Wi-Fi Alliance Research Articles

Wi-Fi Direct에서 VBR 비디오 트래픽을 고려한 동적 에너지 관리 기법

Recently Wi-Fi Alliance defined Wi-Fi direct, which can communicate through a direct connection between the mobile device anytime, anywhere. In Wi-Fi direct, all devices are categorized by group of owner (GO) and client. Since portability is emphasized in Wi-Fi direct devices, it is essential to control the energy consumption of a device very efficiently. In order to avoid unnecessary power consumed by GO, Wi-Fi direct standard defines two power management schemes: Opportunistic power saving scheme and Notice Of Absence (NOA) scheme. But, these two schemes do not consider the traffic pattern, so we cannot expect high energy efficiency. In this paper, we suggest an algorithm to enhance the energy efficiency of Wi-Fi direct power saving, considering the characteristics of multimedia video traffic. Proposed algorithm utilizes the statistical distribution for the size of video frames and adjusts the length of awake interval dynamically. Also, considering the inter-dependency among video frames, the proposed algorithm assigns priorities to video frames and ensures that a video frame with high priority is transmitted with higher probability than other frames with low priority. Simulation results shows that the proposed method outperforms the traditional NOA in terms with average delay and energy efficiency.

Enabling always on service discovery: Wifi neighbor awareness networking

There is untapped potential in the WiFi radios embedded in our smartphone and tablet devices. In this article we introduce the WiFi Neighbor Awareness Networking technology being standardized in the WiFi Alliance®, which leverages this potential by allowing handheld devices to continuously discover other interesting services and devices while operating in the background in an energy-efficient way. In addition, we present a thorough performance evaluation based on packet-level simulations that illustrates the performance of WiFi NAN to be expected in realistic scenarios.

Wi-Fi as a Commercial Service: New Technology and Policy Implications

While Wi-Fi has enjoyed explosive growth and deployment for use in residential homes, the rollout of commercial Wi-Fi service has been more limited. Part of the holdback on large-scale commercial deployment has been the strategic concern that the commons model to spectrum management lacks the incentives for service providers to invest due to the limited ability to manage interference in the unlicensed band. Today, however, this situation appears to have changed. To explain the new confidence by service providers in commercial Wi-Fi, the activities of the Wi-Fi Alliance and IEEE 802.11 standards body are analyzed to show how these groups essentially replicate many, but not all, of the functions traditionally employed by an effective band manager that is optimizing efficiency on a licensed spectrum block more typically associated with the deployment of commercial services. Consequently, with the Wi-Fi ecosystem functioning as an effective spectrum manager, it is concluded that the service provider investment in Public Wi-Fi networks is rational and the risk posed by saturation or overuse has been reduced to an acceptable level. The strategic implications of this finding on the Wi-Fi platform are the examined. How the requirements from service providers are already significantly influencing the evolution of the Wi-Fi standard is discussed, and an attempt is made to address the risks and liabilities associated with the unlicensed spectrum management model. Thus, service providers increasingly need functionality in Wi-Fi technology to manage interference, and monitor and improve network performance. The current ideas under discussion are elaborated for the next version of Wi-Fi to support both commercial Wi-Fi requirements, which address the interference concerns, but only up to a point, as the unlicensed model intrinsically leaves some risk to participants of spectrum saturation through overuse.

Detection of WPS Attacks Based on Multiscale Traffic Analysis

The worldwide adoption of the IEEE 802.11 standard as the solution to provide efficient network coverage with high data-rates raised several security concerns. In a first stage, Wired Equivalent Privacy (WEP) was used to protect wireless networks from intrusions, whose main motivations ranged from simply getting free Internet access to the perpetration of complex attacks in order to retrieve confidential information. However, due to its multiple technical flaws, this approach was not sufficient, leading to the emergence of the Wi-Fi Protected Access (WPA) and WPA2 technologies, which provided more secure mechanisms at the cost of requiring complicated configuration tasks. In order to create a simple configuration interface, the Wi-Fi Alliance proposed a simple configuration approach: the Wi-Fi Protected Setup (WPS), which is used by major network products manufacturers and provides a much easier configuration setup, although in a less efficient security environment. Actually, this implementation is vulnerable to brute force attacks, which are very quick to execute, have little complexity and are difficult to detect. After cracking WPS, attackers can access to WPA/WPA2 login information and illicitly connect to the target wireless network. There are several technical requirements and legal constrains that limit access to the contents of wireless frames, thus preventing their deep analysis. This paper presents a method to detect attacks over WPA-enabled routers with Wi-Fi Protected Setup based only on the amount of generated traffic. The detection methodology uses a monitoring station that exclusively analyzes traffic flows from the router: by monitoring traffic and using a multiscale analysis procedure, the approach is able to accurately identify each intrusion attempt. Keywords: Traffic identification, wavelet transform, scalogram, Wi-Fi, WPS.Traffic identification, wavelet transform, scalogram, Wi-Fi, WPS.Traffic identification, wavelet transform, scalogram, Wi-Fi, WPS.

