Fixed Channel Allocation Scheme Research Articles

Sequential multichannel allocation in cache-enabled multicasting small-cell networks

This paper investigates the optimization of multichannel allocation in cache-enabled multicasting small-cell networks (CMSNs). In the traditional fixed channel allocation scheme (FCA), small-cell base stations (SBSs) allocate a fix channel to each local cache popular content. In order to further increasing the utilization of allocated channels, we first propose a sequential multichannel allocation scheme (SMA), in which SBSs allocate a sequential channel set to their cached files dynamically. We formulate the problem of sequential multichannel allocation as two NP-hard non-linear programming problems with two optimization objectives of minimizing the global collision level (GCL) and maximizing the global file-downloading level (GFL), and demonstrate the advantages of the proposed DSCA over FCA. Then, two channel allocation potential games are proposed to achieve GCL and GFL optimization respectively. To achieve Nash equilibria (NEs) of the proposed games, we present a better response based SMA algorithm (BR-SMA) for both two games, and propose an improved better response based SMA algorithm (IBR-SMA) for the game for GCL maximization which have two exploration modes for each decision-maker.

Capacity Performance for Full-Duplex Multihop Wireless Networks Using Channel Interference Balancing Allocation Scheme.

Full-duplex (FD) communication has been attractive as one of the research interests related to spectrum utilization for wireless networks from the previous evolution of communication systems. Previous studies discuss the realization of the FD system by focusing on self-interference cancellation and transmit power control in low-power wireless network scenarios. Today, capacity maximization is a key challenge in FD multihop wireless networks, in which the multi-channel allocation may lead to imbalance interference power due to the different number of simultaneous transmissions and its group selection that occurred on the same sub-channels. In this paper, we focus on the capacity maximization of the FD system by considering the influence of total interference power on each sub-channel and how to balance by selecting the different number of simultaneous transmissions to form a group that leads to a minimum difference in the total interference power on those sub-channels. Therefore, a channel interference balancing allocation (CIBA) scheme for balancing the total interference power in the multi-channel multihop wireless networks is proposed and further investigated by the idea of cooperative transmission. We also adopt the concept of interference distance to overcome the interference balancing problem of the proposed CIBA scheme. Performance evaluation results reveal that the proposed CIBA scheme achieves lesser total interference power and higher achievable capacity than other fixed channel allocation schemes.

Performance Analysis of Different Channel Allocation Schemes of Random Access (RA) MAC Protocol with Back-Off Algorithm (BOA)

Cognitive radio technology is an effective method to improve the utilization and efficiency of radio spectrum. Cognitive radio technology solves spectrum scarcity problem by allowing cognitive users to use spectrum holes when primary users are absent. Cognitive radio networks are classified according to the infrastructure into: (A) centralized cognitive radio networks and (B) cognitive radio ad-hoc networks. The cognitive media access control (MAC) protocols are the master key of designing cognitive radio network. These allow cognitive users to identify and use the available frequency spectrum in a manner constrains the levels of interference to the primary users. Cognitive radio MAC protocols can be classified into: (A) random access control protocol (B) time slotted control protocols (C) hybrid protocols. In this paper, the dynamic open spectrum sharing (DOSS) MAC protocol is proposed as an example for random access control protocol. Due to the collision among users, the network throughput will be reduced. In order to enhance the performance of DOSS protocol, a back-off algorithm (BOA) will be executed and analyzed to enhance the network throughput. An optimum number of data retransmissions that decrease blocking and dropping ratio are investigated. Moreover, two accessing channels techniques for the proposed algorithm will be presented: fixed channel allocation (FCA) and dynamic channel allocation (DCA) schemes. DCA scheme allows to users to choose the control channel in a dynamic manner. The dynamic behavior decreases the limitation of control channel saturation. So, it can increase the network throughput. The performance analysis of the FCA and DCA schemes for the proposed protocol will be simulated. Finally, the performance analysis of DCA scheme of DOSS mac protocol with BOA will be investigated.

