A Novel Approach for Implementing Worldwide Interoperability for Microwave Access for Video Surveillance

Video surveillance applications have experienced an increase in demand over the last decade. Surveillance systems can easily be found in places such as commercial offices, banks and traffic intersections, parks and recreational areas. Surveillance applications have the potential to be implemented on a WiMAX (Worldwide Interoperability for Microwave Access) network. Moreover, WiMAX devices have been used widely in the market and WiMAX-based video surveillance products have also been available. As a radio technology, WiMAX is a wireless broadband system that offers greater capacity than WiFi networks and wider coverage than cellular networks. The acceptance of WiMAX in the market, the availability of WiMAX products and its technology excellence, contribute to the possibility of implementing it for surveillance application. However, since WiMAX is designed to accommodate various applications with different quality of service (QoS) requirements, dedicated surveillance network implementation of WiMAX may not achieve optimum performance, as all Subscriber Stations (SSs) generate the same QoS requirements. In the medium access (MAC) layer, this thesis proposes a bandwidth allocation scheme that considers the QoS uniformity of the traffic sources. The proposed bandwidth allocation scheme comprises a simplified bandwidth allocation architecture, a packet-aware bandwidth request mechanism and packet-aware scheduling algorithms. The simplified architecture maximizes resources in the Base Station (BS), deactivates unnecessary services and minimizes the processing delay. The proposed bandwidth request mechanism reduces bandwidth grant and transmission delays. The proposed scheduling algorithms prioritize bandwidth granting access to a request that contains important packet(s). The proposed methods in the MAC layer are designed to be applied to existing devices in the market, without the necessity to change hardware. The transport protocol should be able to deliver video with sufficient quality while maintaining low delay connectivity. The proposed transport layer protocol is therefore designed to improve the existing user datagram protocol (UDP) performance by retransmitting packet loss selectively to increase the received video quality, and utilizing MAC support to achieve low delay connectivity. In order to overcome the limitations of the lower layers, this thesis employs a rateless code instead of transport layer redundancy in the application layer. Moreover, this thesis proposes post-decoding error concealment techniques as the last means to overcome packet loss. To evaluate the performances of the proposed methods, simulations are carried out using NS-2 simulator on Linux platform. The proposed methods are compared to existing works to measure their effectiveness. To facilitate the implementation of the transport layer protocols in practical scenarios, UDP packet modification is applied for each transport layer protocol.Indonesian Directorate General of Higher Education (DGHE/DIKTI

Hybrid probabilistic broadcast schemes for mobile ad hoc networks

Broadcasting is one of the fundamental data dissemination mechanisms in mobile ad hoc network (MANET), which is, for instance, extensively used in many routing protocols for route discovery process. The dynamic topology and limited communication bandwidth of such networks pose a number of challenges in designing an efficient broadcasting scheme for MANETs. The simplest approach is flooding, where each node retransmit every unique received packet exactly once on each outgoing link. Although flooding ensures that broadcast packet is received by all network nodes, it generates many redundant transmissions which can trigger high transmission collision and contention in the network, a phenomenon referred to as the broadcast storm. Several probabilistic broadcast algorithms have been proposed that incur low communication overhead to mitigate the broadcast storm problem and tend to show superior adaptability in changing environments when compared to deterministic (i.e., non-probabilistic) schemes. However, most of these schemes reduce redundant broadcasts at the expense of reachability, a requirement for near-global network topological information or support from additional hardware. This research argues that broadcast schemes that combine the important features of fixed probabilistic and counter-based schemes can reduce the broadcast storm problem without sacrificing reachability while still achieving better end-to-end delay. To this end, the first part of this research investigate the effects of forwarding probabilities and counter threshold values on the performance of fixed probabilistic and counter-based schemes. The findings of this investigation are exploited to suggest a new hybrid approach, the Probabilistic Counter-Based Scheme (PCBS) that uses the number of duplicate packets received to estimate neighbourhood density and assign a forwarding probability value to restrict the generation of so many redundant broadcast packets. The simulation results reveal that under various network conditions PCBS reduces the number of redundant transmissions, collision rate and end-to-end delay significantly without sacrificing reachability when compared against counter-based, fixed probabilistic and flood broadcasting. Often in MANETs, there are regions of different node density due to node mobility. As such, PCBS can suffer from a degree of inflexibility in terms of rebroadcast probability, since each node is assigned the same forwarding probability regardless of its local neighbourhood conditions. To address this shortcoming, the second part of this dissertation proposes an Adjusted Probabilistic Counter-Based Scheme (APCBS) that dynamically assigns the forwarding probability to a node based on its local node density using a mathematical function. Thus, a node located in a sparse region of the network is assigned a high forwarding probability while a node located in denser region is assigned a relatively lower forwarding probability. These combined effects enhance end-to-end delay, collision rate and reachability compared to PCBS variant. The performance of most broadcasting schemes that have been suggested for MANETs including those presented here, have been analysed in the context of “pure” broadcast scenarios with relatively little investigation towards their performance impact on specific applications such as route discovery process. The final part of this thesis evaluates the performance of the well-known AODV routing protocol when augmented with APCBS route discovery. Results indicate that the resulting route discovery approach reduces the routing overhead, collision rate and end-to-end delay without degrading the overall network throughput compared to the existing approaches based on flooding, counterbased and fixed probabilistic route discovery

