Showing papers on "Cellular network published in 2007"

Joint optimization of relay strategies and resource allocations in cooperative cellular networks

Abstract: This paper considers a wireless cooperative cellular data network with a base station and many subscribers in which the subscribers have the ability to relay information for each other to improve the overall network performance. For a wireless network operating in a frequency-selective slow-fading environment, the choices of relay node, relay strategy, and the allocation of power and bandwidth for each user are important design parameters. The design challenge is compounded further by the need to take user traffic demands into consideration. This paper proposes a centralized utility maximization framework for such a network. We show that for a cellular system employing orthogonal frequency-division multiple-access (OFDMA), the optimization of physical-layer transmission strategies can be done efficiently by introducing a set of pricing variables as weighting factors. The proposed solution incorporates both user traffic demands and the physical channel realizations in a cross-layer design that not only allocates power and bandwidth optimally for each user, but also selects the best relay node and best relay strategy (i.e. decode-and-forward vs. amplify-and-forward) for each source-destination pair

Method and Apparatus for Geographic-Based Communications Service

Abstract: A geographic-based communications service system has a mobile unit for transmitting/receiving information, and access points connected to a network. The access points are arranged in a known geographic locations and transmit and receive information from the mobile unit. When one of the access points detects the presence of the mobile unit, it sends a signal to the network indicating the location of the mobile unit and the information requested by the mobile unit. Based on the signal received from the access point, the network communicates with information providers connected to the network and provides data to the mobile unit through the access point corresponding to the location of the mobile unit.

Wirelessly controlling unmanned aircraft and accessing associated surveillance data

Abstract: Controlling an unmanned aerial vehicle (UAV) may be accomplished by using a wireless device (e.g., cell phone) to send a control message to a receiver at the UAV via a wireless telecommunication network (e.g., an existing cellular network configured primarily for mobile telephone communication). In addition, the wireless device may be used to receive communications from a transmitter at the UAV, wherein the wireless device receives the communications from the transmitter via the wireless network. Examples of such communications include surveillance information and UAV monitoring information.

Channel Estimation for Amplify and Forward Relay Based Cooperation Diversity Systems

Abstract: Cooperation diversity schemes have been proposed for cellular networks that permit a base station (or a mobile station) to relay signals to a destination receiver, thereby increasing the network coverage and reliability. The mobile relays either decode and forward (DF) or amplify and forward (AF) the received signal. Most existing analyses of cooperation diversity assumes perfect channel information at the receiver. A realistic assessment should consider the effects of practical channel estimation schemes. This paper considers pilot symbol aided channel estimation for cooperation diversity systems. Since the overall channel in AF systems is different from conventional cellular channels, the channel estimation problem is interesting and challenging and therefore our focus is on AF systems. The paper addresses issues such as the estimator design, pilot symbol spacing based upon realistic channel models, and an approximate bit error rate (BER) analysis that accounts for imperfect channel estimation.

Context-for-wireless: context-sensitive energy-efficient wireless data transfer

Abstract: Ubiquitous connectivity on mobile devices will enable numerous new applications in healthcare and multimedia. We set out to check how close we are towards ubiquitous connectivity in our daily life. The findings from our recent field-collected data from an urban university population show that while network availability is decent, the energy cost of network interfaces poses a great challenge. Based on our findings, we propose to leverage the complementary strength of Wi-Fi and cellular networks by choosing wireless interfaces for data transfers based on network condition estimation. We show that an ideal selection policy can more than double the battery lifetime of a commercial mobile phone, and the improvement varies with data transfer patterns and Wi-Fi availability.We formulate the selection of wireless interfaces as a statistical decision problem. The key to attaining the potential battery improvement is to accurately estimate Wi-Fi network conditions without powering up its network interface. We explore the use of different context information, including time, history, cellular network conditions, and device motion, for this purpose. We consequently devise algorithms that can effectively learn from context information and estimate the probability distribution of Wi-Fi network conditions. Simulations based on field-collected traces show that our algorithms can improve the average battery lifetime of a commercial mobile phone for a three-channel electrocardiogram (ECG) reporting application by 39%, very close to the theoretical upper bound of 42%. Finally, our field validation of our most simple algorithm demonstrates a 35% improvement in battery lifetime.

