Mechanism In IEEE Research Articles

Analysis of Performance and Energy Consumption Routing Protocol AODV and DSDV in RAW Mechanism for IEEE 802.11ah Standard

Analysis of Performance and Energy Consumption Routing Protocol AODV and DSDV in RAW Mechanism for IEEE 802.11ah Standard

A performance study for the multicast collision prevention mechanism for IEEE 802.11

In IEEE 802.11 networks a data packet is delivered simultaneously to multiple receivers through the multicast paradigm. The standard defines a simple mechanism that does not implement any error-recovery mechanism, thus, the reliability of the service provided to the multicast users is penalized. This issue is more important as the number of collisions increases due to a large number of active stations and/or a high load network. In this paper we carry out a detailed optimization study of the multicast collision prevention (MCP) mechanism, a highly-efficient multicast collision avoidance mechanism for IEEE 802.11 previously introduced by the authors. Besides a more in deep explanation of MCP, this study includes a comparative performance evaluation of the optimized MCP with the IEEE 802.11 standard. Results shown that, through this optimization, the number of collisions in MCP can be made negligible for any network load.

Analysis of CSMA/CA Mechanism of IEEE 802.15.6 under Non-Saturation Regime

We have developed an analytical model for a non-saturated IEEE 802.15.6 wireless body area network (WBAN) operating under an error-prone channel. The most suitable vehicle for improving network performance was found to be the choice of access phase lengths based on traffic loads for different user priorities (UPs). It was also found that the deployment of exclusive access phase (EAP) is not necessary in a typical WBAN; in fact, short exclusive and random access phases (EAP and RAP, respectively) lead to inefficient use of available bandwidth. We have also found that four user priorities (out of the eight available) typically suffice to achieve even the most stringent requirements for WBAN performance.

Analytic Modeling of the Coexistence of IEEE 802.15.4 and IEEE 802.11 in Saturation Conditions

With the increasing deployment of smart wireless devices using different technologies such as IEEE 802.15.4 and IEEE 802.11 which operate in the same frequency band, it becomes urgent to deeply understand the impact of this coexistence on the performance of the involved networks. We present in this letter an analytic framework based on Markov chains that captures accurately the behavior of channel access mechanisms in IEEE 802.11 DCF and the unslotted IEEE 802.15.4 when both technologies are coexisting together. The model allows the derivation of metrics such as the probability of successful transmissions, the probability of collision, and the fraction of time that the channel is idle, or experiences successful transmissions for both 802.11 and 802.15.4 nodes. Through extensive simulations of diverse coexistence scenarios, we validate the accuracy of the proposed model, and we analyze the performance of both 802.11 networks and 802.15.4 networks in saturation conditions.

Improving Ultra-Wideband Positioning Security Using a Pseudo-Random Turnaround Delay Protocol

Ultra-wideband (UWB) technology is very suitable for indoor wireless localization and ranging. IEEE 802.15.4a is the first physical layer standard specifically developed for wireless ranging and positioning. While malicious devices are not typically present, snoopers, impostors and jammers can exist. The data link and network layers in standards such as Wi-Fi, IEEE 802.15.4 and 802.11 mainly provide authentication and encryption support, but security about ranging or location is rarely considered. Ranging can be achieved using just the preamble and start of frame delimiter (SFD), so in this case malicious devices can easily obtain position information. Therefore, the security of ranging or positioning protocols is very important, which differs from the case with data exchange protocols. To provide secure location services, a protocol is presented which is based on a pseudo-random turnaround delay. In this protocol, devices use different turnaround times so that it is difficult for a snooper to figure out the location of sensor devices in protected areas. At the same time, in the period of Hello frame transmission, together with the authentication mechanism of IEEE 802.15.4, an impostor cannot easily engages its deception attack.

