TDMA MAC Protocols Research Articles

Reinforcement Learning TDMA-Based MAC Scheduling in the Industrial Internet of Things: A Survey

As technology progresses, almost all Industrial Internet of Things applications are becoming more data-driven. Hence, more advanced ways of communication are required to both save energy and become efficient to collect huge amounts of data. Researchers have now agreed that the root improvement of IIoT communication can start from a lower layer which is Data Link. Time Division Medium Access-based protocols on this layer have drawn academia's attention to decrease the energy consumption of IIoT devices and achieve higher levels of throughput. Yet, a problem arises, that is, developing a scheduler has always been troublesome while designing a Medium Access Control protocol. Scheduling communication in TDMA-based MAC protocols is considered an NP-hard problem. It is one of the topics highly debated among researchers to make the scheduling adaptive to the huge variation of IIoT application requirements. Conventional scheduling algorithms may suffer from the rapid changes in sensor network topology, network throughput, and applications’ delay targets. Therefore, Reinforcement Learning algorithms are being integrated into scheduling techniques because of their adaptability and efficiency. This paper surveys RL-based TDMA MAC protocols and compares them in terms of several unified features. Each protocol is explained and discussed with others regarding its advantages and drawbacks.

Implementation of FMAC in Healthcare System of Wireless Sensor Network

Wireless sensor network is the network of sensor nodes. The nodes transmit data to the sink node. Each sensor nodes have its own battery and ability to communicate with sink node. Network of such nodes is called sensor network. The successful operation of WSN largely depends on MAC sublayer which deals with addressing and channel access control. WSN has varied design constraints such as energy consumption, scalability, delay, traffic control, packet delivery throughput and overheads that need an effective MAC protocol to deal with these problems. Energy must be utilized efficiently in order to increase the lifetime of the Wireless Sensor Network. MAC protocols reduce the cost of energy consumption by providing an efficient communication for transmission and hence improves network lifetime. This paper shows the implementation of FMAC Protocol in healthcare system for different reporting rates. The purpose of the study is to identify the best MAC protocol in Healthcare System. Results for implementation of Hybrid MAC for hospital network are presented in the paper. Results for Data transmission between nodes and sink node has been evaluated to identify Good MAC protocol. Paper represents how low energy consumption can be achieved by combining TDMA and CSMA MAC protocols.

Deep-Reinforcement Learning Multiple Access for Heterogeneous Wireless Networks

This paper investigates a deep reinforcement learning (DRL)-based MAC protocol for heterogeneous wireless networking, referred to as a Deep-reinforcement Learning Multiple Access (DLMA). Specifically, we consider the scenario of a number of networks operating different MAC protocols trying to access the time slots of a common wireless medium. A key challenge in our problem formulation is that we assume our DLMA network does not know the operating principles of the MACs of the other networks—i.e., DLMA does not know how the other MACs make decisions on when to transmit and when not to. The goal of DLMA is to be able to learn an optimal channel access strategy to achieve a certain pre-specified global objective. Possible objectives include maximizing the sum throughput and maximizing $\alpha $ -fairness among all networks. The underpinning learning process of DLMA is based on DRL. With proper definitions of the state space, action space, and rewards in DRL, we show that DLMA can easily maximize the sum throughput by judiciously selecting certain time slots to transmit. Maximizing general $\alpha $ -fairness, however, is beyond the means of the conventional reinforcement learning (RL) framework. We put forth a new multi-dimensional RL framework that enables DLMA to maximize general $\alpha $ -fairness. Our extensive simulation results show that DLMA can maximize sum throughput or achieve proportional fairness (two special classes of $\alpha $ -fairness) when coexisting with TDMA and ALOHA MAC protocols without knowing they are TDMA or ALOHA. Importantly, we show the merit of incorporating the use of neural networks into the RL framework (i.e., why DRL and not just traditional RL): specifically, the use of DRL allows DLMA (i) to learn the optimal strategy with much faster speed and (ii) to be more robust in that it can still learn a near-optimal strategy even when the parameters in the RL framework are not optimally set.

