Request-to-send/clear-to-send Research Articles

Multiaccess Point Coordination for Next-Gen Wi-Fi Networks Aided by Deep Reinforcement Learning

Wi-Fi in the enterprise - characterized by overlapping Wi-Fi cells - constitutes the design challenge for next-generation networks. Standardization for recently started IEEE 802.11be (Wi-Fi 7) Working Groups has focused on significant medium access control layer changes that emphasize the role of the access point (AP) in radio resource management (RRM) for coordinating channel access due to the high collision probability with the distributed coordination function (DCF), especially in dense overlapping Wi-Fi networks. This paper proposes a novel multi-AP coordination system architecture aided by a centralized AP controller (APC). Meanwhile, a deep reinforcement learning channel access (DLCA) protocol is developed to replace the binary exponential backoff mechanism in DCF to enhance the network throughput by enabling the coordination of APs. First-Order Model-Agnostic Meta-Learning further enhances the network throughput. Subsequently, we also put forward a new greedy algorithm to maintain proportional fairness (PF) among multiple APs. Via the simulation, the performance of DLCA protocol in dense overlapping Wi-Fi networks is verified to have strong stability and outperform baselines such as Shared Transmission Opportunity (SH-TXOP) and Request-to-Send/Clear-to-Send (RTS/CTS) in terms of the network throughput by 10% and 3% as well as the network utility considering proportional fairness by 28.3% and 13.8%, respectively.

Experimental demonstration of hidden node problem in visible light communication networks

In this paper, hardware investigations show the effects of the hidden and exposed node problems in visible light communication (VLC) networks. Furthermore, the request to send/clear to send (RTS/CTS) mechanism, as a physical layer-independent solution, is used for solving the hidden node problem in VLC networks. A VLC hardware system, called VLCIoT, which was designed and implemented in our laboratory based on PHY I of the IEEE 802.15.7 standard, is used for the physical layer. The medium access control layer of the IEEE 802.15.7 is considered for the network. We implement the multiple access protocol of the IEEE 802.15.7 and the RTS/CTS mechanism on the microcontroller of each device using the C programming language. Goodput, message loss ratio, fairness, average delay, energy efficiency, network load, frame size, number of hidden nodes, and number of contending nodes are the evaluated parameters. The results show that for the IEEE 802.15.7 increase of the hidden nodes decreases the goodput and energy efficiency and increases the message loss ratio and the average delay. But, using the RTS/CTS mechanism, the hidden nodes do not affect the goodput, the message loss ratio, the energy efficiency, and the average delay because this mechanism solves the hidden node problem. The results show that the RTS/CTS mechanism increases the saturation goodput by 300%, decreases the message loss ratio by 94%, decreases the average delay by 50%, and increases the energy efficiency by 300%. The results show that at higher network load, higher data frame size, and more contending nodes, the performance of the RTS/CTS mechanism is better. Also, in symmetric networks, in which all nodes are hidden, or no hidden node exists in the network, fairness is better than the asymmetric networks, in which some nodes are hidden while others are not.

Throughput Analysis for Wireless Full-Duplex Multi-Hop Networks with RTS/CTS-Based MAC

Medium access control (MAC) protocol operations for in-band full duplex multi-hop networks play an important role in efficient data relaying and throughput enhancement. Knowledge of the relationship between essential operations in MAC protocol for full duplex MAC (FD MAC) networks and network performance is important and useful in terms of the protocol and network design. FD MAC protocols often require exchanging control frames, e.g., request to send/clear to send (RTS/CTS). However, the conventional model cannot analyze the performance of wireless multi-hop networks with RTS/CTS-based FD MAC. Thus, this paper proposes a throughput analysis model for wireless multi-hop networks with RTS/CTS-based FD MAC. The proposed model includes novel “airtime expressions”, which allows us to handle RTS/CTS operations under FD MAC. The proposed model provides the end-to-end throughput of multi-hop networks with RTS/CTS-based FD MAC for any number of hops and any payload size. The validity of the analytical expressions is confirmed through comparisons with simulation results.