Device-to-device communications with Wi-Fi Direct: overview and experimentation

Wi-Fi Direct is a new technology defined by the Wi-Fi Alliance aimed at enhancing direct device to device communications in Wi-Fi. Thus, given the wide base of devices with Wi-Fi capabilities, and the fact that it can be entirely implemented in software over traditional Wi-Fi radios, this technology is expected to have a significant impact. In this article we provide a thorough overview of the novel functionalities defined in Wi-Fi Direct, and present an experimental evaluation that portrays the performance to be expected in real scenarios. In particular, our results quantify the delays to be expected in practice when Wi-Fi Direct devices discover each other and establish a connection, and the performance of its novel power saving protocols. To the best of the authors¿ knowledge this is the first article in the state of the art that provides a wide overview and experimental evaluation of Wi-Fi Direct.

Wi-Fi as a Commercial Service: New Technology and Policy Implications

While Wi-Fi has enjoyed explosive growth and deployment for use in residential homes, the rollout of commercial Wi-Fi service has been more limited. Part of the holdback on large-scale commercial deployment has been the strategic concern that the commons model to spectrum management lacks the incentives for service providers to invest due to the limited ability to manage interference in the unlicensed band. Today, however, this situation appears to have changed. To explain the new confidence by service providers in commercial Wi-Fi, we analyze the activities of the Wi-Fi Alliance and IEEE 802.11 standards body to show how these groups essentially replicate many, but not all, of the functions traditionally employed by an effective band manager that is optimizing efficiency on a licensed spectrum block more typically associated with the deployment of commercial services. Consequently, with the Wi-Fi ecosystem functioning as an effective spectrum manager, we conclude that the service provider investment in Public Wi-Fi networks is rational and the risk posed by saturation or overuse has been reduced to an acceptable level. We then examine the strategic implications of this finding on the Wi-Fi platform. We discuss how the requirements from service providers are already significantly influencing the evolution of the Wi-Fi standard, and attempt to address the risks and liabilities associated with the unlicensed spectrum management model. Thus, service providers increasingly need functionality in Wi-Fi technology to manage interference, and monitor and improve network performance. We discuss the current ideas under discussion for the next version of Wi-Fi to support both commercial Wi-Fi requirements, which address the interference concerns, but only up to a point as the unlicensed model intrinsically leaves some risk to participants of spectrum saturation through overuse.

WiGiG: Multi-gigabit wireless communications in the 60 GHz band

The Wireless Gigabit Alliance [1] - commonly called WiGig - is an industry consortium devoted to the development and promotion of wireless communications in the 60 GHz band. Recent advances in 60 GHz technology and demand for higher-speed wireless connections are key drivers for WiGig. Among the unlicensed frequency bands available for wireless networks, 60 GHz is uniquely suited for carrying extremely high data rates (multiple gigabits per second) over short distances. WiGig has developed a medium access control (MAC) layer, a physical (PHY) layer, and several protocol adaptation layers (PALs) to enable interoperable devices that take advantage of these extremely high data rates. WiGig is also working closely with standards bodies, including IEEE 802.11, and other industry groups, such as the Wi-Fi Alliance, to help enable certification of standards-compliant devices.

Designing energy efficient access points with Wi-Fi Direct

Wi-Fi Direct is a new technology defined by the Wi-Fi Alliance in order to enable efficient device-to-device communication. Portable devices are a main target of this technology and hence, power saving is a key objective. In this paper we analyze the power saving protocols defined in Wi-Fi Direct and design two algorithms to efficiently use them: Adaptive Single Presence Period (ASPP) and Adaptive Multiple Presence Periods (AMPP). Operating only with layer two information, our proposed algorithms allow Wi-Fi Direct mobile devices to address the trade-off between performance and energy consumption in a configurable manner when offering access to an external network. The two algorithms presented, ASPP and AMPP, are evaluated by OPNET simulations.

