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VoWiFi Cell Capacity Evaluation using WiFi 7 considering VBR Traffic

Deployment for Wireless Local Area Network (WLAN) technology is experiencing substantial growth. The transmission of Voice over WiFi (VoWiFi) is half-duplex due to its single-talk nature. In order to mitigate the inefficient utilization of available bandwidth, the technique of silent suppression is employed. This feature decreases the level of ambient noise and provides Variable Bit Rate (VBR) communication. To enhance the VoWiFi cell capacity, we utilized VBR traffic instead of Constant Bit Rate (CBR) traffic. In this study, we developed a mathematical model to find the number of VoWiFi users possible within a WLAN Access Point (AP) considering G.729 vocoder. Arbitration inter-frame space (AIFS) has been utilized in our study to evaluate the channel state prior to transmitting real-time data between user equipment (UE) devices. Additionally, short inter-frame spacing (SIFS) has been employed to transmit Request To Send (RTS)/Clear To Send (CTS) and Acknowledgement (ACK) frames, enabling an examination of the VoWiFi cell capacity. Again, to increase the VoWiFi cell capacity, we incorporated the compressed RTP (cRTP) protocol. Further, we conducted an analysis on the impact of retransmission on VoWiFi cell capacity. This analysis involved a comparison of the results using VBR traffic with the previous WLAN standards, namely IEEE 802.11b/g/n/ac/ax. We observed that the improvement in VoWiFi cell capacity in VBR traffic is approximately 2.6 times more than the CBR traffic. Further, our research revealed that the enhancement in VoWiFi cell capacity is approximately 1.5% higher when utilizing AIFS compared to Distributed Coordination Function (DCF) inter-frame spacing (DIFS).

A Collision Avoidance Based Energy Efficient Medium Access Control Protocol for Clustered Underwater Wireless Sensor Networks

Underwater Wireless Sensor Networks (UWSNs) are typically deployed in energy constrained environments where recharging energy sources and replacing batteries are not viable. This makes energy efficiency in UWSNs a crucial directive to be followed during Medium Access Control (MAC) design. Multiplexing and scheduling based protocols are not ideal for UWSNs because of their strict synchronization requirements, longer latencies and constrained bandwidth. This paper presents the development and simulation analysis of a novel cross-layer communication based MAC protocol called Energy Efficient Collision Avoidance (EECA) MAC protocol. EECA-MAC protocol works on the principle of adaptive power control, controlling the transmission power based on the signal strength at the receiver. EECA-MAC enhances the conventional 4-way handshake to reduce carrier sensing by implementing an enhanced Request to Send (RTS) and Clear to Send (CTS) handshake and an improved back-off algorithm. Simulation analysis shows that the measures taken to achieve energy efficiency have a direct effect on the number of packet retransmissions. Compared to the Medium Access with Collision Avoidance (MACA) protocol, EECA-MAC shows a 40% reduction in the number of packets that are delivered after retransmissions. This reduction, coupled with the reduced signal interference, results in a 16% drop in the energy utilized by the nodes for data transmission.

TDMA-clustering-based approach to avoid the reader-to-tag collision problem during the stocktaking process

Abstract The reader-to-tag collision problem occurs when multiple readers try to access the same tag simultaneously. The traditional collision avoidance techniques such as RTS (request to send) and CTS (clear to send) are not applicable because a reader may communicate with multiple tags simultaneously. In this paper, we introduce a collaborative communication protocol to avoid reader-to-tag collisions using TDMA and clustering approaches. The protocol targets the RFID-WSN static systems arranged in a square grid topology, which we can find in different RFID applications such as warehouse stocktaking, parking cars, agricultural fields, and libraries. In such simple topologies, the other proposed reader collision solutions for general use of RFID systems are not efficient since they cannot avoid all possible collisions, and worse of that, some of them are not even detectable, which is intolerable for stocktaking applications. Moreover, they are complicated and heavy in resources, while read throughput is limited. Our protocol presents a simple solution for simple RFID systems with better performances. To validate the proposed protocol, we presented a model using the Process Meta Language (Promela), which is executed under the simple Promela interpreter (SPIN) model checker to verify the protocol properties as deadlocks and livelocks. Also as a proof of concept, we have done a first-step performance analysis using the java runtime.