R-SplitC: Collision minimization for cellular communication in unlicensed spectrum

The 3rd generation partnership project (3GPP) has standardized 5G new radio in unlicensed spectrum (NR-U) that uses a wide unlicensed spectrum as an alternative solution to the insufficient bandwidth problem of the existing NR. NR-U has a listen-before-talk (LBT) operation similar to the carrier sense multiple access with collision avoidance (CSMA/CA) operation of Wi-Fi. It allows nodes to transmit only after LBT success. NR-U suffers from the collision issue because its channel access mechanism is similar to that of Wi-Fi. Wi-Fi solves the collision problem through the request-to-send/clear-to-send (RTS/CTS) mechanism. However, NR-U has no way of solving the collision problem. As a result, NR-U suffers severe performance degradation due to collisions as the number of contending nodes increases. In this paper, we propose to use an extended and split reservation signal (RS) for reservation in NR-U that consists of front RS and rear RS and design a new collision minimization scheme, termed R-SplitC, that contains two components: new RS structure and contention window size (CWS) control. The new RS structure helps to minimize collisions in NR-U transmissions, and CWS control works to protect the performance of other communication technologies such as Wi-Fi. We mathematically analyze and evaluate the performance of our scheme and confirm that R-SplitC improves network throughput by up to 99.3% compared to the baseline RS scheme without degrading Wi-Fi performance.

Developing an asynchronous NoAck-based full-duplex MAC for IEEE 802.11 networks in a systems approach

Many studies have introduced full-duplex (FD) medium access controls (MAC) in wireless networks that realize the physical FD capability of the latest devices. However, practical experiences with 802.11 wireless LANs (WLANs) have not yet been addressed. This study proposes a novel FD MAC that extends the IEEE 802.11 based on no acknowledgment (NoAck) data transmission. Because ACK is not needed after data transmission, the MAC can be purely asynchronous; there is neither overhead required for synchronizing transmission, such as request-to-send/clear-to-send (RTS/CTS) handshaking, nor wasted time even in asymmetric traffic. The proposed MAC also provides access point (AP) initiated uni-directional full-duplex (AP-initiated UFD) transmission, which has mostly not been supported in practice, by extending the carrier sense condition. An approximated collision avoidance method is also introduced, where a CTS frame without a preceding RTS is transmitted by AP using FD capability to protect the frame being received. A prototype of the proposed MAC is implemented in ns-3 network simulator, and extensive simulation experiments are conducted in various test setups to validate the correct MAC behaviors, performance improvement, and fairness. The results show that performance improvements, more than twice as high under favorable conditions, are possible while maintaining interoperability with legacy devices.

Improving the Throughput in Lightly Disturbed IEEE 802.11 DCF Saturated Network Using the Fragmentation Mechanism Under Basic Access Mode

The IEEE 802.11 is the most dominating protocol in the wireless local area networks and in which, the fundamental mechanism to access the channel is called distributed coordination function (DCF). As this mechanism is random, the calculation of the performance metrics for IEEE 802.11 networks is focused on the determination of probabilities such as collision probability and successful transmission probability. Recently, there are performance studies in the literature are based on the mathematical models developed using the Markov chains, which model the DCF mechanism with fragmentation in IEEE 802.11 network under imperfect channel. Yet, these models suffer with high collision probability and low successful transmission probability and as a result, the transmission with fragmentation is not recommended at all in the IEEE 802.11 basic DCF networks when the bit error rate is low $$\left( {BER < 5 \times 10^{ - 5} } \right)$$ . In order to solve this, a new analytical model of the basic DCF mechanism with fragmentation is presented in this paper to accurately evaluate throughput metric in the lightly disturbed IEEE 802.11 network at $$BER = 10^{ - 5}$$ under saturated traffic. Analytical results show that our model significantly improves the throughput of the IEEE 802.11 DCF network compared with existing model and hence, provides a higher throughput than that is improved with the request to send/clear to send (RTS/CTS) mode, regardless to network size.

A Novel QoS-Aware A-MPDU Aggregation Scheduler for Unsaturated IEEE802.11n/ac WLANs

Improving the quality of service (QoS) performance to support existing and upcoming real-time applications is critical for IEEE 802.11n/ac devices. The mechanisms of the media access control (MAC) layer, including the aggregate MAC protocol data unit (A-MPDU) aggregation, greatly affect the QoS performance in wireless local area networks (WLANs). To investigate the impact of the aggregation level on the QoS performance for real-time multimedia applications, a novel end-to-end delay model for the unsaturated settings is proposed in this paper. The presented model considers the gathering procedure of packets, queuing behaviors, and transmissions using the RTS/CTS (request to send/clear to send) mechanism on error-prone channels. Based on the model, a novel QoS-aware A-MPDU aggregation scheduler for IEEE802.11n/ac WLANs was shown to obtain better QoS performance with lower latency and less packet loss, a larger capacity to hold higher data rates, and more working nodes. The validation of the proposed model and the promotion of the proposed scheduler are well benchmarked by ns-3.

