Performance Analyses and Improvements for the IEEE 802.15.4 CSMA/CA Scheme with Heterogeneous Buffered Conditions

Studies of the IEEE 802.15.4 Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) scheme have been received considerable attention recently, with most of these studies focusing on homogeneous or saturated traffic. Two novel transmission schemes—OSTS/BSTS (One Service a Time Scheme/Bulk Service a Time Scheme)—are proposed in this paper to improve the behaviors of time-critical buffered networks with heterogeneous unsaturated traffic. First, we propose a model which contains two modified semi-Markov chains and a macro-Markov chain combined with the theory of M/G/1/K queues to evaluate the characteristics of these two improved CSMA/CA schemes, in which traffic arrivals and accessing packets are bestowed with non-preemptive priority over each other, instead of prioritization. Then, throughput, packet delay and energy consumption of unsaturated, unacknowledged IEEE 802.15.4 beacon-enabled networks are predicted based on the overall point of view which takes the dependent interactions of different types of nodes into account. Moreover, performance comparisons of these two schemes with other non-priority schemes are also proposed. Analysis and simulation results show that delay and fairness of our schemes are superior to those of other schemes, while throughput and energy efficiency are superior to others in more heterogeneous situations. Comprehensive simulations demonstrate that the analysis results of these models match well with the simulation results

An analysis of IEEE 802.11 DCF and its application to energy-efficient relaying in multihop wireless networks

Cataloged from PDF version of article.We present an analytical model for the IEEE 802.11 DCF in multihop wireless networks that considers hidden terminals and accurately works for a large range of traffic loads. An energy model, which considers energy consumption due to collisions, retransmissions, exponential backoff and freezing mechanisms, and overhearing of nodes, and the proposed IEEE 802.11 DCF analytical model are used to analyze the energy consumption of various relaying strategies. The results show that the energy-efficient relaying strategy depends significantly on the traffic load. Under light traffic, energy spent during idle mode dominates, making any relaying strategy nearly optimal. Under moderate traffic, energy spent during idle and receive modes dominates and multihop transmissions become more advantageous where the optimal hop number varies with processing power consumed at relay nodes. Under very heavy traffic, where multihopping becomes unstable due to increased collisions, direct transmission becomes more energy efficient. The choice of relaying strategy is observed to affect energy efficiency more for large and homogeneous networks where it is beneficial to use multiple short hops each covering similar distances. The results indicate that a cross-layered relaying approach, which dynamically changes the relaying strategy, can substantially save energy as the network traffic load changes in time. © 2011 IEEE

Performance Analysis of Synchronous Duty-Cycled MAC Protocols

© 2015 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.In this letter, we propose an analytical model to evaluate the performance of the S-MAC protocol. The proposed model improves the accuracy of previous models in two aspects. First, it incorporates the dependence among the nodes within a cluster by defining a DTMC that models the number of active nodes, whereas the previous models considered that nodes were mutually independent. Second, it proposes new methods for calculating packet delay and energy consumption. The analytical model is validated through discrete-event based simulations. Numerical results demonstrate that the proposed analytical model and methods yield accurate results under realistic assumptionsThis work was supported in part by the Spanish Government through project TIN2013-47272-C2-1-R. The associate editor coordinating the review of this paper and approving it for publication was J.-C. Chen.Martínez Bauset, J.; Guntupalli, L.; Li, F. (2015). Performance Analysis of Synchronous Duty-Cycled MAC Protocols. IEEE Wireless Communications Letters. 4(5):469-472. https://doi.org/10.1109/LWC.2015.2439267S4694724

Enabling Green Wireless Sensor Networks: Energy Efficient T-MAC Using Markov Chain Based Optimization

