Showing papers on "Backhaul (telecommunications) published in 2007"

Network MIMO: Overcoming Intercell Interference in Indoor Wireless Systems

Abstract: Network MIMO is a family of techniques whereby each user in a wireless system is served through all the access points within its range of influence By tightly coordinating the transmission and reception of signals at multiple access points, network MIMO transcends the limits on spectral efficiency due to intercell interference Taking prior information- theoretic analyses of Network MIMO to the next level, this paper quantifies the spectral efficiency gains obtainable under realistic propagation and operational conditions Our study relies on detailed simulations and, for specificity, is conducted within the framework of the IEEE 80216e Mobile WiMAX system All the relevant physical-layer functionalities of Mobile WiMAX are accurately replicated Furthermore, to facilitate the coordination between access points, we postulate an indoor deployment organized around a gigabit-ethernet backhaul The results confirm that Network MIMO stands to provide a multiple-fold increase in spectral efficiency under such conditions

Mobile broadband wireless access point network with wireless backhaul

Abstract: A WiMAX network and communication method, the network including a plurality of WiMAX nodes deployed in micro or pico cells for providing access service to a plurality of mobile subscribers, a plurality of these nodes being arranged in a cluster, one of the nodes in each cluster being a feeder node coupled to a core network, the nodes in each cluster being coupled for multi-hop transmission to the feeder node. According to a preferred embodiment, each node includes a transceiver with associated modem, an antenna arrangement coupled to the modem and arranged for multiple concurrent transmissions, and a MAC controller for controlling the transceiver, modem and antenna arrangement for providing both access and backhaul communication.

Wimax access point network with backhaul technology

Abstract: A WiMAX network and communication method, the network including a plurality of WiMAX nodes (Fig.1, 12) deployed in micro or pico cells for providing access service to a plurality of mobile subscribers, a plurality of these nodes being arranged in a cluster (Fig.), 14), one of the nodes in each cluster being a feeder node coupled to a core network, the nodes in each cluster being coupled for multi-hop transmission to the feeder node. According to a preferred embodiment, each node includes a transceiver with associated modem, an antenna arrangement coupled to the modem and arranged for multiple concurrent transmissions, and a MAC controller for controlling the transceiver, modem and antenna arrangement for providing both access and backhaul communication.

Fixed mobile convergence (FMC) architectures for broadband access: integration of EPON and WiMax

Abstract: EPON and WiMAX are two promising broadband access technologies for new-generation wired and wireless access. Their complementary features motivate interest in using EPON as a backhaul to connect multiple dispersed WiMAX base stations. In this article we propose four broadband access architectures to integrate EPON and WiMAX technologies. The integrated architectures can take advantage of the bandwidth benefit of fiber communications, and the mobile and non-line-of-sight features of wireless communications. Based on these integrated architectures, we elaborate on related control and operation issues to address the benefits gained by this integration. Integration of EPON and WiMAX enables fixed mobile convergence, and is expected to significantly reduce overall design and operational costs for new-generation broadband access networks.

Fixed Mobile Convergence Architectures for Broadband Access: Integration of EPON and WiMAX [Topics in Optical Communications]

Abstract: EPON and WiMAX are two promising broadband access technologies for new-generation wired and wireless access. Their complementary features motivate interest in using EPON as a backhaul to connect multiple dispersed WiMAX base stations. In this article we propose four broadband access architectures to integrate EPON and WiMAX technologies. The integrated architectures can take advantage of the bandwidth benefit of fiber communications, and the mobile and non-line-of-sight features of wireless communications. Based on these integrated architectures, we elaborate on related control and operation issues to address the benefits gained by this integration. Integration of EPON and WiMAX enables fixed mobile convergence, and is expected to significantly reduce overall design and operational costs for new-generation broadband access networks.

