Earticle

A cross-layer design is developed which combines the Adaptive Modulation and Coding (AMC) at the physical layer and truncated Automatic Repeat Request (ARQ) at the data link layer to maximize the spectral efficiency under prescribed error performance constraints. Depending on the error correcting capability of the truncated ARQ, which depends on the maximum allowable number of retransmissions, we design AMC transmission modes, with each mode consisting of a specific modulation and FEC code pair as in IEEE 802.16 standard, that guarantee the required performance. Numerical results reveal that retransmissions at the data link layer relieve stringent error control requirements at the physical layer and thereby enable considerable spectral efficiency gain. This gain is provided by the maximum number of retransmissions per packet which equals the diversity order. The improvement on spectral efficiency decreases when the number of retransmissions increases, suggest that a small number of retransmissions offers a desirable delay-throughput tradeoff, in practice. The performance analysis is done in terms of outage probability also.

Mobility of nodes is an important issue in mobile adhoc networks (MANET). Nodes in MANET move from one network to another individually and in the form of group. In single node mobility scheme every node performs registration individually in new MANET whereas in group mobility scheme only one node in a group i.e group representative (GR) performs registration on behalf of all other nodes in the group and is assigned Care of Address (CoA). Internet protocol (IP) of all other nodes in the group remains same. Our simulated results prove that group mobility scheme reduces number of messages and consumes less time for registration of nodes as compared to single node mobility scheme. Thus network load is reduced in group mobility scheme. This research paper evaluates the performance of group mobility with single node mobility scheme. Test bed for this evaluation is based on Network Simulator 2 (NS-2) environment.

Finding nearest neighbors in large multi-dimensional data has always been one of the research interests in data mining field. In this paper, we present our continuous research on similarity search problems. Previously we have worked on exploring the meaning of K nearest neighbors from a new perspective in PanKNN [20]. It redefines the distances between data points and a given query point Q, efficiently and effectively selecting data points which are closest to Q. It can be applied in various data mining fields. A large amount of real data sets have irrelevant or obstacle information which greatly affects the effectiveness and efficiency of finding nearest neighbors for a given query data point. In this paper, we present our approach to solving the similarity search problem in the presence of obstacles. We apply the concept of obstacle points and process the similarity search problems in a different way. This approach can assist to improve the performance of existing data analysis approaches.

Wireless sensor networks (WSN) technologies are widely used in today’s world for monitoring purposes. In most applications, the sensors are not plugged in. Instead, they get power from the batteries they carry. To keep the network alive for a long time with such limited power, it is very important to conserve energy while the network is functioning. In this paper, we present an energy efficient routing algorithm for WSN. In this algorithm, we divide the sensor nodes into several scheduling sets and let them work alternatively. In this way, the sensors do not have to be active all the time which saves a lot of energy. When choosing the next sensor to forward the information to, we consider both the distance from the base station to the sensor and its current energy level. So the network power consumption will be distributed among the sensors. When the network does not have enough sensors that have sufficient energy to run, it generates new scheduling sets automatically. Simulations and comparisons demonstrate that our algorithm outperforms the previous work on energy efficient routing algorithms.

In modern generation, the applications of MANET are increasing in use. But MANET are more vulnerable to many attacks because of their adhoc nature. The security issue is the main concern in the use of MANET application.Therefor, the selection of efficient methodologies and techniques to protect MANET is an important aspect. Detecting malicious nodes in an open adhoc network in which participating nodes have no previous security associations presents a number of challenges not faced by the traditional wired networks. Traffic monitoring in wired network is usually preferred at switches, routers and gateways, but adhoc network does not have these types of network elements where the Intrusion Detection System (IDS) can collect and analyze audit data for the entire network. This paper presents an approach for determining conditions under which critical nodes should be monitored. Here, we focus on the trigger mechanism for the invocation of critical node test for MANET Intrusion Detection system.

As the feature sizes of the manufacturing processes is constantly shrinking, the possibility and demand for more functionality on a single chip goes up. This can lead to many problems,e.g. as the memory access bandwidth through the bus gets too low to cope with the demand, also the electrical performance of the bus gets degraded as the number of modules are increased. Our proposed architecture makes use of a switch fabric structure to eliminate the traditional drawbacks of bus based design. Scheduler becomes the integral part of the switch which decides the scheduling of the SOC devices. In this paper, we have proposed an area efficient scheduler which saves around 22 - 26% of the total scheduler area on the silicon die. This becomes possible because the arbiter we designed is capable of executing two different steps of Islip algorithm in two different clock cycles. In the first cycle, it acts as a grant arbiter while the next cycle makes it an accept arbiter. The design is modified using the folding concept which is used to reduce the silicon area by time multiplexing many algorithm operations into a single functional unit. Both the design of the scheduler is synthesized using 90nm SAED library using Design Compiler of SYNOPSYS with the design constraint of input delay, output delay and clock skew. The original scheduler occupies around 22206 area unit while the proposed scheduler occupies around 17285 area unit of the total silicon area considering the constraint of input delay, output delay and clock skew. The area includes both cell area (Combinational + NCombinational) and Interconnect area.

Multimedia Broadcast Multicast Service (MBMS) permits the efficient usage of radio and core networks by sharing the network resources. However, this efficient usage of resources has not been explored for the case where source and destination of the MBMS service belongs to the same Gateway General Packet Radio Service support node (GGSN) implying that one of the user equipment acts as a source of MBMS data. This paper considers a new mechanism for MBMS service for this particular scenario and compares its performance with existing scheme in Universal Mobile Telecommunication System (UMTS). The proposed scheme has been simulated and results are presented.