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Full- or Half-Duplex? A Capacity Analysis with Bounded Radio Resources
Vaneet Aggarwal, N Shankaranarayanan, Melissa Duarte, Ashutosh Sabharwal
IEEE ITW 2012,
2012.
[PDF]
[BIB]
IEEE Copyright
This version of the work is reprinted here with permission of IEEE for your personal use. Not for redistribution. The definitive version was published in 2012. , 2012-09-03
{Full duplex communication requires nodes to cancel their own interference. Recent
work have proved the feasibility of full duplex communications using software radios.
In this paper, we address capacity comparisons when the total amount of analog radio hardware is bounded. Under this constraint, it is not immediately clear if one should use these radios to perform full-duplex self-interference cancelation or use the radios to give additional MIMO multiplexing advantage. We find that repurposing radios for cancellation, instead of using all of them for half-duplex over-the-air transmission, can be
beneficial since the resulting full-duplex system performs better in some practical SNR regimes and almost always outperforms half duplex in symmetric degrees-of-freedom (large SNR regime).}
Modeling and Characterization of Large-Scale Wi-Fi Traffic in Public Hot-Spots
Amitabha Ghosh, Rittwik Jana, Vaidyanathan Ramaswami, James Rowland, N Shankaranarayanan
Infocom 2011,
2011.
[BIB]
{Server side measurements from several Wi-Fi hotspots
deployed in a nationwide network over different types of
venues from small coffee shops to large enterprises are used to
highlight differences in traffic volumes and patterns. We develop
a common modeling framework for the number of simultaneously
present customers. Our approach has many novel elements: (a)
We combine statistical clustering with Poisson regression from
Generalized Linear Models to fit a non-stationary Poisson process
to the arrival counts and demonstrate its remarkable accuracy;
(b) We model the heavy tailed distribution of connection durations
through fitting a Phase Type distribution to its logarithm
so that not only the tail but also the overall distribution is
well matched; (c) We obtain the distribution of the number
of simultaneously present customers from an Mt/G/infty queuing
model using a novel regenerative argument that is transparent and
avoids the customarily made assumption of the queue starting
empty at an infinite past; (d) Most importantly, we validate
our models by comparison of their predictions and confidence
intervals against test data that is not used in fitting the models.}
Characterizing Fairness for 3G Wireless Networks
Vaneet Aggarwal, Rittwik Jana, Kadangode Ramakrishnan, Jeffrey Pang, N Shankaranarayanan
IEEE LANMAN 2011,
2011.
[PDF]
[BIB]
IEEE Copyright
This version of the work is reprinted here with permission of IEEE for your personal use. Not for redistribution. The definitive version was published in IEEE LANMAN 2011. , 2011-10-13
{The end to end system data performance over a 3G cellular network depends on many factors such as the number of users, interference, multipath propagation, radio resource management techniques as well as the interaction between these mechanisms and the transport protocol's flow and congestion mechanisms. Using controlled experiments in a public cell site, we investigate the interaction between TCP and the 3G UMTS/HSPA network's resource allocation, and its effect on fairness in the throughput achieved across multiple (up to 26) TCP flows in a loaded cell sector. Our field measurement results indicate that TCP fairness fluctuates significantly when the air interface (radio link) is the bottleneck. We also observe that TCP fairness is substantially better when the backhaul link (a fixed wired link) is the bottleneck, instead of the air interface. We speculate that the fairness of TCP flows is adversely impacted by the mismatch between the resource allocation mechanisms of TCP's flow and congestion control and that of the Radio Access Network (RAN).}
Infrastructure Mesh Broadband Wireless System: Example of Cooperative Wireless
Byoung Kim, N Shankaranarayanan, Amit Saha
IEEE 802.16 Planery,
2007.
