Wi-Fi Direct Research Articles

Autonomous Wi-Fi Direct connectivity maintenance scheme

In the emergency situations, Wi-Fi Direct (WFD) can provide group-based communications between group owner (GO) and group members (GMs). However, when GO disappears voluntarily or involuntarily, the group connectivity is terminated. For the re-connection, a group reformation procedure including device discovery, GO negotiation, Wi-Fi protected setup (WPS), and address configuration is needed, which consumes much time. In addition, current WFD requires user intervention to initiate the group reformation. To mitigate this problem, this paper proposes an AWS: an Autonomous WFD connectivity maintenance Scheme. In AWS, GO determines a candidate GO (CGO) in advance and transmits the GO information including addresses and credentials to CGO. When GO disappears, based on the GO information, CGO activates virtual GO (VGO) that can operate exactly the same as the disappeared GO (e.g., with same addresses and operating channel). Simulation results are given to validate AWS and to show the performance of AWS in terms of the group disruption time.

Proposal and Performance Evaluation of Information Diffusion Technique with Novel Virtual-Cell-Based Wi-Fi Direct

Wi-Fi Direct (WFD) has attracted much attention in recent years as a device-to-device communication technology that enables the sharing and diffusion of information in disaster areas that lack existing communication infrastructures. In WFD, mobile devices such as smartphones and tablets establish communication groups (a wireless local area network (WLAN)), and transmit and/or receive data by Wi-Fi among devices autonomously. However, WFD is not effective for spreading data throughout a wide range because it randomly selects communication partners and needs to wait uselessly for random lengths of time to maintain access control. Thus, we propose a novel and efficient information diffusion method exploiting WFD and delay-tolerant networking (DTN). This method involves a unique virtual cell design based on device locations and enables efficient information diffusion without interference by assigning communication times to the virtual cells. As there is no deterministic means of evaluating multihop communication exploiting WFD and a mathematical model is needed to quantitatively indicate the performance of our method, we further construct a performance evaluation model using the reaction–diffusion model, which is a partial differential equation used to mathematically describe the spread of epidemic diseases. The effectiveness of this proposed diffusion method is evaluated exploiting the constructed model.

A measurement study on device-to-device communication technologies for IIoT

Industrial Internet of Things (IIoT) connect all components of the factory by constructing low-delay and high-reliability network (wired or wireless), realizing ubiquitous interconnection and smooth data communication, and finally forming an intelligent and efficient industrial ecosystem. There are three widely used device-to-device (D2D) techniques, including Bluetooth (BT), WiFi Hotspot (WFH) and WiFi Direct (WFD), which could provide wireless connections and communications for IIoT devices when the WLANs or cellular networks are unavailable. These D2D communication techniques have gained popularity with the emergence of offloading computing as well as edge computing. Existing studies investigate the outdated versions of BT and WFH, and there are no studies comprehensively comparing them together.In this paper, we conduct a comparative study of the three D2D communication techniques from the aspects of power consumption and transmission performance. Experimental results indicate that BT consumes the lowest power. Power consumption of BT in working state is almost equal to that of WFH and WFD in idle states. However, BT exhibits a poor performance in data transmission. The maximum transmission rate for BT is 1.6 Mbps, while the value is around 50 Mbps for WFH and WFD. We find that TCP/UDP performance of WFH is a little better than WFD. However, WFH also consumes a bit more power than WFD. As a result, WFH is nearly at the same level as WFD when considering the throughput and power consumption together. Taken the results at 2.4 GHz band as an example, the TCP throughput/power for both of them is 4.63 KB/mWs at the sender, while at the receiver, they also have the same value of 6 KB/mWs. We believe that the measurement results are fundamental for constructing high-performance and power-efficient device-to-device communication networks with IIoT devices.

A Local Communication System Over Wi-Fi Direct: Implementation and Performance Evaluation

Wireless communication demands increase sharply with the explosive growth of mobile devices. The communications mainly depend on the infrastructure-based networks, e.g., WLANs and cellular networks. However, such wireless connections may be unavailable in crowded areas (e.g., concert and conference hall) or interrupted by infrastructure failures caused by earthquake or tsunami. These promote the evolution of local communication systems over device-to-device communication, such as Bluetooth and Wi-Fi Direct (WFD). However, none of the existing studies construct a full-featured local communication system, and they do not consider how to support the user mobility either. In this article, we implement and evaluate the performance of a WFD-based local communication system. First, we improve the intragroup communication by the native implementation of WFD on the Android platform, and propose an application-layer forwarding solution for the intergroup communication, which can be applied to three or more connected groups. Then, we put forward a self-adaptive handover mechanism taking user mobility and node failures into account. To deal with the uncertainty in the handover decision procedure, a fuzzy-logic-based normalized quantitative decision algorithm (FNQD) with the weights derived from the fuzzy analytic hierarchy process (FAHP) is utilized. Finally, we evaluate the performance of the system through both simulation and experiment analysis. Results show that we can get a maximum throughput of 31.7 Mb/s for the intragroup communication and a maximum goodput of 4.76 Mb/s for the intergroup communication. What is more, mobile devices could perform various types of handover according to their roles and status, which could improve the robustness of the local communication system.