Modelling link failure in the presence of extended hidden terminals over multi-hop wireless ad hoc networks

IEEE 802.11 uses RTS/CTS (request to send/clear to send) reservation mechanism in multi-hop ad hoc networks to prevent collision drops caused by the hidden terminals. Extended hidden nodes impose great challenges to RTS/CTS mechanism by creating additional interferences and route failures. We introduce a Markov model to compute the probability of collision due to hidden and extended hidden nodes present in multi-hop ad hoc network under saturated traffic loads. This model is derived from the well-known Bianchi Markov chain model of IEEE 802.11 Distributed coordination function by introducing additional states in every back-off stage. Our model differentiates the collisions that could happen to RTS/CTS and data packets. We also compute the probability of link failure that occurs when the maximum retry limit is exceeded. The model is tested for varying network sizes with number of nodes 10, 50, 100, 150 and 200. The model validates the throughput, collision probability and link failure probability against the Bianchi model and ns-2.35 simulation result.

Performance Analysis of DSRC-Based Vehicular Safety Communication in Imperfect Channels

Vehicle-to-vehicle (V2V) communication empowers vehicles to share information by broadcasting basic and critical safety messages. Dedicated short-range communication (DSRC), the medium access control (MAC) layer of which utilizes the IEEE 802.11p protocol, is a promising candidate technology for vehicular communication. Safety applications usually demand safety message dissemination to be prompt and reliable. To satisfy these strict requirements, the MAC layer of vehicular safety communication tends to adopt Distributed Coordination Function (DCF) or single-class Enhanced Distributed Channel Access (EDCA) without request-to-send/clear-to-send (RTS/CTS), acknowledgment (ACK) and retransmission mechanisms as the access scheme. As far as we know, although many numerical models have been provided to understand the IEEE 802.11 DCF performance, there is no precise model that examines the performance of vehicular safety communication exploiting such an access scheme in imperfect channels with different incoming traffic loads. In this paper, we settle this problem by developing an analytical model where the impacts of various incoming traffic loads, packet length distribution, hidden terminal effects, node mobility, the MAC layer queuing system, and the faulty radio channels are all included which no one has done this before. The experimental and numerical results reveal that the constructed model can exactly forecast the vehicular network performance of packet delay, delivery rate, and reception rate under different traffic and channel circumstances.

A Systematic Study of IEEE 802.11 DCF Network Optimization From Theory to Testbed

In IEEE 802.11 wireless local area networks (WLANs), an important technique for medium access control (MAC) is the distributed coordination function (DCF). Two access mechanisms are provided by DCF, the default basic access mechanism and the optional request-to-send/clear-to-send (RTS/CTS) mechanism. The performance of IEEE 802.11 DCF networks has been predicted recently by NS-2 simulator based on a unified analytical model presenting the delay, throughput and stability. NS-3 and OMNeT++ provide an essential platform to model IEEE 802.11 physical (PHY) and MAC layers, nevertheless the accuracy of which is yet not investigated. In this article we present two studies, first is a comparative simulation study of the unified IEEE 802.11 DCF analytical model, by considering distinct network conditions, various topologies, different access modes and discrete system parameters in NS-3 and OMNeT++. A Linux based testbed is setup to validate the mathematical model and the simulation results. The second is the optimization study to adaptively tune the RTS threshold, so that the network operates in an access mode which steers to the maximum network throughput performance. An explicit expression of RTS threshold, verified by the simulations in NS-3 and OMNeT++, is obtained in contrast to previous studies based on channel estimation and numerical calculations. Performance evaluation is done by comparing the simulation, testbed and theoretical results. This study not only proves the credibility of the theoretical model of IEEE 802.11 DCF, but also assures that the results obtained from NS-3 and OMNeT++ are persuasive and provides a foundation for RTS threshold analysis in IEEE 802.11 WLANs for practical network design considerations.