Due to the rapidly growing sensor-enabled connected world around us, with the continuously decreasing size of sensors from smaller to tiny, energy efficiency in wireless sensor networks has drawn ample consideration in both academia as well as in industries’ R&D. The literature of energy efficiency in wireless sensor networks (WSNs) is focused on the three layers of wireless communication, namely the physical, Medium Access Control (MAC) and network layers. Physical layer-centric energy efficiency techniques have limited capabilities due to hardware designs and size considerations. Network layer-centric energy efficiency approaches have been constrained, in view of network dynamics and available network infrastructures. However, energy efficiency at the MAC layer requires a traffic cooperative transmission control. In this context, this paper presents a one-dimensional discrete-time Markov chain analytical model of the Timeout Medium Access Control (T-MAC) protocol. Specifically, an analytical model is derived for T-MAC focusing on an analysis of service delay, throughput, energy consumption and power efficiency under unsaturated traffic conditions. The service delay model calculates the average service delay using the adaptive sleep wakeup schedules. The component models include a queuing theory-based throughput analysis model, a cycle probability-based analytical model for computing the probabilities of a successful transmission, collision, and the idle state of a sensor, as well as an energy consumption model for the sensor’s life cycle. A fair performance assessment of the proposed T-MAC analytical model attests to the energy efficiency of the model when compared to that of state-of-the-art techniques, in terms of better power saving, a higher throughput and a lower energy consumption under various traffic loads

PERFORMANCE ANALYSIS OF CHANNEL ACCESS MODEL FOR MAC IN RANDOMLY DISTRIBUTED WIRELESS SENSOR NETWORKS

ABSTRACT Medium Access control (MAC) is one of the fundamental problems i

Throughput Maximization in Unmanned Aerial Vehicle Networks

The use of Unmanned Aerial Vehicles (UAVs) swarms in civilian applications such as surveillance, agriculture, search and rescue, and border patrol is becoming popular. UAVs have also found use as mobile or portable base stations. In these applications, communication requirements for UAVs are generally stricter as compared to conventional aircrafts. Hence, there needs to be an efficient Medium Access Control (MAC) protocol that ensures UAVs experience low channel access delays and high throughput. Some challenges when designing UAVs MAC protocols include interference and rapidly changing channel states, which require a UAV to adapt its data rate to ensure data transmission success. Other challenges include Quality of Service (QoS) requirements and multiple contending UAVs that result in collisions and channel access delays. To this end, this thesis aims to utilize Multi-Packet Reception (MPR) technology. In particular, it considers nodes that are equipped with a Successive Interference Cancellation (SIC) radio, and thereby, allowing them to receive multiple transmissions simultaneously. A key problem is to identify a suitable a Time Division Multiple Access (TDMA) transmission schedule that allows UAVs to transmit successfully and frequently. Moreover, in order for SIC to operate, there must be a sufficient difference in received power. However, in practice, due to the location and orientation of nodes, the received power of simultaneously transmitting nodes may cause SIC decoding to fail at a receiver. Consequently, a key problem concerns the placement and orientation of UAVs to ensure there is diversity in received signal strength at a receiving node. Lastly, interference between UAVs serving as base station is a critical issue. In particular, their respective location may have excessive interference or cause interference to other UAVs; all of which have an impact on the schedule used by these UAVs to serve their respective users

A Game Theory based Contention Window Adjustment for IEEE 802.11 under Heavy Load

The 802.11 families are considered as the most applicable set of standards for Wireless Local Area Networks (WLANs) where nodes make access to the wireless media using random access techniques. In such networks, each node adjusts its contention window to the minimum size irrespective of the number of competing nodes, so in saturated mode and excessive number of nodes available, the network performance is reduced due to severe collision probability. A cooperative game is being proposed to adjust the users’ contention windows in improving the network throughput, delay and packet drop ratio under heavy traffic load circumstances. The system’s performance evaluated by simulations indicate some superiorities of the proposed method over 802.11-DCF (Distribute Coordinate Function)

Aggregated Packet Transmission in Duty-Cycled WSNs: Modeling and Performance Evaluation

