Showing papers by "Zhongjiang Yan published in 2015"

An OFDMA based concurrent multiuser MAC for upcoming IEEE 802.11ax

Abstract: Recently, IEEE drew up a new task group named TGax to draft out the standard IEEE 802.11ax for next generation WLANs. However, the average throughput is very low due to the current medium access control (MAC) protocol. A promising solution for this problem is to draw Orthogonal Frequency Division Multiple Access (OFDMA) into IEEE 802.11ax to enable multiuser access. The key challenges of adopting OFDMA are synchronization and overhead reduction. In this paper, we propose an OFDMA based Multiple Access for IEEE 802.11ax (OMAX) protocol to solve both two challenges above. The whole channel physical channel sensing and fast backoff are adopted to ensure synchronization, while enhanced RTS/CTS mechanism and new frame structure are designed to reduce overhead. Moreover, the mathematic model of OMAX is formulated, and the performance of OMAX is analyzed. The analysis and simulation result indicate that the proposed OMAX protocol increases the throughput to 160%.

Survey on OFDMA based MAC protocols for the next generation WLAN

Abstract: The physical (PHY) layer peak rate of the wireless local area network (WLAN) has been almost exponentially improved over the past 15 years since 1999. However, it is proved that the throughput is very low comparing to the PHY peak rate, and the media access control (MAC) efficiency is very low in the current WLANs specification, especially in dense deployment scenarios. Therefore, to achieve high MAC efficiency the IEEE Standards Association Standards Board (IEEE-SA) approves IEEE 802.11ax in March 2014, to draw up a brand new amendment for the next generation WLAN. One of the promising technologies to improve MAC efficiency is Orthogonal Frequency Division Multiple Access (OFDMA). In this paper, we firstly investigate the existing OFDMA based MAC protocols in the literature. Then, a framework of OFDMA based MAC protocol for the next generation WLAN is proposed. Finally, all of the existing OFDMA based MAC protocols listed in this paper are compared according to the proposed design issues. To the best of our knowledge this paper is the first survey focusing on OFDMA based MAC protocols for the next generation WLAN.

A 3D geometry-based stochastic model for 5G massive MIMO channels

Abstract: Massive MIMO is one of the most promising technologies for the fifth generation (5G) mobile communication systems. In order to better assess the system performance, it is essential to build a corresponding channel model accurately. In this paper, a three-dimension (3D) two-cylinder regular-shaped geometry-based stochastic model (GBSM) for non-isotropic scattering massive MIMO channels is proposed. Based on geometric method, all the scatters are distributed on the surface of a cylinder as equivalent scatters. Non-stationary property is that one antenna has its own visible area of scatters by using a virtual sphere. The proposed channel model is evaluated by comparing with the 3GPP 3D channel model [1]. The statistical properties are investigated. Simulation results show that close agreements are achieved between the characteristics of the proposed channel model and those of the 3GPP channel model, which justify the correctness of the proposed model. The model has advantages such as good applicability.

FuPlex: A full duplex MAC for the next generation WLAN

Abstract: IEEE 802.11 wireless local area network (WLAN) has been increasingly developed over several decades. It requires four times throughput improvement in the next generation WLAN. Thus, researchers focus on the co-frequency co-time full duplex technology, which makes the devices transmit and receive packets simultaneously and theoretically doubles the throughput. Some existing works proposed several media access control (MAC) protocols on the assumption that all nodes have full duplex capability. However, it is more practicable that only AP possesses full duplex capability whereas STAs have no full duplex capability in the early stage of introducing full duplex technology into the next generation WLAN. In this paper, a simple and compatible full duplex MAC protocol named FuPlex is proposed. The design details of FuPlex, including primary access, secondary access and data transmission, are introduced. Simulation results show that FuPlex improves the throughput to 150% compared with legacy IEEE 802.11 MAC protocol.

