Adaptive Concurrent Medium Access Control for Wireless Mesh Network

This paper proposes an adaptive concurrent transmission protocol implemented in Wireless Mesh Network (WMN), which reduces the overhead due to signalling of the existing concurrent transmission protocols such as Medium Access Control (MAC) protocol with Acknowledgment and Parallel mechanism (MACA-P), Concurrent MAC with Short Signalling (CMAC-SS) and Distribution Coordination Function (DCF). DFC protocol is widely used and implemented in the existing IEEE 802.11b/g/n standard wireless networks. The use of DCF in WMN reduces the throughput per hop significantly due to exposed node avoidance mechanism such as Ready-to-Send and Clear-to-Send (RTS-CTS) signalling which allows only one transaction per node at one time; meaning that the waiting delay is higher in Wireless Mesh Network (WMN). MACA-P and CMAC-SS protocols introduce concurrent transmission mechanism that allows multiple transactions per hop at one time. The results from the simulation show that the performance of CMAC-SS is better than the MACA-P. However the design of both MACA-P and CMAC-SS considers fixed size of signalling which makes the protocol not scalable when the number of user within the network increases. In order to provide scalability, an adaptive size of signalling is introduced in this paper by manipulating the broadcast nature of the wireless network within the slotted framework. Such adaptive mechanism improves scalability and also the throughput per hop by 45% compared to CMAC-SS when the number of nodes is higher than 10

Adaptive Concurrent Transmission Protocol for Wireless Mesh Network

This paper proposes an adaptive concurrent transmission protocol implemented in Wireless Mesh Network (WMN), which reduces the overhead due to signaling of the existing concurrent transmission protocols such as Medium Access Control (MAC) protocol with Acknowledgment and Parallel mechanism (MACA-P), Concurrent MAC with Short Signaling (CMAC-SS) and Distribution Coordination Function (DCF). DFC protocol is widely used and implemented in the existing IEEE 802.11b/g/n standard wireless networks. The use of DCF in WMN reduces the throughput per hop significantly due to exposed node avoidance mechanism such as Ready-to-Send and Clear-to-Send (RTS-CTS) signaling which allows only one transaction per node at one time; meaning that the waiting delay is higher in Wireless Mesh Network (WMN). MACA-P and CMAC-SS protocols introduce concurrent transmission mechanism that allows multiple transactions per hop at one time. The results from the simulation show that the performance of CMAC-SS is better than the MACA-P. However the design of both MACA-P and CMAC-SS considers fixed size of signaling which makes the protocol not scalable when the number of user within the network increases. In order to provide scalability, an adaptive size of signaling is introduced in this paper by manipulating the broadcast nature of the wireless network within the slotted framework. Such adaptive mechanism improves scalability and also the throughput per hop by 45% compared to CMAC-SS when the number of nodes is higher than 10

A REVIEW OF MULTIHOP BASED MEDIUM ACCESS CONTROL (MAC) PROTOCOL TO TACKLE BOTH MULTIPLE ACCESS AND MULTIHOP ISSUES IN WIRELESS MESH NETWORK (WMN)

Multihop WMN plays an important role in the next-generation wireless communication. It promised a solution to provide ubiquitous wireless access at low cost and with architecture that easy to be deployed and maintained. A big challenge in designing WMN is to utilize the shared medium, the wireless communication channel, effectively. MAC protocol, the shared medium access controller, therefore plays a critical role in the channel utilization. The better the channel is utilized in WMN, the better is the performance of the WMN. One of the techniques to improve channel utilization is by enabling the concurrent transmission and providing an efficient forwarding operation. However, the existing IEEE 802.11 MAC does not supports those operations in WMN thus degrades the throughput significantly. To date, various multihop based MAC protocols was developed and proposed by researchers with the aim to regulate and solve access issues among all radio nodes in the network. This article presents an exhaustive survey of multihop based contention MAC protocols that proposed to solve exposed node and forwarding issues in multihop WMN. Besides that, the comparison, their operations, advantages and disadvantages of all identified MAC protocols also will be explained and presented in this article

