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Anand Balachandran

Bio: Anand Balachandran is an academic researcher from Microsoft. The author has contributed to research in topics: The Internet & Wireless network. The author has an hindex of 13, co-authored 19 publications receiving 2061 citations. Previous affiliations of Anand Balachandran include Intel & University of California, San Diego.

Papers
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Proceedings ArticleDOI
01 Jun 2002
TL;DR: The goals of this study are to extend the understanding of wireless user behavior and wireless network performance, and to characterize wireless users in terms of a parameterized model for use with analytic and simulation studies involving wireless LAN traffic.
Abstract: This paper presents and analyzes user behavior and network performance in a public-area wireless network using a workload captured at a well-attended ACM conference. The goals of our study are: (1) to extend our understanding of wireless user behavior and wireless network performance; (2) to characterize wireless users in terms of a parameterized model for use with analytic and simulation studies involving wireless LAN traffic; and (3) to apply our workload analysis results to issues in wireless network deployment, such as capacity planning, and potential network optimizations, such as algorithms for load balancing across multiple access points (APs) in a wireless network.

566 citations

Proceedings ArticleDOI
19 Sep 2003
TL;DR: The authors draw on their experiences with campus and building-scale location systems to identify the technological and social barriers to a truly ubiquitous deployment of location-aware computing.
Abstract: To be widely adopted, location-aware computing must be as effortless, familiar and rewarding as web search tools like Google. We envisage the global scale Place Lab, consisting of an open software base and a community building activity as a way to bootstrap the broad adoption of location-aware computing. The initiative is a laboratory because it will also be a vehicle for research and instruction, especially in the formative stages. The authors draw on their experiences with campus and building-scale location systems to identify the technological and social barriers to a truly ubiquitous deployment. With a grasp of these "barriers to adoption," we present a usage scenario, the problems in realizing this scenario, and how these problems will be addressed. We conclude with a sketch of the multi-organization cooperative being formed to move this effort forward.

241 citations

Proceedings ArticleDOI
20 Jun 2002
TL;DR: Two new approaches, explicit channel switching and network-directed roaming for providing hot-spot congestion relief while maintaining pre-negotiated user bandwidth agreements with the network are described and evaluated.
Abstract: Wireless LAN administrators are often called upon to deal with the problem of sporadic user congestion at certain popular spaces ("hot-spots") within the network. To address this problem, we describe and evaluate two new approaches, explicit channel switching and network-directed roaming for providing hot-spot congestion relief while maintaining pre-negotiated user bandwidth agreements with the network. The goals of these algorithms are: (i) to accommodate more users by dynamically providing capacity where it is needed, when it is needed; (ii) to improve overall network utilization by making more efficient use of deployed resources; and (iii) to guarantee at least a minimum amount of bandwidth to users. We propose that both the network and its users should explicitly and cooperatively adapt themselves to changing load conditions depending on their geographic location within the network. We describe how these algorithms enable the network to transparently adapt to user demands and balance load across its access points (APs). We evaluate the effectiveness of these algorithms on improving user service rates and network utilization using simulations. Our algorithms improve the degree of load balance in the system by over 30%, and user bandwidth allocation by up to 52% in comparison to existing schemes that offer little or no load balancing.

229 citations

01 Jan 2000
TL;DR: A software system to locate mobile users connected to an in-building radiofrequency (RF) wireless LAN using signal strength information extracted from the wireless network interface, in conjunction with a Radio Map of the building, to determine location.
Abstract: We have built a software system, RADAR, to locate mobile users connected to an in-building radiofrequency (RF) wireless LAN. RADAR uses signal strength information extracted from the wireless network interface, in conjunction with a Radio Map of the building, to determine location. Over the past year we have deployed this system in multiple buildings on our campus using two different wireless LAN technologies and two widely used operating systems. This experience has led us to identify some shortcomings of the basic RADAR system and fundamental limitations in the way wireless network hardware is abstracted in contemporary operating

181 citations

Patent
28 Apr 2004
TL;DR: In this article, the authors describe an architecture for providing Internet access, which includes a host organization network through which network access is provided, and an access module is provided through which individual client computing devices can access the Internet.
Abstract: Systems and methods for providing network access, e.g. Internet access, are described. An architecture includes a host organization network through which network access is provided. The host organization network can be advantageously deployed in public areas such as airports and shopping malls. An authentication/negotiation component is provided for authenticating various users and negotiating for services with service providers on behalf of the system users. The authentication/negotiation component can include one or more specialized servers and a policy manager that contains policies that govern user access to the Internet. An authentication database is provided and authenticates various users of the system. An access module is provided through which individual client computing devices can access the Internet. In one embodiment, the access module comprises individual wireless access points that permit the client computing devices to wirelessly communicate data packets that are intended for the Internet. In one aspect, users are given a variety of choices of different service levels that they can use for accessing the Internet. The service levels can vary in such things as bandwidth allocation and security measures. The various service levels can be purchased by the users using their computing devices.