[PPT]
[BIB]
{}
Internet Roaming - An Enterprise-Oriented WLAN/Cellular Data Network Integration Solution
Hui Luo, Byoung-Jo Kim, N Shankaranarayanan, Paul Henry, Zhimei Jiang
Internet Computing Magazine,
2003.
[BIB]
{Internet Roaming is an IP-based corporate data network architecture that provides convenient secure mobile networking across office WLANs, residential WLANs, public WLANs, and cellular data networks for corporate wireless data users. It has three building blocks: the IRC (Internet Roaming Client), the SMG (Secure Mobility Gateway), and the VSA (Virtual Single Account) server. Working with an SMG and a VSA server, an IRC can present a single sign-on authentication interface for a user to initiate a secure connection to a corporate intranet via the best available wireless network, and maintain the secure connectivity thereafter as the user moves from one wireless network to another. As a proof of concept, a software-based prototype system has been developed, which enables a Windows-based computer to seamlessly roam between WLANs attached to different subnets while maintaining an encrypted connection to a Windows-based SMG. A hardware-based IRC that looks like a network interface card is also under development. It can provide secure mobile networking for a variety of mobile devices such as PDAs. The measurements of handoff speed of the software-based prototype system and comparisons between Internet Roaming and other WLAN/cellular integration methods are also given in this paper. }
Integrating wireless LAN and cellular data for the enterprise
Hui Luo, Byoung Kim, N Shankaranarayanan, Paul Henry, Zhimei Jiang
IEEE Internet Computing Magazine,
2003.
[BIB]
{}
AT&T intelligent network card: foundation for a new mobile computing architecture
Hui Luo, Paul Henry, Byoung Kim, N Shankaranarayanan
ACM MobiCom 2003,
2003.
[BIB]
{We propose to demonstrate to the audience of Mobicom '03 a new approach for transparently enhancing mobile networking and application support mechanisms. Until now, such features have required support from the host operating system (OS). The host OS typically is closed and/or proprietary, and this is especially the case for host OS that is dominant in the market. The centerpiece of our new approach is an intelligent network interface card in a CF-to-PCMCIA converter from factor, which we call the "AT&T Intelligent Network Card" or "iCard" [1,2]. previously released: TD-5NNHGH }
Experimental study of user experience for data applications in future cellular wireless networks
Zhimei Jiang, Byoung Kim, N Shankaranarayanan, Paul Henry, Hilary Mason
SAINT'01,
2000.
[BIB]
{This paper presents results from an experimental survey of user experience for data applications in future cellular wireless networks. Using a network emulator, we tested a variety of network scenarios with different channel sharing schemes (dedicated and shared bandwidth), computing models (local processing with remote files and thin-client server based computing), applications (Web browsing, Word, PowerPoint), and devices (laptops and Palm devices). Subjective quality ratings (1 to 5) from 100+ users were collected to generate an average quality score for the user experience in each scenario. We quantify the degradation of user experience with lower bit rates and a larger number of users sharing the channel. We also find that users have a marked preference between local and thin-client computing based on bandwidth conditions and applications. Publisher: IEEE Pub/Conf: SAINT'01 }
Secure Open-Air Communication System Utilizing Multi-Channel Decoyed Transmission,
Tue Sep 04 12:53:30 EDT 2012
A secure, open-air communication system utilizes a plurality of "decoy" data signals to hide one or more true data signals. The true data signal(s) are channel hopped with the plurality of decoy data signals to form a multi-channel "scrambled" output signal that is thereafter transmitted in an open-air communication system. The greater the number of decoy signals, the greater the security provided to the open-air system. Further security may be provided by encrypting both the true and decoy signals prior to scrambling and/or by utilizing a spatially diverse set of transmitters and receivers. Without the knowledge of the channel assignment(s) for the true signal(s), an eavesdropper may be able to intercept (and, with time, perhaps descramble) the open-air transmitted signals, will not be able to distinguish the true data from the decoys without also knowing the channel assignment(s).