A Bidirectional Buck-Boost Converter-Based Switching Ripple Communication Strategy for Intelligent Street Lighting Systems

Abstract The light-emitting diode (LED) is an essential component of intelligent street lighting (ISL) systems. An efficient ISL system can not only reduce power consumption by planning LED illuminating time but also reduce maintenance costs through a high degree of automation. In this paper, a buck-boost converter is used to realise composite transmission of power and signals for an ISL system. The power is modulated by the pulse width modulation (PWM) approach, and the switching ripple generated in the PWM process is utilised as the carrier of the signals transmitted between the remote-control centre and the slave nodes. Moreover, the proposed model involves a ‘request to send (RTS)/confirm to send (CTS)’ mechanism to avoid signal conflicts. Compared with the conventional power line communication (PLC) approach, the proposed transmission scheme has the advantages of simple circuit structure and simple system wiring. Additionally, a simulation model built in MATLAB/Simulink proves the designed transmission method has strong anti-noise ability.

CFFD-MAC: A Hybrid MAC for Collision Free Full-Duplex Communication in Wireless Ad-Hoc Networks

Infrastructure-less (sometimes known as ad-hoc) networking paradigm is very appealing and potentially shaping its future into almost all emerging networks (i.e., IoT, wireless sensor networks, vehicular ad-hoc networks, emergency, and tactical radio networks, etc.). However, when conventional networking protocols are used, such networks often perform poorly, mainly because of interference within the network and limited network throughput. Recent advancements in wireless communications have enabled full-duplex (FD) operation by suppressing self-interference, which can theoretically double the network throughput. However, conventional medium access control (MAC) protocols like carrier-sense multiple access with collision avoidance (CSMA/CA) favor half-duplex (HD) operation and fail to benefit from FD transmission opportunities. This article proposes a novel hybrid MAC protocol for full-duplex ad-hoc networks. The proposed MAC combines time division multiple access (TDMA) and IEEE 802.11 distributed coordination function (DCF) strengths in chains of time-slotted contention-based control frames and collision-free data frames. The aim is to fully utilize FD transmission opportunities to increase network throughput. The proposed protocol modifies request-to-send (RTS) and clear-to-send (CTS) frames in IEEE 802.11 DCF MAC to form FD-RTS/CTS frames. These frames are used to enable collision-free FD communications among neighbors. The proposed scheme mitigates conventional MAC issues like hidden-node problem (HNP) and exposed-node problem (ENP). It also allows concurrent FD data transmissions in a collision-free manner. The model is generic and can be applied to any ad-hoc wireless network. In this article, the design is applied to a single channel ad-hoc network with FD transceivers. We compared the proposed design with IEEE 802.11 CSMA/CA protocol with both HD and FD transceivers. The simulation results show a 30% gain in throughput, reduced latency, and fairness among participating wireless nodes.

Performance Analysis of DCF- Two Way Handshake vs RTS/CTS During Train-Trackside Communication in CBTC based on WLAN802.11b

Background:Wireless Local Area Network (WLAN) is used primarily in CBTC because of easy availability of commercial WLAN equipment. In present scenario, WLAN Medium Access Control (MAC) protocol is a well-known protocol which is used to satisfy real-time traffic and delay- sensitive applications. The bidirectional train-trackside communication is the fundamental key of train control in CBTC.Methods:DCF describes two basic techniques used for packet transmission: First technique is a Two Way Handshake (TWH) mechanism and another is Four Way Handshake (FWH) mechanisms. RTS/CTS FWH protocol specified by IEEE802.11b is introduced to rectify the Hidden Node Problem (HNP) encounters in TWH protocol. That is why the TWH mechanism of DCF technique suffers from higher average packet delay time when this protocol is applied to CBTC. DCF- Four Way Handshake (FWH), Request To Send (RTS) and Clear To Send (CTS) delay model is proposed to develop Communication Based Train Control (CBTC) system.Results:FWH is applied in CBTC to overcome the packet delay and throughput limitations of Two Way Handshake (TWH) mechanism of distributed coordination function (DCF) based technique. An experiment is designed to simulate and compare the performance of RTS/CTS delay model against TWH mechanism of DCF.Conclusion:It was found that the Average packet delay is slightly higher and throughput is lesser in RTS/CTS in comparison to TWH method. By comparing the performance of these two medium access mechanism in CBTC it was found that for multiple retransmissions with various data rates the RTS/CTS model had better packet delay time than TWH.