Modeling the TXOP Sharing Mechanism of IEEE 802.11ac Enhanced Distributed Channel Access in Non-Saturated Conditions

IEEE 802.11ac standard, adopting a downlink multi-user multiple-input and multiple-output (DL-MU-MIMO) scheme, can significantly improve the performance of wireless local area networks (WLANs). To support the DL-MU-MIMO technology, a transmission opportunity (TXOP) sharing mechanism has been proposed to allow an access point (AP) to communicate with multiple users simultaneously. In this letter, we present an analytical model based on Markov chains for a non-saturated IEEE 802.11ac enhanced distributed channel access (EDCA) network, which supports the TXOP sharing mechanism. The analytical model computes the 802.11ac EDCA throughput, in the assumption of ideal channel conditions. Extensive simulation and analysis results show that the analytical model can accurately predict the throughput of the 802.11ac networks under non-saturated operation.

Energy efficiency analysis of aggregation mechanisms in IEEE 802.11n radio-over-fiber-based distributed antenna systems

It is known that distributed antenna systems (DAS) using radio-over-fiber (RoF) links are able to increase coverage and to improve energy efficiency compared to traditional wireless access networks. In this paper, we focus on the energy efficiency of 802.11n RoF DAS architectures and we provide a methodology based on ns-3 to evaluate and optimize energy consumption in those environments. Our results confirm that there exists an optimal number of distributed antennas for a given scenario. Furthermore, we show that aggregation mechanisms included in IEEE 802.11n enable to further improve the energy efficiency in RoF DAS. Finally, we demonstrate that media access control protocol data unit aggregation techniques outperform media access control service data unit aggregation schemes in providing higher end-to-end throughput and a better energy efficiency in IEEE 802.11n RoF DAS.

Analysis and Experimental Verification of Frequency-Based Interference Avoidance Mechanisms in IEEE 802.15.4

More and more wireless networks are deployed with overlapping coverage. Especially in the unlicensed bands, we see an increasing density of heterogeneous solutions, with very diverse technologies and application requirements. As a consequence, interference from heterogeneous sources-also called cross-technology interference-is a major problem causing an increase of packet error rate (PER) and decrease of quality of service (QoS), possibly leading to application failure. This issue is apparent, for example, when an IEEE 802.15.4 wireless sensor network coexists with an IEEE 802.11 wireless LAN, which is the focus of this work. One way to alleviate cross-technology interference is to avoid it in the frequency domain by selecting different channels. Different multichannel protocols suitable for frequency-domain interference avoidance have already been proposed in the literature. However, most of these protocols have only been investigated from the perspective of intratechnology interference. Within this work, we create an objective comparison of different candidate channel selection mechanisms based on a new multichannel protocol taxonomy using measurements in a real-life testbed. We assess different metrics for the most suitable mechanism using the same set of measurements as in the comparison study. Finally, we verify the operation of the best channel selection metric in a proof-of-concept implementation running on the testbed.

Enhanced quality of service support for triple play services in IEEE 802.11 WLANs

Wi-Fi or wireless local area networks (WLANs) are among the most popular wireless internet access technologies used. The major challenge faced by WLANs is the provision of quality of service (QoS) for real-time applications at high congestion periods. IEEE 802.11e draft presents the only comprehensive QoS infrastructure for WLANs which proposes enhanced distributed channel access (EDCA) that propounds the prioritization of medium access for different traffic classes. EDCA while making perceptible improvements for real-time applications neglects non-real-time applications by allocating their share of the bandwidth to the former in an inefficient manner. In our study, we have found that there are considerable design improvements possible for IEEE 802.11e-based QoS propositions. This paper proposes a novel medium access and transmission mechanism for IEEE 802.11 WLANs that is specifically designed to ensure QoS for triple play services. Based on our study regarding the traffic characteristics of triple play services, we propose a mechanism that adaptively uses the medium access and transmission parameters according to the traffic characteristics of the applications, for better utilization of the available bandwidth. The mechanism also proffers higher medium access priority to the access point as compared to the stations in order to cope with the issue of uplink/downlink traffic asymmetry. Simulation-based analysis of the proposed mechanism compares its performance with EDCA. The proposed mechanism offers promising results in terms of packet loss, packet delay and throughput, and thus ensures QoS for voice, video and data transfer applications.

