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Poongodi, C.
- Detection and Defense Scheme against Selfish Nodes in MAC-Layer
Authors
1 Department of Information Technology, Kongu Engineering College, Perundurai - 638052, IN
Source
Wireless Communication, Vol 8, No 1 (2016), Pagination: 29-34Abstract
IEEE 802.11 is a set of media access control (MAC) and physical layer (PHY) specifications for implementing ad hoc networks. In ad hoc networks, selfish nodes deviating from the standard MAC (Medium Access Control) protocol degrades normal nodes performance and are difficult to detect. Specifically, the non-deterministic nature of the IEEE 802.11 MAC protocol imposes great challenges to distinguish selfish nodes from well-behaved nodes. The traditional selfish misbehavior detection approaches either rely on a large amount of historical data to perform detection, or employ throughput or delay models that are only valid in WLANs for detection. Since they are based on large amount of data, the detection may take very long time. The proposed real time detection scheme for multi hop ad hoc networks requires only few samples and can adapt to channel dynamics more quickly. The selfish nodes are detected based on certain parameters such as slot time, SIFS, DIFS. If a node is determined as selfish node, the penalty scheme is applied to punish the selfish node by decreasing its throughput and specifically, all its one hop neighbours stop forwarding the packets for it until they receive another decision notice indicating that this node is not selfish any more. Based on the detection there are 3 defense scheme namely, i) naive selfish node ii) random selfish node iii) γ-persistent selfish nodes. The defense schemes are designed to prevent the selfish nodes from degrading normal nodes performance.
Keywords
Selfish Misbehavior, IEEE 802.11 MAC, Detection, Defense.
- Performance Analysis of IEEE802.16 OFDM Physical Layer under Different SUI Channels
Authors
1 Bannari Amman Institute of Technology, Sathyamangalam-638401, IN
2 Department of ECE, Bannari Amman Institute of Technology, Sathyamangalam-638401, IN
3 Bannari Amman Institute of Technology, Sathyamangalam - 638401, IN
Source
Wireless Communication, Vol 3, No 4 (2011), Pagination: 265-269Abstract
Wimax which represents world wide interoperability for microwave access is a major part of broad band wireless network having IEEE802.16 standard providing fixed and mobile platform for broadband internet access. The Wimax forum has adopted IEEE 802.16 OFDM PHY layer for the equipment manufacturer due to its robust performance in multipath environment. In this paper we investigate the simulation performance of IEEE 802.16 OFDM PHY layer. The Stanford University Interim (SUI) channel models are selected for the wireless channel in the simulation and we also investigate the estimation of channel at high frequencies with conventional Least Square (LS) and Minimum Mean Square (MMSE) estimation algorithms. Channel state information for OFDM systems based on pilot carrier is carried out through Matlab simulation. The performance of MIMO OFDM is evaluated on the basis of Bit Error Rate (BER) and Mean Square Error (MSE) level.
Keywords
Wimax, OFDM, Channel Model.- Cluster Head Bundle Delivery Protocol for Delay Tolerant Networks
Authors
1 Department of Information Technology, Kongu Engineering College, Perundurai, IN
2 Department of Electronics and Communication Engineering, Bannari Amman Institute of Technology, IN
3 Computer Science Engineering Department, Kongu Engineering College, IN