A Performance Study of Deployment Factors in Wireless Mesh Networks

Abstract: We present a measurement-parameterized performance study of deployment factors in wireless mesh networks using three performance metrics: client coverage area, backhaul tier connectivity, and fair mesh capacity. For each metric, we identify and study topology factors and architectural features which strongly influence mesh performance via an extensive set of Monte Carlo simulations capturing realistic physical layer behavior. Our findings include: (i) A random topology is unsuitable for a large-scale mesh deployment due to doubled node density requirements, yet a moderate level of perturbations from ideal grid placement has a minor impact on performance. (ii) Multiple backhaul radios per mesh node is a cost-effective deployment strategy as it leads to mesh deployments costing 50% less than with a single-radio architecture, (iii) Dividing access and backhaul connections onto two separate radios does not use the second radio efficiently as it only improves fair mesh capacity 40% to 80% for most users. This is in contrast to using the second radio to move half the user population to a new network operated on the second radio. This work adds to the understanding of mesh deployment factors and their general impact on performance, providing further insight into practical mesh deployments.

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.

WIRELESS BROADBAND ACCESS: WIMAX AND BEYOND - Integration of WiMAX and WiFi: Optimal Pricing for Bandwidth Sharing

Abstract: Broadband wireless access networks based on WiMAX can provide backhaul support for mobile WiFi hotspots. We consider an integrated WiMAX/WiFi network for such an application where the licensed WiMAX spectrum is shared by the WiFi access points/routers to provide Internet connectivity to mobile WiFi users. The WiMAX backbone network and WiFi hotspots are operated by different service providers. Issues such as protocol adaptation, quality of service support, and pricing for bandwidth sharing that are related to integration of these networks are discussed. In addition, we propose a model for optimal pricing for bandwidth sharing in an integrated WiMAX/WiFi network. A Stackelberg leader-follower game is formulated to obtain the optimal pricing solution for bandwidth sharing. Performance evaluation results reveal some interesting insights into the problem

Hybrid Architecture and Integrated Routing in a Scalable Optical–Wireless Access Network

Abstract: We propose a hybrid optical-wireless access network that consists of reconfigurable optical backhaul and wireless mesh networks (WMNs). The complementary characteristics of wireless and optical networks are combined to provide a broadband and ubiquitous last-mile connection. Wireless mesh routers are deployed to penetrate the vicinity of end users for a flexible and ubiquitous connection. It eliminates massive and geographically scattered deployment of physical infrastructure to reach the end users. The broadband optical backhaul consists of optical ring and multiple tree networks, connecting the central hub and WMNs. The ends of the optical tree networks connect to the wireless gateway routers of WMNs. A hybrid time-division-multiplexing (TDM)/wavelength-division-multiplexing (WDM) optical backhaul is realized by wavelength-multiplexing multiple TDM-passive-optical-network streams. This hybrid architecture provides graceful scalability, cost effectiveness, and bandwidth efficiency. To adapt to a change of the overall demand in different districts, reconfigurability is implemented in the optical backhaul utilizing tunable optical transceivers. An experimental test bed is implemented to evaluate the reconfigurable scheme. Given the synergy of the optical backhaul and WMNs, we propose an integrated-routing algorithm to achieve load balancing on this hybrid architecture. The simulation using NS2 shows an approximately 25% throughput improvement with load balancing.

Architecture, protocols and frame formats for wireless multi-hop relay networks

Abstract: Methods, protocols and systems for communicating in a multi-hop wireless mesh network may include explicitly providing information relating to backhaul wireless link qualities in multi-hop wireless mesh network to next generation subscriber stations in a first mode. In a second mode, embodiments are configured to implicitly provide indicia of multi-hop wireless link qualities to legacy subscriber stations by adjusting a transmit power of frames sent to the legacy subscriber stations. Other embodiments and variations are described in the detailed description.

