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Advancing the efficiency and reliability of wireless sensor networks is a paramount pursuit in modern networking research. In this context, we introduce a groundbreaking approach based on Hidden Markov Chain (HMC) modeling with opportunistic routing, harnessed by the Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) mechanism. Our innovative algorithm addresses key challenges in Wireless Body Area Networks, including delay, throughput, and bandwidth utilization. By strategically integrating the HMC model, which captures intricate state transitions and emission probabilities, our proposed method introduces a robust solution for optimizing node connections and routing decisions. This fusion of HMC and opportunistic routing capitalizes on the strengths of both paradigms, enhancing the network's ability to make intelligent decisions in dynamic scenarios. Through rigorous simulations, we showcase the algorithm's prowess in achieving efficient data transmission. The empirical evidence from these simulations underscores the algorithm's superiority when juxtaposed against state-of-the-art mechanisms such as Simple Multi-Packet Access (SMPA) and Priority-based Congestion-avoidance Routing Protocol (PCRP). Our algorithm not only outperforms existing solutions in terms of delay, throughput, and bandwidth utilization, but it also showcases its ability to adapt to varying network conditions, making it a versatile tool for diverse applications.

Advancing the efficiency and reliability of wireless sensor networks is a paramount pursuit in modern networking research. In this context, we introduce a groundbreaking approach based on Hidden Markov Chain (HMC) modeling with opportunistic routing, harnessed by the Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) mechanism. Our innovative algorithm addresses key challenges in Wireless Body Area Networks, including delay, throughput, and bandwidth utilization. By strategically integrating the HMC model, which captures intricate state transitions and emission probabilities, our proposed method introduces a robust solution for optimizing node connections and routing decisions. This fusion of HMC and opportunistic routing capitalizes on the strengths of both paradigms, enhancing the network's ability to make intelligent decisions in dynamic scenarios. Through rigorous simulations, we showcase the algorithm's prowess in achieving efficient data transmission. The empirical evidence from these simulations underscores the algorithm's superiority when juxtaposed against state-of-the-art mechanisms such as Simple Multi-Packet Access (SMPA) and Priority-based Congestion-avoidance Routing Protocol (PCRP). Our algorithm not only outperforms existing solutions in terms of delay, throughput, and bandwidth utilization, but it also showcases its ability to adapt to varying network conditions, making it a versatile tool for diverse applications. [ABSTRACT FROM AUTHOR]

The Internet of Things (IoT) is globally distributed network systems consisting of small low-cost physical sensor nodes that can sense their environment and communicate with other nodes and computers. They are particularly used for key solutions to monitoring systems such as healthcare monitoring, environmental monitoring, and remote patient monitoring and are also preferred for their vast benefits for precision agriculture, smart building, and smart home applications. Medium Access Control (MAC) schemes are vital part of IoT systems, as the network performance metrics such as throughput, end-to-end packet delay, and energy consumption mostly depend upon the MAC scheme utilized. In this paper, a new hybrid MAC protocol called as Low-Delay Hybrid Medium Access Control (LD-HMAC) for data-gathering purposes in high-density IoT networks is presented with its models and detailed performance evaluation. In the networking application area, an unmanned aerial vehicle is considered as an access point for arranging and scheduling channel access, whereas wireless sensor nodes (IoT nodes) are considered as data-gathering elements from a dense IoT networking environment. The proposed LD-HMAC combines the strengths of both TDMA and CSMA, targeting primarily dense IoT network applications. In the development stages, first the proposed LD-HMAC protocol is designed, modeled, and evaluated analytically by using Discrete-Time Markov Chain. Second, in order to validate the analytical results of the proposed model, a simulation model was developed by using the Riverbed network simulation tool. Finally, the performance results obtained are compared to those of the corresponding MDCA and CCS models referenced in Shrestha (IEEE Trans Wirel Commun 13: 4050–4065, 2014). With respect to the end-to-end delay, the proposed LD-HMAC achieves better results than those of the MDCA and CCS models for time-critical dense IoT network applications. [ABSTRACT FROM AUTHOR]

In this study, we analyze the CSMA Non-Persistent protocol with a finite number of nodes, providing more accurate results for applications like wireless sensor networks. The finite model addresses scenarios where the node count is moderate, capturing realistic system dynamics. Our analysis reveals a dependency on the node count, impacting system throughput. As the node count increases, throughput behavior aligns with Kleinrock's infinite model. We derive a complex closed-form throughput expression for a finite quantity of nodes in the system, solved numerically, and offer an approximate expression for specific conditions. These insights advance understanding of low-contention network performance, especially in scenarios where the infinite model becomes inadequate. [ABSTRACT FROM AUTHOR]

