As Intelligent Transport System (ITS) applications are diversified and amount of ITS data increases, high throughput and reliability are required in next-generation V2X communications. In order to meet such increased throughput and reliability requirements, IEEE 802.11bd, the next-generation V2X communication standard, has commenced standard development. One of the main features of IEEE 802.11bd is a 20-MHz bandwidth transmission. In this paper, a novel wide-bandwidth channel access scheme in next-generation Wireless Local Area Network (WLAN)-based vehicular communications is proposed. The proposed scheme is designed to provide fairness with other ITS devices and channel efficiency considering adjacent channel interference. By using the proposed scheme, through extensive simulations, it is verified that, while satisfying the fairness requirement with other ITS devices, the channel access delay of wide-bandwidth packet transmission can be optimized.

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.

In order to enhance the user experience of virtual reality (VR) devices, multi-user VR environments and wireless connections should be considered for next-generation VR devices. Wireless local area network (WLAN)-based wireless communication devices are popular consumer devices with high throughput and low cost using unlicensed bands. However, the use of WLANs may cause delays in packet transmission, owing to their distributed nature while accessing the channel. In this paper, we carefully examine the feasibility of wireless VR over WLANs, and we propose an efficient wireless multiuser VR communication architecture, as well as a communication scheme for VR. Because the proposed architecture in this paper utilizes multiple WLAN standards, based on the characteristics of each set of VR traffic, the proposed scheme enables the efficient delivery of massive uplink data generated by multiple VR devices, and provides an adequate video frame rate and control frame rate for high-quality VR services. We perform extensive simulations to corroborate the outstanding performance of the proposed scheme.

In this paper, we propose a delay- and power-efficient, multi-user, low-power wireless local area network (WLAN) communication scheme for Internet of Things (IoT) WLAN devices. Extremely low-power operation is one of the key requirements of emerging IoT devices. However, the current duty-cycle-based power saving approach may incur large access delay times owing to the trade-offs between the power consumption and the access delay. In order to reduce this delay and enhance the power-saving performance, wake-up receiver-based schemes have been proposed. However, because wake-up receiver-based schemes do not consider multiuser operation in dense communication environments, large delays are inevitable in the case of multiuser operation. In order to provide extremely low-power operation and under 1-mW standby power with reduced delay, we employed the optimized multiuser transmission scheduling of IEEE 802.11ax in the proposed scheme and proper enhanced distributed channel access (EDCA) parameter settings. This is with the aim to reduce the delay caused by long wake-up times, and to avoid collisions caused by simultaneous transmission in uplink multiuser scenario. By using the proposed scheme, simultaneous IoT communication with multiple mobile IoT devices is possible while providing low-power operation. Simulation results verified the outstanding delay performance of the proposed scheme.

To support a massive number of connected cars, a novel channel access scheme for next-generation vehicle-to-anything (V2X) systems is proposed in this paper. In the design of the proposed scheme, two essential aspects are carefully considered: backward compatibility and massive V2X support. Since IEEE 802.11p-based V2X networks are already being deployed and used for intelligent transport systems, next-generation V2X shall be designed considering IEEE 802.11p-based V2X networks to provide backward compatibility. Since all future cars are expected to be equipped with a V2X communication device, a dense V2X communication scenario will be common and massive V2X communication support will be required. In the proposed scheme, IEEE 802.11-based extension is employed to provide backward compatibility and the emerging IEEE 802.11ax standard-based orthogonal frequency-division multiple access is adopted and extended to provide massive V2X support. The proposed scheme is further extended with a dedicated V2X channel and a scheduled V2X channel access to ensure high capacity and low latency to meet the requirements of the future V2X communication systems. To demonstrate the performance of the proposed scheme thoroughly and rigorously, the proposed scheme is mathematically analyzed using a Markov model and extensive simulations are performed. In the dense V2X communication networks of the future, the proposed V2X communication scheme will provide high performance and reliability.

The reductions of peak-to-average power ratio (PAPR) and block error rate (BLER) are two challenges in wireless systems employing orthogonal frequency-division multiplexing (OFDM)/orthogonal frequency-division multiple access. High BLER renders the system unreliable, and high PAPR is associated with power inefficiency and nonlinearity of the system. These two issues have separately been studied in the literature, but few works have studied simultaneous reductions of PAPR and BLER. In this paper, we propose a new scheme to jointly reduce and tradeoff PAPR and BLER in OFDM systems using random network coding (NC). In our proposed scheme, different representations of the input information block are generated using a special form of NC matrices, for which we prove it achieves the minimum BLER. We then propose an additional step to our proposed scheme to tradeoff a further improvement in PAPR against degradation in BLER using encoded block puncturing. Simulation results show that the proposed scheme achieves the same PAPR as conventional selective mapping (C-SLM) schemes while achieving the minimum BLER. We also show through simulations the PAPR gains achieved by our proposed additional step over C-SLM and the tradeoff of this gain against BLER degradation. Simulations finally show that our proposed scheme achieves the same results for the recently developed cubic metric.