Adaptation, Coordination, and Distributed Resource Allocation in Interference-Limited Wireless Networks

Abstract: A sensible design of wireless networks involves striking a good balance between an aggressive reuse of the spectral resource throughout the network and managing the resulting co-channel interference. Traditionally, this problem has been tackled using a ldquodivide and conquerrdquo approach. The latter consists in deploying the network with a static or semidynamic pattern of resource reutilization. The chosen reuse factor, while sacrificing a substantial amount of efficiency, brings the interference to a tolerable level. The resource can then be managed in each cell so as to optimize the per cell capacity using an advanced air interface design. In this paper, we focus our attention on the overall network capacity as a measure of system performance. We consider the problem of resource allocation and adaptive transmission in multicell scenarios. As a key instance, the problem of joint scheduling and power control simultaneously in multiple transmit-receive links, which employ capacity-achieving adaptive codes, is studied. In principle, the solution of such an optimization hinges on tough issues such as the computational complexity and the requirement for heavy receiver-to-transmitter feedback and, for cellular networks, cell-to-cell channel state information (CSI) signaling. We give asymptotic properties pertaining to rate-maximizing power control and scheduling in multicell networks. We then present some promising leads for substantial complexity and signaling reduction via the use of newly developed distributed and game theoretic techniques.

Multihop Cellular Networks: Potential Gains, Research Challenges, and a Resource Allocation Framework

Abstract: Recently, there has been increasing interest in integrating multihop relaying functionalities into cellular wireless networks. Multihop cellular networks can potentially enhance coverage, data rates, QoS performance in terms of call blocking probability, bit error rate, as well as QoS fairness for different users. However, in-depth investigations and careful system designs are required to exploit these potential advantages. Specifically, routing and resource allocation algorithms should be designed such that the maximum performance gain can be achieved. A number of different architectures, protocols, and analytical models for MCNs have been proposed in the literature where different system aspects were investigated. This article aims to present an overview of existing work in this area, pointing out key research issues and their possible solutions. Also, we present a resource allocation framework for out-of- band relaying. The throughput enhancement due to the proposed framework is demonstrated through numerical results.

Adaptation, Coordination, and Distributed Resource Allocation in Interference-Limited Wireless Networks Joint multicell resource allocation offers an enormous number of degrees of freedom that can be exploited to optimize the network performance.

Abstract: A sensible design of wireless networks involves striking a good balance between an aggressive reuse of the spectral resource throughout the network and managing the resulting co-channel interference. Traditionally, this problem has been tackled using a Bdivide and conquer( approach. The latter consists in deploying the network with a static or semidynamic pattern of resource reutilization. The chosen reuse factor, while sacrificing a substantial amount of efficien- cy, brings the interference to a tolerable level. The resource can then be managed in each cell so as to optimize the per cell capacity using an advanced air interface design. In this paper, we focus our attention on the overall network capacity as a measure of system performance. We consider the problem of resource allocation and adaptive transmission in multicell scenarios. As a key instance, the problem of joint scheduling and power control simultaneously in multiple transmit-receive links, which employ capacity-achieving adap- tive codes, is studied. In principle, the solution of such an optimization hinges on tough issues such as the computational complexity and the requirement for heavy receiver-to- transmitter feedback and, for cellular networks, cell-to-cell channel state information (CSI) signaling. We give asymptotic properties pertaining to rate-maximizing power control and scheduling in multicell networks. We then present some promising leads for substantial complexity and signaling reduction via the use of newly developed distributed and game theoretic techniques.