The wireless sensor network (WSN) is one of the most important achievements of the modern technological revolution and greatly affects human life. These networks suffer from some limitations that affect their performance, such as the limited power of their devices. Clustering technology is one of the effective power conservation techniques that improves the performance of WSNs, so this article focuses on developing aggregation technology by proposing an Energy Saving, Multi-hops, Clustering, and Hierarchy (ESMCH) protocol for homogeneous WSNs. The proposed protocol improves clustering technology in several directions. The first direction is by determining the ideal number of cluster head nodes (CHs) suitable for the network, and the second is through the perfect choice of nodes that will represent CHs. The third trend is the selection of secondary CHs. The last trend is the formation of clusters, which depends on an important parameter (distance to CHs). The proposed system uses the TDMA method to schedule the data transfer process to CHs (inside the cluster) and the CSMA method to organize the exchange of data packets between CHs (outside the clusters) for delivery to the base station. The results of simulation experiments in MATLAB R (2020 a) show that the proposed protocol extends network lifetime by 32% compared to the LEACH algorithm and by 26% compared to the SEP algorithm. The results also display that the ESMCH protocol increased the throughput of the WSN by 16.8% compared to its throughput when using the SEP algorithm and by 30% when using the LEACH algorithm. [ABSTRACT FROM AUTHOR]

The Internet of Things (IoT) has recently received a great deal of research interest due to its broad range of applications. One of the important layers in IoT applications is known as edge computing where resource-constrained devices at the edge form a simple type of network to sense required data. A more powerful edge device is responsible for collecting all sensed data to be transferred to the upper layers. A critical focus is therefore placed on maximum rate of data collection, requiring effective and intelligent solutions to coordinate the channel access of the devices. Medium access control (MAC) protocols take this responsibility as their design mission. Carrier-sense multiple access (CSMA) has been a baseline MAC scheme and many previous traditional networks utilized a CSMA-based solution. The motivation of this paper is to study the performance of a typical network at the edge through the CSMA theme. A practical network is constructed to assess the channel throughput performance via a commercially available radio transceiver. The practical performance observations indicate the suitability of the proposed CSMA-based solution. [ABSTRACT FROM AUTHOR]

The interplay of physical layer enhancements and classic random access protocols is the objective of this paper. Successive interference cancellation (SIC) is among the major enhancements of the physical layer. Considering the classic representatives of random access protocols, Slotted ALOHA and Channel Sensing Multiple Access (CSMA), we show that two regimes can be identified as a function of the communication link spectral efficiency. In case of high levels of spectral efficiency, multi-packet reception enabled by SIC is of limited benefit. Sum-rate performance is dominated by the effectiveness of the Medium Access Control (MAC) protocol. On the contrary, for low spectral efficiency levels, sum-rate performance is essentially dependent on physical layer SIC capability, while the MAC protocol has a marginal impact. Limitations due to transmission power dynamic range are shown to induce unfairness among nodes. However, the unfairness issue fades away when the system is driven to work around the sum-rate peak achieved for low spectral efficiency. This can also be confirmed by looking at Age of Information (AoI) metric. The major finding of this work is that SIC can boost performance, while still maintaining a fair sharing of the communication channel among nodes. In this regime, the MAC protocol appears to play a marginal role, while multi-packet reception endowed by SIC is prominent to provide high sum-rate, low energy consumption, and low AoI. [ABSTRACT FROM AUTHOR]

In this paper, we consider the problem of detecting the channel activity in LoRaWAN networks. To improve the medium access performance, recent implementations of the chipsets for LoRaWAN end nodes are offering a feature called Channel Activity Detection (CAD), as the first step toward the implementation of the Carrier Sense Multiple Access (CSMA) in LoRaWAN networks. The algorithm underlying the CAD is at the moment left undisclosed. In this paper, we propose a possible implementation of the CAD algorithm; we then evaluate its performance in an additive white Gaussian noise (AWGN) channel, and we find the performance being completely satisfactory and matching the one of the undisclosed algorithm. The results we find are encouraging the community to include the CAD feature in open source implementations of a LoRaWAN receiver.

The Internet of Things (IoT) has recently received a great deal of research interest due to its broad range of applications. One of the important layers in IoT applications is known as edge computing where resource-constrained devices at the edge form a simple type of network to sense required data. A more powerful edge device is responsible for collecting all sensed data to be transferred to the upper layers. A critical focus is therefore placed on maximum rate of data collection, requiring effective and intelligent solutions to coordinate the channel access of the devices. Medium access control (MAC) protocols take this responsibility as their design mission. Carrier-sense multiple access (CSMA) has been a baseline MAC scheme and many previous traditional networks utilized a CSMA-based solution. The motivation of this paper is to study the performance of a typical network at the edge through the CSMA theme. A practical network is constructed to assess the channel throughput performance via a commercially available radio transceiver. The practical performance observations indicate the suitability of the proposed CSMA-based solution.