Optimal Traffic Scheduling Between Roadside Units in Vehicular Delay-Tolerant Networks

Abstract: This paper investigates the problem of traffic scheduling between roadside units (RSUs) in a vehicular delay-tolerant network. A source RSU needs the help of passing-by vehicles to forward its traffic to a destination RSU. Costs are associated with energy consumption and information loss. When a vehicle arrives, the source RSU needs to decide whether to stop, i.e., transmit its traffic to the vehicle, or skip this vehicle and continue to wait for other vehicles. The source RSU's objective is to achieve the minimal rate of cost. In this paper, we theoretically derive an optimal stopping strategy of the source RSU. Simulation results are presented to show the effectiveness of the derived strategy.

QoE-aware admission control and MAC layer parameter configuration algorithm in WLAN

Abstract: In IEEE 802.11 wireless local area network (WLAN), the quality of the experience (QoE) of HTTP video streaming is seriously influenced by the restricted bandwidth and shared resources. However, to the best of our knowledge, the assessment and optimization of QoE of HTTP video streaming in WLAN have not been fully studied yet. In this paper, we propose an objective metric to assess the QoE and obtain the relationship between this metric and the achieved MAC layer throughput, which makes the MAC layer be aware of the QoE performance directly. Then, a novel admission control and MAC layer parameter configuration algorithm is proposed, which optimizes the QoE of HTTP video streaming and guarantees the throughput requirement of background traffic. Simulation results show that the proposed algorithm outperforms legacy IEEE 802.11 DCF in QoE optimization by a factor of six or more when the number of background stations is large.

Cross-Layer Software-Defined 5G Network

Abstract: In the past few decades, the world has witnessed a rapid growth in mobile communication and reaped great benefits from it. Even though the fourth generation (4G) mobile communication system is just being deployed worldwide, proliferating mobile demands call for newer wireless communication technologies with even better performance. Consequently, the fifth generation (5G) system is already emerging in the research field. However, simply evolving the current mobile networks can hardly meet such great expectations, because over the years the infrastructures have generally become ossified, closed, and vertically constructed. Aiming to establish a new paradigm for 5G mobile networks, in this article, we propose a cross-layer software-defined 5G network architecture. By jointly considering both the network layer and the physical layer together, we establish the two software-defined programmable components, the control plane and the cloud computing pool, which enable an effective control of the mobile network from the global perspective and benefit technological innovations. Specifically, by the cross-layer design for software-defining, the logically centralized and programmable control plane abstracts the control functions from the network layer down to the physical layer, through which we achieve the fine-grained controlling of mobile network, while the cloud computing pool provides powerful computing capability to implement the baseband data processing of multiple heterogeneous networks. The flexible programmability feature of our architecture makes it convenient to deploy cross-layer technological innovations and benefits the network evolution. We discuss the main challenges of our architecture, including the fine-grained control strategies, network virtualization, and programmability. The architecture significantly benefits the convergence towards heterogeneous networks and enables much more controllable, programmable and evolvable mobile networks. Simulations validate these performance advantages.

An OFDMA based multiple access protocol with QoS guarantee for next generation WLAN

Abstract: To provide better QoS guarantee for the next generation WLAN, IEEE 802.11ax task group is founded in March 2014. As a promising technology to accommodate multiple nodes concurrent transmissions in dense deployment scenario, orthogonal frequency division multiple access (OFDMA) will be adopted in IEEE 802.11ax with great possibility. In this paper, an OFDMA based multiple access protocol with QoS guarantee is proposed for the next generation WLAN. Firstly, a redundant access mechanism is given to increase the access success probability of the video traffic where the video stations can concurrently send multiple RTS packets in multiple subchannels. Secondly, a priority based resource allocation scheme is presented to let AP allocate more resources to the video stations. Simulation results show that our protocol outperforms the existing OFDMA based multiple access for IEEE 802.11ax (OMAX) protocol in terms of delay and delay jitter of video traffic in dense deployment scenario.

A reliable channel reservation based multi-channel MAC protocol with a single transceiver

Abstract: The multi-channel MAC protocols have been proposed recently to improve the network capacity by accommodating more concurrent transmissions. In this paper, we propose a distributed multi-channel MAC protocol using reliable multiple channel reservation with only a single transceiver. Specifically, the control handshake information is reserved to be re-broadcasted over the control channel to address the multi-channel hidden terminal problem. Besides, by reserving multiple data transmission opportunities on the selected data channel, the control channel congestion is further relieved. Then we prove that the multi-channel hidden terminal problem can be addressed using reservation on the control channel, and analyze the effectiveness of the proposed protocol in the aspect of the average number of data channels simultaneously utilized. Extensive simulation results show that the proposed protocol is able to achieve nearly 2.5 times the saturation throughput of DCA protocol [15] when five-step channel reservation is adopted.

