Time Division Multiple Access Frame Research Articles

A State-Interactive MAC Layer TDMA Protocol Based on Smart Antennas

Mobile ad hoc networks are self-organizing networks that do not rely on fixed infrastructure. Smart antennas employ advanced beamforming technology, enabling ultra-long-range directional transmission in wireless networks, which leads to lower power consumption and better utilization of spatial resources. The media access control (MAC) protocol design using smart antennas can lead to efficient usage of channel resources. However, during ultra-long-distance transmissions, there may be significant transport delays. In addition, when using the time division multiple access (TDMA) schemes, it can be difficult to manage conflicts arising from adjacent time slot advancement caused by latency compensation in ultra-long-range propagation. Directional transmission and reception can also cause interference between links that reuse the same time slot. This paper proposes a new distributed dynamic TDMA protocol called State Interaction-based Slot Allocation Protocol (SISAP) to address these issues. This protocol is based on slot states and includes TDMA frame structure, slot allocation process, interference self-avoidance strategy, and slot allocation algorithms. According to the simulation results, the MAC layer design scheme suggested in this paper can achieve ultra-long-distance transmission without conflicts. Additionally, it can reduce the interference between links while space multiplexing. Furthermore, the system exhibits remarkable performance in various network aspects, such as throughput and link delay.

Sustainable optimizing WMN performance through meta-heuristic TDMA link scheduling and routing

Wireless mesh networks (WMNs) have become a popular solution for expanding internet service and communication in both urban and rural areas. However, the performance of WMNs depends on generating optimized time-division multiple access (TDMA) schedules, which distribute time into a list of slots called superframes. This study proposes novel meta-heuristic algorithms to generate TDMA link schedules in WMNs using two different interference/constraint models: multi-transmit-receive (MTR) and full-duplex (FD). The objectives of this study are to optimize the TDMA frame for packet transmission, satisfy the constraints, and minimize the end-to-end delay. The significant contributions of this study are: (1) proposing effective and efficient heuristic solutions to solve the NP-complete problem of generating optimal TDMA link schedules in WMNs; (2) investigating the new FD interference model to improve the network capacity above the physical layer. To achieve these objectives and contributions, the study uses two popular meta-heuristics, the artificial bee colony (ABC) and/or genetic algorithm (GA), to solve the known NP-complete problems of joint scheduling, power control, and rate control. The results of this study show that the proposed algorithms can generate optimized TDMA link schedules for both MTR and FD models. The joint routing and scheduling approach further minimizes end-to-end delay while maintaining the schedule's minimum length and/or maximum capacity. The proposed solution outperforms the existing solutions in terms of the number of active links, end-to-end delay, and network capacity. The research aims to improve the efficiency and effectiveness of WMNs in most applications that require high throughput and fast response time.

A Modified Particle Swarm Optimization Approach for Latency of Wireless Sensor Networks

In time-sensitive applications, such as detecting environmental and individual nuclear radiation exposure, wireless sensor networks are employed.. Such application requires timely detection of radiation levels so that appropriate emergency measures are applied to protect people and the environment from radiation hazards. In these networks, collision and interference in communication between sensor nodes cause more end-to-end delay and reduce the network's performance. A time-division multiple-access (TDMA) media access control protocol guarantees minimum latency and low power consumption. It also overcomes the problem of interference. TDMA scheduling problem determines the minimum length conflict-free assignment of slots in a TDMA frame where each node or link is activated at least once. This paper proposes a meta-heuristic centralized contention-free approach based on TDMA, a modified particle swarm optimization. This approach realizes the TDMA scheduling more efficiently compared with other existing algorithms. Extensive simulations were performed to evaluate the modified approach. The simulation results prove that the proposed scheduling algorithm has a better performance in wireless sensor networks than the interference degree leaves order algorithm and interference degree remaining leaves order algorithm. The results demonstrate also that integrating the proposed algorithm in TDMA protocols significantly optimizes the communication latency reduction and increases the network reliability.