Resource allocation mechanism in IEEE 802.15.3 parent/child model

In this paper, a novel mechanism for access control and resource allocation in a parent/child IEEE 802.15.3 network is proposed. The main objective is twofold; first the idea of using a dynamic superframe size that ensures the efficient use of the superframe is implemented; second, two approaches for resource allocation among child PicoNet Coordinators (PNCs) and DEVices (DEVs) based on the dynamic superframe idea are proposed. These approaches, referred to as "Algorithm with utilization threshold" and "Algorithm with threshold and service differentiation", are studied in comparison with a basic approach. They share the concepts of the dynamic superframe size, the prioritization of child PNCs over DEVs and the admission control strategy. They are then differentiated by applying the superframe utilization threshold concept in the "Algorithm with utilization threshold" and the addition of service differentiation in the "Algorithm with threshold and service differentiation". The superframe utilization threshold allows more devices to access the shared superframe, whereas the service differentiation guarantees the quality of service (QoS) requirements for real-time traffic requests. The proposed mechanism seeks to apply a compromise between the devices satisfaction, the QoS requirements and the requests rejection rate to induce fairness and service differentiation. Simulation results show that the proposed algorithms provide high satisfaction for both child PNCs and DEVs with greater satisfaction for the child PNCs. The superiority of using the dynamic superframe size over the fixed superframe size is also shown by the efficient use of the superframe and the minimized delay between the channel time allocations of the same device in the subsequent superframes.

Exploration on SA Query Mechanism in IEEE 802.11w

Wireless communication has become increasingly popular due to development of internetworking. In this paper, the hidden security problems of IEEE802.11i in wireless LAN are presented. To solve them, the implementation of SA Query Mechanism of wireless devices is well-designed, based on Security Association (SA) Query mechanism proposed according to the IEEE 802.11w protocol. As to the reality, the implementation mentioned above is especially significant while plenty of wireless devices are lack of SA query mechanism, which is necessary in 802.11w protocol. In the last part, certain security risks of SA query mechanism are also discussed in this essay as supplementary.

A Mac Protocol Implementation for Wireless Sensor Network

IEEE 802.15.4 is an important standard for Low Rate Wireless Personal Area Network (LRWPAN). The IEEE 802.15.4 presents a flexible MAC protocol that provides good efficiency for data transmission by adapting its parameters according to characteristics of different applications. In this research work, some restrictions of this standard are explained and an improvement of traffic efficiency by optimizing MAC layer is proposed. Implementation details for several blocks of communication system are carefully modeled. The protocol implementation is done using VHDL language. The analysis gives a full understanding of the behavior of the MAC protocol with regard to backoff delay, data loss probability, congestion probability, slot effectiveness, and traffic distribution for terminals. Two ideas are proposed and tested to improve efficiency of CSMA/CA mechanism for IEEE 802.15.4 MAC Layer. Primarily, we dynamically adjust the backoff exponent (BE) according to queue level of each node. Secondly, we vary the number of consecutive clear channel assessment (CCA) for packet transmission. We demonstrate also that slot compensation provided by the enhanced MAC protocol can greatly avoid unused slots. The results show the significant improvements expected by our approach among the IEEE 802.15.4 MAC standards. Synthesis results show also hardware performances of our proposed architecture.