The latest technologies and communication protocols are arousing a keen interest in automation, in which the field of home area networks is the most prominent area to work upon toward solving the issues and challenges faced by wireless home area networks regarding adaptability, reliability, cost, throughput, efficiency, and scalability. However, managing the immense number of communication devices on the premises of a smart home is a challenging task. Moreover, the Internet of Things (IoT) is an emerging global trend with billions of smart devices to be connected in the near future resulting in a huge amount of diversified data. The continuous expansion of the IoT network causes complications and vulnerabilities due to its dynamic nature and heterogeneous traffic. In the applications of IoT, the wireless sensor network (WSN) plays a major role, and to take benefits from WSN, medium access control (MAC) is the primary protocol to optimize, which helps in allocating resources to a huge number of devices in the smart home environment. Furthermore, artificial intelligence is highly demanded to enhance the efficiency of existing systems and IoT applications. Therefore, the purpose of this research paper is to achieve an optimized medium access control protocol through machine learning. The machine learning classifier, e.g., random forest (RF) and linear regression model, is adopted for predicting the features of home area networks. The proposed technique is helpful and could overcome the demerits of existing protocols in relation to scalability, throughput, access delay, and reliability and help in achieving an autonomous home area network (HAN). [ABSTRACT FROM AUTHOR]

The 3GPP has standardized the 5G New Radio (NR) sidelink (SL) technology that enables direct device-to-device communications. SL will be key in realizing several high-speed, low-latency vehicle-to-everything (V2X) applications, such as automated driving. To meet these applications’ high data rate requirements, operating SL at mmWave and sub-THz frequencies will be essential. However, the current SL design primarily caters to sub-6 GHz frequencies and does not consider the directionality of transmissions at high frequencies. For Mode 2 of SL, where SL UEs perform sensing-based autonomous resource selection, this results in hidden node interference due to the transmit (Tx) UE’s inability to sense transmissions not aligned with the primary direction of communication. We propose paired transmission and sensing of sidelink control information (SCI), whereby SL Tx UEs transmit and receive SCI in an additional paired direction directly opposite to the primary direction. This helps eliminate hidden node interference while reducing the number of exposed nodes. Simulations in NR V2X highway deployments show that the paired scheme improves the average packet reception ratio (PRR) by 27% over the state-of-the-art at the highest traffic loads. We also propose enhanced transmit power control strategies to minimize interference between concurrent SL transmissions. This enables better resource reuse and further improves performance, with our combined solution achieving at least 95% average PRR in all scenarios. Finally, we present a stochastic geometry-based analytical model for a single-lane highway V2X network and validate it against simulation results. Our model provides insights into the reliability and capacity of high-frequency SL networks.

This paper investigates the critical issue of maintaining system stability for multipacket reception (MPR) $p$ -persistent carrier sense multiple access (CSMA) systems. When multiple users with individual queues simultaneously transmit a packet to an access point (AP) via CSMA, the number of successful transmissions and their identities are determined probabilistically in the MPR channel. Stability signifies that none of the users’ queues grows unbounded. The stability region is a significant measure, addressing all potential permutations of mean packet arrival rates for the users to maintain bounded queue lengths. The work begins by considering a system with two users characterized by differing mean packet arrival rates and (re)transmission probabilities. Subsequently, it examines an $N$ -user system in which each user shares an identical packet arrival rate and retransmission probability. A backoff algorithm is then proposed for these $N$ users to utilize in order to stabilize their queues. The paper concludes with numerical studies illustrating the stability region as a function of user parameters, demonstrating how the proposed backoff algorithm can be used to maximize throughput.

The IoT devices placed in remote locations require a battery replacement very often, which is not a convenient option. Backscatter communication can resolve this problem, as backscatter communication is a data transmission in which an RF signal incident from the gateway is used for energy harvesting, and this energy will be employed for data transmission. In this paper, a hybrid contention-based TDMA scheme is proposed, which provides slots to devices by dividing them into groups, and then contention is employed in groups to acquire a slot; if a device is not able to transmit during harvest, then transmit (HTT) period, then it can transmit in variable sub frame and the devices which are not able to completely transmit during HTT period can reserve subframes. The proposed hybrid scheme is compared with the TDMA scheme for average transmission delay.The proposed scheme provides scalability. The difference between the average transmission delay of TDMA and the proposed hybrid scheme is from 6 to 20 s, depending on the number of devices added and when traffic is generated.