Wireless Network Using Hybrid Of Licensed And Unlicensed Spectrum,
Tue Feb 28 12:50:52 EST 2012
A system and method to dynamically allocate licensed transmission spectrum in conjunction with unlicensed transmission spectrum as a communication channel to meet quality of service requirements for cost efficient, high speed and high data capacity communications. The invention uses licensed spectrum to provide a guaranteed level of performance and can dynamically add unlicensed spectrum to enhance performance. Local high speed access can be achieved at low cost using unlicensed spectrum while maintaining a service level guarantees using licensed spectrum.
Secure IP Access Protocol Framework And Supporting Network Architecture,
Tue Oct 25 16:06:21 EDT 2011
A protocol framework for a Secure IP Access (SIA) method, and supporting components deployed on IP hosts and IP networks. Using this method, an IP host can establish a secure data channel within an IP network over an insecure shared link while requesting IP address and networking configuration parameters from the IP network. A system administrator can implement strong access control against various attacks that an edge IP network may have to face, such as a denial-of-service attack that exhausts assignable IP addresses. This is a lightweight, scalable, and backward-compatible solution that can improve security performance for public and corporate LANs having open access such as wireless access points and Ethernet jacks.
Method, System, And Device For Sending Data In A Cable Data Service,
Tue Aug 02 16:05:50 EDT 2011
A method of sending data from a transmit site to a receive device includes dividing a first transmit data stream having a first bit rate into multiple data streams with each of the multiple data streams having a bit rate that is lower than the first bit rate. Each of the multiple data streams is transmitted over a cable network having multiple radio frequency channels. The multiple data streams are recombined at the receive device to provide a receive data stream having a bit rate equal to the first bit rate. A second transmit data stream is transmitted over one of the radio frequency channels to a legacy user connected to the one radio frequency channel between the transmit site and the receive device.
System And Method To Support Networking Functions For Mobile Hosts That Access Multiple Networks,
Tue Apr 19 16:04:54 EDT 2011
An IP-based corporate network architecture and method for providing seamless secure mobile networking across office WLAN, home WLAN, public WLAN, and 2.5 G/3 G cellular networks for corporate wireless data users. The system includes Internet roaming clients (IRCs), a secure mobility gateway (SMG), optional secure IP access (SIA) gateways, and a virtual single account (VSA) server. The IRC is a special client tool installed on a mobile computer (laptop or PDA) equipped with a WLAN adaptor and a cellular modem. It is responsible for establishing and maintaining a mobile IPsec tunnel between the mobile computer and a corporate intranet. The SMG is a mobile IPsec gateway installed between the corporate intranet and the Internet. It works in conjunction with the IRC to maintain the mobile IPsec tunnel when the mobile computer is connected on the Internet via a home WLAN, a public WLAN, or a cellular network. The SIA gateway is a special IPsec gateway installed in the middle of the wired corporate intranet and an office WLAN. It works with the IRC to ensure data security and efficient use of corporate IP addresses when the mobile computer is connected to the office WLAN. The VSA server manages authentication credentials for every corporate user based on a virtual single account concept. The Internet Roaming system can provide secure, always-on office network connectivity for corporate users no matter where they are located using best available wireless networks.
Secure Open-Air Communication System Utilizing Multi-Channel Decoyed Transmission,
Tue Dec 07 15:05:13 EST 2010
A secure, open-air communication system utilizes a plurality of "decoy" data signals to hide one or more true data signals. The true data signal(s) are channel hopped with the plurality of decoy data signals to form a multi-channel "scrambled" output signal that is thereafter transmitted in an open-air communication system. The greater the number of decoy signals, the greater the security provided to the open-air system. Further security may be provided by encrypting both the true and decoy signals prior to scrambling and/or by utilizing a spatially diverse set of transmitters and receivers. Without the knowledge of the channel assignment(s) for the true signal(s), an eavesdropper may be able to intercept (and, with time, perhaps descramble) the open-air transmitted signals, will not be able to distinguish the true data from the decoys without also knowing the channel assignment(s).