Interference Minimization in TDMA MAC Protocols for WSNs

Interference Minimization in TDMA MAC Protocols for WSNs

HTTPDissect: Detailed Performance Analysis of HTTP Web Browsing Traffic in TDMA Mesh Networks

TDMA based wireless mesh networks have gained prominence as some of the recent standards such as WiMAX and 802.11s have proposed the use of TDMA based MAC protocol for mesh networks. Even though HTTP web browsing traffic constitutes a significant percentage of Internet traffic, but as of yet there have been no attempts to study the performance of HTTP based web browsing traffic in TDMA mesh networks. HTTP web browsing traffic has different characteristics compared with other types of traffic. In particular, as HTTP traffic consists of large number of small sized file transfers (median file size is 10 KB), it can impose high scheduling overhead. As we highlight, HTTP traffic requires that RTT (round trip time) be small and also it requires that large sized flows be allocated higher share of bandwidth. Given these characteristics of HTTP traffic, it is not clear what protocol design for TDMA mesh networks performs best. In this work, we have studied the performance comparison of four different TDMA MAC protocols for HTTP web browsing traffic. Two of these protocols follow distributed scheduling, one centralized and the other naive static fixed schedule approach. We compare the TDMA MAC protocols for various aspects such as optimum values of different TDMA MAC parameters, design of TDMA scheduling algorithm, performance under varying load, in presence of wireless loss, etc. Our study highlights a crucial aspect that the two distributed protocols specified by the recent WiMAX and 802.11s standards, are incapable of handling wireless packet loss and perform poorly in presence of large HTTP file downloads. As against this, the centralized protocol performs well for the different experiment cases that we have considered. However, our analysis reveals that the performance of the centralized protocol can be further improved if we eliminate the flow set-up phase and minimize the delay in propagating the TDMA schedule. Likewise, we carry out required modifications to the centralized protocol and observe that the performance of the modified protocol, which we term as the sf-centralized (set-up free centralized) protocol, improves by as much as 19 percent under moderate load and 47 percent under high load.

TDMA MAC Protocols for WiFi-based Long Distance Networks: A Survey

WiFi is widely being researched to use it beyond its original purpose of short-range communication. These kinds of efforts are stimulated due to its mass production and cost-effectiveness. WiFibased Long Distance (WiLD) networks envisage changing the rural communication scenario particularly in the undeveloped nations. However, CSMA/CA, the de-facto MAC protocol of WiFi, is found to be ill-suited for WiLD networks. As a result, various TDMA-based MAC protocols are proposed in the literature as an alternative to CSMA/CA. The proposed protocols have shown significant performance improvement in such scenarios. In this paper, we propose a classification framework of WiLD MAC protocols based on their major characteristics. Using the classification framework, a survey on the MAC protocols proposed for WiLD networks is presented. The distinctive features of the TDMA MAC protocols are critically examined by pointing out their strengths and weaknesses in WiLD environment. In addition, this paper puts forward some state of art open research challenges in this area.

Performance Analysis of Hybrid MAC Protocol for Cognitive Radio Networks

The rapid growth in demand for broadband wireless services coupled with the recent developmental work on wireless communications technology and the static allocation of the spectrum have led to the artificial scarcity of the radio spectrum. The traditional command and control model (Static allocation) of spectrum allocation policy allows for severe spectrum underutilization. Spectrum allocated to TV operators can potentially be shared by wireless data services, either when the primary service is switched off or by exploiting spatial reuse opportunities. This paper describes a hybrid access scheme based on CSMA/CA and TDMA MAC protocols for use in the TV bands. The approach allows secondary users (SU) to operate in the presence of the primary users (PU) and the OPNET simulation and modelling software has been used to model the performance of the scheme. An analysis of the results shows that, the proposed schemes protect the primary user from harmful Interference from the secondary user. In terms of delay, it was found that packet arrival rates, data rates and the number of secondary users have significant effects on delay.

Soft-TDMAC: A Software-Based 802.11 Overlay TDMA MAC with Microsecond Synchronization

We implement a new software-based multihop TDMA MAC protocol (Soft-TDMAC) with microsecond synchronization using a novel system interface for development of 802.11 overlay TDMA MAC protocols (SySI-MAC). SySI-MAC provides a kernel independent message-based interface for scheduling transmissions and sending and receiving 802.11 packets. The key feature of SySI-MAC is that it provides near deterministic timers and transmission times, which allows for implementation of highly synchronized TDMA MAC protocols. Building on SySI-MAC's predictable transmission times, we implement Soft-TDMAC, a software-based 802.11 overlay multihop TDMA MAC protocol. Soft-TDMAC has a synchronization mechanism, which synchronizes all pairs of network clocks to within microseconds of each other. Building on pairwise synchronization, Soft-TDMAC achieves tight network-wide synchronization. With network-wide synchronization independent of data transmissions, Soft-TDMAC can schedule arbitrary TDMA transmission patterns. For example, Soft-TDMAC allows schedules that decrease end-to-end delay and take end-to-end rate demands into account. We summarize hundreds of hours of testing Soft-TDMAC on a multihop testbed, showing the synchronization capabilities of the protocol and the benefits of flexible scheduling.