LoRa is a low-power WAN technology designed for the Internet of Things. When large-scale nodes are deployed in a LoRa network channel conflicts increase and packet transmission collisions will lead to a significant reduction in the transmission efficiency of the network. It has been shown that the CSMA protocol based on the CAD mechanism of LoRa devices can be a good solution to such channel conflict problems, but less research has been done on the limitations of CAD itself. In this paper, we analyze in detail the listening range of LoRa network service area and CAD, get the relationship between ED location and the corresponding number of hidden EDs, and establish the communication model of LoRa network based on CSMA. The analysis shows that the CAD listening range of the nodes does not cover the whole LoRa network due to the limitation of the device performance, and the hidden nodes in their blind zones negatively affect the CSMA operation, and this effect is increasing as the number of deployed nodes increases and the network transmission efficiency keeps decreasing to p-ALOHA. To address this problem, this paper proposes a CSMA channel access scheme based on ED location and communication time planning (LT-CSMA), which plans the communication time of EDs at different locations in the LoRa network, aiming at the communication time of Eds within the CAD listening range of each ED to be adjacent to each other, while hidden nodes outside the listening range will be isolated from them in terms of communication time, thus avoiding the channel conflicts caused by hidden nodes. Simulation experiments prove that LT-CSMA can make full use of idle radio channels and has very good results for packet transmission in LoRa networks with small deployment size, and its packet success probability is much higher than that of channel access mechanisms such as CSMA, s-ALOHA, and p-ALOHA. And as the number of EDs deployed increases, LT-CSMA always outperforms CSMA, p-ALOHA in terms of data transmission efficiency, demonstrating good scalability. [ABSTRACT FROM AUTHOR]

Queue-Sharing Multiple Access (QSMA) is introduced and analyzed. The new channel-access method  consists of establishing  and maintaining a distributed transmission queue among nodes sharing a common channel  and results in   a sequence of queue cycles, with each cycle having one or multiple  queue turns with collision-free transmissions from  nodes that have joined the transmission queue, followed by a joining period for the current cycle.   Nodes can take advantage of carrier sensing to improve the efficiency with which nodes join and use the shared transmission queue. The throughput of  ALOHA with priority ACK's,  CSMA with priority ACK's,  CSMA/CD with priority ACK's, TDMA with a fixed schedule, and QSMA with and without carrier sensing is compared analytically and by simulation in ns-3.  The results show that QSMA is more efficient  than TDMA with the simplicity of CSMA or ALOHA.

ALOHA with Queue Sharing (ALOHA-QS)  maintains most of the simplicity of ALOHA  with priority acknowledgments  (ACK) and attains the high throughput of transmission scheduling methods that  require  clock synchronization.  Channel access with ALOHA-QS  consists of a sequence of queue cycles, with each cycle having one or multiple  collision-free transmissions by nodes that have joined the transmission queue and  a  single request turn to join the queue.    The signaling  of ALOHA-QS  entails adding to  packet headers the size of the shared queue, the position of the sending node in the  queue,  a bit indicating the end of transmissions by the transmitting node, and a bit stating whether or not a new node joined the queue successfully.    The throughput of ALOHA-QS is compared with the throughput of  TDMA with a fixed transmission schedule, ALOHA with priority ACK's,  and CSMA with priority ACK's analytically and by simulation.

Current LoRa networks including those following the LoRaWAN specification use the primitive ALOHA mechanism for media access control due to LoRa’s lack of carrier sense capability. From our extensive measurements, the channel activity detection feature that was recently introduced to LoRa for energy-efficiently detecting preamble chirps can also detect payload chirps reliably. This sheds light on an efficient carrier-sense multiple access protocol that we refer to as LMAC for LoRa networks. This article presents the designs of three advancing versions of LMAC that respectively implement carrier-sense multiple access, and balance the communication loads among the channels defined by frequencies and spreading factors based on the end nodes’ local information and then additionally the gateway’s global information. Experiments on a 50- node lab testbed and a 16-node university deployment show that, compared with ALOHA, LMAC brings up to 2.2× goodput improvement and 2.4× reduction of radio energy per successfully delivered frame. Thus, should LoRaWAN’s ALOHA be replaced with LMAC, network performance boosts can be realized. [ABSTRACT FROM AUTHOR]

This paper investigates the effectiveness of using P-persistent carrier sensing multiple access (P-Persistent CSMA) on vehicular connectivity as vehicles dynamically form temporary communication networks using simulation and mathematical modelling. In the connected and autonomous environment, effective and efficient connectivity between vehicles (V2V) and between vehicles and infrastructure (V2I) is critical. The simulation was performed in MATLAB and included the investigation of the effect of vehicular density, probability value change, and increase in Backoff time, and change in data frame size. The results showed that as vehicular density, probability, and data frame size increased, throughput decreased as data traffic increased, whereas as Backoff time and probability increased, throughput increased. Furthermore, as data size increases with decreasing probability level, channel utilization improves. Based on these findings and the derived mathematical expressions, a proposed dynamic and adaptive model is presented, allowing for maximum throughput while minimizing collisions. This is accomplished by equating four mathematical expressions and substituting them using iteration to achieve a balanced and optimal level of communication channel utilization by dynamically adjusting the three main parameters under consideration as a function of increasing vehicular density (P-Persistent probability level, Backoff time, and data frame length). To achieve such dynamical and adaptive optimization, four mathematical expressions are used. The resulting model is promising and will improve the efficiency of non-adaptive conventional P-Persistent CSMA. The presented work proved to increase the effectiveness of the conventional p-persistent technique using a multi-dimensional parameter correlation, which is more effective than weighted, slotted, or adaptive P-Persistent approaches. [ABSTRACT FROM AUTHOR]

