Showing papers by "Zhongjiang Yan published in 2016"

Integrated Link-System Level Simulation Platform for the Next Generation WLAN - IEEE 802.11ax

Abstract: As the most widely used standards for wireless local area network (WLAN), IEEE 802.11 standards are continuously amended by introducing new techniques so as to meet the increasing demands. In order to verify the performance of amended protocols, network simulation is considered as a significant method. However, as far as we know, current simulation tools are only for either media access control layer (MAC) or physical layer (PHY). The separate simulation of MAC and PHY can hardly evaluate the performance of IEEE 802.11ax in whole system level for authenticity and objectivity. Hence, the next generation WLAN (IEEE 802.11ax) requires integrated system simulation to take impacts of both MAC and PHY techniques into account. Moreover, IEEE 802.11ax introduces some new techniques, such as orthogonal frequency division multiple access (OFDMA), multi-user multiple input multiple output (MU- MIMO) and non-continuous channel bonding. In this paper, we design and further implement the integrated link-system level simulation platform, which makes it possible to evaluate the new technologies for IEEE 802.11ax. Moreover, we propose a MAC protocol combining OFDMA, MU-MIMO, non-continuous channel bonding and link adaptation and further evaluate its performance. Finally, we validate performance gains of IEEE 802.11ax through simulation, and the simulation results show that IEEE 802.11ax has obviously higher throughput, better quality of service (QoS) and higher multi- channel efficiency. To the best of our knowledge, this is the first work to design and implement simulation platform for IEEE 802.11ax with an integrated link- system level framework.

Cell capacity for 5G cellular network with inter-beam interference

Abstract: The emerging 5G cellular networks will operate at millimeter wave (mmWave) frequency bands to enhance the cell capacity. Massive MIMO antenna array and beamforming technology are used in order to overcome propagation limitations of mmWave band. Multi-beam based communication system is considered as the basic structure for 5G mobile network. However, to optimize the cell capacity, the question of how many beams are required remains unclear. In this paper, considering 5G mmWave cellular system with massive MIMO and beamforming technologies, we accurately model the inter-beam interference and evaluate the cell capacity and outage probability of the system. The simulation results give the optimal number of beams to maximize the cell capacity. Our research provides a possible guidance for the design of 5G cellular system.

A distributed Multi-channel MAC protocol with Parallel Cooperation for the Next Generation WLAN

Abstract: As one of the significant driving forces of the future broadband heterogeneous networks (5G), the Next Generation WLAN (NGW) has been initiated following the 802.11 HEW (High-Efficiency WLAN) study group with a focus on improving spectrum efficiency and area throughput. However, Low-Rate-Links (LRLs) severely degrade the overall wireless network performance, particularly under the dense environments in the NGW. To improve the data rate of wireless links, cooperation communication is proposed to divide a low-rate-link into multiple successive wireless links with much higher data rate over the same frequency channel, which is denoted as ‘Serial-Coop’/‘SC’ strategy. However, the existing ‘Serial-Coop’ strategy suffers from the disadvantage of large cumulative delay because the packets are relayed within two successive timeslots. In this paper, a distributed Multi-channel MAC protocol with Parallel Cooperation is proposed for the NGW, called PC-MMAC, to initiate concurrent cooperation communications over multiple frequency channels in a distributed fashion. Then, an approximate analysis on the upper bound of saturation throughput gain is derived. Further, an enhanced mechanism is proposed to strengthen the robustness of PC-MMAC, by dynamically adjusting the cooperation strategy based on the number of available data channels. Extensive simulation results show that the saturation throughput of PC-MMAC outperforms ‘Serial-Coop’ strategy and ‘Non-Coop’ scheme1 by 25% and 33% respectively.

MAC protocol framework for 5G mmWave backhaul network

Abstract: With the rapid growth of the mobile devices and increasingly diverse mobile services, the traditional mobile networks can hardly keep up with these trends. This asks for the 5G network to support ultra-large traffic and guarantee super-massive connections. Recently, the millimeter wave (mmWave) backhaul network is supposed to be a promising technology to significantly improve the network capacity and efficiently connect massive end users to the Internet. However, most studies just study on the network architecture and the physical layer technologies of 5G mmWave backhaul network, and few of them focus on the MAC layer technologies that directly affect its key performance indicators (KPIs). In this paper, we propose a MAC protocol framework for 5G mmWave backhaul network including the wireless frame structure, signalling, uplink/downlink/backhaul resource allocation framework, and the beamforming training procedure. Moreover, we design and implement the integrated link-system level simulation platform. To the best of our knowledge, this is the first work to design the MAC protocol framework and the integrated link-system simulation platform for 5G mmWave backhaul network.