Capacity Analysis of Wireless Ad Hoc Networks with Improved Channel Reservation

Abstract: In ad hoc networks, interference is an important factor limiting the network capacity. Imposing a reservation zone around each receiver has been widely considered to mitigate the interference. A larger reservation zone can decrease the interference, but it also lowers the spatial reuse for reduced simultaneous transmissions. Therefore, there exists an optimal reservation zone to maximize the network capacity. In this paper, rate adaptation is brought to improve the channel reservation scheme, and network capacity achieved by jointly optimizing the data rate and reservation zone is investigated for spread-spectrum (SS) ad hoc networks. Compared to the transmission capacity with fixed data rate assumption, analytical and numerical results show that network capacity can be significantly improved, and the capacity gain remains constant in the order of 300% for direct sequence (DS) SS networks and increases with the growing spreading factors in the range of 300-800% for frequency hopping (FH) SS networks.

A Heuristic Clique Based STDMA Scheduling Algorithm for Spatial Concurrent Transmission in mmWave Networks

Abstract: In this paper, a heuristic clique based spatial time division multiplexing access (STDMA) scheduling algorithm is proposed for concurrent transmission in millimeter wave networks. Firstly, based on the physical interference model an interference level caused by one transmission request to another is defined, which transforms the SINR condition to a summation form. Then, an un-directional conflict graph is constructed, a feasible clique of which is proved corresponding to a feasible concurrent transmission requests group in one timeslot. Finally, a heuristic clique based STDMA scheduling algorithm is proposed to find the maximum feasible concurrent scheduled transmission requests in one timeslot. Extensive simulations are conducted, and the simulation results show that compared to the existing blind scheduling algorithm, the spatial sharing gain is improved by 11%-36%.

Joint optimization of carrier sensing threshold and transmission rate in wireless ad hoc networks

Abstract: The ever-increasing demands of wireless traffic call for continuously growing the wireless network capacity or throughput. Carrier sensing threshold adaptation and transmission rate adaptation, two efficient mechanisms improving the capacity of ad hoc network, have attracted much attention in recent years. However, simply adopting either mechanism can hardly meet the expectation that optimizing the network capacity. In this paper, we investigate the joint optimization of carrier sensing threshold and transmission rate to improve the network capacity or throughput. The area capacity (throughput), which is defined as the network capacity (throughput) per unit area, is theoretically analyzed. Meanwhile, the relationship between carrier sensing threshold and transmission rate is theoretically revealed. Furthermore, the optimal area capacity is obtained by jointly optimizing the carrier sensing threshold and the transmission rate. Simulation results validate our analysis and derived results, and show that the throughput is significantly improved by the joint optimization.

A Reliable Channel Reservation based Multi-channel MAC Protocol with A Single Transceiver

Abstract: The multi-channel MAC protocols have been proposed recently to improve the network capacity by accommodating more concurrent transmissions. In this paper, we propose a distributed multi-channel MAC protocol using reliable multiple channel reservation with only a single transceiver. Specifically, the control handshake information is reserved to be re-broadcasted over the control channel to address the multi-channel hidden terminal problem. Besides, by reserving multiple data transmission opportunities on the selected data channel, the control channel congestion is further relieved. Then we prove that the multi-channel hidden terminal problem can be addressed using reservation on the control channel, and analyze the effectiveness of the proposed protocol in the aspect of the average number of data channels simultaneously utilized. Extensive simulation results show that the proposed protocol is able to achieve nearly 2.5 times the saturation throughput of DCA protocol [15] when five-step channel reservation is adopted.