Optimal replicator factor control in wireless sensor networks

For TDMA MAC protocols in wireless sensor networks (WSNs), redundancy and retransmission are two important methods to provide high end-to-end transmission reliability. Since reliable transmissions will lead to more en- ergy consumption, there exists an intrinsic tradeoff between transmission reliability and energy efficiency. For each link, we name the number of its reserved time slots in each MAC superframe as a replicator factor. In the following paper, we propose a reliability-lifetime tradeoff framework (RLTF) for WSNs to study replicator factor control problem. First, for the redundancy TDMA MAC, we formulate replicator factor control problem as convex programming. By the gradient pro- jection method, we develop a fully distributed algorithm to solve the convex programming. Second, for the retransmission TDMA MAC, we set the retransmission upper bound for each link according to the optimal replicator factors under the redundancy MAC and compute the total communication overhead for the retransmission MAC. Finally, we compare the communication overhead of these two MAC protocols under different channel conditions.

Battery-dynamics driven tdma mac protocols for wireless body-area monitoring networks in healthcare applications

We propose the cross-layer based battery-aware time division multiple access (TDMA) medium access control (MAC) protocols for wireless body-area monitoring networks in wireless healthcare applications. By taking into account the joint effect of electrochemical properties of the battery, time-varying wireless fading channels, and packet queuing characteristics, our proposed schemes are designed to prolong the battery lifespan of the wireless sensor nodes while guaranteeing the reliable and timely message delivery, which is critically important for the patient monitoring networks. In addition, we develop a Markov chain model to analyze the performance of our proposed schemes. Both the obtained analytical and simulation results show that our proposed schemes can significantly increase the battery lifespan of sensor nodes while satisfying the reliability and delay-bound quality of service (QoS) requirements for wireless body-area monitoring networks. Furthermore, the case study of the electrocardiogram (ECG) monitoring application shows that besides meeting the delay requirements, our proposed schemes outperform the IEEE 802.15.4 and Bluetooth protocols in terms of battery lifespan.

Distributed Multiple Access Control for the Wireless Mesh Personal Area Networks

Mesh networking technologies for both high-rate and low-rate wireless personal area networks (WPANs) are under development by several standardization bodies. They are considering to adopt distributed TDMA MAC protocols to provide seamless user mobility as well as a good peer-to-peer QoS in WPAN mesh. It has been, however, pointed out that the absence of a central controller in the wireless TDMA MAC may cause a severe performance degradation: e.g., fair allocation, service differentiation, and admission control may be hard to achieve or can not be provided. In this paper, we suggest a new framework of resource allocation for the distributed MAC protocols in WPANs. Simulation results show that our algorithm achieves both a fair resource allocation and flexible service differentiations in a fully distributed way for mesh WPANs where the devices have high mobility and various requirements. We also provide an analytical modeling to discuss about its unique equilibrium and to compute the lengths of reserved time slots at the stable point.

Energy considerations for topology-unaware TDMA MAC protocols

Since the energy budget of mobile nodes is limited, the performance of a networking protocol for such users should be evaluated in terms of its energy efficiency, in addition to the more traditional metrics such as throughput. In this paper, two topology-unaware MAC protocols—in which the scheduling time slots are allocated irrespectively of the underline topology—are considered and their energy consumption is derived. It turns out that the per frame power consumption is lower for the less throughput-efficient protocol, suggesting that energy savings are achieved at the expense of throughput. A finer energy consumption study is carried out in the sequel, focusing on the amount of energy consumed to successfully transmit a certain number of packets, or equivalently, on the per successful transmission power consumption. It is shown that the more throughput-efficient protocol consumes less energy per successful transmission under certain conditions (which are derived), due to the lower number of transmission attempts before a data packet is successfully transmitted. The same energy-efficiency relation is observed under certain conditions (which are derived) when data packets are delay constrained and, thus, may become obsolete if not transmitted successfully within a specific time interval. The conditions under which the per successful transmission power consumption is minimized for delay-constrained packets, are also established in this work and it is observed that when the system throughput is maximized, the power consumed is close to the minimum. Simulation results support the claims and the expectations of the aforementioned analysis.

Adaptive framed pseudo-Bayesian Aloha algorithmwith priorities

A new wireless framed pseudo-Bayesian Aloha algorithm with adaptive priorities for wireless ATM reservation-based TDMA MAC protocols, is presented. The throughput, in the presence of Rayleigh fading, shadowing and capture, is calculated and the waiting time of the different priority traffic classes is estimated using simulation models.