STATISTICAL MARKOV MODEL BASED NATURAL INSPIRED GLOWWORM SWARM MULTI-OBJECTIVE OPTIMIZATION FOR ENERGY EFFICIENT DATA DELIVERY IN MANET

An interference and collision is a significant problem to be solved in Mobile Ad Hoc Network (MANET). Few techniques were developed in existing work to perform energy aware routing in MANET. But, handling both interference and collision on route path was remained open issues which increases the energy usage and reduces the throughput of MANET. In order to overcome such limitations, Statistical Markov Model Based Natural Inspired Glowworm Multi-objective Optimization (SMM-NIGMO) technique is proposed. The SMM-NIGMO technique contains three key processes namely interference prediction, optimal node selection, route path identification. The SMM-NIGMO technique at first proposes a Statistical Markov Model to determine the interference level of each mobile node in MANET at the time ‘ ’. After that, SMM-NIGMO Technique designs a Natural Inspired Glowworm Swarm Multi-Objective Optimization (NIGSMO) algorithm to carry out the optimal node selection process in MANET. During this process, SMM-NIGMO Technique finds the mobile nodes with lower inferences and higher residual energy as optimal in dynamic environment. After discovering the best nodes, SMM-NIGMO Technique uses the Request-To-Send (RTS) and Clear-To-Send (CTS) mechanism for identifying the best route path in MANET. During the route path finding process, SMM-NIGMO Technique selects the mobile node to transmit the packets to destination without any collisions. As a result, SMM-NIGMO Technique enhances the performance of energy efficient data delivery in MANET as compared to existing works. The simulation of SMM-NIGMO Technique is performed using parameters such as throughput, energy consumption, packet loss rate and end to end delay. The simulation result depicts that the SMM-NIGMO Technique is able to improve the throughput and also reduces the energy consumption of data transmission in MANET as compared to state-of-the-art works.

Byteless CTS for passive load balancing in 802.11 networks

Load balancing in 802.11 networks is aimed at distributing traffics among access points (APs) to avoid overloaded access. Existing works may be classified into passive and active algorithms depending on the Ethernet changes in the user side. Since Ethernet 802.11 has been installed in millions of computers, changes in these user premises are not preferred. Software intervention on manufactured access points should also be kept as minimum as possible. Therefore, this work proposes a passive load balancing algorithm that transmitting byteless clear to send (CTS) signal in response to a request to send (RTS) sent by unwanted users when AP experiences overloaded. This method causes excessive users will passively be encouraged to find an alternative AP. There is no Ethernet change on the user side. Minor improvement is required in AP software to determine whether overload or not, and to decide which node(s) receiving byteless CTS. Evaluations show that average throughput to all connected users decreases as unwanted users failed to transmit. However, the average throughput to prioritized users increases significantly.

Packet Delivery Ratio Fingerprinting: Toward Device-Invariant Passive Indoor Localization

Passive indoor localization for mobile Wi-Fi devices, e.g., smartphones, has attracted increasing attention from research communities recently. Existing passive localization techniques leverage received signal strength (RSS) of packets transmitted by target Wi-Fi devices and do not require a dedicated software installed on the devices. However, RSS-based passive localization techniques: 1) are device dependent, which results in poor localization accuracy for a wide variety of mobile devices and 2) cannot perform real-time passive localization. In this article, we present a novel passive localization technique, namely, packet delivery ratio (PDR) fingerprinting, to address these problems. In PDR fingerprinting, the lowest-power and highest-modulation scheme (LPHMS) is proposed to generate device-invariant PDR, which replaces RSS to construct fingerprints, to achieve device-invariant localization accuracy. Moreover, instead of passively monitoring packets rarely sent by mobile devices, in PDR fingerprinting, access points (APs) actively transmit request-to-send (RTS) frames to trigger target devices to reply clear-to-send (CTS) frames to calculate PDR. The RTS/CTS mechanism enables PDR fingerprinting to perform real-time localization. We have conducted extensive experiments in a real-world testbed. The experimental results demonstrate that PDR fingerprinting presents a competitive localization accuracy compared to RSS-based passive fingerprinting methods but is device invariant.