Wireless wakeups revisited: energy management for voip over wi-fi smartphones

Abstract: IP based telephony is rapidly gaining acceptance over traditional means of voice communication. Wireless LANs are also becoming ubiquitous due to their inherent ease of deployment and decreasing costs. In enterpriseWi-Fi environments, VoIP is a compelling application for devices such as smart phones with multiple wireless interfaces. However, the high energy consumption of Wi-Fi interfaces, especially when a device is idle,presents a significant barrier to the widespread adoption of VoIP over Wi-Fi.To address this issue, we present Cell2Notify, a practical and deployable energy management architecture that leverages the cellular radio on a smart phone to implement wakeup for the high-energy consumption Wi-Fi radio. We present detailed measurements of energy consumption on smart phone devices, and we show that Cell2Notify, can extend the battery lifetime of VoIPover Wi-Fi enabled smart phones by a factor of 1.7 to 6.4.

Effects of User-Deployed, Co-Channel Femtocells on the Call Drop Probability in a Residential Scenario

Abstract: The femtocell concept aims to combine fixed-line broadband access with cellular telephony using the deployment of low-cost, low-power 3G base stations in the subscriber's homes. These plug-and-play residential base stations would be deployed without much consideration to cell planning on the part of the user, relying instead on inbuilt auto-configuration abilities to minimise the impact on the macro cellular network by self-provisioning parameters such as the transmit and pilot power levels. In this paper, simulations of the deployment of such femtocells in a residential scenario were performed to study its effects on the service experienced by users that are connected to the underlay macrocells. The results show that with auto-configuration, the deployment of the femtocells would not pose a significant impact on the dropped call rate, causing an additional 0.45% increase in chance of a macrocell user's call dropping in the simulation's worst case scenario. In addition the impact of such femtocell deployment on the network signalling is discussed.

Voip enabled femtocell with a usb transceiver station

Abstract: Telephone calls between a mobile station (MS) and the mobile network or PSTN are routed through the Internet via VoIP using a femtocell, as opposed to the traditional macrocellular network. The femtocell can comprise a USB Transceiver Station that is connected to a personal computer through a universal serial bus port, which provides both power and a multi-megabit per second connection between the personal computer and the USB transceiver station. The USB transceiver station can comprise a microcontroller to manage signaling between the RF front end/baseband processor and the personal computer, as well as a precise timing mechanism to assist the synchronization of femtocell timing with the surrounding macrocellular network, if it is present. The USB transceiver station can have a compact form factor that that facilitates a high degree of portability by the subscriber, such as being readily attachable to their keychain.

Mobile Wireless Sensor Network: Architecture and Enabling Technologies for Ubiquitous Computing

Abstract: A mobile wireless sensor network owes its name to the presence of mobile sink or sensor nodes within the network. The advantages of mobile WSN over static WSN are better energy efficiency, improved coverage, enhanced target tracking and superior channel capacity. In this paper we present and discuss hierarchical multi-tiered architecture for mobile wireless sensor network. This architecture is proposed for the future pervasive computing age. We also elaborate on the impact of mobility on different performance metrics in mobile WSN. A study of some of the possible application scenarios for pervasive computing involving mobile WSN is also presented. These application scenarios will be discussed in their implementation context. While discussing the possible applications, we also study related technologies that appear promising to be integrated with mobile WSN in the ubiquitous computing. With an enormous growth in number of cellular subscribers, we therefore place the mobile phone as the key element in future ubiquitous wireless networks. With the powerful computing, communicating and storage capacities of these mobile devices, the network performance can benefit from the architecture in terms of scalability, energy efficiency and packet delay, etc.

System and method of reporting and visualizing malware on mobile networks

Abstract: A network management system monitors malware within a mobile network. The system comprises a receiver component that obtains data regarding malware in the mobile network. The data is obtained from a first source and a second source, where the first source is of a different type than the second source. The monitoring system also includes an analysis component that generates a malware analysis of the mobile network as a function of the data.

