International Journal of Communication Networks and Distributed Systems (9 papers in press)

• QoS Aware Congestion Adaptive Routing for Streaming Multimedia in Mobile Ad Hoc Networks
  by Ramesh Boraiah, Manjula D 
  Abstract: Present routing protocols in mobile ad hoc networks are finding feasible route from a source to a destination without considering current network traffic and QoS requirements of multimedia application. The more mobility, congestion, and channel error are the major factors for packet loss, longer delay and routing overhead for streaming multimedia in mobile ad hoc networks. Multimedia applications require quality-of-service (QoS) support from the network and also routing should be adaptive to network congestion. Our proposed QoS Aware Congestion Adaptive Routing (QACAR) can achieve such properties by selecting a route that can satisfy the requirements of applications or by providing suitable network feedback whenever the requirements of applications cannot be met. We also incorporate admission control mechanisms to check the status of the network traffic and a feedback scheme to adapt to network congestion. The novel part of this routing protocol is the use of the approximate QoS estimation to requested applications and adapt to network congestion. We argue that proposed routing protocol should not only be aware of the QoS requirements of real time application, it must also be adaptive to network congestion. This routing protocol will make use of minimal bandwidth estimation methods to react to the network congestion. We have used one of standards (mpeg4) for streaming multimedia and implemented it using ns2. System simulations show that the proposed method can increase the system throughput and reduce both the packet dropping rate and the end-to-end delay. Hence, QACAR is surely an effective routing protocol to provide QoS guarantee as well as to adapt to network congestion for streaming multimedia data in mobile ad hoc networks.
  Keywords: Multimedia; QoS; MANET; Congestion;
   
• Genetic Algorithm approach to Dynamic Multi Constraint Multi Path QoS Routing Algorithm for IP networks (GA-DMCMPRA)
  by Leela Rengaraj, Selvakumar S 
  Abstract: Real-time distributed multimedia applications have special requirements in terms of bandwidth, delay, delay jitter, etc. The current network, essentially being a connection-less network, provides only un-reliable, best-effort service. The data packets may follow different paths to the destination. The network resources, viz., switch buffer and link bandwidth, are fairly shared by packets from different sessions. This type of network is best suitable for applications such as email, ftp, etc., but not suitable for real time multimedia applications such as video-on-demand, video conferencing, Internet telephony, etc., as these applications require different QoS requirements from the underlying network. In order to make the network suitable for such applications many QoS routing algorithms have been proposed. The problem of finding a path with multiple constraints is a NP-complete problem. Hence, various heuristics have been proposed to find a path that satisfies more than one constraint. All these heuristics do not consider the queuing situation at a given node. An alternate path with less queue occupancy may be more convenient to use than the optimum path when a long queue is present in nodes along the path. To search all feasible paths in less time, many researchers have used the concept of Genetic Algorithm (GA), which is a new computational strategy inspired by natural processes.emph{This GA approach has been used in the existing Dynamic Multi Constraint Multi Path QoS Routing Algorithm (DMCMPRA) cite{leela:2008} for IP networks to find k feasible paths satisfying the multi constraint requirement of the multi media applications.} Computer simulations show that GA-DMCMPRA takes less time for path computation when compared to Dynamic Multi Constraint Multi Path QoS Routing Algorithm (DMCMPRA). Further it is also proved that the performance of GA-DMCMPRA with respect to percentage of Packets received and average Delay experienced by packets is at par with DMCMPRA.
  Keywords: QoS, SAMCRA,DMCMPRA, MCP
   
• Stability Analysis of Analytical Hierarchy Process Clustering Protocol in Mobile Ad Hoc Networks
  by sharmila Anand John Francis, Elijah Rajsingh 
  Abstract: Clustering the mobile ad hoc network is a fundamental problem that has been solved by many different approaches. Efficient and stable clustering always depends on choosing an appropriate cluster head in the network. This article proposes a novel efficient AHP clustering protocol called AHPC protocol that employs a powerful analytical hierarchy process methodology. Analytical hierarchy process methodology is a mathematical model that computes relative weights for all the mobile nodes in the network that facilitates the choosing of appropriate cluster heads in the network. The eleven essential factors of the mobile nodes are identified that influence the choosing of cluster heads. The mathematical and experimental analysis of AHPC protocol has been carried out. The results show that the proposed clustering protocol enhances the stability of the network by reducing the frequent cluster head changes, dominant set updates to a great extent, leading to a highly stable clustering protocol in mobile ad hoc networks.
  Keywords: Cluster head, clusters, ad hoc networks, analytical hierarchy process.
   
• A Novel Design of Reconfigurable Fourier Transform Operator Over C and GF(Ft) for Future Multi-standards SDR Equipments
  by Sufi Tabassum GUL, Ali AL GHOUWAYEL, Christophe MOY, Yves LOUËT 
  Abstract: Reed Solomon (RS) encoding/decoding in frequency domain is of significant interest in many wireless systems because the Fast Fourier Transform (FFT) operator is already present, at least in Orthogonal Frequency Division Multiplexing (OFDM) based ones. This paper presents and analyses the role of FFT to perform RS encoding/decoding in frequency domain. After explicating performance comparison, we propose to use RS codes defined over GF(Ft) instead of RS codes over GF(2m). Based on this proposition we have developed a common Dual Mode FFT (DMFFT) operator able to operate over two different domains C and GF(Ft). Various implementation strategies for DMFFT operator have been discussed. We emphasize that this DMFFT operator is a strong candidate for common operators in future air interface standards. We also explain our approach for designing flexible multi-standard radio systems. Finally we incorporate the DMFFT operator in our graph and solve optimization problem by a heuristic based on simulated annealing.
  Keywords: FFT; FNT; Common operators; Software defined radio; Graph exploration; Frequency domain channel coding; Optimization
   