Optimal Transmission Scheduling in Small Multimodal Underwater Networks

We describe a scheduling protocol for multimodal networks of relatively limited size, whose nodes encompass various underwater communication technologies. For such a case, we show that significant improvement in the network operations is possible when the transmission schedule is set to jointly utilize all communication technologies. Our solution is based on per-technology time-division multiple access frames, whose time slots are determined optimally to maximize the overall channel utilization while preserving flow limitations and maintaining fairness in resource allocation. Our numerical simulations and experimental results for multimodal networks with several acoustic technologies show that, while maintaining a fair resource allocation, our scheduling solution provides both high throughput and low packet delivery delay.

Node scheduling problem in underwater acoustic sensor network using genetic algorithm

Underwater acoustic sensor network (UWASN) has recently aroused the interest of researchers and scientists in this field. The acoustic sensor bandwidth is limited in underwater and it causes low successful packet transmission. One of the methods to overcome this handicap is efficient broadcast scheduling of underwater acoustic sensor node (UASN) that would help in transmitting and receiving data without any collision. This can be done with the help of time division multiple access (TDMA). The basic idea is to address broadcast scheduling problem in UWASN for utilizing the limited available bandwidth by parallelizing the node transmission such that it does not interfere with each other in same time slot; it also minimizes the node turnaround transmission time in the network by optimizing the time slots in TDMA frame. The objective of this paper is to maximize the utilization of the available underwater acoustic bandwidth and to achieve high throughput as well as to reduce the node turnaround wait time by using an evolutionary genetic algorithm (GA). The simulation results prove that every node in the UWASN transmits in an average minimal turnaround time by minimizing the time slots and maximizing the throughput in the network by scheduling the possible nodes with parallel transmission.

Underwater Acoustic Sensor Node Scheduling using an Evolutionary Memetic Algorithm

Underwater Acoustic Sensor Networks (UWASNs) play an important role in monitoring the aqueous environment which has created a lot of interest for researchers and scientists. Utilization of underwater acoustic sensor node (UASN) scheduling for transmission remains, due to the limited acoustic bandwidth available, a challenge in such an environment. One of the methods to overcome this problem is to efficiently schedule UASN data using time division multiple access (TDMA) protocols the parallel transmissions, simultaneously avoiding interference. The paper shows how to optimize the utilization of acoustic sensor node bandwidth by maximizing the possible node transmissions in the TDMA frame and also by minimizing the node's turnaround wait time for its subsequent transmissions by using an evolutionary memetic algorithm (MA). The simulation of MA-TDMA proves that as the size of the network increases, every node in UWASN transmits with an average minimal turnaround transmission time. It also proves that as the TDMA cycle repeats, the overall network throughput gets maximized by increasing the possible node transmissions in the MA-TDMA frame.

Proportional Fair Scheduling in Wireless Networks With RF Energy Harvesting and Processing Cost

In this letter, we apply the notion of proportional fair (PF) scheduling to wireless powered communication networks, which consist of a base station that broadcasts radio-frequency energy over the downlink [energy harvesting (EH) phase] and EH users that transmit information over the uplink [information transmission (IT) phase]. The doubly near fair problem hinders the fair resource allocation in these networks, but can be successfully overcome by an opportunistic policy for scheduling of a single EHU per time-division multiple access (TDMA) frame. It turns out that the optimal PF scheduling is realized when each TDMA frame consists of either an EH or an IT phase. The proposed online solution is asymptotically optimal but also applicable for a finite number of transmission epochs.

TDMA Scheduling with Leach protocol

In this paper, we propose a solution to the scheduling problem in clustered wireless sensor networks (WSNs). The objective is to provide network-wide optimized time division multiple access (TDMA) schedules that can achieve high power efficiency, zero conflict, and reduced end-to-end delay. To achieve this objective, we first build a nonlinear cross-layer optimization model involving the network, medium access control (MAC), and physical layers, which aims at reducing the overall energy consumption. We solve this problem by transforming the model into two simpler sub problems. Based on the network-wide flow distribution calculated from the optimization model and transmission power on every link, we then propose an algorithm for deriving the TDMA schedules, utilizing the slot reuse concept to achieve minimum TDMA frame length. Numerical results reveal that our proposed solution reduces the energy consumption and delay significantly, while simultaneously satisfying a specified reliability objective.In wireless sensor networks (WSNs), due to the limitation of nodesenergy, energy efficiency is an important factor should beconsidered when the protocols are designing. As a typical representative of hierarchical routing protocols, LEACH Protocol plays an important role. In response to the uneven energy distribution that is caused by the randomness of cluster heads forming , this paper proposes a new improved algorithm ofLEACH protocol (LEACH-TLCH) which is intended to balance the energy consumption of the entire network and extend the life of the network . The new algorithm simulation results indicate that both energy efficiency and the lifetime of the network are better than that of LEACH Protocol.