Handover prioritizing scheme for reducing call failure probability in cellular wireless network

AbstractThis paper proposes a scheme suitable for managing handover in wireless cellular network. The main objective of the proposed scheme is to reduce the probability of forced termination of ongoing call due to handover failure. The scheme employs a queuing discipline, and the priority of queued is based on the residual time of the mobile user in the overlap region between two adjacent cells, assuming that the user's location and speed can be determined, then we applied the ascending priority; it means that the users having a shorter residual time join the head of the queue (i.e., high priority) while those having longer residual time at the end of the queue (i.e., low priority). Fixed channel allocation strategy (FCA) is employed and simulation results obtained concern: call blocking probability (CBP), handover failure probability, and average waiting time in the queue. Also simulation results are compared to those obtained by: non‐prioritized scheme (FCA), and FCA queuing with FIFO discipline. Results show that our proposed method decreases significantly handover failure probability compared with other two schemes. Copyright © 2009 John Wiley & Sons, Ltd.

Supporting Asymmetric Traffic in a TDD/CDMA Cellular Network via Interference-Aware Dynamic Channel Allocation and Space–Time LMMSE Joint Detection

In a time-division duplexing (TDD)/code-division multiple-access (CDMA) cellular network with asymmetric data traffic, dynamic channel allocation (DCA) enhances resource utilization compared with fixed channel allocation (FCA). However, it also induces base-to-base and mobile-to-mobile crossed-slot intercell interference, which can severely degrade system performance. To deal with this problem, a decentralized scheme is proposed, which combines an interference-aware DCA algorithm with space-time linear minimum-mean-square-error (LMMSE) joint detection at the base and mobile stations. The former assigns active links to timeslots in a way that crossed-slot interference is mitigated, while the latter suppresses the remaining intercell interference (along with intersymbol and intracell interference), exploiting its spatio-temporal autocorrelation statistics. The performance of this scheme is evaluated in terms of downlink and uplink signal-to-interference-plus-noise ratio (SINR) outage and average throughput via analytical approximations and Monte Carlo simulations, and it is compared with that of benchmark random DCA (RDCA) and FCA schemes. The cases of single- and dual-antenna reception with perfect and imperfect channel state information are examined. It is shown that the proposed scheme achieves higher average throughput than FCA (particularly for dual-antenna reception) as well as RDCA (for heavy traffic loads). These throughput gains are more significant in uplink than in downlink.

Traffic Model and Performance Analysis of Cellular Mobile Systems for General Distributed Handoff Traffic and Dynamic Channel Allocation

An analytical model for channelized cellular mobile circuit-switched systems that support general arbitrary distributed handoff traffic has been proposed. The model is applicable for a dynamic channel allocation scheme. A 2-D Markov chain is developed, which can be used to compute congestion for all kinds of traffic streams. The proposed model is not restricted by a limited range of user mobility and can be reduced to predict congestion for Poisson-distributed handoff traffic and fixed channel allocation scheme.

Capacity optimizing channel allocation schemes for multi‐service cellular systems with mobile users

AbstractIn this paper, we study the blocking and dropping probability of mobile users in the multi‐service cellular systems with mobile users. Based on the idea that different services may require different signal‐to‐interference ratios and different reuse factors, we proposed a channel allocation scheme called channel partitioning to support different services using different reuse factors. Under channel partitioning scheme, the channels in each cell are divided into two or more sets of channels and each set of the channels supports certain service, depending on the required reuse factor of the service. We first apply this channel partitioning with fixed channel allocation scheme called fixed channel partitioning (FCP), where a three‐dimensional Markov chain is developed to analyze the impact of the mobile user. After that a simpler model, which can estimate the numeric result from the closed‐form solution, is presented to make the analysis easier. In order to cater for the traffic variation between services and between cells, a dynamic channel partitioning with flexible channel combination scheme, called FDCP, is proposed to support multiple services. This FDCP tries to minimize the effect of assigned channels on the availability of channels for use in the interfering cells. The analysis and the simulation results show that for equal arrival rate of two services, the proposed FCP and FDCP scheme can provide about 32% and 54% improvement, respectively, in terms of grade of service as compared with conventional FCA scheme using a single reuse factor to support two services for the mobile users. Copyright © 2006 John Wiley & Sons, Ltd.