• Minimum-Cost Gateway Placement in Wireless Mesh Networks with QoS Constraints
  by Zhigang Chen, Feng Zeng 
  Abstract: In wireless mesh networks (WMNs), gateway optimal placement is key to network performance, QoS and construction cost. This paper focuses on gateway placement with QoS constraints in WMNs, and aims to minimize the cost of gateway placement. Firstly, a new concept of Limited Dominating Set (LDS) in graph is presented to address the minimum-cost gateway placement problem, which is converted to find the minimum weighted LDS in a graph. Secondly, we propose a heuristic algorithm WMB-LDS to find the minimum weighted LDS for a graph, which takes the performance/cost ratio of gateway candidates as heuristic information. Furthermore, we design a genetic algorithm GA-LDS to search for the global optimal solution. At last, simulation is done, and the experimental results show that, compared with previous work, WMB-LDS has better performance and lower computing complexity, and GA-LDS has the best experiment result at the price of the increasing computing complexity.
  Keywords: wireless mesh network; gateway placement; dominating set; QoS constraint; genetic algorithm
   
• Scalable Merger of Chord-rings
  by Zoltán Lajos Kis, Róbert Szabó 
  Abstract: In our previous work we investigated how distributed hash tables { speci¯cally Chord-rings { can be merged in an e±cient manner, thereby supporting compositions of dynamic networks relying on DHTs as management substrates. As a result we presented the Chord-Zip algorithm. In this paper we present our investigations and ¯ndings on how the Chord-Zip algorithm can be parallelized in order to achieve scalability in the merger of Chord-rings.
  Keywords: distributed hash table (DHT); distributed processing; network composition; overlay network
   
• Optimization of Base Station Location in Broadband Power Line Communications Access Networks
  by Abdelfatteh Haidine 
  Abstract: In this paper we investigate the planning and optimization of the Broadband Power Line Communications (B-PLC) access networks. The B-PLC is a recent access technology that is considered as an alternative for the realization of the broadband access networks, allowing bit rates up to 200Mbps. This technique uses the wiring of the low-voltage grid in order to offer to the users the telecommunications services, such as Internet, Voice-over-IP, video, etc. In this paper, the B-PLC planning process is sub-divided into two parts, which are the Generalized Base Station Placement (GBSP) and the PLC Channel Allocation Problem (P-CAP). This paper focuses on the GBSP that is formulated as multi-objective combinatorial optimization. The analysis of this problem covers the problem description, the mathematical modelling of the different optimization objectives (namely the network costs and the end-to-end delay -in uplink as well as in downlink) and its solution by means of metaheuristics. Two optimization approaches are used to solve it: the classical approach based on single-objective optimization and the modern approach based on multi-objective optimization. Different algorithm variants are used, which are all based on the evolutionary search. The performances of these approaches are evaluated.
  Keywords: Base station placement, broadband Power Line Communications, network planning, multi-objective optimization, evolutionary algorithm.
   
• A Novel Radon-based Multi-Carrier Direct Sequence-Code Division Multiple Access Transceiver Design and Simulation
  by Abbas Kattoush, Waleed Al-Jawhar 
  Abstract: Multicarrier direct-sequence code-division multiple access (MC-DS-CDMA) has emerged recently as a promising candidate for the next generation broad-band mobile networks. Multi-path fading channels have a severe effect on the performance of wireless communication systems even those systems that exhibit efficient bandwidth, like orthogonal frequency division multiplexing (OFDM) and MC-DS-CDMA, there is always a need for developments in the realization of these systems as well as efficient channel estimation and equalization methods to enable these systems to reach their maximum performance. A novel MC-DS-CDMA transceiver based on the Radon Based-OFDM which was recently proposed as a new technique in the realization of OFDM systems, will be used here as a basic building block in the design of MC-DS-CDMA transceiver to increase the orthogonality against the multi-path frequency selective fading channels. Simulation results are provided to demonstrate the significant gains in performance and simplicity due to the proposed techniques.
  Keywords: Multi carrier; Finite Radon Transform; Radon based OFDM, MC-DS-CDMA
   
• Effects of Multi-cell Beamforming on Downlink Data Services in Cellular CDMA
  by Sanjay Dhar Roy, Sumit Kundu 
  Abstract: This paper proposes and evaluates a scheme of combining multicell beamforming, power control, soft handoff in physical layer and automatic repeat request (ARQ) in link layer for improving the performance of data service in forward link of cellular CDMA. The present paper also proposes a scheme of beamforming based power control scheme in physical layer for forward link of Cellular CDMA. Beamforming has been assumed at three base stations (BSs) in our system model. A stop and wait ARQ scheme has been assumed for forward link data service. Joint effects of beamforming, power control, number of retransmission and soft handoff via cross layer interaction reduce delay, bit error rate (BER) and increase throughput significantly. Impacts of several parameters of soft handoff, power control and beamforming and their cross layer interaction on data performance have been evaluated. Both the cases of perfect and imperfect beamforming have been investigated. Effects of DOA (direction of arrival) estimation error associated with beamforming have also been indicated on data service.
  Keywords: Multicell beamforming, Soft handoff, CDMA, Data Service