Data Timed Sending (DTS) Energy Efficient Protocol for Wireless Sensor Networks: Simulation and Testbed Verification

The Data Timed Sending (DTS) protocol contributes to the energy savings in Wireless Sensor Networks (WSNs) and prolongs the sensor nodes’ battery lifetime. DTS saves energy by transmitting short packets, without data payload, from the sensor nodes to the base station or the cluster head according to the Time Division Multiple Access (TDMA) scheduling. Placing the short packets into appropriate slots and subslots in the TDMA frames transfers the information about the measured values and node identity. This paper presents the proof of concept of the proposed DTS protocol and provides verification of the energy savings using the QualNet®; communication simulation platform (QualNet) and the SunTM Small Programmable Object Technology (Sun SPOT) testbed platform (for single hop and multi hop scenarios). The simulations and the testbed measurements confirm that the DTS protocol can provide energy savings up to 30% when compared with the IEEE 802.15.4 standard in unslotted Carrier Sense Multiple Access with Collision Avoidance (CSMA-CA) mode at 2.4 GHz frequency band.

Broadcast Scheduling Problem in TDMA Ad Hoc Networks using Immune Genetic Algorithm

In this paper, a new efficient immune genetic algorithm (IGA) is proposed for broadcast scheduling problem in TDMA Ad hoc network. Broadcast scheduling is a primary issue in wireless ad hoc networks. The objective of a broadcast schedule is to deliver a message from a given source to all other nodes in a minimum amount of time. Broadcast scheduling avoids packet collisions by allowing the nodes transmission that does not make interference of a time division multiple access (TDMA) ad hoc network. It also improves the transmission utilization by assigning one transmission time slot to one or more non-conflicting nodes such a way that every node transmits at least once in each TDMA frame. An optimum transmission schedule could minimize the length of a TDMA frame while maximizing the total number of transmissions. The aim of this paper is to increase the number of transmissions in fixed Ad hoc network with time division multiple access (TDMA) method, with in a reduced time slot. The results of IGA are compared to the recently reported algorithms. The simulation result indicates that IGA performs better even for a larger network.

Minimizing Power Cost in QoS Constrained Wireless Sensor Networks

This paper studies the problem of simultaneous support of energy efficiency and quality of service (QoS) in time division multiple access (TDMA) based wireless sensor networks (WSNs), utilizing the concept of cross-layer optimization. We show that by taking slot reuse into account, the problem has combinatorial complexity, which is determined by the TDMA frame length and the number of links. An iterative reuse factor (IRF) approach is proposed to efficiently solve the problem. By skillfully introducing and iteratively adjusting a slot reuse factor, cross-layer optimization and slot reuse are jointly inter-connected to obtain a TDMA schedule with optimal power consumption and desired QoS objectives in polynomial time. Extensive simulations with a random topology WSN show that the proposed IRF approach provides a flexible tradeoff between energy efficiency and QoS objectives. Under the same packet loss rate objective, the IRF approach achieves up to 30 % of power saving compared to the existing approaches in the literature.

Towards probabilistic arbitration in sensors integration

PurposeThe purpose of this paper is to model an important aspect of the problem of sensor information integration that arises in wireless communications, where N sensors try to communicate with a receiver using a single un‐shareable radio channel. If several sensors transmit at the same time, their transmissions collide at the receiver resulting in garbled messages and the need for re‐transmission. This is highly undesirable since the sensors are energy‐constrained and the radio interface is known to be the most significant source of energy expenditure. Consequently, it is of paramount importance to design arbitration protocols that are highly efficient in stamping out collisions and that are, at the same time, as lightweight as possible.Design/methodology/approachThe receiver advertises a time division multiple access (TDMA) frame consisting of n slots, numbered from 1 to n, where n is an application‐dependent parameter. Each sensor generates uniformly at random, and independently of other sensor, an integer i between 1 and n and transmits in the i‐th slot of the TDMA frame. If two or more sensors are transmitting in the same slot their messages will be lost to collision. Similarly, slots that carry no transmission are wasted. The authors model the arbitration strategy discussed above as a Bose‐Einstein occupancy problem where N indistinguishable balls are thrown at random into n distinguishable bins and all distinguishable outcomes are considered to be equally likely.FindingsIn this paper the authors present a distributed probabilistic mechanism that aims to arbitrate between several competing requests by various sensors for the radio channel. The mechanism is simple, energy‐efficient and does not rely on the existence of unique sensor identifiers (IDs).Originality/valueThe Bose‐Einstein occupancy model presented in this paper will help the receiver to tailor an appropriate number of timeslots in TDMA frame during the integration process, such that collisions are minimized, and hence integration between sensors can be done effectively.