An interference and latency aware uplink scheduling mechanism in IEEE 802.16j networks

IEEE 802.16j spreads out the coverage of WiMAX networks and strengthens wireless signal transmission using relay technology. To take advantage of relaying in IEEE 802.16j networks, an efficient scheduling schedule with quality of service (QoS) provision for multiple link transmissions is necessary, especially when link interference exists. In this paper, we propose an uplink scheduling mechanism in the transparent mode of IEEE 802.16j, which enables multiple devices to transmit without interference. The maximum latency of each connection has been considered in order to optimize the violation and transmission rate. An interference detection task is first carried out, and then a resource allocation algorithm and a dynamic frame adjustment method are developed. Two simulation experiments were conducted with different interference levels. The results demonstrate that under a fixed QoS type of connection, when the total number of connections goes up to 360 and 420 and the maximum latency violation rate approaches 20%, the average uplink transmission rate of the proposed mechanism can achieve 6.67 and 7.92 Mbps, which apparently outperform regular relay scheduling schemes with rate of 4 and 3.91 Mbps, respectively.

SECURITY ASSESSMENT OF IEEE 802.16 (WIMAX) – A SHORT COMPARISON BETWEEN IEEE 802.16d AND 802.16e

The importance of IEEE-Standard 802.16 (WiMAX) is growing and will compete with technologies such as UMTS. However, acceptance and adoption of technologies and services also depend on security. Therefore, this article will deal with some of the basic security features of IEEE 802.16d (Fixed WiMAX). It will summarize the most important elements of the security architecture, present some of its weaknesses, potential attacks and viable counter measurements. Furthermore, we will introduce the basic improvements made by the IEEE 802.16e standard (Mobile WiMAX) compared to Fixed WiMAX. This article extends the paper [11] presented at the IDAACS'2007 conference by describing the data encryption mechanisms in IEEE 802.16e in chapter 4.

Performance evaluation for delay time estimation in IEEE 802.16m sleep mode

Frequent use of various mobile application services consumes a great amount of battery power in mobile devices. In order to satisfy user convenience and keep the portability of mobile devices, a power saving mechanism is essential for the success of mobile communication technologies. This paper evaluates performances of the power saving mechanism of IEEE 802.16m, one of the solutions for the fourth generation mobile communication technology. When a mobile device does not communicate with a base station, it temporarily shuts down communication-related modules and circuits in order to save the battery power. During that period, the device cannot listen to incoming traffic from the base station, which causes an inevitable delay at the expense of reducing power consumption. Arriving packets are transmitted only after the device enters either the awake mode or the listening window in the sleep mode. Four power saving mechanisms are examined in the simulation:1) fixed maximum operating parameters, 2) fixed minimum operating parameters, 3) moving average policy, and 4) exponential increase policy. To evaluate the performance of the sleep mode operation in IEEE 802.16m, an analytical model is developed for delay time based on M/D/1 queueing system. Performances of the power saving mechanisms are evaluated with Poisson and traffic models for five applications: WEB, FTP, GAME, VIDEO, and VOICE, which reflects real service environment.

Increasing Performance in IEEE 802.11 for High Traffic by MIDD Backoff Algorithm

The main mechanism in IEEE 802.11 to access the medium is distributed coordination function (DCF) as a random access scheme based on carrier sense multiple access with collision avoidance. DCF describes two access techniques for packet transmission, namely basic access mechanism and request to send/clear to send mechanism. A new backoff algorithm has been proposed here for high load traffic in IEEE 802.11. The proposed algorithm is called maximum increment double decrement (MIDD) which gradually reduces the size of windows in a successful transmission and maximizes it in an unsuccessful one. Meanwhile, a mathematical analysis has been developed for MIDD algorithm based on studying Markov chain and performance analysis of the suggested algorithm. Results from this analytical model of MIDD algorithm are compared with those of IEEE 802.11 and double increase, double decrease algorithm, while the results of the throughput analysis have been examined on these three algorithms. The obtained results demonstrate that a great increase of windows size in the unsuccessful transmission as well as a small decrease of windows size in the successful transmission are beneficial for the high traffic conditions. However, a small increase of the windows size in the unsuccessful transmission and a large decrease of it in the successful transmission are ideal for the low traffic case.