A Framework for Optimizing the Uplink Performance of Distributed Antenna Systems under a Constrained Backhaul

Abstract: It has recently been shown that multi-cell cooperations in cellular networks, enabling distributed antenna systems and joint transmission or joint detection across cell boundaries, can significantly increase capacity, especially that of users at cell borders. Such concepts, typically implicitly assuming unlimited information exchange between base stations, can also be used to increase the network fairness. In practical implementations, however, the large amounts of received signals that need to be quantized and transmitted via an additional backhaul between the involved cells to central processing points, will be a non-negligible issue. In this paper, we thus introduce an analytical framework to observe the uplink performance of cellular networks in which joint detection is only applied to a subset of selected users, aiming at achieving best possible capacity and fairness improvements under a strongly constrained backhaul between sites. This reveals a multi-dimensional optimization problem, where we propose a simple, heuristic algorithm that strongly narrows down and serializes the problem while still yielding a significant performance improvement.

Load balancing for cellular/WLAN integrated networks

Abstract: The interworking between heterogeneous third-generation cellular networks and wireless local area networks is one promising evolution approach to fourth-generation wireless networks, which can exploit the complementary advantages of the cellular network and WLANs. Resource management for the 4G-oriented cellular/WLAN integrated network is an important open issue that deserves more research efforts. In this article we present a policy framework for resource management in a loosely coupled cellular/WLAN integrated network, where load balancing policies are designed to efficiently utilize the pooled resources of the network. A two-phase control strategy is adopted in the load balancing policies, in which call assignment is used to provide a statistical quality of service guarantee during the admission phase, and dynamic vertical handoff during the traffic service phase is used to minimize the performance variations. Numerical results are presented to demonstrate that the proposed load balancing solution achieves significant performance improvement over two other reference schemes

Coordinating Base Stations for Greater Uplink Spectral Efficiency in a Cellular Network

Abstract: We propose an ambitious approach towards lifting the limits imposed by cochannel interference on the uplink spectral efficiency of a cellular network, viz., coordinating several base stations in the reception of users within their coverage area, and suppressing interference between users by means of coherent linear beamforming across the base stations. We evaluate by simulation the potential gain in spectral efficiency from such coordination, when there is 1 user per base station antenna in the network, and all users (but for a small fraction in outage) must be served at a constant and common data rate. We highlight the dependence of the spectral efficiency gain on the number of rings of neighbors with which each base station is coordinated, as well as the underlying signal-to-noise ratio (SNR) distribution in the network. Results from this study point to the possibility of doubling the uplink spectral efficiency with 1-ring coordination and nearly quadrupling it with 4-ring coordination, under high-SNR conditions.

Malware detection system and method for mobile platforms

Abstract: In one example, a management server is configured to provide malware protection for one or more client mobile platforms in communication with the management server via a mobile network. In the example, the management server includes a processor configured to detect malware in the mobile network, select a client mobile platform having a malware scanning agent, and, manage the malware scanning agent of the client mobile platform using a device independent secure management protocol based at least in part on the malware detected in the mobile network.

Methods and apparatuses for using mobile GPS receivers to synchronize basestations in cellular networks

Abstract: Methods and apparatuses for establishing time at a first basestation, and synchronizing the first basestation with other basestations in a cellular network. The method may be performed using a mobile (cellular communication) station that includes a satellite position system receiver. One method comprises determining a location of the mobile station, determining a time indicator that represents a time-of-day at the mobile station, wherein the time indicator is determined relative to a signal available at the first basestation, transmitting at least one of the position information and location, and transmitting the time indicator from the mobile station. The time indicator and at least one of the position information and the location are used to establish a time at the first basestation such that the first basestation is synchronized to other basestations in the cellular communication system. Other methods and apparatuses are also described for synchronizing basestations in a cellular network.

Financial Analysis of a Pico-Cellular Home Network Deployment

Abstract: The increasing demand for higher data rates in cellular networks has resulted in a trend to smaller cell sizes (femto cells) and pico-cellular hot spot coverage. In this paper the financial impact of pico-cellular home base station deployment in a macro-cellular network is explored. For increasing data rates, it becomes evident that current macro-cellular network deployment becomes less economically viable. It is shown that in urban areas a combination of publicly accessible home base stations, randomly deployed by the end user, and macro-cells for area coverage, deployed by an operator, can result in significant reductions (up to 70% in the investigated scenario) of the total annual network costs compared to a pure macro-cellular network.