Cross-Layer Optimization for Multimedia Transport over Multicode CDMA Networks

Most previous work on code division multiple access (CDMA) considers the bit error ratio (BER) at the physical layer and the frame drop ratio (FDR) at the medium access control layer separately. However, a better system performance, e.g., in terms of a lower overall frame loss ratio (FLR), can be achieved if BER and FDR are jointly optimized. In this paper, we propose a cross-layer optimization scheme called traffic-adaptive scheme for multicode CDMA operating over a time division multiple access (TDMA) channel. Based on the traffic condition and buffer status, this scheme employs a Markov Decision Process (MDP) to determine the optimal value of the maximum number of simultaneous data frames that can be transmitted in each time slot of a TDMA frame so as to minimize the overall FLR of the system. To facilitate implementation, we also propose an approximation scheme named the rate-adaptive scheme to reduce the computation cost. Simulation and analytical results show that both the traffic-adaptive scheme and rate-adaptive scheme can significantly reduce FLR, increase the system throughput, and optimize the packet access delay of the system. Furthermore, the rate-adaptive scheme can achieve a performance close to the traffic-adaptive scheme when the traffic load in the system is high.

A Learning Automata-Based Cognitive Radio for Clustered Wireless Ad-Hoc Networks

In current wireless networks, the radio systems are regulated by a fixed spectrum assignment strategy. This policy partitions the whole radio spectrum into a fixed number of radio ranges, each exclusively assigned to a specific user. Such a spectrum assignment strategy leads to an undesirable condition under which some systems only use a small portion of the allocated spectrum while the others have very serious spectrum insufficiency. The learning automata-based cognitive radio which is proposed in this paper is a highly potential technology to address the spectrum scarcity challenges in wireless ad hoc networks. This paper proposes a learning automata-based dynamic frame length TDMA scheme for slot assignment in clustered wireless ad-hoc networks with unknown traffic parameters, where the intra-cluster communications are scheduled by a TDMA scheme, and a CDMA scheme is overlaid on the TDMA to handle an interference-free inter-cluster communication. In this method, each cluster-head is responsible for a collision-free slot assignment within the cluster and determines the input traffic parameters of its own cluster members. It then takes these traffic parameters into consideration for an optimal channel access scheduling in the cluster. The medium access control layer in each cluster is based on a time division multiple access (TDMA) scheme, in which each host is assigned a fraction of the TDMA frame proportional to its traffic load. The simulation experiments show the superiority of our proposed slot assignment algorithm over the existing methods in terms of the channel utilization, control overhead, and throughput, specifically, under bursty traffic conditions.

Novel Hysteretic Noisy Chaotic Neural Network for Broadcast Scheduling Problems in Packet Radio Networks

Noisy chaotic neural network (NCNN), which can exhibit stochastic chaotic simulated annealing (SCSA), has been proven to be a powerful tool in solving combinatorial optimization problems. In order to retain the excellent optimization property of SCSA and improve the optimization performance of the NCNN using hysteretic dynamics without increasing network parameters, we first construct an equivalent model of the NCNN and then control noises in the equivalent model to propose a novel hysteretic noisy chaotic neural network (HNCNN). Compared with the NCNN, the proposed HNCNN can exhibit both SCSA and hysteretic dynamics without introducing extra system parameters, and can increase the effective convergence toward optimal or near-optimal solutions at higher noise levels. Broadcast scheduling problem (BSP) in packet radio networks (PRNs) is to design an optimal time-division multiple-access (TDMA) frame structure with minimal frame length, maximal channel utilization, and minimal average time delay. In this paper, the proposed HNCNN is applied to solve BSP in PRNs to demonstrate its performance. Simulation results show that the proposed HNCNN with higher noise amplitudes is more likely to find an optimal or near-optimal TDMA frame structure with a minimal average time delay than previous algorithms.