An accurate and complete performance modeling of the IEEE 802.11p MAC sublayer for VANET

This paper proposes an analytical model for the throughput, channel access delay, and queueing delay of the IEEE 802.11p enhanced distributed channel access (EDCA) mechanism in the medium-access control (MAC) sublayer. In order to make the proposed analytical model explicitly solvable and to avoid computation complexity caused by most of existing 3-D or 4-D Markov-chain-based analytical models, a combination of 2-D and 1-D Markov chain model is used. The 2-D Markov chain is established to model the backoff procedure of each access category (AC) queue, deriving a relationship between the transmission probability and collision probability for each AC queue. Afterwards, a 1-D discrete-time Markov chain is established to model the contention period caused by the distinction of four different arbitration inter-frame space (AIFS) and contention window (CW) values, deriving another relationship between the transmission probability and collision probability of each AC queue. In order to consider both saturated and non-saturated cases, an infinite-long 1-D Markov chain model is used. In the proposed analytical model, all the features in the EDCA such as different CW and AIFS for each AC, various saturation status, internal collision, backoff counter freezing, up-to-date standard parameters, and initial-carrier-sensing procedure are taken into consideration. Based on the two Markov models, we further derive performance models which describe the relationships between the network parameters and channel access performance metrics in terms of normalized throughput, channel access delay, and queueing delay, respectively. The proposed analytical model applies to both basic access mode and request-to-send/clear-to-send (RTS/CTS) access mode, and is suitable for four access categories of traffic in the IEEE 802.11p. The proposed model can be employed to analyze the performance of real-world vehicular network. Simulation results are shown to verify the accuracy and effectiveness of the proposed analytical model.

Device-to-Device Communications in Unlicensed Spectrum: Problem Identification and Performance Maximization

Device-to-device (D2D) communication is such a paradigm that anticipated to play a cabalistic role for the next-generation cellular networks especially for the 5G cellular network as it promises to extend the network coverage and offload some traffics from the cellular transceiver’s side to the user devices’ side and it may operate in both licensed and unlicensed spectra simultaneously. D2D communication in the unlicensed spectrum may facilitate the purpose of D2D communication as the licensed spectrum almost possessed. Interference is the main drawback of the unlicensed spectrum. In this paper, we propose the request-to-send/clear-to-send (RTS/CTS) mechanism with the free-to-receive (FTR)-MNAV technique to improve the performance of the D2D communication in the unlicensed spectrum. Deployment of the carrier sense multiple access with collision avoidance (CSMA/CA) protocol can alleviate interference, but collisions occur due to the hidden node problem. The integration of the RTS/CTS mechanism with the CSMA/CA protocol can minimize the hidden node problem, but the blocking and false blocking problems are introduced. The proposed scheme can reduce the blocking and false blocking problems, which improves the performance of the D2D communication in the unlicensed spectrum where neighbor nodes maintain Multiple Network Allocation Vector (MNAV) to resolve the blocking problem and broadcast the FTR control packet to the respective neighbor nodes if the transmission is completed prior to the expiration of the timer or actual communication does not take place due to any reason, thus solving the false blocking problem and improving the performance of the D2D communication in the unlicensed spectrum.

Fuzzy logic-based performance improvement on MAC layer in wireless local area networks

There are many studies that have been done to improve the quality of service of wireless local area networks (WLANs). Institute of Electrical and Electronic Engineers (IEEE) WLAN are based on IEEE 802.11 protocol. The 802.11e medium access control (MAC) protocol is generally recommended for efficient quality of service in WLANs. There are many parameters in the MAC protocol that affect quality of services. Among these parameters, request to send threshold value (RSTV), fragmentation threshold value (FTV) and buffer size (BS) directly affect network performance. RSTV is used in the request to send/clear to send (RTS/CTS) mechanism in the carrier sense multiple access with collision avoidance (CSMA/CA) protocol for collision prevention. This parameter specifies the threshold used to activate the CSMA/CA protocol. FTV is another parameter that is used to send large-sized packets by dividing them into appropriate fragments during CSMA/CA transmission and reduces packet loss in WLAN. BS is another parameter that has a significant cost in the CSMA/CA model and also directly affects the performance. In this article, to improve the performance of WLANs, OPNET Modeler was used and ideal values were obtained for RSTV, FTV and BS by using fuzzy logic-based method. The values obtained by fuzzy logic were re-tested in OPNET Modeler, and the achieved improvement was as follows: for delay 36–38%, for load 2–10% and for throughput 25–44%, respectively. Thus, in WLANs, performance was improved by using fuzzy logic-based method.