A QoE aware fairness bi-level resource allocation algorithm for multiple video streaming in WLAN

Abstract: With the increasing of smart devices such as mobile phones and tablets, the scenario of multiple video users watching video streaming simultaneously in one wireless local area network (WLAN) becomes more and more popular. However, the quality of experience (QoE) and the fairness among multiple users are seriously impacted by the limited bandwidth and shared resources of WLAN. In this paper, we propose a novel bi-level resource allocation algorithm. To maximize the total throughput of the network, the WLAN is firstly tuned to the optimal operation point. Then the wireless resource is carefully allocated at the first level, i.e., between AP and uplink background traffic users, and the second level, i.e., among downlink video users. The simulation results show that the proposed algorithm can guarantee the QoE and the fairness for all the video users, and there is little impact on the average throughput of the background traffic users.

Mi-MMAC: MIMO-Based Multi-Channel MAC Protocol for WLAN

Abstract: In order to meet the proliferating demands in wireless local area networks (WLANs), the multi-channel media access control (MMAC) technology has attracted a considerable attention to exploit the increasingly scarce spectrum resources more efficiently. This paper proposes a novel multi-channel MAC to resolve the congestion on the control channel, named as Mi-MMAC, by multiplexing the control-radio and the data-radio as a multiple-input multiple-output (MIMO) array, working on both the control channel and the data channels alternately. Furthermore, we model Mi-MMAC as an M/M/k queueing system and obtain a closed-form approximate formula of the saturation throughput. Simulation results validate our model and analysis, and we demonstrate that the saturation throughput gain of the proposed protocol is close to 3.3 times compared with the dynamical channel assignment (DCA) protocol [1] under the few collisions condition.

A QoE Aware Fairness Bi-level Resource Allocation Algorithm for Multiple Video Streaming in WLAN

Abstract: With the increasing of smart devices such as mobile phones and tablets, the scenario of multiple video users watching video streaming simultaneously in one wireless local area network (WLAN) becomes more and more popular. However, the quality of experience (QoE) and the fairness among multiple users are seriously impacted by the limited bandwidth and shared resources of WLAN. In this paper, we propose a novel bi-level resource allocation algorithm. To maximize the total throughput of the network, the WLAN is firstly tuned to the optimal operation point. Then the wireless resource is carefully allocated at the first level, i.e., between AP and uplink background traffic users, and the second level, i.e., among downlink video users. The simulation results show that the proposed algorithm can guarantee the QoE and the fairness for all the video users, and there is little impact on the average throughput of the background traffic users.

Mi-MMAC: MIMO-based multi-channel MAC protocol for WLAN

Abstract: In order to meet the proliferating demands in wireless local area networks (WLANs), the multi-channel media access control (MMAC) technology has attracted a considerable attention to exploit the increasingly scarce spectrum resources more efficiently. This paper proposes a novel multi-channel MAC to resolve the congestion on the control channel, named as Mi-MMAC, by multiplexing the control-radio and the data-radio as a multiple-input multiple-output (MIMO) array, working on both the control channel and the data channels alternately. Furthermore, we model Mi-MMAC as an M/M/k queueing system and obtain a closed-form approximate formula of the saturation throughput. Simulation results validate our model and analysis, and we demonstrate that the saturation throughput gain of the proposed protocol is close to 3.3 times compared with the dynamical channel assignment (DCA) protocol [1] under the few collisions condition.

Joint Optimization of Carrier Sensing Threshold and Transmission Rate in Wireless Ad Hoc Networks

Abstract: The ever-increasing demands of wireless traffic call for continuously growing the wireless network capacity or throughput. Carrier sensing threshold adaptation and transmission rate adaptation, two efficient mechanisms improving the capacity of ad hoc network, have attracted much attention in recent years. However, simply adopting either mechanism can hardly meet the expectation that optimizing the network capacity. In this paper, we investigate the joint optimization of carrier sensing threshold and transmission rate to improve the network capacity or throughput. The area capacity (throughput), which is defined as the network capacity (throughput) per unit area, is theoretically analyzed. Meanwhile, the relationship between carrier sensing threshold and transmission rate is theoretically revealed. Furthermore, the optimal area capacity is obtained by jointly optimizing the carrier sensing threshold and the transmission rate. Simulation results validate our analysis and derived results, and show that the throughput is significantly improved by the joint optimization.