Distributed Time Division Multiple Access Research Articles

A novel distributed multi-slot TDMA-based MAC protocol for LED-based UOWC networks

Underwater optical wireless communication (UOWC) networks are promising for many civilian and industrial applications due to underwater high-speed data transmission demand. This paper focuses on the distributed time division multiple access (TDMA) protocol design for UOWC networks. Unlike existing research, we focus on a more general underwater communication scenario where nodes are scattered, and node mobility is considered. We propose a distributed TDMA-based medium access control(MAC) protocol, called cluster-based cross-layer multi-slot MAC(CCM-MAC), which can assign multiple slots to each node according to the slot-occupying information. When using CCM-MAC, the network is divided into clusters. Each node maintains knowledge of the cluster topology and slot-occupying information of surrounding nodes through routing techniques; by updating this knowledge, collisions can also be detected and eliminated dynamically. Analysis results are presented to evaluate the performance of CCM-MAC, and simulations show that high network throughput and low collision rate can be realized in comparison with existing contention-based MAC protocols.

Incorporation of Energy Efficient Computational Strategies for Clustering and Routing in Heterogeneous Networks of Smart City

For decision-making and governance, smart cities depend on tracking data collected via a substantial percentage of wireless sensing nodes. However, several limitations affect Wireless Sensor Network (WSN)-based Internet of Things (IoT) services, such as low battery life, recurrent connectivity problems due to multi-hop connections, and a limited channel capacity. Furthermore, in many systems, clustering and routing are handled independently, which prevents the adaptation of effective strategies for optimal energy usage and prolonged network lifespan. This research gathers data from heterogeneous IoT nodes linked via WSN and distributed across a smart infrastructure. There are two interrelated problems to be addressed with respect to energy efficiency computations: clustering and routing. We provide a new clustering strategy through which efficient routing of critical and regular data is handled. As a result, both clustering and routing have been significantly strengthened, which balances the communication load across different sectors of the smart infrastructure network. Minkowski distance and ranking strategy are used for routing and selecting cluster heads, respectively. Deterministic distributed–time division multiple access (DD-TDMA) scheduling is employed to balance the communication load across the network. The experimental results show that the proposed work outperforms some of the popular cluster-based routing strategies.

Distributed Time Division Multiple Access Protocol Based on Energy Harvesting

Distributed Time Division Multiple Access Protocol Based on Energy Harvesting

BLAS: Broadcast Relative Localization and Clock Synchronization for Dynamic Dense Multiagent Systems

The spatiotemporal information plays crucial roles in a multi-agent system (MAS). However, for a highly dynamic and dense MAS in unknown environments, estimating its spatiotemporal states is a difficult problem. In this paper, we present BLAS: a wireless broadcast relative localization and clock synchronization system to address these challenges. Our BLAS system exploits a broadcast architecture, under which a MAS is categorized into parent agents that broadcast wireless packets and child agents that are passive receivers, to reduce the number of required packets among agents for relative localization and clock synchronization. We first propose an asynchronous broadcasting and passively receiving (ABPR) protocol. The protocol schedules the broadcast of parent agents using a distributed time division multiple access (D-TDMA) scheme and delivers inter-agent information used for joint relative localization and clock synchronization. We then present distributed state estimation approaches in parent and child agents that utilize the broadcast inter-agent information for joint estimation of spatiotemporal states. The simulations and real-world experiments based on ultra-wideband (UWB) illustrate that our proposed BLAS cannot only enable accurate, high-frequency and real-time estimation of relative position and clock parameters but also support theoretically an unlimited number of agents.

An Efficient Broadcast Scheme for Safety-Related Services in Distributed TDMA-Based VANETs

The medium access control (MAC) protocol should provide an efficient broadcast service to support the high-priority safety applications in vehicular ad hoc networks (VANETs). Basic safety messages (BSMs) transmitted through vehicle-to-vehicle and vehicle-to-infrastructure architectures are the most fundamental of these applications. The periodic transmission of BSMs results in a heavy burden on the load of the VANETs when traffic density is high, and the presence of hidden terminals degrade the performance of the network. This letter introduces a distributed time division multiple access (TDMA)-based scheme that controls the transmission range to improve the efficiency of BSM transmissions in VANETs. The transmission collisions can be reduced without lowering the awareness quality of the surrounding nodes at a close range. Meanwhile, merging collisions can be pre-detected and eliminated by cooperation among the nodes. Simulation results demonstrate that our strategies can provide an efficient and reliable BSM broadcast service.

Enhancing Transmission Collision Detection for Distributed TDMA in Vehicular Networks