Opportunistic Routing with Network Coding in Powerline Communications

Opportunistic Routing (OR) can be used as an alternative to the legacy routing (LR) protocols in networks with a broadcast lossy channel and possibility of overhearing the signal. The power line medium creates such an environment. OR can better exploit the channel than LR because it allows the cooperation of all nodes that receive any data. With LR, only a chain of nodes is selected for communication. Other nodes drop the received information. We investigate OR for the one-source one-destination scenario with one traffic flow. First, we evaluate the upper bound on the achievable data rate and advocate the decentralized algorithm for its calculation. This knowledge is used in the design of Basic Routing Rules (BRR). They use the link quality metric that equals the upper bound on the achievable data rate between the given node and the destination. We call it the node priority. It considers the possibility of multi-path communication and the packet loss correlation. BRR allows achieving the optimal data rate pertaining certain theoretical assumptions. The Extended BRR (BRR-E) are free of them. The major difference between BRR and BRR-E lies in the usage of Network Coding (NC) for prognosis of the feedback. In this way, the protocol overhead can be severely reduced. We also study Automatic Repeat-reQuest (ARQ) mechanism that is applicable with OR. It differs to ARQ with LR in that each sender has several sinks and none of the sinks except destination require the full recovery of the original message. Using BRR-E, ARQ and other services like network initialization and link state control, we design the Advanced Network Coding based Opportunistic Routing protocol (ANChOR). With the analytic and simulation results we demonstrate the near optimum performance of ANChOR. For the triangular topology, the achievable data rate is just 2% away from the theoretical maximum and it is up to 90% higher than it is possible to achieve with LR. Using the G.hn standard, we also show the full protocol stack simulation results (including IP/UDP and realistic channel model). In this simulation we revealed that the gain of OR to LR can be even more increased by reducing the head-of-the-line problem in ARQ. Even considering the ANChOR overhead through additional headers and feedbacks, it outperforms the original G.hn setup in data rate up to 40% and in latency up to 60%.:1 Introduction 2 1.1 Intra-flow Network Coding 6 1.2 Random Linear Network Coding (RLNC) 7 2 Performance Limits of Routing Protocols in PowerLine Communications (PLC) 13 2.1 System model 14 2.2 Channel model 14 2.3 Upper bound on the achievable data rate 16 2.4 Achieving the upper bound data rate 17 2.5 Potential gain of Opportunistic Routing Protocol (ORP) over Common Single-path Routing Protocol (CSPR) 19 2.6 Evaluation of ORP potential 19 3 Opportunistic Routing: Realizations and Challenges 24 3.1 Vertex priority and cooperation group 26 3.2 Transmission policy in idealized network 34 3.2.1 Basic Routing Rules (BRR) 36 3.3 Transmission policy in real network 40 3.3.1 Purpose of Network Coding (NC) in ORP 41 3.3.2 Extended Basic Routing Rules (BRR) (BRR-E) 43 3.4 Automatic ReQuest reply (ARQ) 50 3.4.1 Retransmission request message contents 51 3.4.2 Retransmission Request (RR) origination and forwarding 66 3.4.3 Retransmission response 67 3.5 Congestion control 68 3.5.1 Congestion control in our work 70 3.6 Network initialization 74 3.7 Formation of the cooperation groups (coalitions) 76 3.8 Advanced Network Coding based Opportunistic Routing protocol (ANChOR) header 77 3.9 Communication of protocol information 77 3.10 ANChOR simulation . .79 3.10.1 ANChOR information in real time .80 3.10.2 Selection of the coding rate 87 3.10.3 Routing Protocol Information (RPI) broadcasting frequency 89 3.10.4 RR contents 91 3.10.5 Selection of RR forwarder 92 3.10.6 ANChOR stability 92 3.11 Summary 95 4 ANChOR in the Gigabit Home Network (G.hn) Protocol 97 4.1 Compatibility with the PLC protocol stack 99 4.2 Channel and noise model 101 4.2.1 In-home scenario 102 4.2.2 Access network scenario 102 4.3 Physical layer (PHY) layer implementation 102 4.3.1 Bit Allocation Algorithm (BAA) 103 4.4 Multiple Access Control layer (MAC) layer 109 4.5 Logical Link Control layer (LLC) layer 111 4.5.1 Reference Automatic Repeat reQuest (ARQ) 111 4.5.2 Hybrid Automatic Repeat reQuest (HARQ) in ANChOR 114 4.5.3 Modeling Protocol Data Unit (PDU) erasures on LLC 116 4.6 Summary 117 5 Study of G.hn with ANChOR 119 5.1 ARQ analysis 119 5.2 Medium and PHY requirements for “good” cooperation 125 5.3 Access network scenario 128 5.4 In-home scenario 135 5.4.1 Modeling packet erasures 136 5.4.2 Linear Dependence Ratio (LDR) 139 5.4.3 Worst case scenario 143 5.4.4 Analysis of in-home topologies 145 6 Conclusions . . . . . . . . . . . . . . . 154 A Proof of the neccessity of the exclusion rule 160 B Gain of ORPs to CSRPs 163 C Broadcasting rule 165 D Proof of optimality of BRR for triangular topology 167 E Reducing the retransmission probability 168 F Calculation of Expected Average number of transmissions (EAX) for topologies with bi-directional links 170 G Feedback overhead of full coding matrices 174 H Block diagram of G.hn physical layer in ns-3 model 175 I PER to BER mapping 17