Busy-Tone Multiple Access with Collision Avoidance and Detection (BTMA/CAD) is introduced. BTMA/CAD integrates collision avoidance and collision detection mechanisms in ad-hoc networks of nodes with half-duplex radios by means of a single busy tone transmitted over an orthogonal narrowband channel. The throughput of BTMA/CAD is compared with that of Carrier-Sense Multiple Access (CSMA) and CSMA with Collision Avoidance (CSMA/CA) using an analytical model. It is shown that BTMA/CAD is more efficient than CSMA and CSMA/CA in ad-hoc networks with hidden terminals.

A simple variation of Carrier Sense Multiple Access (CSMA), CUE-CSMA (for Channel Utilization Estimation), is introduced in which the transmission-persistence probability is a function of the perceived average length of idle periods, which is used as a cue of channel utilization. Nodes need not know or estimate the number of nodes in the network. A simple analytical model is used to derive the throughput of CUE-CSMA and compare it with non-persistent and 1-persistent CSMA without having to assume saturation mode as several prior studies have done. The model considers the effect of acknowledgments (ACK) and receive-to-transmit turnaround times. The results clearly show that using estimates of average idle periods as simple cues of channel utilization can provide the benefits of 1-persistent CSMA at light loads and match or outperform non-persistent CSMA at higher loads.

CSMA/CAP (Carrier-Sense Multiple Access with Collision Avoidance and Pilots) is introduced for ad-hoc networks in which each node has a single half-duplex radio. Using carrier sensing to access the common channel, a node with a data packet to send transmits a request-to-send (RTS) packet. If the RTS is sent without interference, the receiver sends a clear-to-send (CTS) packet followed by a pilot. A sender that receives a CTS for itself sends its data packet after a delay to let the pilot be heard and and then transmits its own pilot to make the total transmission time equal to a maximum data-packet length. The receiver sends its ACK after receiving the data packet and pilot from the sender. It is shown that no channel-access protocol based on the traditional RTS-CTS handshake over a single channel can guarantee collision-free transmissions of variable-length data packets and ACK’s, and that CSMA/CAP does ensure that data packets and their ACK’s are sent without multiple-access interference. The throughput of CSMA/CAP is compared with the throughput of CSMA in networks with and without hidden terminals, and the results show that the overhead of CSMA/CAP to eliminate collisions is small and that CSMA/CAP performs far better than CSMA when hidden terminals are present.

This paper introduces Carrier-Sense Multiple Access with Transmission Acquisition (CSMA/TA) for wireless local area networks (WLANs) with stations endowed with half-duplex radios using single antennas. In contrast to traditional contention-based channel-access methods, CSMA/TA seeks to increase the likelihood of having the last transmission from a group of colliding transmissions succeed. To accomplish this, a station senses the channel before sending a pilot packet. After finishing the transmission of the pilot, the station is required to wait for a certain amount of time before sensing the channel again. If the channel is sensed to be idle again, the station understands that ``it has acquired its right to transmit a data frame'' and proceeds with that. The throughput of CSMA/TA is compared with the throughputs of CSMA and CSMA/CD. An important feature of the analysis presented in this paper is the consideration of the impact of the receive-to-transmit and transmit-to-receive turnaround times. It is shown that CSMA/TA performs better than ideal CSMA and CSMA/CD if the propagation delays in  the network are larger than the turnaround times, and its performance can still surpass CSMA/CD and CSMA if turnaround times are larger than propagation delays but not too much larger.

Low latency and reliable information transfer are highly demanded in fifth generation (5G) and beyond 5G wireless communications. A novel delay-bounded wireless media access control (MAC) protocol called Carrier Sense Multiple Access with Arbitration Point (CSMA/AP) was established to strictly ensure the upper boundary of communication delay. CSMA/AP enables collision-free and delay-bounded communications with a simple arbitration mechanism exploiting the precise time synchronization achieved by Wireless Two-Way Interferometry (Wi-Wi). Experimental demonstration and proving the feasibility in wireless environments are among the most critical steps before any further discussion of CSMA/AP and extension to various applications can take in place. In this work described in this paper, we experimentally demonstrated the fundamental principles of CSMA/AP by constructing a star-topology wireless network using software-defined radio terminals combined with precise time synchronization devices. We show that CSMA/AP was successfully operated, even with dynamic changes of the spatial position of the terminal or the capability to accommodate mobility, thanks to the real-time adaption to the dynamically changing environment by Wi-Wi. We also experimentally confirmed that the proposed CSMA/AP principle cannot be executed without Wi-Wi, which validates the importance of precise time synchronization. This study paves the way toward realizing delay-bounded wireless communications for future low-latency and highly reliable critical applications.