[EN] Duty cycling (DC) is a popular technique for energy conservation in wireless sensor networks (WSNs) that allows nodes to wake up and sleep periodically. Typically, a single-packet transmission (SPT) occurs per cycle, leading to possibly long delay. With aggregated packet transmission (APT), nodes transmit a batch of packets in a single cycle. The potential benefits brought by an APT scheme include shorter delay, higher throughput, and higher energy efficiency. In the literature, different analytical models have been proposed to evaluate the performance of SPT schemes. However, no analytical models for the APT mode on synchronous DC medium access control (MAC) mechanisms exist. In this paper, we first develop a 3-D discrete-time Markov chain (DTMC) model to evaluate the performance of an APT scheme with packet retransmission enabled. The proposed model captures the dynamics of the state of the queue of nodes and the retransmission status and the evolution of the number of active nodes in the network, i.e., nodes with a nonempty queue. We then study the number of retransmissions needed to transmit a packet successfully. Based on the observations, we develop another less-complex DTMC model with infinite retransmissions, which embodies only two dimensions. Furthermore, we extend the 3-D model into a 4-D model by considering error-prone channel conditions. The proposed models are adopted to determine packet delay, throughput, packet loss, energy consumption, and energy efficiency. Furthermore, the analytical models are validated through discrete-event-based simulations. Numerical results show that an APT scheme achieves substantially better performance than its SPT counterpart in terms of delay, throughput, packet loss, and energy efficiency and that the developed analytical models reveal precisely the behavior of the APT scheme.This work was supported in part by the EU FP7-PEOPLE-IRSES Program under Grant 247083 (Project S2EuNet). The work of J. Martinez-Bauset was supported in part by the Ministry of Economy and Competitiveness of Spain under Grant TIN2013-47272-C2-1-R. The work of M. A. Weitnauer was supported in part by the U.S. National Science Foundation under Grant CNS-1017984.Guntupalli, L.; Martínez Bauset, J.; Li, FY.; Weitnauer, MA. (2017). Aggregated Packet Transmission in Duty-Cycled WSNs: Modeling and Performance Evaluation. IEEE Transactions on Vehicular Technology. 66(1):563-579. https://doi.org/10.1109/TVT.2016.2536686S56357966

An analytical model of IEEE 80211 DCF for multi-hop wireless networks and its application to goodput and energy analysis

Ankara : The Department of Electrical and Electronics Engineering and the Institute of Engineering and Sciences of Bilkent University, 2010.Thesis (Ph. D.) -- Bilkent University, 2010.Includes bibliographical references leaves 168-181.In this thesis, we present an analytical model for the IEEE 802.11 DCF in multihop networks that considers hidden terminals and works for a large range of traffic loads. A goodput model which considers rate reduction due to collisions, retransmissions and hidden terminals, and an energy model, which considers energy consumption due to collisions, retransmissions, exponential backoff and freezing mechanisms, and overhearing of nodes, are proposed and used to analyze the goodput and energy performance of various routing strategies in IEEE 802.11 DCF based multi-hop wireless networks. Moreover, an adaptive routing algorithm which determines the optimum routing strategy adaptively according to the network and traffic conditions is suggested. Viewed from goodput aspect the results are as follows: Under light traf- fic, arrival rate of packets is dominant, making any routing strategy equivalently optimum. Under moderate traffic, concurrent transmissions dominate and multihop transmissions become more advantageous. At heavy traffic, multi-hoppingbecomes unstable due to increased packet collisions and excessive traffic congestion, and direct transmission increases goodput. From a throughput aspect, it is shown that throughput is topology dependent rather than traffic load dependent, and multi-hopping is optimum for large networks whereas direct transmissions may increase the throughput for small networks. Viewed from energy aspect similar results are obtained: Under light traf- fic, energy spent during idle mode dominates in the energy model, making any routing strategy nearly optimum. Under moderate traffic, energy spent during idle and receive modes dominates and multi-hop transmissions become more advantageous as the optimum hop number varies with processing power consumed at intermediate nodes. At the very heavy traffic conditions, multi-hopping becomes unstable due to increased collisions and direct transmission becomes more energy-efficient.The choice of hop-count in routing strategy is observed to affect energyefficiency and goodput more for large and homogeneous networks where it is possible to use shorter hops each covering similar distances. The results indicate that a cross-layer routing approach, which takes energy expenditure due to MAC contentions into account and dynamically changes the routing strategy according to the network traffic load, can increase goodput by at least 18% and save energy by at least 21% in a realistic wireless network where the network traffic load changes in time. The goodput gain increases up to 222% and energy saving up to 68% for denser networks where multi-hopping with much shorter hops becomes possible.Aydoğdu, CananPh.D