Uplink Macro Diversity with Limited Backhaul Capacity

Abstract: In this contribution we present new achievable rates, for the non-fading uplink channel of a cellular network, with joint cell-site processing, where unlike previous results, the error-free backhaul network has finite capacity per-cell. Namely, the cell-sites are linked to the central joint processor via lossless links with finite capacity. The cellular network is modeled by the circular Wyner model, which yields closed form expressions for the achievable rates. For this idealistic model, we present achievable rates for cell-sites that use compress-and forward scheme, combined with local decoding, and inter-cell time-sharing. These rates are then demonstrated to be rather close to the optimal unlimited backhaul joint processing rates, already for modest backhaul capacities, supporting the potential gain offered by the joint cell-site processing approach.

Backhaul-level call admission control for a wireless mesh network

Abstract: One embodiment includes tracking utilization of the backhaul wireless bandwidth of a mesh network related to time sensitive packet data, receiving a call admission request for a call from a client station of a first mesh access point of the mesh, ascertaining using the tracked utilization whether to approve the call admission request using a backhaul call admission control method, and approving the call by sending a positive call admission response if the backhaul call admission control method approves the call and if an access level call admission control method ascertains to approve the call admission request at the access level.

WiMAX: Standards and Security

Abstract: As the demand for broadband services continues to grow worldwide, traditional solutions, such as digital cable and fiber optics, are often difficult and expensive to implement, especially in rural and remote areas. The emerging WiMAX system satisfies the growing need for high data-rate applications such as voiceover IP, video conferencing, interactive gaming, and multimedia streaming. WiMAX deployments not only serve residential and enterprise users but can also be deployed as a backhaul for Wi-Fi hotspots or 3G cellular towers. By providing affordable wireless broadband access, the technology of WiMAX will revolutionize broadband communications in the developed world and bridge the digital divide in developing countries. Part of the WiMAX Handbook, this volume focuses on the standards and security issues of WiMAX. The book examines standardized versus proprietary solutions for wireless broadband access, reviews the core medium access control protocol of WiMAX systems, and presents carriers' perspectives on wireless services. It also discusses the main mobility functions of the IEEE 802.16e standard, describes how to speed up WiMAX handover procedures, presents the 802.16 mesh protocol, and surveys the testing and certification processes used for WiMAX products. In addition, the book reviews the security features of both IEEE 802.16 and WiMAX. With the revolutionary technology of WiMAX, the lives of many will undoubtedly improve, thereby leading to greater economic empowerment.

Dynamic Cross-Layer Association in 802.11-Based Mesh Networks

Abstract: In IEEE 802.11-based wireless mesh networks a user is associated with an access point (AP) in order to communicate and be part of the overall network. The association mechanism specified by the IEEE 802.11 standard does not consider the channel conditions and the AP load in the association process. Employing the mechanism in its plain form in wireless mesh networks we may only achieve low throughput and low user transmission rates. In this paper, we propose an association mechanism that is aware of the uplink and downlink channel conditions. We introduce a metric that captures the channel conditions and the load of the APs in the network. The users use this metric in order to optimally associate with the available APs. We then extend the functionality of this mechanism in a cross-layer manner taking into account information from the routing layer. The novelty of the mechanism is that the routing QoS information of the back haul is available to the end users. This information can be combined with the uplink and downlink channel information for the purpose of supporting optimal end-to-end communication and providing high end-to-end throughput values. We evaluate the performance of our system through simulations and we show that 802.11-based mesh networks that use the proposed association mechanism are more capable in meeting the needs of QoS-sensitive applications.

Method for channel estimation in a point-to-point communication network

Abstract: A method of using pilot signals in a wireless communication network including encoding pilot signals, and transmitting the encoded pilot signals over an in-band backhaul link between two nodes in the network. Preferably, the pilot signals are encoded with a CDMA codeword associated with a link. The pilot signals can be decoded to permit estimation of a channel and interference attributable to each link.