Efficient RTS and CTS Mechanism Which Save Time and System Resources

It is a well-known fact that the forthcoming names are distinctively different: interference range, career sense, and transmission. The given paper reveals the underlying study of disengagement of a request to send (RTS)/ clear to send (CTS) dialog. It was basically adopted under the influence of both; the presence of distributed coordination function of IEEE 802.11 and a sub-layer protocol which is called media access control (MAC) protocol. The demonstration was seen when applying a type of traffic flows such as Constant Bit Rate (CBR), Transmission Control Protocol (TCP), and besides User Datagram Protocol (UDP). When these are applied the output performance in term of throughput shows a very linear topology configuration of the network. To sum up, a new RTS /CTS mechanism was proposed based on the results obtained from the above suggestions. The detailing for the new mechanism showed that a terminal node will be responsible for deciding if it is authorized to use an RTS/CTS protocol dialog to send one of its packets or not. Needless to say, this process will be dynamic in nature.

DCN-MAC: A Dynamic Channel Negotiation MAC Mechanism for Underwater Acoustic Sensor Networks.

In the design of media access control (MAC) mechanism in underwater acoustic sensor networks (UASNs), due to the propagation characteristic of low-speed underwater acoustic signals, it is necessary to solve the spatial–temporal uncertainty problem. In order to avoid the multi-user access conflict in underwater networks, reduce the energy cost and improve the throughput and fairness across the network, a dynamic channel negotiation MAC mechanism based on spatial–temporal mapping of receiving queue (DCN-MAC) was proposed. DCN-MAC uses a duty cycle mechanism and implements a network management based on dynamic single node wake-up. The awakening node collects the request to send (RTS) and network status information in the network to solve the problem of space-temporal uncertainty and the highly dynamic needs of network access nodes and access services. The simulation results show that in different network scenarios, especially in those featuring high density and heavy network load, compared with the traditional underwater acoustic network MAC protocols, this protocol can effectively improve the network throughput and reduce the packet loss probability caused by multi-node conflict.

RTS Threshold Variation Study on Contention-based IEEE 802.11n EDCA for Real-time Services

As a “wide-deployed” wireless local area networks (WLANs) standard, the IEEE 802.11n was designed to support a high data transmission rate (up to 600 Mbps) and maintain a compatibility with the previous versions. Due to a substantial demand of real-time data services, such as VoIP and video conference, an enhanced quality of service (QoS) mechanism become crucially important. The IEEE 802.11n standard inherits the enhanced distributed channel access (EDCA) mechanism from the IEEE 802.11e, as the MAC layer improvement. It classifies the traffic into four different classes of data, called access categories (ACs). However, EDCA still suffers from a data packet collision, caused by hidden nodes problems. The packet loss ratio and end-to-end delay increase along with the escalation of real-time traffic. To address the issue, we conduct a simulation in Riverbed Modeler 17.5 environment with a 128, 256, 512, and 1,024 Bytes of request to send (RTS) threshold variation value to overcome a collision caused by hidden nodes problem. The result shows that the 512 Bytes of RTS threshold value gives the best QoS output among them all.

Distributed Triggered Access for BSM Dissemination in 802.11bd V2V Networks

In this paper, a novel channel access scheme, Distributed Triggered Access (DTA), is proposed for distributed V2V Basic Safety Message (BSM) dissemination in future platooning environment. To meet the stringent delay requirements of platooning communications, the proposed scheme is designed to use Wireless Local Area Network (WLAN) multi-user channel access in a distributed manner. The proposed scheme leverages advanced Medium Access Control (MAC) layer features, such as Triggered Uplink Access and Multi-user Request-To-Send (RTS), introduced in the 6th generation mainstream WLAN standard, IEEE 802.11ax, based upon a conceptual Physical (PHY) layer frame structure for IEEE 802.11bd, the successor of IEEE 802.11p. The proposed scheme is analyzed by mathematical model and simulations from transmission delay and successful transmission rate perspective. The mathematical model includes a Markov chain analysis that models the Enhanced Distributed Channel Access (EDCA) backoff procedure of DTA considering the effect of resumed backoff procedure with empty buffer caused by triggered access. Also, a Markov arrival/General service distribution/1 service channel (M/G/1) queuing model is provided to analyze the transmission delay of a BSM under unsaturated traffic condition. The extensive simulation results corroborate that DTA effectively improves the transmission success rate and reduces the average BSM collecting delay in a highly congested environment.