Performance Evaluation of an Enhanced Ethernet Energy Saving Mechanism in IEEE 802.3az

In order to reduce the energy consumption and improve the response performance, by introducing the strategies of sleep-delay, pre-awake and split timing to IEEE 802.3az, an enhanced Ethernet energy saving mechanism is proposed. Considering the digital nature of modern communications, a discretetime queueing model with multiple-vacation and N -strategy is built. With the method of an embedded Markov chain, we evaluate the energy saving efficiency of the system and the response performance of the data frames mathematically. Numerical experiments and simulation results show that, in the enhanced Ethernet energy saving mechanism, the average packet latency is reduced, while the energy saving ratio is satisfactory.

Investigations on enhanced power saving mechanism for IEEE 802.16m network with heterogeneous traffic

In this paper, power management mechanisms for IEEE 802.16m network using power saving class (PSC) are suggested for heterogeneous traffic. The proposed algorithms, namely, combined cyclic binary exponent (CCBE), combined anti-cyclic binary exponent (CABE) and combined truncated binary exponent (CTBE) are derived by combining the existing PSC-I and PSC-II with appropriate modifications. The mobile station (MS) with existing PSC-I, PSC-II and combined PSC (CPSC) suffers from high response delay and/or more energy consumption if the packet interarrival time of heterogeneous traffic increases. The main reason behind reduced performance is due to the fixed position and duration of the listen interval in these PSC. To optimize the listen interval, the sleep interval of PSC-I is customized to realize the three proposed algorithms. In addition, the modified sleep interval of PSC-I is combined with fixed sleep interval of PSC-II. Finally, the resultant combined PSC is formulated by applying a scaling rule that minimizes and positions the duration of listening interval by referring the current listen interval of PSC-II. The performance of three PSC is studied by varying the interarrival time, minimum and maximum sleep intervals at the MS. It is observed with CCBE algorithm, the number of listen intervals, response delay and power consumption is reduced by 8.02%, 22.71% and 15.60%, than CABE, respectively. Similarly, CCBE shows an improvement of 28.62%, 25.24% and 31.97% than CTBE algorithm. Also, the performance of CCBE is improved by 57.82%, 89.67% and 64.16% than conventional CPSC algorithm.

Performance and fairness enhancement in IEEE 802.11 WLAN networks

The multi-rate transmission mechanism in IEEE 802.11 can improve its reliability and robustness. However, it causes a performance anomaly. After analyzing the reasons for the performance anomaly in multi-rate mechanism, we propose a new scheme to solve the performance anomaly. By adjusting packet size according to the transmission rate, this scheme guarantees that these nodes with different transmit rates can access wireless channel fairly. Theoretical analysis and performance evaluation show that the proposed scheme can well solve the performance anomaly problem.

Study on the influence of transmission errors on RSNA authentication mechanisms in IEEE 802.11 WLAN

Wireless Local Area Networks have been increasingly deployed and become very popular. They offer important advantages such as the higher flexibility and user mobility, however, this kind of networks also present some security concerns due to its broadcast nature. Security mechanisms can be classified into two groups: user authentication and data confidentiality.The IEEE 802.11i specification presents RSNA authentication mechanism, which allows user authentication employing IEEE 802.1x protocol and EAP methods. Authentication mechanisms consist in an important step of the handoff process, which occurs when a mobile node leaves the coverage area of an access point and performs association with another. Handoff results in a critical function for IEEE 802.11 MAC operation due to important delay restrictions. Thus, pre-authentication and IEEE 802.11r mechanisms have been presented to allow important latency reduction, which provide interesting results in real time communications.Besides, usually, WLAN users employ mobile devices, which provide limited capabilities in terms of energy management.In this way, in this paper, we evaluate authentication latency and battery consumption by means of an analytical model that we have developed for this purpose. The analysis also includes the influence of transmission errors, which allows the evaluation of authentication mechanisms in error-prone scenarios.