Conditional Electronic Coupon Distribution Method And System,
Tue Aug 03 15:04:21 EDT 2010
A conditional e-coupon distribution method distributes e-coupons predefined by sellers to mobile users only if the number of mobile users requesting such e-coupons equals or exceeds a threshold. The method receives a request to browse e-coupons from a mobile user. The method receives the location of the mobile user and determines a plurality of sellers local to the mobile electronic device and a plurality of corresponding e-coupons available from the local sellers. The method receives a request for a particular e-coupon from a seller and authorizes the provision of said e-coupon to the mobile user. At the end of a processing cycle, the mobile user receives the requested e-coupon if all conditions, such as a period of time and threshold, have been met. A computer-usable medium having computer-readable program code embodied therein allows for storage of the method.
Method And System For Assigning Channels In A Wireless LAN,
Tue Jun 01 15:03:57 EDT 2010
Described is a system and method for receiving traffic load information for a plurality of access points, each of the access points including at least two channels for communicating and neighboring at least one of the other access points. A throughput of each channel of each access point is determined based on the traffic load information for each access point and any neighboring access points. A channel with a maximum determined throughput is selected for each access point. Each access point then switches to the selected channel at a defined probability rate.
Channel Efficiency Based Packet Scheduling For Interactive Data In Cellular Networks,
Tue Oct 13 16:08:07 EDT 2009
The present packet scheduling algorithm gives cellular network operators greater flexibility in adjusting the way resources are allocated among interactive best-effort data users. The present packet scheduling algorithm is capable of allocating radio resource dynamically, not only based on channel conditions, but also to achieve different performance trade-offs among users with different link qualities. According to the algorithm, channel quality is determined for each user. Channel efficiency is calculated and the channel efficiency value is used as the primary factor in weighting the delivery of packets to (or from) a given user. In a packet schedule weighting equation, a value of exponent may be varied from negative to positive to give good (or bad) users better service. However, performance of users with bad channel qualities degrades the performance of good channel users in a disproportionate manner.
System and method to support networking functions for mobile hosts that access multiple networks,
Tue Oct 21 18:13:05 EDT 2008
An IP-based corporate network architecture and method for providing seamless secure mobile networking across office WLAN, home WLAN, public WLAN, and 2.5G/3G cellular networks for corporate wireless data users. The system includes Internet roaming clients (IRCs), a secure mobility gateway (SMG), optional secure IP access (SIA) gateways, and a virtual single account (VSA) server. The IRC is a special client tool installed on a mobile computer (laptop or PDA) equipped with a WLAN adaptor and a cellular modem. It is responsible for establishing and maintaining a mobile IPsec tunnel between the mobile computer and a corporate intranet. The SMG is a mobile IPsec gateway installed between the corporate intranet and the Internet. It works in conjunction with the IRC to maintain the mobile IPsec tunnel when the mobile computer is connected on the Internet via a home WLAN, a public WLAN, or a cellular network. The SIA gateway is a special IPsec gateway installed in the middle of the wired corporate intranet and an office WLAN. It works with the IRC to ensure data security and efficient use of corporate IP addresses when the mobile computer is connected to the office WLAN. The VSA server manages authentication credentials for every corporate user based on a virtual single account concept. The Internet Roaming system can provide secure, always-on office network connectivity for corporate users no matter where they are located using best available wireless networks.