Revision of Request to Send (RTS) Threshold to Improve Efficiency of IEEE 802.11n Wireless Ad hoc Networks

In this study, we show that high-speed IEEE 802.11n wireless ad hoc networks suffer from loss of efficiency at network layer. Through extensive simulations, we find the problems of unfairness among traffic flows, packet drops, increased delay and decreased throughput in these networks. We believe the root cause of these problems is RTS Threshold implying that setting an appropriate threshold value can solve most of the problems. To the best of our knowledge, this is the first work that finds this problem and to solve it, we propose an analytical model by which the RTS threshold is set. The simulation shows that this setting can improve the efficiency of IEEE 802.11n networks up to 25% in terms of throughput.

Capacity utilization based on contention window management in mobile ad hoc network

AbstractA major challenge to the mobile ad hoc network (MANET) is the ability to efficiently utilize the available capacity. The exposed terminal problem (ETP) and the hidden terminal problem (HTP) are considered as major concerns in the media access control (MAC) layers of MANET. During transmission, there is an increase in energy consumption, unnecessary delay, overhead, and the number of retransmission due to the request to send (RTS) packet collision. To eliminate these problems, we have developed an algorithm called receiver collision sensing scheme in multiple access control (RCSS‐MAC) for collisions detection by the receiver. This method uses appeal for RTS (ARTS) packet to detect unsuccessful RTS packet. Here, we use only the minimal number of ARTS to reduce unnecessary retransmission, delay, and RTS collision. The performance of this method can be improved using the contention window (CW) management scheme to reset and renovate the failed system. In RCSS‐MAC, an additional field (victory rate) in MAC frame is utilized to control the CW management to reflect the network condition in and around the receiver. Simulation is carried out under the open‐source second version of the network simulator (NS2). As a result, RCSS‐MAC algorithm achieves better performance than conventional techniques in terms of delay, throughput, and energy consumption and network lifetime.

Performance Analysis of MultiACK-SFAMA for Underwater Acoustic Networks

MultiACK-Slotted Floor Acquisition Multiple Access (MultiACK-SFAMA) is a medium access control (MAC) protocol that has been proposed for underwater acoustic networks to overcome the problems of repeating the entire Request To Send (RTS) and Clear To Send (CTS) contention and DATA transmission cycle. In Slotted Floor Acquisition Multiple Access (S-FAMA), when an acknowledgement (ACK) fails to reach the transmitter, the entire cycle repeats. Multi-ACK mechanism has been analyzed in Shahabudeen et al. (IEEE J Ocean Eng 39(1):74–89, 2014). We chose to incorporate this mechanism in S-FAMA to enhance its performance. MultiACK-SFAMA is a modified version of S-FAMA and is aimed to avoid that a successful data transmission is wasted because the acknowledgement is lost, thus saving energy, by using a train of ACKs instead of a single ACK for each DATA packet. By using MultiACK, the probability that an ACK would be received successfully increases. In underwater acoustic networks, due to high propagation delay the cost of losing an ACK is very high and significantly impacts the performance of the protocol. The MultiACK mechanism has been proposed and analyzed to improve the S-FAMA performance. The MultiACK mechanism increases the probability of receiving at least one ACK packet by replying with a train of ACK packets. In this paper we present a mathematical analysis of MultiACK-SFAMA. The paper presents analysis of the performance of MultiACK-SFAMA as a function of transmission range, number of nodes and bit error rates. The results show that the throughput improvement (%) achieved is improved by using a MultiACK train instead of a single ACK. The MultiACK train improves the probability of receiving an ACK by 65.05%, for a BER of 0.005 and saves energy.

Packet Rate Adaptation Protocol Based on Bloom Filter for Hidden Node Avoidance in Vehicular Ad-Hoc Networks

Most of the vehicular ad-hoc networks (VANETs) use the medium access control (MAC) layer of IEEE 802.11p, which is an extension of IEEE 802.11a standard. One of the critical issues with IEEE 802.11 networks is the hidden terminal problem. IEEE 802.11 networks use Request To Send (RTS) and Clear To Send (CTS) mechanism to alleviate the hidden terminal problem. The RTS/CTS mechanism, however, is inapplicable in broadcast communication. Since the safety data in VANET is transmitted over broadcast, the hidden terminal collision is still a critical problem. In this paper, we propose a hidden terminal collision mitigation protocol for broadcast communication of safety data, called Packet Rate Adaptation based on the Bloom filter (PRAB). The protocol derives the optimal packet generation rate as a function of the average number of hidden terminals. To estimate the number of hidden terminals, we introduce a notion of Bloom filter, which piggybacks the neighbor vehicles’ information at a low overhead of packet size. We implemented the proposed protocol and evaluated with various vehicular networks. The simulation results exhibit that the proposed protocol provides 90% or higher packet reception probability even for high vehicle density networks, which correspond to 15% ~24% improvement over the previous protocols considered.