An efficient channel allocation scheme for cellular network using maximum channel packing

AbstractThis paper introduces a channel assignment scheme called the maximum channel packing (MCPCA) for mobile cellular network. As the title suggests, the scheme reduces future call blocking probability by increasing the frequency of channel reuse (or channel packing). The scheme is simulated along with the simple fixed channel allocation scheme and a variation of the channel borrowing allocation scheme, under different traffic patterns and intensity. The results show that MCPCA scheme performs better than the other schemes under all conditions. Copyright © 2004 John Wiley & Sons, Ltd.

Dynamic channel allocation for ongoing calls in UTRA TDD system

A comparative analysis of different dynamic channel allocation (DCA) schemes for ongoing calls in a UTRA time division duplex (TDD) system is presented. The proposed study shows that DCA results in a reduction of up to 2.2 dB transmission power as well as a packet loss reduction up to 20% compared to a fixed channel allocation scheme

Performance Evaluation of a Virtual Queuing --- Channel Allocation Scheme for Microcellular Networks

This paper deals with the performance evaluation of a novel distributed channel allocation scheme that attains a high resource reuse in cellular networks. A suitable interference model has been envisaged. Resources are nominally assigned to cells with Fixed Channel Allocation (FCA), according to a given reuse distance. Whenever a channel demand from a mobile user does not find a free nominal resource in a cell, a channel is temporarily borrowed violating the reuse distance constraint, provided that the co-channel interference level is acceptable. As soon as a nominal channel becomes available in this cell, the borrowed resource is released (virtual queuing). The performance of the proposed channel allocation scheme has been evaluated considering both uniform and non-uniform traffic patterns. A performance analysis approach has been also developed and validated by simulations. Comparisons with the classical FCA scheme and other dynamic and borrowing channel allocation strategies have permitted to highlight the good performance of the proposed technique.

Fixed channel allocation scheme performance enhancement for cellular mobile systems

An optimisation technique for fixed channel allocation (FCA) schemes is proposed. This mechanism can respond to the variations in traffic to reassign channels to cells. Traffic variability can be automatically adapted after applying this mechanism to FCA schemes. It is unnecessary to handoff a call when its allocated channel is reassigned to other cells. Moreover, freedom from deadlock and starvation is ensured. Simulation results demonstrate that this mechanism enhances the traffic-carrying capacity of FCA schemes with the flexibility and adaptability to handle variations in traffic.

Handover queuing strategies with dynamic and fixed channel allocation techniques in low Earth orbit mobile satellite systems

This paper deals with the performance evaluation of various resource management strategies that are suitable for low Earth orbit mobile satellite systems (LEO-MSSs). A user mobility model has been proposed and its statistical parameters have been derived. Both fixed channel allocation (FCA) and dynamic channel allocation (DCA) techniques have been considered. Moreover, in order to reduce the handover failure probability, we have assumed that interbeam handover requests which do not immediately obtain service can be queued. In particular, two different queuing disciplines have been compared: (a) the first input first output (FIFO) scheme and (b) a new technique called last useful instant (LUI) which is based on the knowledge of the maximum time within which the handover procedure must be accomplished. Implementation aspects for the LUI technique in a LEO-MSS have been discussed also in comparison with the measurement-based priority scheme (MBPS), previously proposed in the literature on this subject. The efficiency of the LUI queuing scheme as regards the FIFO technique has been investigated by simulations for both DCA and FCA techniques. An analytical approach has been also presented in order to allow the performance evaluation of the FCA scheme with different handover queuing disciplines.

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.

Asymptotic bounds on the performance of a class of dynamic channel assignment algorithms

Dynamic channel assignment, adapting both to traffic variations as well as to changing mobile locations, is investigated. Several ad hoc schemes of this type have been described in the literature and found to yield interesting performance improvements. However, very little is known about the performance of the optimum assignment schemes. Both upper and lower bounds for the performance of optimum algorithms within the class of reuse-type dynamic channel assignment (DCA) for a simple propagation model are established. The authors focus on the asymptotic performance, i.e., the performance in systems with large traffic loads. As a performance measure, the probability of assignment failure (intracell handoff failure) is used. Results show that the capacity one may expect to achieve with these algorithms in the asymptotic case is just above twice the capacity of a fixed channel allocation scheme.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>