Integration of WiMAX and WiFi: Optimal Pricing for Bandwidth Sharing

Abstract: Broadband wireless access networks based on WiMAX can provide backhaul support for mobile WiFi hotspots. We consider an integrated WiMAX/WiFi network for such an application where the licensed WiMAX spectrum is shared by the WiFi access points/routers to provide Internet connectivity to mobile WiFi users. The WiMAX backbone network and WiFi hotspots are operated by different service providers. Issues such as protocol adaptation, quality of service support, and pricing for bandwidth sharing that are related to integration of these networks are discussed. In addition, we propose a model for optimal pricing for bandwidth sharing in an integrated WiMAX/WiFi network. A Stackelberg leader-follower game is formulated to obtain the optimal pricing solution for bandwidth sharing. Performance evaluation results reveal some interesting insights into the problem.

Method and system of using a wireless link in the backhaul connection

Abstract: One embodiment of the communication system includes a switch, at least one base station, and a backhaul connection including at least one wireless link connecting the at least one base station to the switch. The wireless link may include at least one of a WiMax carrier and a WiFi carrier.

WiMAX: Technologies, Performance Analysis, and QoS

Abstract: As the demand for broadband services continues to grow worldwide, traditional solutions, such as digital cable and fiber optics, are often difficult and expensive to implement, especially in rural and remote areas. The emerging WiMAX system satisfies the growing need for high data-rate applications such as voiceover IP, video conferencing, interactive gaming, and multimedia streaming. WiMAX deployments not only serve residential and enterprise users but can also be deployed as a backhaul for Wi-Fi hotspots or 3G cellular towers. By providing affordable wireless broadband access, the technology of WiMAX will revolutionize broadband communications in the developed world and bridge the digital divide in developing countries. Part of the WiMAX Handbook, this volume focuses on the technologies behind WiMAX, its performance capabilities, and its control mechanisms. The book introduces programmable baseband processors suited for WiMAX systems, describes an innovative methodology for the design of multi-band WiMAX antennas, addresses space-time block codes, and reviews space-frequency/space-time-frequency code design criteria. It also proposes a combined call admission control and scheduling scheme, focuses on the performance analysis of the IEEE 802.16 mesh mode, and analyzes the performance of both single-input-single-output and space-time-block-coded OFDM systems in mobile environments. The final section establishes a framework of an ideal reservation period controller, examines the ecosystem in which scheduling for IEEE 802.16e systems must be performed, and presents a fuzzy logic controller for admission control. With the revolutionary technology of WiMAX, the lives of many will undoubtedly improve, thereby leading to greater economic empowerment.

Dynamic beam steering of backhaul traffic

Abstract: A communication system (100) and a method (500) of communicating backhaul data. The communication system can include a controller (160, 225). The controller can dynamically select from a plurality of backhaul sites (120, 125) at least a first backhaul site to establish a backhaul communication link with an access point (115). The controller also can generate a control signal that indicates to the access point to beam steer a backhaul signal to the first backhaul site. The access point can include a phased array (215) that dynamically beam steers the backhaul signal in azimuth and elevation.

DARA: Delay-Aware Routing Algorithm in a Hybrid Wireless-Optical Broadband Access Network (WOBAN)

Abstract: Hybrid wireless-optical broadband access network (WOBAN) is a promising architecture for future network operations. Recently, the wireless part of WOBAN has been gaining increasing attention and early versions are being deployed as a municipal access solution to eliminate the wired backhaul to every wireless router. This architecture saves on network deployment costs because fiber (or wiring) does not need to extend to the end user, and it extends the reach of emerging optical access solutions, e.g., passive optical network (PON)-based access solutions. However, a major research opportunity exists in developing an efficient routing algorithm for the wireless front end of WOBAN. We propose and investigate the characteristics of "delay- aware routing algorithm (DARA)" that minimizes the average packet delay in the wireless front end of a WOBAN. We model wireless routers as queues and predict wireless link states periodically. Our simulation experiments show that DARA achieves better load balancing and less congestion compared to tradional approaches such as minimum-hop routing algorithm (MHRA) and shortest- path routing algorithm (SPRA). In addition to minimizing the delay, DARA also improves the average hop count compared to the predictive throughput routing algorithm (PTRA), a popular protocol used in several deployments for the wireless front end of a WOBAN.

