Dynamic Channel Allocation Scheme Research Articles

A prioritized handoff dynamic channel allocation strategy for PCS

An analytical method is developed to calculate the blocking probability (p/sub b/), the probability of handoff failure (p/sub h/), the forced termination probability (p/sub ft/), and the probability that a call is not completed (p/sub nc/) for the no priority (NPS) and reserved channel (RCS) schemes for handoff, using fixed channel allocation (FCA) in a microcellular system. Based only on the knowledge of the new call arrival rate, a method of assessing the handoff arrival rate for any kind of traffic is derived. The analytical method is valid for uniform and nonuniform traffic distributions and is verified by computer simulations. An extension (generalization) to the nonuniform compact pattern allocation algorithm is presented as an application of this analysis. Based on this extended concept, a modified version of a dynamic channel allocation strategy (DCA) called compact pattern with maximized channel borrowing (CPMCB) is presented. With modifications, it is shown that CPMCB is a self-adaptive prioritized handoff DCA strategy with enhanced performance that can be exploited in a personal communications service (PCS) environment leading either to a reduction in infrastructure or to an increase in capacity and grade of service. The effect of user mobility on the grade of service is also considered using CPMCB.

Borrowing channel assignment strategies based on heuristic techniques for cellular systems

The demand for more efficient and fast channel allocation techniques in cellular systems increases day by day. Borrowing channel assignment (BCA) was introduced in the literature as a compromise between the classic fixed and dynamic channel allocation schemes. This paper examines the behavior of three heuristic BCA techniques based alternatively on a Hopfield neural network, an efficient evolutionary algorithm named combinatorial evolution strategy (CES) and a third heuristic which combines the basic advantages of the two above computational intelligence methods. By considering some specific assumptions that follows an ideal cellular mobile model, BCA is formulated as a combinatorial optimization problem. The above heuristics have been extensively applied to solve efficiently such problems in the past. Simulation results, derived for uniform and nonuniform traffic load conditions, are used to compare these BCA schemes each other as also with other well-established allocation techniques.

Fast channel access and DCA scheme for connection and connectionless-oriented services in UMTS

An efficient MAC protocol and flexible dynamic channel allocation (DCA) scheme for the UMTS-TDD mode is presented which exploits the characteristics of connectionless and connection-oriented services. The proposed protocol gives fast channel access and high bandwidth efficiency in any traffic scenario asymmetric between uplink and downlink channels, particularly in the presence of Internet traffic.

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.

Radio resource management in future wireless networks: requirements and limitations

Comparing market estimates for wireless personal communication and considering proposals for wideband multimedia services with the existing spectrum allocations for these types of systems show that spectrum resource management remains an important topic in the near and distant future. In this article the authors start by presenting a quite general formulation of the radio resource management problem where the three key allocation decisions are concerned with waveforms ("channels"), access ports (or base stations), and, finally, with transmitter power. Some approaches to these problems found in the literature are reviewed. In particular, the principles of random channel allocation schemes, as found in frequency-hopping or direct-sequence CDMA systems, are compared with deterministic dynamic channel allocation schemes. The article closes by giving an outlook of some of the key problems in resource management in future wireless multimedia systems.

Application of dynamic channel allocation strategies to the GSM cellular network

We refer to the implementation and the performance of a specific class of dynamic carrier allocation (DCA) strategies which is suitable for being introduced in the pan-European Global System for Mobile communications (GSM) cellular network. One of the main concerns of this work is to verify if and to what extent strategies belonging to this class can offer better performance than fixed channel allocation (FCA) in realistic traffic and propagation conditions. The impact of the introduction in a real network of two of the more promising DCA strategies in the considered class is assessed. In particular, solutions are presented concerning the signaling exchanges entailed by the implementation of each of the considered DCA strategies. A performance evaluation of a realistic cellular network exploiting the above-mentioned DCA strategies is carried out, taking into account all of the main GSM transmission and network aspects. The simulations have been performed by considering a realistic cell layout corresponding to the urban area of Rome, its realistic propagation environment, and a user mobility model based on the building percentages in such an area. The results of the performance evaluation show that, by carefully choosing the values of the parameters characterizing each of the considered DCA strategies, a conspicuous increase in the number of users supported by the cellular network can be achieved.