TDMA Scheduling with Optimized Energy Efficiency and Minimum Delay in Clustered Wireless Sensor Networks

In this paper, we propose a solution to the scheduling problem in clustered wireless sensor networks (WSNs). The objective is to provide network-wide optimized time division multiple access (TDMA) schedules that can achieve high power efficiency, zero conflict, and reduced end-to-end delay. To achieve this objective, we first build a nonlinear cross-layer optimization model involving the network, medium access control (MAC), and physical layers, which aims at reducing the overall energy consumption. We solve this problem by transforming the model into two simpler subproblems. Based on the network-wide flow distribution calculated from the optimization model and transmission power on every link, we then propose an algorithm for deriving the TDMA schedules, utilizing the slot reuse concept to achieve minimum TDMA frame length. Numerical results reveal that our proposed solution reduces the energy consumption and delay significantly, while simultaneously satisfying a specified reliability objective.

Getting the most of WiFi mesh networks with 802.16 mesh emulation

Currently deployed wireless mesh networks are based on 802.11, WiFi technology, which is not efficient in multihop scenarios. We present a method, which emulates 802.16 mesh networks over 802.11 hardware. The method works by embedding 802.16 packets into 802.11 broadcast packets and padding the 802.11 broadcast payload, so that the broadcasts are aligned to 802.16 time division multiple access frame boundaries. The method requires only software changes on the nodes using 802.11a for mesh communications. This means that the mesh networks installed with 802.11a hardware today can be upgraded with a software patch to take advantage of quality-of-service available in 802.16. We use ns2 simulations to show the performance of the 802.11 based mesh networks with the embedded 802.16. We show that the hybrid system can achieve throughputs in multiples of what is possible with 802.11 hardware alone. First, the efficiency of the new system is significantly higher than the efficiency of 802.11 based systems, because we use broadcast packets. Second, the new system eliminates unnecessary collisions in the wireless channel since it takes advantage of scheduled wireless access with 802.16 mesh coordination function.

Dynamic resource allocation for DVB‐RCS networks

AbstractTo provide high‐speed multimedia services using the digital video broadcasting‐return channel satellite (DVB‐RCS) standard, it is imperative to efficiently assign timeslots according to user demands and dynamically take into account the variations of the propagation conditions. In satellite networks operating above 10 GHz, rain fading constitutes the dominant factor deteriorating the quality of service. In this paper, a novel two‐phase resource allocation scheme for a DVB‐RCS compliant satellite network is proposed. The scheme operates in two phases, the resource calculation and the resource assignment. In the resource calculation phase, based on a dynamic channel model, an efficient algorithm is presented to determine the superframe design that maximizes system throughput. In the resource assignment phase, a novel Hybrid Bin‐packing algorithm is introduced maximizing the utilization of the multi‐frequency time division multiple access frame. The proposed algorithm has been compared with existing schemes exhibiting significantly better results with regard to overall system throughput. Copyright © 2008 John Wiley & Sons, Ltd.

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.

A Gradual Noisy Chaotic Neural Network for Solving the Broadcast Scheduling Problem in Packet Radio Networks

In this paper, we propose a gradual noisy chaotic neural network (G-NCNN) to solve the NP-complete broadcast scheduling problem (BSP) in packet radio networks. The objective of the BSP is to design an optimal time-division multiple-access (TDMA) frame structure with minimal TDMA frame length and maximal channel utilization. A two-phase optimization is adopted to achieve the two objectives with two different energy functions, so that the G-NCNN not only finds the minimum TDMA frame length but also maximizes the total node transmissions. In the first phase, we propose a G-NCNN which combines the noisy chaotic neural network (NCNN) and the gradual expansion scheme to find a minimal TDMA frame length. In the second phase, the NCNN is used to find maximal node transmissions in the TDMA frame obtained in the first phase. The performance is evaluated through several benchmark examples and 600 randomly generated instances. The results show that the G-NCNN outperforms previous approaches, such as mean field annealing, a hybrid Hopfield network-genetic algorithm, the sequential vertex coloring algorithm, and the gradual neural network.