Pretend that it is real!: Convergence Culture in Practice

Media convergence has mainly been defined and explained as a technological and industrial phenomenon; as the process where new technologies are accommodated by existing media and communication industries and their cultures of production. One consequence of convergence in today’s hybrid media landscape is that the previously distinct borders between production and consumption have become blurred. This means that convergence also takes place as a bottom-up social process initiated by media users that move almost anywhere and everywhere in search of entertainment experiences of their liking. This thesis sheds light on the different types of media convergence that took place in the process of making the transmedia storytelling production Sanningen om Marika. The Swedish public service provider, SVT, and the pervasive games upstart company, The company P, combined their expertise in broadcasting and games development to craft this ‘participation drama’. During five months in 2007, the production offered Swedes nationwide rich possibilities to interact and participate, or just to watch or lurk on the production’s various platforms. Using an ethnographic approach, field studies were conducted throughout the design, implementation and production phases. The analysis shows that even if instances of convergence could be identified, the collaboration did not proceed smoothly. The companies’ different media logics with their differing cultures of production created tensions and frictions. The different logics of television, internet and games - different in quality demands and with different audience participation models - made it difficult to create a hybrid production. Television genres blurred fiction and facts, and the ordinary was blurred with activities of games and play in the production, making the audience reception and interpretations differ extensively. Lastly, the designed audience participation did not remove the asymmetrical relationship between producers and users in media, but instead highlighted issues of hierarchies, lack of participant empowerment and inequality between participants

A Comparative Survey of VANET Clustering Techniques

© 2016 Crown. A vehicular ad hoc network (VANET) is a mobile ad hoc network in which network nodes are vehicles - most commonly road vehicles. VANETs present a unique range of challenges and opportunities for routing protocols due to the semi-organized nature of vehicular movements subject to the constraints of road geometry and rules, and the obstacles which limit physical connectivity in urban environments. In particular, the problems of routing protocol reliability and scalability across large urban VANETs are currently the subject of intense research. Clustering can be used to improve routing scalability and reliability in VANETs, as it results in the distributed formation of hierarchical network structures by grouping vehicles together based on correlated spatial distribution and relative velocity. In addition to the benefits to routing, these groups can serve as the foundation for accident or congestion detection, information dissemination and entertainment applications. This paper explores the design choices made in the development of clustering algorithms targeted at VANETs. It presents a taxonomy of the techniques applied to solve the problems of cluster head election, cluster affiliation, and cluster management, and identifies new directions and recent trends in the design of these algorithms. Additionally, methodologies for validating clustering performance are reviewed, and a key shortcoming - the lack of realistic vehicular channel modeling - is identified. The importance of a rigorous and standardized performance evaluation regime utilizing realistic vehicular channel models is demonstrated