Near-optimality of distributed load-adaptive Dynamic Channel Allocation strategies for cellular mobile networks

In this paper we focus on the so-called load-adaptive Dynamic Channel Allocation (DCA) strategies for cellular mobile networks. Such strategies envisage the dynamic assignment of radio resources with the constraint that the outage probability (i.e. the probability that the carrier-to-interference power ratio be less than a given threshold) be less than a specified value, even in the worst foreseen propagation scenario. We identify a set of constraints to be satisfied in order that a DCA strategy belongs to the load-adaptive class. This provides a tight lower bound on traffic blocking and dropping performance such that: (i) it implies a dramatically lower computational effort than the known optimum strategy (based on the Maximum Packing algorithm); (ii) it is much tighter than the bound provided by the simple Erlang-B formula. A performance evaluation is carried out to compare the call blocking and dropping probabilities resulting from the tight bound above with those relevant to the Fixed Channel Allocation and to some recently proposed DCA strategies, including the Geometric DCA. The simulations exploit a mobility model that provides different degrees of offered traffic peakedness. It emerges that the Geometric DCA yields a practical way to attain near optimal performance in the load-adaptive class, leading a viable pathway to enhance the capacity of nowadays 2nd generation cellular networks in the short-medium term.

Resource allocation in wireless networks

Wireless services are one of the strongest growth areas in telecommunications today. Dynamic channel allocation schemes have garnered a considerable amount of attention as methods for achieving efficient use of system resources. Various combinations of permanent channel assignment, channel borrowing, shared pools of channels, channel ordering, channel reassignment, and dynamic adjustment of parameters have been suggested. In this paper, we suggest a categorization of dynamic channel allocation policies. We hope that this categorization will help distill the concepts involved and encourage the research that is necessary to extend these concepts to future integrated service wireless systems.

Interruption characteristics of distributed dynamic channel allocation with reuse partitioning and power control

AbstractDistributed dynamic channel allocation (DDCA) schemes are important because they allow flexible handling of variations in traffic. It has been clarified by simulation that better call‐loss and interference characteristics are obtained by combining reuse partitioning and transmission power control schemes. Channel allocation and interference in DDCA are formalized in this article. It is also shown that a lower limit can be established in the signal‐to‐interference ratio (SIR) degradation caused by interference accompanying calls to other stations when channel allocation is performed such that reuse partitioning is ideally realized simultaneously. It is shown that this lower limit is described by the SIR margin and reuse partitioning characteristics and power control schemes. In addition, it is shown that the degrees of degradation in SIR of the mobile station and the base station in conversation can be predicted in advance, including the case in which reuse partitioning may not be performed ideally.

The asynchronous technique for carrier acquisition coordination

In third-generation mobile systems cell dimensions will become lower and lower. So, on the one hand, an higher variance of the offered traffic per cell is expected and, on the other hand, the issue of reducing the signaling exchanges among base stations (BS's) becomes very important. A solution to the above-mentioned problems is the implementation of a dynamic channel allocation (DCA) strategy with distributed control. The DCA strategy foresees that the assignment of the carriers to the various cells is dynamically rearranged on a real time basis, in order to track the traffic evolution in the various cells. The distributed control entails that carrier acquisitions (and releases) are made by the BS's with minimal signaling exchanges. A fundamental problem of DCA strategies with distributed control concerns the coordination among BS's in order to avoid conflicting acquisitions of a same carrier from two BS's located at a distance lower than the reuse distance. This paper considers two techniques for performing the above-mentioned coordination: the synchronous technique and the asynchronous technique. Both techniques are suitable for being applied in a possible evolution of the pan-European Global System for Mobile communications (GSM). These techniques base on the presence of an acquisition delay between the acquisition stimulus time and the actual acquisition time; such acquisition delay permits coordination among BS's, but worsens performance in terms of blocking and dropping probabilities. It is shown that, in most cases, the asynchronous technique entails shorter acquisition delays than the synchronous one and thus attains better performance.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The geometric dynamic channel allocation as a practical strategy in mobile networks with bursty user mobility

In this paper we refer to a specific class of Dynamic Channel Allocation (DCA) strategies, namely the inferferencefree, timid, not-conditioned class. The main concern of this work is to verify if and to what extent strategies belonging to this class can offer better performance than Fixed Channel Allocation (FCA). The interest in this kind of strategies is motivated by their feasibility with current TDM technologies, the limited amount of information required to carry out channel assignments and their intrinsic stability. In this framework we present a simple, but very attractive DCA strategy, the so-called Geometric DCA (GDCA). A performance evaluation is carried out to compare some representative DCA strategies of the considered class, by using a user mobility model that accounts for the large fluctuations of the number of users in a cell coverage area expected in a microcellular environment. The effect of the non-null propagation time required by the information exchange in the DCA strategies is also taken into account. It emerges that the proposed GDCA allows better performance than more sophisticated strategies already proposed, at the expense of a frequency planning carried out only at network configuration. This is due to the ability of GDCA to exploit the a priori information to maintain a tight geometric packing of used carriers. The reported results also show that DCA strategies in the considered class cope with large and sudden traffic fluctuations remarkably better than the FCA scheme does and that the advantage becomes more evident as the burstiness of the user mobility process (hence of the offered traffic) increases.