Wireless sensor network system for supporting nursing context-awareness

We developed a wireless sensor network system for supporting context-awareness of nursing activities in hospitals. Our system is aimed at automated recording of nursing work, providing context-aware services to nurses and visualising analytical results from nursing histories. The system consists of heterogeneous devices utilising three kinds of wireless networks: a ZigBee TM (ZigBee is a registered trademark of the ZigBee Alliance)-based location sensor network, a Bluetooth TM (Bluetooth is a trademark owned by Bluetooth SIG, Inc., USA)-based body-area sensor network for capturing nurse activities and a Wi-Fi TM (Wi-Fi is a registered trademark of the Wi-Fi Alliance)-based network for communication between PDAs worn by nurses and a server PC. We illustrate the layered structure of the entire system as well as algorithms for estimating nurse locations and activities during their operations in a hospital. These estimated results are managed by a real-time database system with which nurse contexts can be visualised in real time on a server PC and/or PDAs. We also show empirical results evaluating the performance of retrieving, analysing and visualising detailed nursing contexts.

On Maximizing VoIP Capacity and Energy Conservation in Multi-Rate WLANs

This letter highlights a key problem that arises when frame aggregation, a popular method for boosting VoIP capacity, is used in Wireless Local Area Networks (WLANs) that employ asynchronous power save mode (PSM). Specifically, it shows how the PSM proposed by the Wi-Fi Alliance renders frame aggregation ineffective. It then proposes a novel opportunistic scheduler that restores the benefits of frame aggregation whilst ensuring stations have minimal energy expenditure.

New Wi-Fi Technology Racing Past Standards Process

While the IEEE Task Group for the 802.11n network standard stalls on ratification, successful network deployments proceed apace, especially in universities. The IEEE 802.11n Task Group keeps pushing back the date for full ratification of the latest edition of the popular wireless network standard. The market, however, isn't waiting. Spearheaded by universities, the 802.11n technology has recently entered "enterprise" architectures with a flourish. According to the BT survey, While many new technologies take years to be adopted, 802.11n appears to be exceeding the typical adoption curve. Although the IEEE might not be ready to ratify its standard, the Wi-Fi Alliance - an umbrella group of 802.11 technology vendors - has been certifying the interoperability of the new gear's Draft 2.0 version since June 2007. Alliance executive director Edgar Figueroa sainteroperability of the new gear's Draft 2.0 version sinceys the 11n technology is booming in the marketplace.

The Performance Implications of Timing of Entry and Involvement in Multipartner Alliances

We examined the distribution of benefits to partners in multipartner alliances by concentrating on dynamics of partner entry and involvement. Testing hypotheses in the Wi-Fi Alliance, we observed heterogeneity of benefits. In particular, the extent of organizational involvement in this alliance enhanced partners' reputation and market success with related product introductions but reduced their productivity. Participation in competing alliances enhanced productivity and market success despite potential efficiency losses. Finally, early alliance entrants gained market success, and both early and late entrants were more productive than intermediate entrants. These findings illuminate multipartner alliance complexity and disparity between common and private benefits.

Cross-Layer Perceptual ARQ for Video Communications over 802.11e Wireless Networks

This work presents an application-level perceptual ARQ algorithm for video streaming over 802.11e wireless networks. A simple and effective formula is proposed to combine the perceptual and temporal importance of each packet into a single priority value, which is then used to drive the packet-selection process at each retransmission opportunity. Compared to the standard 802.11 MAC-layer ARQ scheme, the proposed technique delivers higher perceptual quality because it can retransmit only the most perceptually important packets reducing retransmission bandwidth waste. Video streaming of H.264 test sequences has been simulated withnsin a realistic 802.11e home scenario, in which the various kinds of traffic flows have been assigned to different 802.11e access categories according to the Wi-Fi alliance WMM specification. Extensive simulations show that the proposed method consistently outperforms the standard link-layer 802.11 retransmission scheme, delivering PSNR gains up to 12 dB while achieving low transmission delay and limited impact on concurrent traffic. Moreover, comparisons with a MAC-level ARQ scheme which adapts the retry limit to the type of frame contained in packets and with an application-level deadline-based priority retransmission scheme show that the PSNR gain offered by the proposed algorithm is significant, up to 5 dB. Additional results obtained in a scenario in which the transmission relies on an intermediate node (i.e., the access point) further confirms the consistency of the perceptual ARQ performance. Finally, results obtained by varying network conditions such as congestion and channel noise levels show the consistency of the improvements achieved by the proposed algorithm.