Geographic Multipath Routing based on Triangle Link Quality Metric with Minimum Inter-path Interference for Wireless Multimedia Sensor Networks

Wireless Multimedia Sensor Networks (WMSNs) have emerged as the new class of wireless sensor networks (WSNs) to meet the stringent Quality of Service (QoS) requirements of emerging applications. Multipath routing with cross-layer approach appears to be a potential solution for supporting the distinct characteristics of WMSNs. However, due to the broadcast nature of the underlying medium, multiple paths are exposed to inter-path interference. In addition, low-power wireless links are asymmetric, error-prone and unreliable in nature. Consequently, an accurate and stable link quality estimation is essential to guarantee the performance of routing protocol. This paper proposes Triangle link quality metric and minimum inter-path Interference based Geographic Multipath Routing (TIGMR) protocol which finds multiple node-disjoint paths in IEEE 802.15.4 compliant network. This cross-layer routing protocol selects forwarding node based on a triangle link quality metric, remaining energy, and distance while anticipating minimum adjacent path interference effect. In addition, TIGMR protocol avoids Hidden Node Problem (HNP) at the sink node without using Request-To-Send/Clear-To-Send (RTS/CTS) handshake mechanism. Simulation results indicate TIGMR protocol optimizes overall performance and improves network lifetime as compared with state-of-the-art Two-Phase Geographic Forwarding (TPGF) and Link Quality and Energy-Aware Routing (LQEAR) protocols.

Directional MAC protocol for IEEE 802.11ad based wireless local area networks

IEEE 802.11ad defines a new physical and medium access control layer for IEEE 802.11 networks to operate in the unlicensed 60 GHz millimeter wave spectrum for multi-gigabit wireless communications. Higher frequency waves have higher propagation loss but smaller antenna size. Hence, for millimeter wave networks, higher number of antennas can be packed together, enabling beamforming with very large gains. In this paper, we propose a novel Directional MAC protocol for Basic Stations (DMBS) with the goal of fully leveraging spatial reusability, and limiting deafness and hidden terminal problems with minimal overhead, and without using any complicated hardware for localization. The distinguishing features of DMBS are threefold. First, DMBS extends the association beamforming training time (A-BFT) of IEEE 802.11ad, during which the stations perform initial beamforming training with the access point (AP), by an intelligent listening mechanism. This mechanism allows the stations to passively learn about the best direction of the neighboring stations, decreasing the associated beamforming training overhead. Second, DMBS determines the best transmission direction by using multi-directional sequential (circular) RTS/CTS (Request To Send/ Clear To Send) (CRTS/CCTS) packets, and tracks the best direction by updating its beamforming table upon reception of every RTS/CTS packet, without requiring any additional hardware for localization. If the location information of the destination is up-to-date, the source station only transmits directional RTS/CTS (DRTS/DCTS) in the known direction. Third, DMBS uses two network allocation vectors (NAVs). The first NAV, denoted by NAV1, is used to reduce deafness by determining the busy nodes upon the reception of every RTS/CTS packet. The second NAV, called NAV2, is used to limit hidden terminal problem while maximizing spatial reusability by determining whether a transmission can interfere with active communication links. If NAV2 is set, then the node defers its multi-directional communication but still communicates directionally. We provide a novel Markov chain based analytical model to calculate the aggregate network throughput of DMBS. We demonstrate via extensive simulations that DMBS performs better than existing directional communication protocols in terms of throughput for different network sizes, mobilities and number of receivers.

Misbehavior analysis of IEEE 802.11 MAC layer in mobile ad hoc network using stochastic reward nets

SummaryIn this paper, we present a Petri net model for performance evaluation of IEEE 802.11 distributed coordination function as a popular media access control layer protocol in mobile ad hoc network. The goal of this evaluation is to examine this protocol under the existing of misbehavior nodes that selfishly try to grasp common channel in a neighbor area. The presented model consists of 2 separate models based on stochastic reward net (SRN), as a variation of stochastic Petri net. The first model, which is called one node operation model, is supposed for presenting all distributed coordination function operations in a single node such as collision avoidance, request to send/clear to send (RTS/CTS) handshake, and backoff mechanism. The next SRN model, all node operation model, is used for modeling nodes competition for occupying channel in a neighbor area. The models could be adjusted to a dynamic network with any number of nodes, dimension scale, and nodes' speed. For evaluation purpose, 4 distinct attack types implemented by modifying associated transitions in SRN models. The proposed SRN model has been quantified by deriving 2 performances metrics as Throughput and Delay. Both metrics are also compared to the value obtained from NS‐2 in terms of different number of nodes and 3 packet generation rates. Three additional metrics measuring the channel usage are also quantified in terms of different attack strategies using only presented SRN model.