Nowadays multiple wireless communication systems operate in industrial environments side by side. In such an environment performance of one wireless network can be degraded by the collocated hostile wireless network having higher transmission power or higher carrier sensing threshold. Unlike the previous research works which considered IEEE 802.15.4 for the Industrial Wireless communication systems (iWCS) this paper examines the coexistence of IEEE 802.11 based iWCS used for delay-stringent communication in process automation and gWLAN (general-purpose WLAN) used for non-real time communication. In this paper, we present a Markov chain-based performance model that described the transmission failure of iWCS due to geographical collision with gWLAN. The presented analyticmodel accurately determines throughput, packet transaction delay, and packet loss probability of iWCS when it is collocated with gWLAN. The results of the Markov model match more than 90% with our simulation results. Furthermore, we proposed an adaptive transmission power control technique for iWCS to overcome the potential interferences caused by the gWLAN transmissions. The simulation results show that the proposed technique significantly improves iWCS performance in terms of throughput, packet transaction, and cycle period reduction. Moreover, it enables the industrial network for the use of delay critical applications in the presence of gWLAN without affecting its performance. [ABSTRACT FROM AUTHOR]

Carrier-Sense Multiple Access with Collision Avoid- ance and Detection (CSMA/CAD) is introduced and analyzed. The new protocol operates in a single channel and consists of taking advantage of self-interference cancellation to enable collision detection (CD) in the context of collision-avoidance (CA) handshakes in multi-hop wireless networks. It is shown that CSMA/CAD eliminates the collisions of data packets in the presence of hidden terminals. The throughput of CSMA/CAD is analyzed and compared with the throughput of CSMA, CSMA/CA, and dual busy-tone multiple access (DBTMA). The analysis results show that CSMA/CAD provides better perfor- mance than the other channel-access schemes aimed at combating hidden terminals, and that the throughput degradation due to hidden terminals in CSMA/CAD is limited compared to CSMA.

Prior work on persistent and non-persistent transmission strategies of CSMA and CSMA/CD indicated that no persistence provides better performance; however, this result applies only to a specific approach to persistence. We introduce time-based persistence in which a node with a packet to send that finds the channel busy persists for a limited amount of time, and provide a simple unifying analysis of the impact of time-based persistence in channel-access protocols that use carrier sensing and operate in ad-hoc wireless networks. We focus on CSMA with priority acknowledgments (ACK) and CSMA with collision detection (CSMA/CD) and ACKs. Our analysis takes into account the effect that receive-to-transmit turnaround times have on performance, and shows that CSMA and CSMA/CD with time-based persistence can attain the same throughput values relative to a non-persistent strategy.

Wireless sensor network is gaining popularity due to its large-scale deployment in Internet of Things. The constraints of resources influence the protocol design at every layer. The management of radio scheduling takes place at physical layer by means of suitable design of MAC protocol to ensure optimal use of energy. The optimization takes place by synchronizing the carrier sensing multiple access mechanism. The traditional MAC protocol like IEEE-802.15.6 with CSMA is delays intensive as well as consumes more energy. Therefore, this paper introduces an analytical modeling of cross layer design approach of MAC protocol with clustering to ensure better network performance and prolonged lifetime with optimal use of energy. The average packet delay of the proposed MAC protocol as synchronous radio scheduling(ProP-SRS) reduces by 14 and 0.77% with respect to the S-MAC and Q-MAC respectively, whereas, The energy utilization for transferring per bit of data of the ProP-SRS reduces by 39.32 and 1.78% with respect to the S-MAC and Q-MAC respectively. The trend of the average packet delay for a MIAT = 4 with varying value of the slot exhibit lower trend for the Prop-SRS, whereas Q-MAC is immediately inferior and S-MAQ provide higher delay. The trend of the energy utilization per bit with varying value of the slot exhibit lower trend for the Prop-SRS, whereas Q-MAC is immediately inferior and S-MAQ comes higher energy per bit. [ABSTRACT FROM AUTHOR]