Encounter gossip: a high coverage broadcast protocol for MANET

PhD ThesisMobile Ad-hoc Networks (MANETs) allow deployment of mobile wireless devices or nodes in a range of environments without any fixed infrastructure and hence at a minimal setup cost. Broadcast support that assures a high coverage (i.e., a large fraction of nodes receiving a broadcast) is essential for hosting user applications, and is also non-trivial to achieve due to the nature of devices and mobility. We propose Encounter Gossip, a novel broadcast protocol, which holds minimal state and is unaware of network topology. Coverage obtained can be made arbitrarily close to 1 at a moderate cost of extra message tra c, even in partition-prone networks. Under certain simplifying assumptions, it is shown that a high coverage is achieved by making a total of O(n ln n) broadcasts, where n is the number of nodes, and the time to propagate a message is O(ln n). The e ect of various network parameters on the protocol performance is examined. We then propose modifications to minimise the number of redundant transmissions without compromising the achieved coverage. Two approaches are pursued: timer based and history based. The e ectiveness of each of these approaches is assessed through an extensive set of simulation experiments in the context of two mobility models. Specifically, we introduce a new heuristic alpha policy which achieves significant reduction in redundancy with negligible reduction in coverage. A generalisation to multiple broadcasts proceeding in parallel is proposed and the protocol is refined to reduce problems that can occur due to the effects of high mobility when transmitting a large number of messages. Finally, we implement and validate Encounter Gossip in the context of a real-life mobile ad-hoc network. All these investigations suggest that the protocol, together with the proposed modifications and re nements, is suited to MANETs of varying degrees of node densities and speeds

Network coding-aided MAC protocols for cooperative wireless networks

The introduction of third generation (3G) technologies has caused a vast proliferation of wireless devices and networks, generating an increasing demand for high level Quality of Service (QoS). The wide spread of mobile applications has further reinforced the user need for communication, motivating at the same time the concepts of user cooperation and data dissemination. However, this trend towards continuous exchange of information and ubiquitous connectivity is inherently restricted by the energy-greedy functionalities of high-end devices. These limitations, along with the pressure exerted on the Information and Communications Technology (ICT) industry towards energy awareness, have induced the design of novel energy efficient schemes and algorithms. In this context, the Medium Access Control (MAC) layer plays a key role, since it is mainly responsible for the channel access regulation, the transmission scheduling and the resource allocation, thus constituting an appropriate point to effectively address energy efficiency issues that arise due to the users overcrowding. This dissertation provides a contribution to the design, analysis and evaluation of novel MAC protocols for cooperative wireless networks. In our attempt to design energy efficient MAC schemes, we were extensively assisted by the introduction of new techniques, such as Network Coding (NC), that intrinsically bring considerable gains in system performance. The main thesis contributions are divided into two parts. The first part presents NCCARQ, a novel NC-aided Cooperative Automatic Repeat reQuest (ARQ) MAC protocol for wireless networks. NCCARQ introduces a new access paradigm for cooperative ARQ schemes, exploiting NC benefits in bidirectional communication among wireless users. The NCCARQ performance in terms of QoS and energy efficiency is assessed by means of analytical probabilistic models and extensive computer-based simulations, revealing the significant gains we can achieve compared to standardized MAC solutions. In addition, the impact of realistic wireless channel conditions on the MAC protocol operation further motivated us to study the NCCARQ performance in wireless links affected by correlated shadowing, showing that the channel correlation may adversely affect the distributed cooperation benefits. The second part of the thesis is dedicated to the investigation of MAC issues in wireless data dissemination scenarios. In particular, the existence of multiple source nodes in such scenarios generates conflicting situations, considering the selfish behavior of the wireless devices that want to maximize their battery lifetime. Bearing in mind the energy efficiency importance, we propose game theoretic medium access strategies, applying energy-based utility functions which inherently imply energy awareness. In addition, Random Linear NC (RLNC) techniques are adopted to eliminate the need of exchanging excessive control packets, while Analog NC (ANC) is employed to efface the impact of collisions throughout the communication. During the elaboration of this thesis, two general key conclusions have been extracted. First, there is a fundamental requirement for implementation of new MAC protocols in order to effectively deal with state-of-the-art techniques (e.g., NC), recently introduced to enhance both the performance and the energy efficiency of the network. Second, we highlight the importance of designing novel energy efficient MAC protocols, taking into account that traditional approaches - designed mainly to assist the collision avoidance in wireless networks - tend to be obsolete.La presente tesis doctoral contribuye al diseño, análisis y evaluación de nuevos protocolos MAC cooperativos para redes inalámbricas. La introducción de nuevas técnicas, tales como la codificación de red (NC), que intrínsecamente llevan un considerable aumento en el rendimiento del sistema, nos ayudó ampliamente durante el diseño de protocolos MAC energéticamente eficientes. Las principales contribuciones de esta tesis se dividen en dos partes. La primera parte presenta el NCCARQ, un protocolo cooperativo de retransmisión automática (ARQ), asistido por NC para redes inalámbricas. La segunda parte de la tesis se centra en el diseño de protocolos de capa MAC en escenarios inalámbricos de difusión de datos. Teniendo en cuenta la importancia de la eficiencia energética, se proponen técnicas de acceso al medio basadas en teoría de juegos dónde las funciones objetivo están motivadas por el consumo energético. Las soluciones propuestas son evaluadas por medio de modelos analíticos y simulaciones por ordenador