A Framework for Enabling Internet Access Using Wi-Fi Peer-to-Peer Links

To realize the vision of ubiquitous computing and reachability, major technological advances have been achieved to make smart portable devices both highly capable and affordable. To facilitate connectivity to the Internet, these smart devices are equipped with different network interface cards (4G, Bluetooth and Wi-Fi). However, such connectivity may become seriously reduced in places with intermittent network services and/or shortage of Wi-Fi coverage. This limitation may be seriously harmful in rescue scenarios during and after a disastrous event, since blocked users may become difficult to reach. In this paper we present a novel framework to overcome such issue by implementing a hot-spot accessible through device-to-device (D2D) links. In this work, Wi-Fi direct (WFD) is used in order to establish multi-hop P2P paths to the hot-spot. WFD has the same features that carries the standard Wi-Fi in terms of range and speed without using the infrastructure. Wi-Fi direct is largely emerging as a network technology standard enabled in the majority of smartphones. By exploiting nearby devices, which have Internet access, our framework enables users to publish contents. Moreover, our model is validated by using different smartphones and through extensive simulation experiments.

On the Design of a WiFi Direct 802.11ac WLAN under a TGn MIMO Multipath Fading Channel

WiFi Direct (WD) is a state of the art technology for a Device-to-Device (D2D) communication in 802.11 networks. The performance of the WD system can be significantly affected by some key factors such as the type of application, specifications of MAC and PHY layer parameters, and surrounding environment etc. It is, therefore, important to develop a system model that takes these factors into account. In this paper, we focus on investigating the design parameters of the PHY layer that could maximize the efficiency of the WD 802.11 system. For this purpose, a basic theoretical model is formulated for a WD network under a 2x2 Multiple In Multiple Out (MIMO) TGn channel B model. The design level parameters such as input symbol rate and antenna spacing, as well as the effects of the environment, are thoroughly examined in terms of path gain, spectral density, outage probability and Packet Error Rate (PER). Thereafter, a novel adaptive algorithm is proposed to choose optimal parameters in accordance with the Quality of Experience (QoE) for a targeted application. The simulation results show that the proposed method outperforms the standard method thereby achieving an optimal performance in an adaptive manner.

M3-Cast: A Novel Multicast Scheme in Multi-Channel and Multi-Rate WiFi Direct Networks for Public Safety

WiFi direct (WD) network is of significant interest during public safety scenarios due to its easy, quick, and efficient implementation. WD provides device to device communication using the MAC and PHY layers specifications of 802.11 standards, which facilitate multiple communications channels and a number of transmission rates to cope with the requirements and challenges of emerging applications in public safety and disaster management. Although they achieve substantial benefits in terms of high throughput, it creates a performance anomaly problem, wherein the selection of a particular communication channel and transmission rate can significantly affect the performance of a wireless communication system. This paper investigates the problem of selecting the most favorable channel and rate for a multicast communication system in the context of public safety using a WD 802.11 network. To this end, M3-Cast protocol is proposed, which refers to a novel multi-rate multi-channel multicast scheme. M3-Cast not only chooses the most favorable communication channel and transmission rate, but also considers the implementation details of the underlying WD technology, thereby optimizing the overall system performance. M3-Cast is formulated analytically and evaluated by a complete system level simulation. The detailed results and the analysis considers a number of performance metrics, such as bit error rate, multicast capacity, and system throughput under different multiple input multiple output configurations, channel bandwidths, and various network radii. Consequently, the simulation and analytical results show that M3-Cast protocol outperforms the standard multicast protocol of WD by almost twofold in terms of system throughput.

3GPP LTE-Assisted Wi-Fi-Direct: Trial Implementation of Live D2D Technology

This paper is a first-hand summary on our comprehensive live trial of cellular-assisted device-to-device (D2D) communications currently being ratified by the standards community for next-generation mobile broadband networks. In our test implementation, we employ a full-featured 3GPP LTE network deployment and augment it with all necessary support to provide real-time D2D connectivity over emerging Wi-Fi-Direct (WFD) technology. As a result, our LTE-assisted WFD D2D system enjoys the required flexibility while meeting the existing standards in every feasible detail. Further, this paper provides an account on the extensive measurement campaign conducted with our implementation. The resulting real-world measurements from this campaign quantify the numerical effects of D2D functionality on the resultant system performance. Consequently, they shed light on the general applicability of LTE-assisted WFD solutions and associated operational ranges.