177 citations


Cited by
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Book ChapterDOI
08 May 2005
TL;DR: Experimental results are presented showing that 802.11 and GSM beacons are sufficiently pervasive in the greater Seattle area to achieve 20-30 meter median accuracy with nearly 100% coverage measured by availability in people's daily lives.
Abstract: Location awareness is an important capability for mobile computing. Yet inexpensive, pervasive positioning—a requirement for wide-scale adoption of location-aware computing—has been elusive. We demonstrate a radio beacon-based approach to location, called Place Lab, that can overcome the lack of ubiquity and high-cost found in existing location sensing approaches. Using Place Lab, commodity laptops, PDAs and cell phones estimate their position by listening for the cell IDs of fixed radio beacons, such as wireless access points, and referencing the beacons' positions in a cached database. We present experimental results showing that 802.11 and GSM beacons are sufficiently pervasive in the greater Seattle area to achieve 20-30 meter median accuracy with nearly 100% coverage measured by availability in people's daily lives.

1,218 citations

Patent
29 Oct 2007
TL;DR: In this paper, the protection of data on a client mobile computing device by a server computer system such as within an enterprise network or on a separate mobile computing devices is described, and different security policies to be enforced based on a location associated with a network environment in which a mobile device is operating.
Abstract: The protection of data on a client mobile computing device by a server computer system such as within an enterprise network or on a separate mobile computing device is described. Security tools are described that provide different security policies to be enforced based on a location associated with a network environment in which a mobile device is operating. Methods for detecting the location of the mobile device are described. Additionally, the security tools may also provide for enforcing different policies based on security features. Examples of security features include the type of connection, wired or wireless, over which data is being transferred, the operation of anti-virus software, or the type of network adapter card. The different security policies provide enforcement mechanisms that may be tailored based upon the detected location and/or active security features associated with the mobile device. Examples of enforcement mechanisms are adaptive port blocking, file hiding and file encryption.

967 citations

Journal ArticleDOI
01 Apr 2003
TL;DR: This paper presents an empirical study of this handoff process at the link layer, with a detailed breakup of the latency into various components, showing that a MAC layer function - probe is the primary contributor to the overall handoff latency.
Abstract: IEEE 802.11 based wireless networks have seen rapid growth and deployment in the recent years. Critical to the 802.11 MAC operation, is the handoff function which occurs when a mobile node moves its association from one access point to another. In this paper, we present an empirical study of this handoff process at the link layer, with a detailed breakup of the latency into various components. In particular, we show that a MAC layer function - probe is the primary contributor to the overall handoff latency. In our study, we observe that the latency is significant enough to affect the quality of service for many applications (or network connections). Further we find variations in the latency from one hand-off to another as well as with APs and STAs used from different vendors. Finally, we discuss optimizations on the probe phase which can potentially reduce the probe latency by as much as 98% (and a minimum of 12% in our experiments). Based on the study, we draw some guidelines for future handoff schemes.

954 citations

Proceedings ArticleDOI
06 Jun 2004
TL;DR: Confab provides basic support for building ubiquitous computing applications, providing a framework as well as several customizable privacy mechanisms that allow application developers and end-users to support a spectrum of trust levels and privacy needs.
Abstract: Privacy is the most often-cited criticism of ubiquitous computing, and may be the greatest barrier to its long-term success. However, developers currently have little support in designing software architectures and in creating interactions that are effective in helping end-users manage their privacy. To address this problem, we present Confab, a toolkit for facilitating the development of privacy-sensitive ubiquitous computing applications. The requirements for Confab were gathered through an analysis of privacy needs for both end-users and application developers. Confab provides basic support for building ubiquitous computing applications, providing a framework as well as several customizable privacy mechanisms. Confab also comes with extensions for managing location privacy. Combined, these features allow application developers and end-users to support a spectrum of trust levels and privacy needs.

663 citations

Proceedings ArticleDOI
01 Jun 2002
TL;DR: The goals of this study are to extend the understanding of wireless user behavior and wireless network performance, and to characterize wireless users in terms of a parameterized model for use with analytic and simulation studies involving wireless LAN traffic.
Abstract: This paper presents and analyzes user behavior and network performance in a public-area wireless network using a workload captured at a well-attended ACM conference. The goals of our study are: (1) to extend our understanding of wireless user behavior and wireless network performance; (2) to characterize wireless users in terms of a parameterized model for use with analytic and simulation studies involving wireless LAN traffic; and (3) to apply our workload analysis results to issues in wireless network deployment, such as capacity planning, and potential network optimizations, such as algorithms for load balancing across multiple access points (APs) in a wireless network.

566 citations