Method and apparatus for providing a communication unit with a handoff between networks

Abstract: A communication unit (10) includes a mobility agent (225) for providing handoffs between a cellular network and a wireless local area network (11). The communication unit (10) determines if it should switch between the wireless local area network (11) and the cellular network for obtaining service, requests a handoff to the wireless local area network (11) or to the cellular network by sending a SIP message addressed to either a public number (229) or a private number (231) associated with the communication unit (10) upon making the determination. The communication unit (10) accepts a new call from an enterprise server (12) over the determined network. Corresponding methods of providing a hand-off is described.

Network Mobility Route Optimization Problem Statement

Abstract: With current Network Mobility (NEMO) Basic Support, all communications to and from Mobile Network Nodes must go through the bi-directional tunnel established between the Mobile Router and Home Agent when the mobile network is away. This sub-optimal routing results in various inefficiencies associated with packet delivery, such as increased delay and bottleneck links leading to traffic congestion, which can ultimately disrupt all communications to and from the Mobile Network Nodes. Additionally, with nesting of Mobile Networks, these inefficiencies get compounded, and stalemate conditions may occur in specific dispositions. This document investigates such problems and provides the motivation behind Route Optimization (RO) for NEMO. This memo provides information for the Internet community.

The Design and Evaluation of Unified Cellular and Ad-Hoc Networks

Abstract: In third-generation (3G) wireless data networks, providing service to low data-rate users is required for maintaining fairness, but at the cost of reducing the cell's aggregate throughput. In this paper, we propose the unified cellular and ad hoc network (UCAN) architecture for enhancing cell throughput while maintaining fairness. In UCAN, a mobile client has both 3G interface and IEEE 802.11 -based peer-to-peer links. The 3G base station forwards packets for destination clients with poor channel quality to proxy clients with better channel quality. The proxy clients then use an ad hoc network composed of other mobile clients and IEEE 802.11 wireless links to forward the packets to the appropriate destinations, thereby improving cell throughput. We refine the 3G base station scheduling algorithm so that the throughput gains are distributed in proportion to users' average channel rates, thereby maintaining fairness. With the UCAN architecture in place, we propose novel greedy and on-demand protocols for proxy discovery and ad hoc routing that explicitly leverage the existence of the 3G infrastructure to reduce complexity and improve reliability. We further propose secure crediting mechanisms to motivate users that are not actively receiving to participate in relaying packets for others. Through both analysis and extensive simulations with HDR and IEEE 802.11b, we show that the UCAN architecture can increase individual user's throughput by more than 100 percent and the aggregate throughput of the HDR downlink by up to 50 percent.

Limited Downlink Network Coordination in Cellular Networks

Abstract: We investigate the downlink throughput of cellular systems where groups of M antennas - either co-located or spatially distributed - transmit to a subset of a total population of K > M users in a coherent, coordinated fashion in order to mitigate intercell interference. We consider two types of coordination: the capacity-achieving technique based on dirty paper coding (DPC), and a simpler technique based on zero-forcing (ZF) beamforming with per-antenna power constraints. During a given frame, a scheduler chooses the subset of the K users in order to maximize the weighted sum rate, where the weights are based on the proportional-fair scheduling algorithm. We consider the weighted average sum throughput among K users per cell in a multi-cell network where coordination is limited to a neighborhood of M antennas. Consequently, the performance of both systems is limited by interference from antennas that are outside of the M coordinated antennas. Compared to a 12-sector baseline which uses the same number of antennas per cell site, the throughput of ZF and DPC achieve respective gains of 1.5 and 1.75.