Capacity analysis of dense wireless networks with joint optimization of reservation and cooperation

Abstract: Due to the increasingly scarce spectrum resources and densely deployed wireless networks, how to increase the spectrum utilization efficiency becomes a hot topic. Channel reservation and cooperative transmission have shown great potential to improve the spatial reuse and network capacity. However, it is difficult to avoid the shortcomings that simply adopting either scheme. In this paper, we propose the concept of reserved cooperative link and investigate the joint optimization of channel reservation and cooperative transmission to improve the network capacity. The concept of area capacity is introduced to characterize the spectral efficiency. After deriving its closed-form expression, the area capacity can be optimized by jointly selecting the optimal helper and employing the optimal reservation zone. Simulation results well validate our analysis, and show that the optimal reservation zone size is reduced by 30% compared with direct transmission with channel reservation. The corresponding optimal area capacity is significantly improved, and a gain of 140% can be obtained for the path loss exponent of 4.

Outage analysis for 5G beamforming heterogeneous networks

Abstract: With an explosion of wireless mobile devices and services, beam-based communication in 5G heterogeneous network (HetNet) has attracted extensive attention recently due to some potential technologies in 5G such as massive MIMO and millimeter wave. This paper proposes an outage probability analysis framework for 5G beamforming HetNet, which is composed of a multi-layer cellular network including macrocells and small cells. The HetNet is affected by base station (BS) densities, transmission powers, beam gains, beamwidths, path loss exponents and cell association bias factors. We derive the association probability, average number of users in a layer and the PDF of the distance to the serving BS for the proposed beamforming HetNet. Then the SINR (Signal to Interference plus Noise Ratio) function is formulated. Moreover, we derive the outage probability of the network and use stochastic geometry to simulate the system performance.

The neighbor channel sensing capability for wireless networks

Abstract: In wireless networks, the capability of sensing the received power variation on wireless channel is named as channel sensing capability (CSC). However, as wireless networks become increasingly dense, it decreases the reliability of multiuser transmission if only CSC is simply used for indicating channel state. Thus, in this paper, a novel conception named as neighbor channel sensing capability (NCSC) is proposed to describe the capability of nodes for sensing the channel state of their neighbor nodes. We prove that the consistency of NCSC, defined as the variable of the difference of the received power of two neighboring nodes, obeys a Gaussian distribution when the location of all transmitting nodes obeys a homogeneous Poisson point process. Moreover, we derive the mean and variance of the consistency of NCSC, and give the expression of NCSC to accurately describe the capability of sensing the channel state of neighbor nodes. The simulation results show that NCSC can efficiently indicate and validate our analysis model and derivation.

A channel reservation based multi-channel MAC protocol with serial cooperation for the next Generation WLAN

Abstract: Most recently, an enhancement amendment named IEEE 802.11ax is proposed by the High-Efficiency WLAN (HEW) Task Group for the Next Generation WLAN (NGW), with a focus on improving spectrum efficiency as well as area throughput. However, collisions among stations (STAs) and Low-Rate-Links (LRLs) severely degrade the network performance, which have become a great matter of concern. In this paper, a channel reservation based multi-channel MAC protocol with serial cooperation is proposed for the next generation WLAN, called CRSC-MMAC, to explore the capabilities of both cooperative relay and channel reservation. In particular, with cooperative relay available, a LRL is divided into two wireless links that sequentially occur on the same data channel with higher data rate. Besides, by using multi-step channel reservation, multiple cooperative transmission opportunities can be reserved in advance with only one successful handshake on the control channel, and thus collisions are effectively alleviated. Extensive simulations are deployed using ns-2 simulator, simulation results show that saturation throughput of the proposed CRSC-MMAC protocol is nearly two times of that of the ‘Baseline’ scheme, and average packet delay of CRSC-MMAC is decreased by nearly 33%.