A Smooth Forwarding Operation in Wireless Mesh Network

The IEEE 802.11 Distributed Coordination Function (DCF) Medium Access Control (MAC) protocol is designed to efficiently facilitate the limited communication bandwidth of wireless channel. This protocol uses Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) mechanism. This mechanism continues suffer from throughput degradation when directly applied in multihop Wireless Mesh Network (WMN). The major reason for this poor performance is due to larger signaling overheads (RTS and CTS signaling packet) introduced in order to forward a single data packet in multihop WMN. This inefficient forwarding operation caused the throughput degradation signifficantly. Therefore, an efficient forwarding operation is proposed in this paper to reduce the amount of signaling overheads which are needed to forward a single packet in multihop WMN. The proposed protocol uses the capability of overhearing in order to forward the data packet from one hop to another hop. This process will continue until the data packet reaches the respective destination. As a result, the enhanced protocol reduces the latency caused by signaling thus improve its throughput in multihop WMN. The multihop network performances are evaluated analytically in terms of throughput and delay. Through the simulation, it is proven that the proposed protocol provides significant improvement in throughput and delay. The results show that the proposed protocol outperforms the existing IEEE DCF MAC protocol when it is evaluated in multihop WMN

A SURVEY OF CONTENTION BASED MEDIUM ACCESS CONTROL (MAC) PROTOCOLS IN WIRELESS LAN

In wireless network, all radio nodes are tuned to the same frequency to interconnect and establish communication between each other. All nodes in the network broadcasts their packets over a common medium and in such scenario collisions are considered as instinctive attribute. Therefore, a proper method/regulation known as Medium Access Control (MAC) protocol is required to regulate and manage an efficient access to the common channel. The protocol is designed to allow radio nodes in wireless network to broadcast their packets in an orderly and efficient manner to eliminate the collision among them. It also provides a fair bandwidth sharing to all contending nodes in the network. To date, various MAC protocols was developed to regulate the communication access among all radio nodes in wireless network. This article presents an exhaustive survey of existing contention based MAC protocols, their operations, advantages and disadvantages. Other than that, a typical MAC protocol used in IEEE 802.11 wireless networks standard, such as Carrier Sense Multiple Access (CSMA) and Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) also explained and presented in this article

An Enhancement of RTS/CTS Control Handshake in CSMA/CA Based MAC Protocol for an Efficient Packet Delivery over Multihop Wireless Mesh Network (WMN)

The Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) based Medium Access Control (MAC) protocol uses a short request-to-send (RTS) and clear-to-send (CTS) control packets prior of actual data packet transmission. The function of the CSMA/CA based MAC protocol in wireless communication is to facilitate wireless nodes (i.e. laptop, PC, smart phones and etc) to access a wireless medium efficiently. Besides, it is also efficiently manage the wireless medium when more wireless nodes involving in transmission activity in the network. This protocol allows all wireless nodes in the network to communicate between each other without collision. Since collisions may only occurred on the RTS control packets thus it can reduce the actual data collision on the medium. The RTS/CTS control handshake provides better performance and reduce the duration of collision especially when long data packets are transmitted over wireless medium. However, even though the CSMA/CA based MAC protocol working effectively and provides better throughput performance over single hop communication but it performance degrade significantly when directly applied in multihop Wireless Mesh Network (WMN). The reason behind this poor performance is due to the inefficient packet delivery of CSMA/CA based MAC protocol in multihop network. The exchange of RTS and CTS signaling that required at each hop throughout the multihop network eventually will cause the large overheads and subsequently degrade network throughput. Therefore, in this paper, an enhancement of RTS/CTS handshake has been proposed in order reduces the signaling overheads and ultimately allows a smooth packet delivery in the multihop network without any collision. In this work, the multihop network performances are evaluated analytically in terms of throughput and overhead. It is proven that the new method of RTS/CTS handshake provides significant improvement in throughput and overhead