System for and method of for providing dedicated capacity in a cellular network

Abstract: The present invention comprises systems for and methods of providing dedicated capacity in a wireless cellular network. In an embodiment, a system for providing dedicated capacity in a cellular network comprises: a first base station positioned at a first location and being communicatively coupled to a telephone network, the first base station having an outdoor cellular antenna for forming a local coverage area, a second base station positioned at the first location and being communicatively coupled to the telephone network; and an indoor cellular antenna for forming a coverage area at a second location. The second location is geographically remote from the First location and the indoor cellular antenna is communicatively coupled to the second base station such that mobile communications equipment located within the coverage area at the second location are communicatively coupled to the telephone network via the indoor cellular antenna and the second base station.

Signaling over cellular networks to reduce the Wi-Fi energy consumption of mobile devices

Abstract: Techniques for increasing the battery life on a mobile device by decreasing the energy consumption of the mobile device's wireless fidelity (Wi-Fi) interface are described. In one embodiment, the mobile device's Wi-Fi interface is automatically disabled when the device is not engaged. When the device receives a wake up call from a server via its Cellular interface, the Wi-Fi interface is enabled if the device answers the wake up call and the Wi-Fi interface is available. Using its Wi-Fi interface, the mobile device then connects to an IP-based network via a Wi-Fi access point.

System and method of network access security policy management for multimodal device

Abstract: A system and method are provided for management of access security for access by a multimodal device to a converged fixed/mobile network. An inter-technology change-off monitoring entity (ICME) is provided to monitor an inter-technology change-off of the multimodal device and to notify a policy manager of the inter-technology change-off. The policy manager looks up in a policy database, security policies applicable to the user of the multimodal device and the particular technology being used by the multimodal device. The policy manager conveys to various policy enforcement points throughout the converged fixed/mobile network the applicable security policies which take into account the user's identity and the access technology being used.

Performance Analysis of the WLAN-First Scheme in Cellular/WLAN Interworking

Abstract: In the interworking between a cellular network and wireless local area networks (WLANs), a two-tier overlaying structure exists in the WLAN-covered areas. Due to the heterogeneous underlying quality-of-service (QoS) support, the admission of traffic in these areas has a significant impact on QoS satisfaction and overall resource utilization, especially when multiple services are considered. In this paper, we analyze the performance of a simple admission strategy, referred to as WLAN-first scheme, in which incoming voice and data service requests always first try to get admission to the WLAN whenever it is available. It is observed that the overall resource utilization can be maximized when the admission regions for voice and data services in a cell and a WLAN are properly configured

Uplink Capacity and Interference Avoidance for Two-Tier Cellular Networks

Abstract: Two-tier femtocell networks-comprising a conventional macrocellular network plus embedded femtocell hotspots- offer an economically viable solution to achieving high cellular user capacity and improved coverage. This paper develops an uplink capacity analysis and interference avoidance strategy in such a two-tier CDMA network with universal frequency reuse. We evaluate a network-wide area spectral efficiency metric called the Operating Contour (OC) defined as the combinations of the average macrocell users and femtocell BS per cell-site that meet a target outage constraint. A contribution of this work is an accurate characterization of the uplink outage probability taking cross-tier power control, path-loss and shadowing into account. Considering worst case interference at a corner femtocell, results reveal that interference avoidance through a time-hopped CDMA physical layer and sectorized antennas allows about a 7x higher femtocell BS density, relative to a split spectrum network with omnidirectional femtocell antennas. These results provide guidelines for the design of robust shared spectrum two-tier networks.

Call flow system and method for use in a legacy telecommunication system

Abstract: A method of operating a network server, such as a mobile application gateway, connect devices on a cellular or carrier network with individual networks, such as enterprise voice and data networks or residential networks. The effects of the present invention are far reaching in terms of transferring effective call control from the cellular network into the control of the individual network, such as the enterprise, and enabling new business models for the purchase of cellular service from a public cellular carrier by an enterprise.

System and method for managing malware protection on mobile devices

Abstract: A system and method for providing malware protection on client mobile platforms (1010) in a mobile network The system and method manages the malware scanning agents (1012) of the client mobile platforms from a managment server (1502) using a device independent secure management protocol The management server (1502) downloads new malware definition to client mobile platforms (1010) and remotely initiate malware scanning on the client mobile platforms (1010).