Supporting delay-constrained traffic becomes more and more critical in multimedia communication systems, tactile Internet, networked control systems, and cyber-physical systems, etc. In delay-constrained traffic, each packet has a hard deadline. When it is not delivered before the hard deadline, it becomes useless and will be removed from the system. This feature is completely different from that of traditional delay-unconstrained traffic and brings new challenge to network protocol design. In this work, we study the widely-used (slotted) ALOHA and CSMA wireless access protocols but under the new delay-constrained setting. Our goal is to compare delay-constrained ALOHA and CSMA for different system settings and thus give network operators guidelines on protocol selection. We use two Markov chains to analyze delay-constrained ALOHA and CSMA, respectively. However, the number of states of Markov chains increases exponentially with respect to the number of users in the network. Therefore, we can only compare the exact performance of delay-constrained ALOHA and CSMA for small-scale networks. To address the curse of dimensionality, we design a single-user parameterized ALOHA (resp. CSMA) system, where the parameters are to be learned to approximate the original multi-user ALOHA (resp. CSMA) system. In addition, our low-complexity approach preserves the Markov-chain structure of the systems and thus enables us to compute some other interested performance metrics such as average delivery time. We use our low-complexity approach to reveal the conditions under which ALOHA (resp. CSMA) outperforms CSMA (resp. ALOHA) in the delay-constrained setting via extensive simulations.

The importance of reliable information transfer in wireless networks, especially regarding communication delay, is drastically increasing to fulfill safe and high-quality communication in the 5G and post-5G era. However, conventional media access control (MAC) protocol for wireless networks, notably Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA), sometimes yields unexpectedly significant delay due to its complex arbitration mechanism assuming asynchronous communication among terminals. As the delay cannot be strictly bounded by a deterministic value, this causes a vulnerability of systems relying on wireless networks. This paper utilizes precise time synchronization achieved by Wireless Two-way Interferometry (Wi-Wi), enabling all terminals to be time-synchronized via wireless signals. We show that by an appropriate periodic assignment of each terminal’s data transmission timing, named Arbitration Point (AP), a simple arbitration algorithm obtains a strictly bounded maximum value for the delay while ensuring equalities among all participants. Furthermore, we demonstrate that the total number of terminals manageable in a star-topology wireless network significantly increases by densely packing AP timings, taking into account the spatial geometry information of terminals, which is another feature delivered by Wi-Wi measurement. In the meantime, we experimentally constructed a star-topology wired network where all terminals are time-synchronized via Wi-Wi to confirm the fundamental properties identified in the proposed arbitration protocol. This study paves a new way for future wireless networks where the delay is strictly bounded and provides the basis for ultra-reliable and high-quality information transfer functionalities by utilizing precise time synchronization and space localization (space-time synchronization).

In this paper, a dense Internet of Things (IoT) monitoring system is studied in which a large number of devices contend for transmitting timely status packets to their corresponding receivers over wireless noisy channels, using a carrier sense multiple access (CSMA) scheme. When each device completes one transmission, due to possible transmission failure, two cases with and without transmission feedback to each device must be considered. Particularly, for the case with no feedback, the device uses policy (I): It will go to an idle state and release the channel regardless of the outcome of the transmission. For the case with perfect feedback, if the transmission succeeds, the device will go to an idle state, otherwise it uses either policy (W), i.e., it will go to a waiting state and re-contend for channel access; or it uses policy (S), i.e., it will stay at a service state and occupy this channel to attempt another transmission. For those three policies, the closed-form expressions of the average age of information (AoI) of each device are characterized under schemes with and without preemption in service. It is shown that, for each policy, the scheme with preemption in service always achieves a smaller average AoI, compared with the scheme without preemption. Then, a mean-field approximation approach with guaranteed accuracy is developed to analyze the asymptotic performance for the considered system with an infinite number of devices and the effects of the system parameters on the average AoI are characterized. Simulation results show that the proposed mean-field approximation is accurate even for a small number of devices. The results also show that olicy (S) achieves the smallest average AoI compared with policies (I) and (W), and the average AoI does not always decrease with the arrival rate for all three policies. [ABSTRACT FROM AUTHOR]

Mobile traffic volumes have grown exponentially because of the increase in services and applications. Traditional networks are complex to manage because the forwarding, control, and management planes are all bundled together and, thus, administrators are supposed to deploy high-level policies, as each vendor has its own configuration methods. Software-Defined Networking (SDN) is considered the future paradigm of communication networks. It decouples control logic from its underlying hardware, thereby promoting logically centralized network control and making the network more programmable and easy to configure. Low-power wireless technologies are moving toward a multitenant and multiapplication Internet of Things (IoT), which requires an architecture with scalable, reliable, and configured solutions. However, employing an SDN-based centralized architecture in the environment of a low-power wireless IoT network introduces significant challenges, such as difficult-to-control traffic, unreliable links, network contention, and high associated overheads that can significantly affect the performance of the network. This paper is a contribution toward a performance evaluation for the use of SDN in wireless networking by evaluating the latency, packet drop ratio (PDR), data extraction rate (DER), and overheads. The results show that SDN adds a high percentage of overheads to the network, which is about 43% of the 57% user packets, and the DER drops when the number of mesh nodes are increased, in addition to the high loss that was observed for packets that traveled over more hops.