Cooperative Multi-Cell Networks: Impact of Limited-Capacity Backhaul and Inter-Users Links

Abstract: Cooperative technology is expected to have a great impact on the performance of cellular or, more generally, infrastructure networks. Both multicell processing (cooperation among base stations) and relaying (cooperation at the user level) are currently being investigated. In this presentation, recent results regarding the performance of multicell processing and user cooperation under the assumption of limited-capacity interbase station and inter-user links, respectively, are reviewed. The survey focuses on related results derived for non-fading uplink and downlink channels of simple cellular system models. The analytical treatment, facilitated by these simple setups, enhances the insight into the limitations imposed by limited-capacity constraints on the gains achievable by cooperative techniques.

Base-station selection in cooperative single frequency cellular network

Abstract: Single frequency cellular network (SFCN) combined with virtual MIMO (VMIMO) and cooperation is a novel and competitive deployment which allows a more efficient spectrum usage for the next generation wireless networks. However, for uplink transmission, cooperative techniques induce a large amount of data to be transmitted on the backhaul of the infrastructure. In order to reduce the backhaul load we want to select for each user only a small number of decoding base- stations. This contribution presents two possible selection algorithms: the first is based on genetic approach and the second is inspired from the sphere decoder. Both are compared with classical selection techniques: SNR sort and exhaustive search.

Performance of packet voice transmission using IEEE 802.16 protocol

Abstract: The IEEE 802.16 standard defines three types of scheduling services for supporting real-time traffic, unsolicited grant service (UGS), real-time polling service (rtPS), and extended real-time polling service (ertPS). In the UGS service, the base station (BS) offers a fixed amount of bandwidth to a subscriber station (SS) periodically, and the SS does not have to make any explicit bandwidth requests. The bandwidth allocation in the rtPS service is updated periodically in the way that the BS periodically polls the SS, which makes a bandwidth request at the specified uplink time slots and receives a bandwidth grant in the following downlink subframe. In the ertPS service, the BS keeps offering the same amount of bandwidth to the SS unless explicitly requested by the SS. The SS makes a bandwidth request only if its required transmission rate changes. In this article we study the performance of voice packet transmissions and BS resource utilization using the three types of scheduling services in IEEE 802.16-based backhaul networks, where each SS forwards packets for a number of voice connections. Our results demonstrate that while the UGS service achieves the best latency performance, the rtPS service can more efficiently utilize the BS resource and flexibly trade-off between packet transmission performance and BS resource allocation efficiency; and appropriately choosing the MAC frame size is important in both the rtPS and ertPS services to reduce packet transmission delay and loss rate

OFDMA resource allocation in multi-hop wireless mesh networks

Abstract: A method, apparatus and system for communicating in a multi-hop wireless mesh network may entail allocating orthogonal frequency division multiple access (OFDMA) resources based, at least in part, on throughput characteristics associated with a multi-hop path. OFDMA allocation may be centralized by a macro base station for assigning resources between backhaul links and micro base stations in the network may independently assign resources for communications to mobile stations within its own radio access network (RAN). Other embodiments and variations are described in the detailed description.

Method and device for providing an alternative backhaul portal in a mesh network

Abstract: A method and device for providing an alternative backhaul portal at a mesh access point in a mesh network as provided enables improved backhaul services. The method includes processing a registration of the mesh access point as an alternative backhaul portal in the mesh network. It is then determined that additional backhaul capacity is required in the mesh network. Next, the mesh access point is activated as an alternative backhaul portal in the mesh network in response to determining that additional backhaul capacity is required. Mesh network data are then routed through the alternative backhaul portal at the mesh access point until it is determined that additional backhaul capacity is no longer required. The mesh access point is then deactivated as an alternative backhaul portal in the mesh network.