CB‐MAC: a novel cluster‐based MAC protocol for VANETs

Due to relative mobility, topology changes rapidly with frequent link breakage in vehicular ad hoc networks (VANETs). Clustering VANETs into small groups limits channel contention and controls the network topology efficiently. In this study, a novel cluster-based medium access control (CB-MAC) protocol is proposed for VANETs. The cluster formation process is defined. Moreover, cluster head election and cluster merging processes are described for efficient communication in the cluster as well as out of the cluster. The mechanism defined in IEEE 802.11 standard is specially designed for only direct communications and is not suitable for cluster-based communications. Therefore, new control packets are introduced and the existing control packet format is modified to support cluster-based communications. For effective MAC protocol design, the request to send (RTS)/clear to send (CTS) mechanism is not used for safety messages which are of broadcast nature. On the other hand, the RTS/CTS mechanism is used for non-safety data delivery to eliminate hidden node problem. Markov chain model-based analytical model is presented to explore the performance of the proposed CB-MAC protocol. The proposed protocol is validated by numerical studies. The numerical results exhibit that the proposed CB-MAC protocol improves system performance and satisfies the delay constraint of 100 ms for safety messages.

Saturation Throughput and Delay Performance Evaluation of the IEEE 802.11g/n for a Wireless Lossy Channel

Non-ideal channel conditions degrade the performance of wireless networks due to the occurrence of frame errors. Most of the well-known works compute the saturation throughput and packet delay for the IEEE 802.11 Distributed Coordination Function (DCF) protocol with the assumption that transmission is carried out via an ideal channel (i.e., no channel bit errors or hidden stations), and/or the errors exist only in data packets. Besides, there are no considerations for transmission errors in the control frames (i.e., Request to Send (RTS), Clear to Send (CTS), and Acknowledgement (ACK)). Considering the transmission errors in the control frames adds complexity to the existing analysis for the wireless networks. In this paper, an analytical model to evaluate the Medium Access Control (MAC) layer saturation throughput and packet delay of the IEEE 802.11g and IEEE 802.11n protocols in the presence of both collisions and transmission errors in a non-ideal wireless channel is provided. The derived analytical expressions reveal that the saturation throughput and packet delay are affected by the network size (n), packet size, minimum backoff window size (Wmin), maximum backoff stage (m), and bit error rate (BER). These results are important for protocol optimization and network planning in wireless networks.

A fairness-based MAC protocol for 5G Cognitive Radio Ad Hoc Networks

Fifth Generation (5G) technique aims at achieving high data rate and capacity for large numbers of users. Cognitive Radio (CR) is a promising technical to boost the development of 5G networks, which can significantly increase the spectrum efficiency by letting unlicensed Secondary Users (SUs) utilize the idle licensed spectrum without interfering licensed Primary Users (PUs) dynamically. Owing to dynamic available channels, SUs need firstly meet with their target SUs on common available channels to realize communications rapidly in CR Ad Hoc Networks (CRAHNs). Channel Hopping (CH) is a superior technique for achieving rendezvous in CRAHNs. Most of existing researches on CH problem focus on designing CH sequences that can make SUs rendezvous with each other quickly. For reducing congestion, the CH protocols spread the rendezvous in time and channel in general. However, the handshaking process for data link establishment is barely considered. Besides, there is few research on handshaking process in CRAHNs considering fair data link allocation among SUs. In this paper, we first propose novel structures for Request To Send (RTS) frame and Clear To Send (CTS) frame, which combined the characteristics of CRAHN. Then, we present a Fairness-based MAC (FMAC) protocol, which considers fair data link allocation among SUs. Simulation results demonstrate that our proposed protocol gains better performance in terms of time and fairness.