In nonsaturated 802.11 distributed coordination function (DCF) networks, existing studies had observed a salient phenomenon: the maximum stable throughput may be far higher than the saturation throughput and last for a long duration (say, months). Such a maximum stable throughput is called the presaturation throughput peak. The long-duration peak suggests that 802.11 DCF networks may provide a far higher stable throughput than what we generally believe, without worrying about a sudden deterioration of quality of service (QoS). This paper is devoted to developing a general theoretical framework to predict the peak. In the framework, we define a backoff entropy to quantify the uncertainty of the inherent random backoff process of 802.11 DCF networks, and then innovatively introduce a BackoffEntropy-Peak linearity property (i.e., the peak is linearly proportional to the backoff entropy) for the peak prediction. This framework is applicable for a general configuration of contention windows (CWs). It enables us to reveal the most essential dependency of the peak on the initial CW size and the number of network nodes. Further, we design peak-based call admission control (CAC) schemes that can be performed quickly and easily, without requiring network performance measurements and complex calculations. We verify our framework and CAC schemes via widely adopted 802.11 DCF ns2 and ns3 simulators (mostly with typical 802.11 standard settings). Extensive simulations show that our framework and CAC schemes trade within 9% peak prediction errors for making 802.11 DCF networks provide high stable throughput with good QoS (such as short delay and low collision probability). This paper is the first to propose applying the information entropy to study the throughput-stability problem. We believe that this study makes a crucial breakthrough in thoroughly investigating nonsaturated performance and network stability of random access wireless networks. [ABSTRACT FROM AUTHOR]

Named Data Networking (NDN) is a promising architecture that aims to natively satisfy emerging applications such as the Internet of Things (IoT). Therefore, enabling NDN in real-world IoT deployments is becoming essential in order to benefit from Information Centric Networking (ICN) features. To design realistic NDN-based communication solutions for IoT, revisiting mainstream technologies such as low-power wireless standards may be the key. In this paper, we explore NDN forwarding over IEEE 802.15.4 following two steps. First, we mathematically model a broadcast-based forwarding strategy for NDN over constrained networks with the IEEE 802.15.4 technology in mind. The model estimates the number of frames transmitted and the mean round-trip time per request, under content popularity considerations. Second, based on mathematical and experimental observations of the broadcast-based forwarding at network level, we elaborate Named-Data Carrier-Sense Multiple Access (ND-CSMA), an adaptation of the Carrier-Sense Multiple Access (CSMA) algorithm used in IEEE 802.15.4. Results show that adaptations such as ND-CSMA may be reasonably envisioned to improve NDN efficiency with current IoT technologies. [ABSTRACT FROM AUTHOR]

AODV (Ad hoc On‐Demand Distance Vector) is a well‐known routing protocol for wireless networks. Recently, Time Slotted Channel Hopping (TSCH) was proposed as a MAC layer protocol, specified in the IEEE 802.15.4e standard. As MAC layer protocols can impact the performance of protocols in the layers above, we examine the performance of AODV over TSCH and compare it with CSMA. We investigate using different metrics, such as latency, packet delivery rate, and energy consumption. We implemented AODV, as defined by the RFC 3561, using the embedded systems operational system Contiki‐NG, a well established platform for Low power and Lossy Networks (LLNs), and the Internet of things (IoT). Our results, running on the Cooja platform, show that TSCH can greatly improve the performance of AODV, achieving a packet delivery rate of almost 100%. Moreover, our results also show that TSCH consumes less energy than CSMA. [ABSTRACT FROM AUTHOR]

Brain computer interface (BCI) systems permit individuals with motor disorders to utilize their thoughts as a mean to control external devices. BCI is a promising interdisciplinary field that gained the attention of many researchers. Yet, the development of BCI systems is facing several challenges, such as network lifetime. TheMedium Access Control (MAC) Protocol is the bottle-neck of network reliability. There are many MAC protocols that can be utilized for dependable transmission in BCI applications by altering their control parameters. However, modifying these parameters is another source of concern due to the scarcity in knowledge about the effect of modification. Also, there is still no instrument that can receive and actualize these parameters on transmitters embedded inside the cerebrum. In this paper, we propose two novelMAC protocols using passive UHF-RFID, the proposed protocols provide efficient and reliable communication between the transmitters and the receiver. The UHF-RFID transmitters were used because they are energy efficient which makes them compatible with BCI application. The first protocol is designed for the EEG signals. While the second protocol was designed for the ECoG signals. The evaluation results showed the validity of the proposed protocols in terms of network performance. The results also proved that the protocols are suitable and reliable for designing efficient BCI applications. [ABSTRACT FROM AUTHOR]