COMPARATIVE STUDY ON SINGLE- AND DOUBLE-PASS CONFIGURATIONS FOR SERIAL DUAL-STAGE HIGH CONCENTRATION EDFA

A comparative study on a single- and double-pass configurations for Erbium-doped fiber amplifier (EDFA) are demonstrated using a gain media of high concentration Silica-based erbium doped fiber (EDF). The amplifier has two stages comprising a 1.5 m and 9 m long EDF optimized for C-band and L-band operations respectively, in a single-pass and double-pass configuration s. The CFBG is used at the end of EDF stage to allow a double propagation of signal and thus increases the attainable gain in both C- and L-band spectra. At an input signal power of -30 dBm, a flat gain of 22 dB is achieved with a gain variation of ±3 dB within a wide wavelength range from 1530 to 1600nm (C- and L-band) in double-pass configurations. The corresponding noise figure varies from 4 to 8 dB within this wavelength region. The flat gains for single-pass configuration only amplify within 1555 nm to 1600 nm (L-band)

Alleviate exposed node issues in Wireless Mesh Network (WMN) using a novel approach of Concurrent Medium Access Control (C-MAC) protocol

The importance and high growth of the communication infrastructure is clearly stated under the Malaysia Economic Transformation Programme (ETP). The most popular technology that used to provide the internet service to public is the IEEE 802.11a/b/g/n based WiFi. However, the coverage provided by the WiFi technology is only limited up to certain range. In addition, the performance of the WiFi network also will become poorer and poorer as the number of users associate with that WiFi network increases. In order to address these issues, the best topology configuration known as mesh is proposed by wireless research community. This technology is also called as Wireless Mesh Networks (WMN) and it became an emerging technology which is plays an important role in the next generation wireless communication. However, the implementation of IEEE 802.11 Medium Access Control (MAC) protocol in WMN significantly degrades the network performance due to the presence of exposed node problem. The presence of exposed nodes in WMN caused waiting delay (prevent the surrounding neighboring nodes to involve in transmission activity for entire duration of ongoing transmission) and it is subsequently leads to poor throughput achievement. The significance of this research is to investigate the cause of exposed nodes that degrade the performance of WMN and proposed a novel protocol to solve it to provide better network performance and throughput

ZIGBEE-BASED SMART FALL DETECTION AND NOTIFICATION SYSTEM WITH WEARABLE SENSOR (e-SAFE)

Fall is one of the serious health issues among elderly population in Malaysia. In the event of a fall, a strong impact may be inflicted on the elderly causing severe injuries or even death. Another research by the National Institutes of Health found that 67% of elderly who fall and fail to seek help within 72 hours are unlikely to survive. Current Personal Emergency Respond System (PERS) often employs the use of a manual emergency button. However this approach may not be useful if the fall victim become unconscious or even not be able to move to reach the emergency button. In addition, such as this approach also requires more time and inadequate to notify and seek for immediate help. This paper attempts to design and implement a smart fall detection system for real time notification known as e-SAFE. This system will automatically detect a fall and notifies the incident instantly to internal and external correspondence. The e-SAFE equipped with a wearable accelerometer sensor, microcontroller, ZigBee transceiver module and Global System for Mobile communications (GSM) device. The in-house correspondence will be notifies though the ZigBee technology, meanwhile the external correspondence will be notified through GSM. Once a fall has been detected by e-SAFE system, a Short Message Service (SMS) and an E-mail will be sent to predefined contacts which is stored in the system. This system will provide a path toward independent living for the elderly while keeping them save

A review on various types of Software Defined Radios (SDRs) in radio communication

Software Defined Radio (SDR) promises to deliver a cost effective and flexible solution by implementing a wide variety of wireless protocols in software. The SDR became more popular in recent years because of its abilities to realize many applications without a lot of efforts in the integration of different component. This software based radio device allows engineers to add more features to the communication system and implement any number of different signal processing elements or protocols without changing the original system hardware and its architecture. It provides a customizable and portable communications platform for many applications, including the prototyping and realization of wireless protocols and their performances. It is also able to interface with a separate hardware module to communicate over a real channel. In this article we described and compared the various SDRs that currently has been using by the researchers to study the performance of wireless protocol. Among the SDRs that we focused in this article are USRP, SORA, Air blue, SODA, and WARP