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Cross-layer design is becoming a popular design methodology for the IP-based next-generation wireless systems 3G/4G. Several cross-layer methods are emerging to enhance the performance of the applications and achieve better Quality of Service (QoS) support. Through these methods, the refined wireless systems are expected to gain significant performance improvement and obtain extended functionality...
Random sensor deployments following Poisson or Gaussian distribution are the most widely adopted deployment strategies for hostile and unpredictable application scenarios such as environment surveillance and malicious mobile target detection. In the literature, researchers assume either Poisson distributed or Gaussian distributed sensors in modeling wireless sensor networks for performance evaluation...
In this paper we extend our recent work [3] by analyzing the behavior of mobility scenario in saturation conditions for evaluating packet delays. For the first time we have shown that the normalized measure of dispersion for service time intervals and offered load dependency holds for multi-hop IEEE 802.11 wireless networks with mobile nodes, as well. Thus this paper not only extends and validates...
Energy conservation is a critical issue in the emerging standard IEEE 802.16e/m WiMAX supporting mobility. To guarantee QoS requirements in real-time services such as VoIP, traditional energy saving strategies adopt constant listen-sleep intervals, ignoring the On-Off characteristics of human speech. However, statistically the silence period can account for nearly 60% of the whole speech in time scale...
Choosing the shortest path for real-time flows is insufficient. Respecting the deadline cannot be insured nor guaranteed neither with exhausted energy resource nor with overloaded intermediate mobile nodes. The main problem is to choose the reliable, efficient and correct routing protocol to route real-time flows with respect to their deadlines within MANET constraints. This paper introduces the Energy...
In this paper, we focus on the low complexity algorithm of turbo receivers over double selective channels for the Lone Term Evolution (LTE) single user uplink. Based on the analysis of the physical meaning of the frequency channel matrix, we propose a low complexity algorithm which is significant for the existent frequency LDL turbo receivers. To further reduce the receiver complexity, based on the...
In this paper, the mutual information transfer characteristics of turbo Multiuser Detector (MUD) for a novel air interface scheme, called Low Density Signature Orthogonal Frequency Division Multiplexing (LDS-OFDM) are investigated using Extrinsic Information Transfer (EXIT) charts. LDS-OFDM uses Low Density Signature structure for spreading the data symbols in frequency domain. This technique benefits...
In this work the labelling diversity scheme is developed. The Binary Switching Algorithm is employed to find an optimized 2-dimensional labelling map of 16-QAM constellation, which, applied in conjunction with the best map for iteratively-decoded bit-interleaved space-time coded modulation (BI-STCM-ID), enhances the advantages of multi-antenna transmission. Properties of the proposed scheme are compared...
In this paper, a new channel coding scheme for the narrowband powerline communication (PLC) system employing quasi-cyclic (QC) low-density parity-check (LDPC) codes of multiple code rate and multiple code length is proposed. Combined with proper constellation mappings, 4 transmission modes can be supported, which provides different error correction capabilities. A comparison with the coding scheme...
Recently, we proposed a novel differential encoder for non-constant energy signals, by a look-up table instead of a rule. In this paper, we present further research results on this subject. We first propose a new bit-assigning algorithm and some constellations maximizing minimum noncoherent distance. Then we show that differential encoding by a table is equivalent to differential encoding by a trellis,...
Recently, a new multiple access scheme called interleave-division multiple access (IDMA) has been studied where different interleavers are used to distinguish users. This paper focuses on orthogonal frequency division multiplexing (OFDM) -IDMA, which is a combination of OFDM and IDMA, and investigates the throughput performance of OFDM-IDMA for the uplink in multi-cell environment. We analyze the...
Deployment of cameras in Wireless Multimedia Sensor Networks (WMSNs) is crucial in achieving good coverage, accuracy and fault tolerance. With the decreased costs of wireless cameras, WMSNs provide opportunities for redundant camera deployment in order to get multiple disparate views of events. Referred to as multi-perspective coverage (MPC), this paper proposes an optimal solution for camera deployment...
In this paper, we first survey cross layer architectures for Wireless Sensor Networks and Wireless Multimedia Sensor Networks (WMSNs). Afterwards, we introduce a novel framework for supporting multiple applications in WMSNs. The proposed framework supports heterogeneous flows and it classifies WMSN traffic into six classes. The framework partitions the network into hexagonal cells and it uses the...
Wireless Multimedia Sensor Networks (WMSN) have an increasing variety of multimedia based applications including image and video transmission. In these types of applications, multimedia sensor nodes should ideally maximize perceptual quality and minimize energy expenditures in communication. To obtain the required perceptual quality, quality of service (QoS) support is needed at the network level...
The demand of quality of service (QoS) for multimedia transmission over wireless network raises huge challenges such as time-varying channel conditions, limited resources, tight delay constraints, high bandwidth demand and complex protocol design. Layered design is proven to perform well in wired networks. However, doing so is not suitable in wireless networks due to the dynamics in wireless medium...
In this paper, we consider the replication strategy for the applications of video streaming in wireless mesh networks (WMNs). In particular, we propose a closed-form of optimal replication densities for a set of frames of a video streaming based on exploiting not only the skewed access probability of each frame but also the skewed loss probability and skewed encoding rate-distortion information. The...
Security in resource-limited environments poses a great challenge as the nodes comprising such a network are severely limited in processing power and storage. Various security protocols have been proposed for sensor networks and RFID that try to mitigate this problem but they provide security on a point-to-point basis which is weak and easily vulnerable to a number of attacks. In this paper, we discuss...
Among the challenges facing the Internet, DoS/DDoS are a critical concern for Internet Service Providers. DDoS attacks can cause country-wide infrastructure problems, and can disrupt communications on a national level. Frequently, Botnets are used to carry out source-spoofed DDoS attacks. The problem of tracing such attacks has been the subject of significant inquiry.
Packet injection by an attacker can trigger flooding-based DOS attacks. This paper seeks to provide a simple and robust approach to protect the access control, data integrity and sender authentication security services in resource-constrained delay tolerant networks. The aim is to make security protocols providing these mandatory security services resilient to resource exhaustion DOS attacks. To achieve...
Voice over IP (VoIP) technology has proven to be an immensely useful technology during the last decade. Not only it provides various services to users (e.g. calls, instant messaging, internet conferencing etc), but it is also in a process of extending services (e.g. fax service). Due to the open environment of packet switched network, the signaling protocols (such as SIP and H.323) and the transport...
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