Government Intervention in Standardization: The Case of WAPI

Government bodies have been playing an active and frequently controversial role in many standards competitions in recent decades. The growing literature on standards by economists has largely neglected this role. This paper seeks to take an initial step in addressing this gap in the literature, by examining the experience of one current, and quite contentious, public effort to promote a standard: the Chinese efforts to promote a wireless networking standard and the ensuing interactions with the efforts to create a standard in Europe and the United States. We highlight several observations from this case, which are particularly striking when we contrast this with the experience of the 802.11 technology - which also facilitates wireless computer networking - developed in the West. First, the role of the public sector was quite different. The development of the 802.11 standards in the Institute of Electrical and Electronics Engineers was driven by major technology firms, both within the standardization body and through the non-profit Wi-Fi Alliance, which played a more aggressive promotional role. Much of the success of the firms in promoting technologies that they had sponsored seemed to be driven by their size and market power. The WAPI process, on the other hand, was almost completely driven by the public sector. There was no significant investment by any major technology firm. Unlike the WAPI process - where the initial technology did not mature in the market, but was almost immediately sponsored by the national standardization body - the 802.11 standard was developed over time. Various companies brought forward technologies that they had developed, and in many cases refined in the marketplace and sought to obtain super-majority approvals from the IEEE. The standardization process was transparent and open for all who wished to participate. By way of contrast, substantial ambiguities surrounded the WAPI program. For instance, the objectives of the national standardization body sponsoring the project was a mystery. Some speculated that there were two factions (with more and less pro-market views) that were fighting over how and whether WAPI should be made into an international standard. The treatment of intellectual property was quite different as well. The IEEE standardization included requirements that firms make their intellectual property available on reasonable and non-discriminatory terms. At the same time, at least some ambiguities appear to have surrounded the nature of the commitments to make intellectual property available: the IEEE required disclosure, but the terms of disclosure were not entirely clear. With WAPI, on the other hand, there were considerable ambiguities surrounding the technology, with no access to relevant intellectual property. The only way to build to the technology was to partner with one of 24 firms involved in the promulgating the standard, but the nature of these partnerships was unclear, and outside firms worried about revealing related intellectual property in exchange. The disparities in the strategies adopted by Western and Chinese governments correspond to the typologies developed in the theoretical literature. At the same time, the realities of the two cases raise a variety of questions that have not been explicitly considered by economists, such as the appropriate strategy in settings where less developed nations are competing with established countries. It is hard to conclude that either the bottom up approach of IEEE or the top-down national approach of China was necessarily superior: each may have been appropriate given the different circumstances of the nations.

In brief: Wi-Fi certification program aims to boost battery life

The Wi-Fi Alliance's new WMM (Wi-Fi Multimedia) Power Save certification framework addresses the need for expanded battery life in Wi-Fi cell phones and other mobile devices. WMM Power Save is an extension of the Wi-Fi Multimedia program, which improves user experience with multimedia and latency-sensitive content.

China lays down a standards marker

WiFi equipment makers will have to adhere to a locally developed standard to compete in China. The controversial decision in late December 2003 to mandate a proprietary encryption scheme for wireless LANs (WLAN) for use within its borders-that is incompatible with the existing IEEE 802.11 specifications-has already ruffled a few feathers. Worryingly, neither is support for the scheme included in the upcoming security specifications such as WiFi-Protected Access (WPA), or 802.11i, developed and administered by industry groups such as the IEEE and the WiFi Alliance. Technical details of the so-called Wired Authentication and Privacy Infrastructure (WAPI), part of China's WiFi standard, are just starting to emerge. The announcement by the Standardisation Administration of China caught much of the WiFi industry off guard. It has aroused concerns-perhaps even paranoia-among Western suppliers that the edict would seriously disadvantage them from entering the fast growing Chinese market for WLAN gear. And by implying that it needed to develop its own encryption algorithm because of `flaws' in the present version of 802.11 a and b, the Chinese have, in effect, reopened the debate about WiFi security.

Wireless security's future

Standards bodies and industry organizations are spending a great deal of time and money on developing and deploying next-generation solutions that address growing wireless network security problems. The 802.11i IEEE draft standard provides next-generation authentication, authorization, and encryption capabilities. The WiFi Alliance, a wireless industry organization, has jumped the gun and created the WiFi Protected Access (WPA) standard, a subset of the 802.11i draft. These new standards are more complicated than their predecessors but are more scalable and secure than existing wireless networks. They also dramatically raise the bar for attackers and administrators. The new standards will employ a phased adoption process because of the large installed base of 802.11 devices. Proper migration to 802.11i and mitigating the legacy wireless risks will be a bumpy road. However, the end result will provide users a secure base for mobile computing needs.