CRJT: Channel Reservation Based Joint Transmission MAC Protocol for the Next Generation WLAN

Wireless Local Area Network (WLAN) has been greatly developed for the last twenty years. Quality of Service (QoS) and Quality of Experience (QoE) in high-dense deployment scenario greatly challenges the next-generation WLAN [1]. To address this challenge, researchers proposed channel reservation mechanism for WLAN, but the premise of channel reservation mechanism is to know the next packets exact arrival time. This assumption is impractical since the next packets arrival time is a stochastic process. In order to solve the above problem, this paper proposes an arrival prediction based channel reservation media access control (MAC) for the next generation WLAN. Simulations show that the protocol can reduce the network collisions generated by concurrency to a certain extent and improve network throughput.

Over the past few years, mobile networks have emerged as a promising approach for future mobile IP applications. With limited frequency resources, designing an effective MAC (Medium Access Control) protocol is a hot challenge. IEEE 802.11b/g/a/n networks are currently the most popular wireless LAN products on the market [1]. The conventional IEEE 802.11b and 802.11g/a specification provide up to 11 and 54 Mbps data rates, respectively. However, the MAC protocol that they are based upon is the same and employs a CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance) protocol with binary exponential back-off. IEEE 802.11 DCF (Distributed Coordination Function) is the de facto MAC protocol for wireless LAN because of its simplicity and robustness [2,3]. Therefore, considerable research efforts have been put on the investigation of the DCF performance over wireless LAN [2]. With the successful deployment of IEEE 802.11a/b/g wireless LAN and the increasing demand for real-time applications over wireless, the IEEE 802.11n Working Group standardized a new MAC and PHY (Physical) layer specification to increase the bit rate to be up to 600 Mbps [3]. The throughput performance at the MAC layer can be improved by aggregating several frames before transmission [3]. Frame aggregation not only reduces the transmission time for preamble and frame headers, but also reduces the waiting time during CSMA/CA random backoff period for successive frame transmissions. The frame aggregation can be performed within different sub-layers. In 802.11n, frame aggregation can be performed either by A-MPDU (MAC Protocol Data Unit Aggregation) or A-MSDU (MAC Service Data Unit Aggregation). Although frame aggregation can increase the throughput at the MAC layer under ideal channel conditions, a larger aggregated frame will cause each station to wait longer before its next chance for channel access. Under errorprone channels, corrupting a large aggregated frame may waste a long period of channel time and lead to a lower MAC efficiency [4]. On the other hand, wireless LAN mobile stations that are defined as the stations that access the LAN while in motion are considered in this chapter. The previous paper analyzed the IEEE 802.11b/g/n MAC performance for wireless LAN with fixed stations, not for wireless LAN with mobile stations [5, 6, 7, 8, 9, 10]. On the contrary, Xi Yong [11] and Ha Cheol Lee [12] analyzed the MAC performance for IEEE 802.11 wireless LAN with mobile stations, but considered only IEEE 802.11 and 802.11g/a wireless LAN specification. So, this chapter summarizes all the reference papers and analyzes the IEEE 802.11b/g/a/n MAC performance for wireless LAN with fixed and mobile stations. In other words, we will present the analytical evaluation of saturation

The next generation wireless local area network (WLAN) 802.11ax standards committee takes high quality of service(QoS) guarantee as one of important technology goals of the next generation WLAN. As a result of a variety of wireless traffics, so the requirements of the QoS must also be varied. However, the existing media access control(MAC) protocol based on orthogonal frequency division multiple access(OFDMA) can’t support QoS diversification and high requirement well. To solve this problem, this paper presents a QoS-oriented OFDMA MAC for the next generation WLAN. On one hand, for backward compatibility consideration, continue to use four priority traffics of 802.11e in this protocol; on the other hand, the introduction of QoS-oriented priority scheduling algorithm to support future wireless traffic feature which is QoS of diversification and high requirements. Finally, through the simulation, the system effective throughput of the proposed QoS-OFDMA MAC is 57.8% and 59% higher than the OFDMA MAC of the sequential scheduling algorithm and the OFDMA MAC of the proportional fairness algorithm.

As wireless devices boom and bandwidth-hungry applications (e.g., video and cloud uploading) get popular, today's wireless local area networks (WLANs) become not only crowded but also stressed at throughput. Multiuser multiple-input-multiple-output (MU-MIMO), an advanced form of MIMO, has gained attention due to its huge potential in improving the performance of WLANs. This paper surveys random access-based medium access control (MAC) protocols for MU-MIMO-enabled WLANs. It first provides background information about the evolution and the fundamental MAC schemes of IEEE 802.11 Standards and Amendments, and then identifies the key requirements of designing MU-MIMO MAC protocols for WLANs. After this, the most representative MU-MIMO MAC proposals in the literature are overviewed by benchmarking their MAC procedures and examining the key components, such as the channel state information acquisition, decoding/precoding, and scheduling schemes. Classifications and discussions on important findings of the surveyed MAC protocols are provided, based on which, the research challenges for designing effective MU-MIMO MAC protocols, as well as the envisaged MAC's role in the future heterogeneous networks, are highlighted.

We consider the CSMA/CA based uplink medium access control (MAC) protocol design for a wireless local area network (WLAN) with the use of multi-beam directional antennas at the access point. Our MAC protocol intends to fully utilize the spatial reuse by allowing as many parallel uplink data transmissions as possible. Since all nodes including the access point run in the contention-based MAC protocol, it is not easy to realize multiple collision-free parallel data transmissions while preserving the ad hoc nature of CSMA/CA based MAC. In addition to improving channel efficiency, we also consider the backward compatibility in our design, whereby a 802.11 limited node can transparently access a multi-beam access point. Our simulation results show that our scheme can improve throughput significantly.