Modeling Handovers in Cellular Mobile Networks with Dynamic Channel Allocation

A model for a cellular mobile network is given which uses the dynamic channel allocation strategy proposed by Everitt and Macfadyen (Everitt, D. E., N. W. Macfadyen. 1983. Analysis of multicellular mobile radiotelephone systems with loss. British Telecom. Tech. J. 137–45.). In this model, handovers of calls from one cell to another are explicitly included. The equilibrium distribution of this network is shown to have product form under certain reversibility conditions. The conditions are restrictive and are, perhaps, unlikely to hold in practical models. However, their study does provide insight into the behavior of cellular systems with dynamic channel allocation. Using the product-form equilibrium distribution we are able to express the blocking probability for new calls, and the blocking probability for handover calls in terms of appropriate normalizing constants. The model is also extended to allow directed retry for handovers in which blocked handover attempts may try to gain access via another cell. This provides differential service for handovers. Again, some reversibility conditions ensure product form, and the blocking probabilities for both new and handover calls are given in terms of normalizing constants.

Demand assignment multiple access and dynamic channel allocation strategies for integrating radio dispatch and telephone services over mobile satellite systems

The authors discuss the performance analyses of a novel demand assignment multiple access (DAMA) scheme addressing the special characteristics of the mobile radio service (MRS), and a new method for dynamically allocating a common pool of channels to both MRS and mobile telephone service (MTS) to improve channel utilization. The new DAMA scheme makes use of call queuing, batch processing, and pipelined signaling to minimize call setup overhead for MRS traffic. MRS call setup delays were analyzed by simulation modeling of a mobile satellite system (MSS) with many mobile voice-dispatch networks operating over a multiple spot beam satellite to investigate the effects of traffic volume, batch size, and batch service disciplines. A reserved channel margin algorithm for dynamic channel allocation was shown to be effective in harmonizing the different call setup performance requirements for MTS and MRS. Numerical results show that dynamic channel allocation applied to a common pool of 40 channels enables a 20-25% increase in the number of mobile terminals compared with a fixed allocation of 20 channels to each of the two services. >

Performance analysis of cellular networks

Dynamic channel allocation can reduce the probability of blocking in cellular telephone networks. However, more is needed to achieve optimal performance. The author aims at estimating the minimal blocking probability for some simple cellular networks. Some dynamic channel allocation strategies are analyzed, the optimal performance (obtained by dynamic allocation and flow control) of some very simple networks is computed, and simple bounds on optimal performance are presented. These results lead to a better understanding of cellular networks and can be used to evaluate new control algorithms.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A model for dynamic channel allocation in an ISDN

The authors propose a dynamic channel allocation strategy in an integrated services digital network (ISDN) based on traffic characteristics and channel utilization. Conventional channel allocation schemes such as complete sharing channel allocation, complete allocation, and moving boundary channel allocation are examined and compared with the proposed dynamic channel allocation scheme. An analytic model is developed and a solution based on the moment-generating functional technique is given. Numerical examples are also presented. The result shows that the scheme improves the system performance. >

Video distribution in the EUREKA-IHS network

A dynamic channel allocation strategy with integral signal leveling is described providing an installation adaptive network. It is independent of topology, since internal signals must always avoid interference with external signals and each other. Control of signal ensures optimum signal-to-noise performance. The complete spectrum from 40 to 860 MHz is available and channel spacing and carrier frequencies are under software control so that regional deviations are easily accommodated. This strategy is a practical implementation of one aspect of the EUREKA Integrated Home System (IHS) Project, a collaborative European initiative, aimed at specifying a complete home network using the physical and data-link layers (OSI layers 1 & 2) of the coaxial medium required to support audio-video applications. >

Dynamic channel allocation schemes for cordless telephones

A comparison is made between the traffic capacity of two multichannel cordless telephone systems using different dynamic channel allocation schemes in their call set-up and termination procedures. One uses a dedicated control channel and the other uses any free channel for signalling purposes.