Asynchronous epidemic algorithms for consistency in large-scale systems

Achieving and detecting a globally consistent state is essential to many services in the large and extreme-scale distributed systems, especially when the desired consistent state is critical for services operation. Centralised and deterministic approaches for synchronisation and distributed consistency are not scalable and not fault-tolerant. Alternatively, epidemic-based paradigms are decentralised computations based on randomised communications. They are scalable, resilient, fault-tolerant, and converge to the desired target in logarithmic time with respect to system size. Thus, many distributed services have adopted epidemic protocols to achieve the consensus and the consistent state, mainly due to scalability concerns. The convergence of epidemic protocols is stochastically guaranteed. However, the detection of the convergence is probabilistic and non-explicit. In a real-world environment, systems are unreliable, and epidemic protocols cannot converge to the desired state. Thus, achieving convergence by itself does not ensure making a system-wide consistent state under dynamic conditions. The research work presented in this thesis introduces the Phase Transition Algorithm (PTA) to achieve distributed consistent state based on the explicit detection of convergence. Each phase in PTA is a decentralised decision-making process that implements epidemic data aggregation, in which the detection of convergence implies achieving a global agreement. The phases in PTA can be cascaded to achieve higher certainty as desired. Following the PTA, two epidemic protocols, namely PTP and ECP, are proposed to acquire of consensus, i.e. for the consistency in data dissemination and data aggregation. The protocols are examined through simulations, and experimental results have validated the protocols ability to achieve and explicitly detect the consensus among system nodes. The research work has also studied the epidemic data aggregation under nodes churn and network failures, in which the analysis has identified three phases of the aggregation process. The investigations have shown a different impact of nodes churn on each phase. The phase that is critical for the aggregation process has been studied further, which led to propose new robust data aggregation protocols, REAP and REAP+. Each protocol has a different decentralised replication method, and both implements distributed failure detection and instantaneous mass restoration mechanisms. Simulations have validated the protocols, and results have shown protocols ability to converge, detect convergence, and produce competitive accuracy under various levels of nodes churn. Furthermore, distributed consistency in continuous systems is addressed in the research. The work has proposed a novel continuous epidemic protocol with the adaptive restart mechanism. The protocol restarts either upon the detection of system convergence or upon the detection of divergence. Also, the protocol introduces the seed selection method for the peak data distribution in decentralised approaches, which was a challenge that requires single-point initialisation and leader-election step. The simulations validated the performance of the algorithm under static and dynamic conditions and approved that convergence and divergence detection accuracy can be tuned as desired. Finally, the research work shows that combining and integrating of the proposed protocols enables extreme-scale distributed systems to achieve and detect global consistent states even under realistic and dynamical conditions

High Performance Wireless Sensor-Actuator Networks for Industrial Internet of Things

