and compared for transmission through a nonlinear satellite channel in the presence of thermal noise and external interference, in addition to the self-interference that is intrinsic to the SSMA system. Optimum operating points for the nonlinear amplifier are also determined. As for the linear channel, spread FDMA shows higher efficiency than SSMA for the nonlinear channel. >
Patent•
05 Jul 1989
TL;DR: In this paper, the authors propose a channel allocation in a multicarrier hopping TDMA system, where a new call is generated from respective slave stations 21-2L and channel allocating requests are received, a control station 1 decides channel positions (a carrier (f) and a time unit) to the calls.
Abstract: PURPOSE:To efficiently use a wireless circuit by rearranging channels when prescribed conditions are satisfied in the case where a new call is generated in a multicarrier hopping TDMA system. CONSTITUTION:When the calls are generated from respective slave stations 21-2L and channel allocating requests are received, a control station 1 decides channel positions (a carrier (f) and a time unit (t)) to the calls. The channel allocation is executed in a way mentioned below. Namely, in the case where the total number of the transmitting channels of the slave stations at a transmitting side and total number of the receiving channels of the slave stations at a receiving side of the above-mentioned new call in respective time units are equal to the permissible number of the channels or below even at the time of allocating an unoccupied channel to the new call to request the channel, even when the other respective slave stations use any of the channels, respective channels in the middle of communications are rearranged.
09 Apr 1989
TL;DR: It is shown that good delay performance can be achieved by using the channel allocation algorithm and a simple fixed routing algorithm, and it is concluded that this fact makes the proposed reconfigurable network architecture very attractive.
Abstract: A reconfigurable communication network in which the capacity of its multiple-channel links can by dynamically adjusted through activating different numbers of channels to comply with traffic fluctuations has been proposed previously (C.Y Chao and M. Ilyas, 1988). It has been shown that the reconfigurable network can perform significantly better than networks with fixed link capacity. Here, a distributed channel allocation algorithm which can be applied to the reconfigurable network is developed. The algorithm requires local traffic statistics only and converges to an optimum configuration in most cases. The number of iterations is bounded from above by the maximum number of transmitters at each node. It is shown that good delay performance can be achieved by using the channel allocation algorithm and a simple fixed routing algorithm. It is concluded that this fact makes the proposed reconfigurable network architecture very attractive. >
01 Jan 1989
TL;DR: It is now possible to examine in more detail the system requirements of the cellular radio network and to see how these are met in the available radio channels to assess the implications of the channel characteristics in structuring the different messages which sustain voice circuits to mobiles and hand-portables.
Abstract: In the last chapter, the principles of channel allocation and frequency re-use were set out in general terms. It is now possible to examine in more detail the system requirements of the cellular radio network and to see how these are met in the available radio channels; that is, to assess the implications of the channel characteristics in structuring the different messages which sustain voice circuits to mobiles and hand-portables.
Patent•
21 Jun 1989
TL;DR: In this article, the most advantageous free channel is selected in each case for the modulator tuning, and the channel having the greatest channel spacing with respect to the allocated channels is selected.
Abstract: The novel method is to ensure fast and accurate modulator tuning. In addition, the most advantageous free channel is to be automatically selected in each case for the modulator tuning. The channel allocation of the receivable transmitters available at the respective receiving site is determined via an automatic tuner tuner. In addition, a permanently stored tuning range of the modulator is interrogated channel by channel in order to determine the free channels still available for the channel selection. Of the available channels, the channel having the greatest channel spacing with respect to the allocated channels is selected. The novel method can be advantageously applied particularly in the case of video recorders having automatic tuners.