Optimisation methods for performance of communication interaction based on cooperative vehicle infrastructure system

Vehicular ad-hoc network (VANET) is the main information distribution way in VANET. In this paper, the traditional handshake mechanism of enhanced distributed channel access (EDCA) model protocol in IEEE 802.11p and the request to send/clear to send (RTS/CTS) control frame were optimised, then a more reasonable and adaptive back off algorithm based on contention window was proposed, and it's called A-EDCA, and then the competition mechanism of multi communication mode based on adaptive neural network was proposed. After finishing the nonlinear neural network modelling and least mean square (LMS) learning algorithm, variety of traffic scenarios were built to verify and evaluate competition mechanism in OPNET Modeller. The simulation results show that A-EDCA can reduce the likelihood of wireless channel conflict effectively and has significant performance in term of transmission delay and throughput. The proposed competition mechanism of multi communication mode can mainly forecast the optimal communication mode accurately.

Performance Analysis of a RTS/CTS-Based Channel Accessing Mechanism for MU-MIMO WLANs

This paper focuses on the uplink channel accessing problem of multiple user multiple input multiple output (MU-MIMO) wireless local access networks (WLANs). The existing channel accessing mechanisms of MU-MIMO WLANs have poor performance in busy network environment due to heavy collisions, thus a novel channel accessing mechanism that based on request to send/clear to send (RTS/CTS) frames is proposed in this paper. Moreover, saturation throughput and average delay of MU-MIMO WLANs are also obtained through analytic model. Simulation results validate the accuracy of the proposed analytic model. And comparisons between the proposed RTS/CTS channel accessing mechanism and an existing channel accessing mechanism prove that the proposed mechanism performs much better especially in heavy network environment.

Approaching Single-Hop Performance in Multihop Networks: End-to-End Known-Interference Cancelation (E2E-KIC)

To improve the efficiency of wireless data communications, new physical-layer transmission methods based on known-interference cancellation (KIC) have been developed. These methods share the common idea that the interference can be cancelled when the content of it is known. Existing work on KIC mainly focuses on single-hop or two-hop networks, with physical-layer network coding (PNC) and full-duplex (FD) communications as typical examples. This paper extends the idea of KIC to general multi-hop networks, and proposes an end-to-end KIC (E2E-KIC) transmission method together with its MAC design. With E2E-KIC, multiple nodes in a flow passing through a few nodes in an arbitrary topology can simultaneously transmit and receive on the same channel. We first present a theoretical analysis on the effectiveness of E2E-KIC in an idealized case. Then, to support E2E-KIC in multi-hop networks with arbitrary topology, we propose an E2E-KIC-supported MAC protocol (E2E-KIC MAC), which is based on an extension of the Request-to-Send/Clear-to-Send (RTS/CTS) mechanism in the IEEE 802.11 MAC. We also analytically analyze the performance of the proposed E2E-KIC MAC in the presence of hidden terminals. Simulation results illustrate that the proposed E2E-KIC MAC protocol can improve the network throughput and reduce the end-to-end delay.

A Three-way Handshaking Access Mechanism for Point to Multipoint In-band Full-duplex Wireless Networks

In-band Full-duplex (IBFD) wireless communication allows improved throughput for wireless networks. The current Half-duplex (HD) medium access mechanism Request to Send/Clear to Send (RTS/CTS) has been directly applied to IBFD wireless networks. However, this is only able to support a symmetric dual link, and does not provide the full advantages of IBFD. To increase network throughput in a superior way to the HD mechanism, a novel three-way handshaking access mechanism RTS/SRTS (Second Request to Send)/CTS is proposed for point to multipoint (PMP) IBFD wireless networks, which can support both symmetric dual link and asymmetric dual link communication. In this approach, IBFD wireless communication only requires one channel access for two-way simultaneous packet transmissions. We first describe the RTS/SRTS/CTS mechanism and the symmetric/asymmetric dual link transmission procedure and then provide a theoretical analysis of network throughput and delay using a Markov model. Using simulations, we demonstrate that the RTS/SRTS/CTS access mechanism shows improved performance relative to that of the RTS/CTS HD access mechanism.