The increasing number of road accidents has led to the evolution of vehicular ad hoc networks (VANETs), which allow vehicles and roadside infrastructure to continuously broadcast safety messages, including necessary information to avoid undesired events on the road. To support reliable broadcast of safety messages, distributed time division multiple access (D-TDMA) protocols are proposed for medium access control in VANETs. Existing D-TDMA protocols react to a transmission failure without distinguishing whether the failure comes from a transmission collision or from a poor radio channel condition, resulting in degraded performance. In this article, we present the importance of transmission failure differentiation due to a poor channel or due to a transmission collision for D-TDMA protocols in vehicular networks. We study the effects of such a transmission failure differentiation on the performance of a node when reserving a time slot to access the transmission channel. Furthermore, we propose a method for transmission failure differentiation, employing the concept of deep-learning techniques, for a node to decide whether to release or continue using its acquired time slot. The proposed method is based on the application of a Markov chain model to estimate the channel state when a transmission failure occurs. The Markov model parameters are dynamically updated by each node (i.e., vehicle or roadside unit) based on information included in the safety messages that are periodically received from neighboring nodes. In addition, from the D-TDMA protocol headers of received messages, a node approximately determines the error in estimating the channel state based on the proposed Markov model and then uses this channel estimation error to further improve subsequent channel state estimations. Through mathematical analysis, we show that transmission failure differentiation, or transmission collision detection, helps a node to efficiently reserve a time slot even with a large number of nodes contending for time slots. Furthermore, through extensive simulations in a highway scenario, we demonstrate that the proposed solution significantly improves the performance of D-TDMA protocols by reducing unnecessary contention on the available time slots, thus increasing the number of nodes having unique time slots for successful broadcast of safety messages.

Distributed and Adaptive Medium Access Control for Internet-of-Things-Enabled Mobile Networks

In this paper, we propose a distributed and adaptive hybrid medium access control (DAH-MAC) scheme for a single-hop Internet of Things (IoT)-enabled mobile ad hoc network supporting voice and data services. A hybrid superframe structure is designed to accommodate packet transmissions from a varying number of mobile nodes generating either delay-sensitive voice traffic or best-effort data traffic. Within each superframe, voice nodes with packets to transmit access the channel in a contention-free period (CFP) using distributed time division multiple access, while data nodes contend for channel access in a contention period (CP) using truncated carrier sense multiple access with collision avoidance. In the CFP, by adaptively allocating time slots according to instantaneous voice traffic load, the MAC exploits voice traffic multiplexing to increase the voice capacity. In the CP, a throughput optimization framework is proposed for the DAH-MAC, which maximizes the aggregate data throughput by adjusting the optimal contention window size according to voice and data traffic load variations. Numerical results show that the proposed MAC scheme outperforms existing quality-of-service-aware MAC schemes for voice and data traffic in the presence of heterogeneous traffic load dynamics.

Toward In-Band Self-Organization in Energy-Efficient MAC Protocols for Sensor Networks

This paper presents a self-organizing medium access control (MAC) protocol framework for distributed sensor networks with arbitrary mesh topologies. The novelty of the proposed In-band self-organized MAC (ISOMAC) protocol lies in its in-band control mechanism for exchanging time-division multiple access (TDMA) slot information with distributed MAC scheduling. A fixed-length bitmap vector is used in each packet header for exchanging relative slot timing information across immediate and up to two-hop neighbors. It is shown that, by avoiding explicit timing information exchange, ISOMAC can work without networkwide time synchronization, which can be prohibitive for severely cost-constrained sensor nodes in very large networks. A slot-clustering effect, caused by in-band bitmap constraints, enables ISOMAC to offer better spatial channel reuse compared to traditional distributed TDMA protocols. ISOMAC employs a partial node wake-up and header-only transmission strategy to adjust energy expenditure based on the instantaneous nodal data rate. Both analytical and simulation models have been developed for characterizing the proposed protocol. Results demonstrate that, with in-band bitmap vectors of moderate length, ISOMAC converges reasonably quickly, that is, approximately within a four to eight TDMA frame duration. Also, if the bitmap header duration is restricted within 10 percent of packet duration, then the energy penalty of the in-band information is quite negligible. It is also shown that ISOMAC can be implemented in the presence of network time synchronization, although its performance without synchronization is just marginally worse than that with synchronization.

Time-synchronized Forwarding Protocol for Remote Control of Home Appliances Based on Wireless Sensor Network

This paper presents a time synchronized forwarding protocol for remotely controlling home appliances connected to wireless sensor networks (WSNs) that have extremely large latency for transferring data to another node. The protocol basically uses distributed time division multiple access (TDMA) and provides scalability by a self-organization function based on a virtual sensor line. Time synchronized forwarding and self organization protocols using virtual sensor lines achieve not only low latency but also low power consumption for future consumer applications .

Ad hoc on demand multipath distance vector routing (AOMDV) over a distributed TDMA MAC protocol for QoS support in wireless ad hoc networks: integration issues and performance evaluation

AbstractThis paper focuses on the problem of QoS multi‐path in wireless ad hoc networks. An integration of a novel multi‐path routing protocol and a distributed time division multiple access (TDMA) MAC protocol is proposed. The MAC considered is called evolutionary TDMA (E‐TDMA) and the analysed multi‐path routing protocol is the ad hoc on demand multi‐path distance vector (AOMDV) protocol. The integrated approach multi‐path routing and TDMA MAC protocol offers advantages typical of multi‐path routing, in terms of reduced route discovery frequency and increased throughput. The advantage of the E‐TDMA MAC is a higher throughput in comparison with the standard IEEE 802.11 MAC and the reduction of the contention interference due to the slot reservation mechanism for high‐data traffic. Two schemes to build the multi‐route are exploited. The simulation results show the benefits of the integrated routing‐MAC protocol in terms of reduced overhead, higher throughput and reduced end‐to‐end delay for a scenario with very high mobility and heavy data traffic. Copyright © 2006 AEIT