Earticle

A novel front-end noise power and SNR estimation technique based on one OFDM preamble is proposed and compared with previously published SNR estimators – none of which are front-end estimators. This paper is extended and expanded version of our previous work. It provides complete mathematics and discussion of designed algorithms for front end SNR estimation. The proposed technique is divided into two parts. In the first part, SNR estimation technique for AWGN channel and wireless multipath channels is considered. In the second part, the proposed estimator takes into consideration the different noise power levels over the OFDM sub-carriers. The OFDM band is divided into several sub-bands using wavelet packet decomposition and noise in each sub-band is considered white. The second-order statistics of the transmitted OFDM preamble are calculated in each sub-band and the noise power is estimated. The proposed estimator in first part is compared with Reddy estimator and Subspace based estimator for AWGN channel in terms of normalized mean square error and in the second part it is compared with Reddy’s estimator for colored noise in terms of mean square error (MSE). It is observed that current estimator gives better SNR estimates than Reddy and subspace estimators and can estimate local statistics of the noise power when the noise is colored.

The key performance metrics in wireless sensor networks are both network lifetime and an average time required to report an event reliably. The optimal solution must be taken into account to meet these metrics. Considering energy-latency constraints in sensor networks, we have developed a cluster architecture using mobile agents to detect the yarn break in spinning machine in textile industry. We have used the latency improved MAC layer protocol to access the channel in the cluster and also used energy efficient cluster formation algorithm based on residual energy of the sensor node. This protocol can handle multiple event messages efficiently. And, we mainly focused on simulating the behavior of mobile agents for information retrieval from a wireless sensor network in a event driven and poll driven wireless sensor network model.

In this paper, a new SCTP congestion control mechanism is introduced in multi-homing mode. Congestion in each route can be avoided or can be controlled, based on an Active Queue Management (AQM) method. Also, routers compute probability of congestion for the sources on the paths and then notify them. Therefore, the sources can adjust their sending rates on each path effectively and if necessary, can switch to an alternate path to prevent congestion. Simulations have been conducted with Opnet linked with MATLAB. The simulation shows that the new method can decrease packet loss, increase the amount of transmissions and stabilize queue length, as compared with standard SCTP.

Animal-vehicle collisions (AVC) affect human safety, property and wildlife. The number of collisions with large animals worldwide and especially in the Saudi Arabia Kingdom has increased substantially over the last decades. This paper provides a survey of the existing systems that mitigate the AVC. Moreover, this paper presents the high-level design of a deployable and intelligent Camel-Vehicle Accident Avoidance System (CVAAS) using global positioning system (GPS) technology. The use of the GPS technology in this kind of application is a novel idea. To evaluate the CVAAS system a simulator has been implemented.

An overview is given of the new OFDM based wireless LAN standard which is being developed by IEEE 802.11, ETSI and MMAC. Signal processing issues are described and some simulations are shown to demonstrate the achievable performance in multipath fading channels.

In this paper, the detailed design of the 1.8 GHz band Y-junction stripline circulator with the low pass filter circuit in the center conductor in order to higher attenuations below value of -30 dB at 3rd order harmonics is proposed and presented. The HFSS is used to simulate designed 1.8GHz band circulator to check the non-reciprocal characteristics at operating frequency range and the results are compared with the experiment data. From these measurement results, We confirm that the proposed Y-junction stripline circulator using center conductor with filter circuit is effective in achieving very high attenuations below of -30 dB at 3rd order harmonics.

In this paper, we propose a fragile watermarking hybrid approach using rough set kmeans and exponential particle swarm optimization (EPSO) systems. It is based on a block-wise dependency mechanism which can detect any alterations made to the protected image. Initially, the input image is divided into blocks with equal size in order to improve image tamper localization precision. Then feature sequence is generated by applying rough k-means and EPSO clustering to create the relationship between all image blocks and cluster all of them since EPSO is used to optimize the parameters of rough k-means. Both feature sequence and generated secret key are used to construct the authentication data. Each resultant 8-bit authentication data is embedded into the eight least significant bits (LSBs) of the corresponding image block. We gives experimental results which show the feasibility of using these optimization algorithms for the fragile watermarking and demonstrate the accuracy of the proposed approach. The performance comparison of the approach was also realized. The performance of a fragile watermarking approach has been improved in this paper by using exponential particle swarm optimization (EPSO) to optimize the rough kmean parameters. The proposed approach can embed watermark without causing noticeable visual artifacts, and does not only achieve superior tamper detection in images accurately, it also recovers tampered regions effectively. In addition, the results show that the proposed approach can effectively thwart different attacks, such as the cut-and paste attack and collage attack, while sustaining superior tamper detection and localization accuracy.

In this paper, the functional architecture for short messaging, payment, and account management RESTful web services was designed that enables IT developers to create applications using telecommunications network elements. Especially, to support a business model that enables operators to offer integrated billing, payment and account management APIs are crucial. In the modeling of short messaging, payment, and account management, we proposed resource definitions and the HTTP verbs applicable for each of these resources. And we measured the TPS of the open service gateway including RESTful web services. Also, using the above model, an example service (i.e. fare payment) consisting of a short messaging service, a payment service, and an account management service was created. Through short messaging, payment, and account management process, the feasibility of the creation of a new service using the proposed architecture and resources was confirmed.

Mobility management in heterogeneous wireless networks is always considered as a challenging task in terms of interoperability, service availability and session continuity. This research proposes a new IEEE 802.21 based multihoming architecture for vertical handover between heterogeneous wireless networks. The framework is used to optimize handover at link layer (L2) and network layer (L3). Media Independent Handover (MIH) layer is added in the protocol stack which uses its defined services for network detection and selection. It collects information from link and network layer and forwards them to upper layers which are used to take optimized L2 and L3 handover decision. In addition, Mobile IP is incorporated with multihoming for simultaneous bindings for Mobile Node (MN). This hybrid approach reduces network selection time and improves data throughput and end-to-end delay. Using MIH, available networks are detected ahead of time and binding with the target network is achieved. The proposed approach is implemented in Network Simulator (ns-2). The comparative analysis of simulation results show that the proposed approach has improved data throughput and end-to-end delay by 49.8% and 89.9% respectively.

Next generation wireless systems consist of heterogeneous wireless networks. Wireless LAN (WLAN) and cellular mobile radio systems will be important part of heterogeneous networks. Universal mobile telecommunication system (UMTS) provides wide-area coverage, high mobility but relatively low data rate. WLAN is designed for low-range, high/medium data rate access, low mobility and can be used as a complement to larger cellular mobile radio systems. In this paper, we consider a simple heterogeneous system of WLAN and UMTS cell. Vertical handover plays a vital role in ensuring quality of service in heterogeneous networks. In this paper, we proposed a vertical handover algorithm for an integrated cellular/wireless LAN system. The design goal is to provide the user the best available quality of service (QoS) at any time. Moreover, connections are handed over independently between UMTS and WLAN, aiming at seamless service continuity. Here we have taken handover rate, probability of outage and probability of handover as the performance metrics. Simulation results show that adaptive vertical handover algorithm improves the performance.