Wireless Sensor-Actuator Networks (WSANs) enable cost-effective communication for Industrial Internet of Things (IIoT). To achieve predictability and reliability demanded by industrial applications, industrial wireless standards (e.g., WirelessHART) incorporate a set of unique features such as a centralized management architecture, Time Slotted Channel Hopping (TSCH), and conservative channel selection. However, those features also incur significant degradation in performance, efficiency, and agility. To overcome these key limitations of existing industrial wireless technologies, this thesis work develops and empirically evaluates a suite of novel network protocols and algorithms. The primary contributions of this thesis are four-fold. (1) We first build an experimental testbed realizing key features of the WirelessHART protocol stack, and perform a series of empirical studies to uncover the limitations and potential improvements of existing network features. (2) We then investigate the impacts of the industrial WSAN protocol’s channel selection mechanism on routing and real-time performance, and present new channel and link selection strategies that improve route diversity and real-time performance. (3) To further enhance performance, we propose and design conservative channel reuse, a novel approach to support concurrent transmissions in a same wireless channel while maintaining a high degree of reliability. (4) Lastly, to address the limitation of the centralized architecture in handling network dynamics, we develop REACT, a Reliable, Efficient, and Adaptive Control Plane for centralized network management. REACT is designed to reduce the latency and energy cost of network reconfiguration by incorporating a reconfiguration planner to reduce a rescheduling cost, and an update engine providing efficient and reliable mechanisms to support schedule reconfiguration. All the network protocols and algorithms developed in this thesis have been empirically evaluated on the wireless testbed. This thesis represents a step toward next-generation IIoT for industrial automation that demands high-performance and agile wireless communication

Innovative energy-efficient wireless sensor network applications and MAC sub-layer protocols employing RTS-CTS with packet concatenation

of energy-efficiency as well as the number of available applications. As a consequence there are challenges that need to be tackled for the future generation of WSNs. The research work from this Ph.D. thesis has involved the actual development of innovative WSN applications contributing to different research projects. In the Smart-Clothing project contributions have been given in the development of a Wireless Body Area Network (WBAN) to monitor the foetal movements of a pregnant woman in the last four weeks of pregnancy. The creation of an automatic wireless measurement system for remotely monitoring concrete structures was an contribution for the INSYSM project. This was accomplished by using an IEEE 802.15.4 network enabling for remotely monitoring the temperature and humidity within civil engineering structures. In the framework of the PROENEGY-WSN project contributions have been given in the identification the spectrum opportunities for Radio Frequency (RF) energy harvesting through power density measurements from 350 MHz to 3 GHz. The design of the circuits to harvest RF energy and the requirements needed for creating a WBAN with electromagnetic energy harvesting and Cognitive Radio (CR) capabilities have also been addressed. A performance evaluation of the state-of-the art of the hardware WSN platforms has also been addressed. This is explained by the fact that, even by using optimized Medium Access Control (MAC) protocols, if the WSNs platforms do not allow for minimizing the energy consumption in the idle and sleeping states, energy efficiency and long network lifetime will not be achieved. The research also involved the development of new innovative mechanisms that tries and solves overhead, one of the fundamental reasons for the IEEE 802.15.4 standard MAC inefficiency. In particular, this Ph.D. thesis proposes an IEEE 802.15.4 MAC layer performance enhancement by employing RTS/CTS combined with packet concatenation. The results have shown that the use of the RTS/CTS mechanism improves channel efficiency by decreasing the deferral time before transmitting a data packet. In addition, the Sensor Block Acknowledgment MAC (SBACK-MAC) protocol has been proposed that allows the aggregation of several acknowledgment responses in one special Block Acknowledgment (BACK) Response packet. Two different solutions are considered. The first one considers the SBACK-MAC protocol in the presence of BACK Request (concatenation) while the second one considers the SBACK-MAC in the absence of BACK Request (piggyback). The proposed solutions address a distributed scenario with single-destination and single-rate frame aggregation. The throughput and delay performance is mathematically derived under both ideal conditions (a channel environment with no transmission errors) and non ideal conditions (a channel environment with transmission errors). An analytical model is proposed, capable of taking into account the retransmission delays and the maximum number of backoff stages. The simulation results successfully validate our analytical model. For more than 7 TX (aggregated packets) all the MAC sub-layer protocols employing RTS/CTS with packet concatenation allows for the optimization of channel use in WSNs, v8-48 % improvement in the maximum average throughput and minimum average delay, and decrease energy consumption