Channel efficiency based packet scheduling for interactive data in cellular networks,
Tue May 16 18:11:13 EDT 2006
The present packet scheduling algorithm gives cellular network operators greater flexibility in adjusting the way resources are allocated among interactive best-effort data users. Best effort data users with different radio link qualities may have different amounts of data delivered to them using the same amount of radio resource. In the context of link adaptation, this characteristic complicates the fairness issue in cellular environments and has a profound impact on the overall system performance. As a result, the present packet scheduling algorithm is capable of allocating radio resource dynamically, not only based on channel conditions, but also to achieve different performance trade-offs among users with different link qualities. According to the algorithm, channel quality is determined for each user, channel efficiency is calculated and the channel efficiency value is used as the primary factor in weighting the delivery of packets to (or from) a given user. In a packet schedule weighting equation, a value of exponent may be varied from negative to positive to give good (or bad) users better service. However, performance of users with bad channel qualities degrades the performance of good channel users in a disproportionate manner. It is shown that it is frequently preferable to favor users with good channel qualities.
E-coupon service for location-aware mobile commerce which determines whether to supply requested e-coupons based on the number of requests received in a processing cycle...,
Tue Feb 07 18:10:51 EST 2006
A conditional e-coupon distribution method distributes e-coupons predefined by sellers to mobile users only if the number of mobile users requesting such e-coupons equals or exceeds a threshold. The method receives a request to browse e-coupons from a mobile user. The method receives the location of the mobile user and determines a plurality of sellers local to the mobile electronic device and a plurality of corresponding e-coupons available from the local sellers. The method receives a request for a particular e-coupon from a seller and authorizes the provision of said e-coupon to the mobile user. At the end of a processing cycle, the mobile user receives the requested e-coupon if all conditions, such as a period of time and threshold, have been met. A computer-usable medium having computer-readable program code embodied therein allows for storage of the method.
Cable data service method,
Tue Jan 31 17:08:41 EST 2006
A method for sending data from a transmit site to a receive site which includes dividing a transmit data stream having a first bit rate into multiple data streams with each of the multiple data streams having a bit rate which is lower than the first bit rate, transmitting each of the multiple data streams over a plurality of RF channels and recombining the multiple data streams at the receive site to provide a receive data stream having a bit rate equal to the first bit rate.
Transmit and receive system for cable data service,
Tue Jan 31 17:08:40 EST 2006
A transmit and receive system for transmitting data between a transmit site and a receive site. The system includes a tunnel source, router and modulator for dividing a transmit data stream having a first bit rate into multiple data streams with each of the multiple data streams having a bit rate which is lower than the first bit rate, transmitting each of the multiple data streams over a plurality of RF channels. The system further includes a demodulator and destination source for recombining the multiple data streams at the receive site to provide a receive data stream having a bit rate equal to the first bit rate.
Method And Apparatus For Providing High Speed Services Using A Wireless Communications System,
Tue Dec 02 18:08:54 EST 2003
A method and apparatus for scheduling transmissions between a plurality of communications sites within a communications system. The communications system provides service to a service area which is divided into sectors. Each sector is assigned a time subframe in a pattern where adjacent sectors use different subframes. Communications sites within each sector communicate packets of information in at least one time subframe according to a schedule to minimize interference from other communications sites.
Method and apparatus for sector based resource allocation in a broadhand wireless communications system,
Tue Jun 04 18:08:04 EDT 2002
A method and apparatus for sector based resource allocation in a broadband wireless communications system. A service region is divided into a plurality of cells, and each cell is divided into a plurality of labeled sectors. Each label is selected to avoid an unacceptable amount of interference from any other sector while ensuring that at least two sectors in a cell share the same label. Transmissions are scheduled for a cell by assigning each communications site a channel, such as a time slot associated with the sector's label. The transmissions are then communicated according to this schedule.
Method and apparatus for providing high speed services using a wireless communications system,
Tue May 30 18:05:32 EDT 2000
A method and apparatus for scheduling transmissions between a plurality of communications sites within a communications system. The communications system provides service to a service area which is divided into sectors. Each sector is assigned a time subframe in a pattern where adjacent sectors use different subframes. Communications sites within each sector communicate packets of information in at least one time subframe according to a schedule to minimize interference from other communications sites.
WiMAX Forum Individual Contributor Award, 2006.
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