Full-duplex MAC protocol using buffer status reports during unused uplink periods in WLAN

Multi-carrier code division multiple access (MC-CDMA), a novel, high capacity, multicarrier modulation scheme, is developing to a key radio transmission technology for future wireless local area networks (W-LANs). However in ad hoc code division multiple access (CDMA) networks near-far effects can block a receiver due to high interference. These effects occur when a receiving station is closer to an interferer than to its corresponding transmitter. Accordingly, the receiver cannot detect the intended signal out of the received one and the data transmission fails. In this work, we present an adaptive medium access control (MAC) protocol for ad hoc MC-CDMA based W-LANs, based on the IEEE 802.11 MAC protocol. The new protocol has the ability to overcome the near-far-problem by employing a frequency adaptation method. The key of the proposed method is an interference estimate built at each receiving mobile station (MS). Aided by its estimate, a MS can calculate whether the quality of service (QoS) expectations of the incoming link can be accomplished. If the interference is too high, the receiving MS initiates a frequency channel change and informs the corresponding transmitter over the control packets about the Id of the new channel. It is shown that this concept can deploy the high capacity characteristics of MC-CDMA in wireless environments

Nowadays, Wireless Body Area Networks (WBANs) are used in many fields. WBANs are described as small sensor nodes that communicate wirelessly and provide services to the personal area. Quality of Service (QoS) is an essential issue for WBANs due to the importance of human life. QoS problems can only be solved with a robust Medium Access Control (MAC) protocol in WBANs. To find a solution to this problem, developers performed many MAC protocols for WBANs. ISO/IEEE 11073 health informatics defines the standard of personal health information and purposes to provide interoperability between medical technologies. This paper presents a MAC protocol that provides ISO/IEEE 11073 communication standards with QoS support, bases on cross-layer architecture. We designed a slot assignment scheme, prioritization mechanism, admission control mechanism to provide QoS. The performance evaluation of the proposed MAC protocol is compared with IEEE 802.15.4 and IEEE 802.15.6 protocols by considering end-to-end delay, packet loss ratio, and throughput parameters, and it has achieved out performance. It is observed that the proposed protocol doesn't exceed 45 ms delay, reached 81% traffic load, and a maximum error rate of 0.162%.

The following paper is restricted on investigating the capability of the medium access control (MAC) protocol for wireless local area network (WLAN) to transmit burst and sensitive time traffic. The burst traffic is represented in a realistic model, which is more suitable for Internet traffic applied over WLAN. Two models are considered, the first is an ad-hoc network intended for data transmission, and the second is an infrastructure network with multimedia transmission between the terminals considering the suitable protocol for each model. The quality of service of the multimedia transmission is determined in terms of loss probability, average delay, throughput and the number of stations the network can support. New factors arise on simulating the multimedia transmission over the WLAN MAC protocol, which are inspected and defined.

The Point Coordination Function (PCF) of the IEEE 802.11 standard represents a well-known Medium Access Control (MAC) protocol providing Quality-of Service guarantees in Wireless Local Area Networks (WLANs). However, with the currently employed polling mechanism WLANs consume a significant amount of the energy resources from battery-powered user devices. To provide energy saving, an improved MAC protocol is presented in this paper, where bidirectional transmissions of fixed duration are incorporated into PCF in order to enable dynamic scheduling of real-time traffic. Based on this new strategy, wireless access points (APs) can estimate the proper duration of the Contention Free Period (CFP), in order to allow mobile stations to acknowledge any received data packet with a data packet equal to the received packet in size. Having this information, a mobile station, following the data exchange with the AP, can determine its wake-up timer and activate the sleep mode for the rest of the CFP interval. Comprehensive computer-based simulations demonstrate the feasibility of the proposed MAC improvements to achieve energy efficiency with negligible impact on packet delivery delay.

The quality of service (QoS) support in wireless local area networks (WLANs) faces a big challenge due to time-correlated fading channel. Conventional automatic repeat reQuest (ARQ) schemes based on time diversity may result in consecutive retransmission failures degrading QoS severely. This paper proposes a novel Differentiated cooperative medium access control (MAC) protocol, called DC-MAC, to enhance QoS in WLANs based on the IEEE 802.11e architecture. The retransmission is initiated from an appropriate transmission queue of an appropriate relay node instead of the original source to exploit spatial diversity. A novel negative acknowledgement (NAK) feedback mechanism is introduced for loss distinguishing and channel estimation such that cooperative retransmission will be employed only when necessary and only by competent nodes. Simulations conducted on the OPNET platform show that the proposed scheme significantly improves the performances of both multimedia applications and data applications in terms of throughput and delay while supporting service differentiation.

Utility maximization of capacity entropy for multi-user access for the next generation WLANs

Power efficient ultra-wideband based wireless communication for wireless body area network applications

High throughput and fair resource sharing are two of the most important objectives in designing a medium access control (MAC) protocol. Currently, most MAC protocols including IEEE 802.11 DCF adopt a random access based approach in a distributed manner in order to coordinate the wireless channel accesses among competing stations. In this paper, we first identify that a random access–based MAC protocol may suffer from MAC protocol overhead such as a random backoff for data transmission and a collision among simultaneously transmitting stations. Then, we propose a new MAC protocol, called sequential coordination function (SCF), which coordinates every station to send a data frame sequentially one after another in a distributed manner. By defining a service period and a joining period, the SCF eliminates unnecessary contentions during the service period, and by explicitly determining the sequence of frame transmission for each stations, it reduces collision occurrences and ensures fairness among stations in the service period. The performance of SCF is investigated through intensive simulations, which show that the SCF achieves higher throughput and fairness performances than other existing MAC protocols in a wide range of the traffic load and the number of stations.

Orthogonal signaling-based queue status investigation method in IEEE 802.11