On the deployment of wireless data back-haul networks

Abstract: We study the deployment of data back-haul nodes for wireless networks with energy constraints. We address the following problem: given the required lifetime of a sensor network, the energy constraint of back-haul nodes, and the area to be covered, what is the minimum number of nodes needed to construct such a back-haul network and what is the corresponding deployment scheme? Finding an efficient deployment scheme involves location management, routing, and power management. We focus on linear networks and formulate a deployment optimization problem. We then propose and analyze a greedy deployment scheme that achieves close to optimal performance. We reveal the closed-form relationship among different design parameters, namely, the number of sensor nodes, the desired lifetime, and the coverage distance. We also study the effect of miscellaneous power consumptions and non-uniform data density, and consider extensions to planar networks

Application of IEEE 802.16 Mesh Networks as the Backhaul of Multihop Cellular Networks

Abstract: Cellular networks have been widely used to support many new audio-and video-based multimedia applications. The demand for higher data rate and diverse services has driven the research on multihop cellular networks (MCNs). With its ad hoc network features, an MCN can offer many additional advantages, such as increased network throughput, scalability and coverage. However, providing ad hoc capability to MCNs is challenging as it may require proper wireless interfaces. In this article, the architecture of IEEE 802.16 network interface to provide ad hoc capability for MCNs is investigated, with its focus on the IEEE 802.16 mesh networking and scheduling. Several distributed routing algorithms based on network entry mechanism are studied and compared with a centralized routing algorithm. It is observed from the simulation results that 802.16 mesh networks have limitations on providing sufficient bandwidth for the traffic from the cellular base stations when a cellular network size is relatively large.

Cross-Layer Optimization for OFDMA-Based Wireless Mesh Backhaul Networks

Abstract: In this paper, we propose a cross layer optimization framework for multi-hop routing and resource allocation design in an orthogonal frequency division multiple access (OFDMA) based wireless mesh network. The network under consideration is assumed to consist of fixed mesh routers (or base station routers) inter-connected using OFDMA wireless links with some of the mesh routers functioning as gateways to a wired network. The objective of our cross-layer formulation is to allow joint determination of power control, frequency-selective OFDMA scheduling and multi-hop routing in order to maximize the minimum throughput that can be supported to all mesh routers. Results of our investigations under typical cellular deployment, propagation and channel model assumptions show that this approach achieves significant mesh throughput improvements primarily due to the following: (a) frequency selective scheduling with OFDMA which provides improved tone diversity thus allowing more efficient bandwidth utilization relative to single carrier methods; and (b) multi-hop routing which provides improved path diversity relative to single hop transmissions.

A Decentralized Optimization Approach to Backhaul-Constrained Distributed Antenna Systems

Abstract: It has been shown that multi-cell co-operations in cellular networks, enabling distributed antenna systems and joint signal processing across cell boundaries, can significantly increase system capacity and fairness. In recent work on this topic, we have proposed an optimization framework and algorithm that applies joint detection in the uplink or joint transmission in the downlink, respectively, to only a selected subset of users. This already yields a large extent of capacity and fairness improvements, while requiring only comparatively small backhaul capacity between co-operating base stations, which is usually the main issue connected to distributed antenna systems. In the following paper, we will introduce a novel concept of partitioning a cellular network and its resources into small subsystems, within which the optimization algorithm can be applied in a decentralized way. While each subsystem requires only very limited system knowledge, and joint detection and transmission is constrained to within subsystems, the performance improvements are still promising and approach those of a centralized optimization scheme in scenarios of strongly constrained backhaul.

Deployment and radio resource reuse in IEEE 802.16j multi-hop relay network in Manhattan-like environment

Abstract: IEEE 80216j is an amendment to the IEEE 80216 broadband wireless access standard to enable the operation of multi-hop relay stations (RS) It aims to enhance the coverage, per user throughput and system capacity of IEEE 80216e Compared with base station (BS), RS does not need a wire-line backhaul and has much lower hardware complexity Using RSs can significantly reduce the deployment cost of the system In this paper, the RS deployment and radio-resource reuse strategies for IEEE 80216j multi-hop relay (MR) networks are investigated Simulation results show that the per-user throughput and system capacity of IEEE 80216j MR network can be substantially improved by the proposed method