Showing papers on "Backhaul (telecommunications) published in 2009"

Uplink Macro Diversity of Limited Backhaul Cellular Network

Abstract: In this work, new achievable rates are derived for the uplink channel of a cellular network with joint multicell processing (MCP), where unlike previous results, the ideal 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 new rates are based on compress-and-forward schemes combined with local decoding. Further, the cellular network is abstracted by symmetric models, which render analytical treatment plausible. For this family of idealistic models, achievable rates are presented for both Gaussian and fading channels. The rates are given in closed form for the classical Wyner model and the soft-handover model. These rates are then demonstrated to be rather close to the optimal unlimited backhaul joint processing rates, even for modest backhaul capacities, supporting the potential gain offered by the joint MCP approach. Particular attention is also given to the low-signal-to-noise ratio (SNR) characterization of these rates through which the effect of the limited backhaul network is explicitly revealed. In addition, the rate at which the backhaul capacity should scale in order to maintain the original high-SNR characterization of an unlimited backhaul capacity system is found.

Downlink multicell processing with limited-backhaul capacity

Abstract: Multicell processing in the form of joint encoding for the downlink of a cellular system is studied under the assumption that the base stations (BSs) are connected to a central processor (CP) via finitecapacity links (finite-capacity backhaul). To obtain analytical insight into the impact of finite-capacity backhaul on the downlink throughput, the investigation focuses on a simple linear cellular system (as for a highway or a long avenue) based on the Wyner model. Several transmission schemes are proposed that require varying degrees of knowledge regarding the system codebooks at the BSs. Achievable rates are derived in closed-form and compared with an upper bound. Performance is also evaluated in asymptotic regimes of interest (high backhaul capacity and extreme signal-to-noise ratio, SNR) and further corroborated by numerical results. The major finding of this work is that even in the presence of oblivious BSs (that is, BSs with no information about the codebooks) multicell processing is able to provide ideal performance with relatively small backhaul capacities, unless the application of interest requires high data rate (i.e., high SNR) and the backhaul capacity is not allowed to increase with the SNR. In these latter cases, some form of codebook information at the BSs becomes necessary.

The next challenge for cellular networks: backhaul

Abstract: Growth in the number of mobile users, coupled with the strong uptake of wireless broadband services, is driving high transport capacity requirements among cellular networks. However, revenues are not scaling linearly with increases in traffic. Demand for optimizing the cost efficiency of backhaul is becoming as critical as investment in the radio infrastructure. As a result, new transmission technologies, topologies, and network architectures are emerging in an attempt to ease the backhaul cost and capacity crunch.

Local Base Station Cooperation Via Finite-Capacity Links for the Uplink of Linear Cellular Networks

Abstract: Cooperative decoding at the base stations (or access points) of an infrastructure wireless network is currently well recognized as a promising approach for intercell interference mitigation, thus enabling high frequency reuse. Deployment of cooperative multicell decoding depends critically on the tolopology and quality of the available backhaul links connecting the base stations. This work studies a scenario where base stations are connected only if in adjacent cells, and via finite-capacity links. Relying on a linear Wyner-type cellular model with no fading, achievable rates are derived for the two scenarios where base stations are endowed only with the codebooks of local (in-cell) mobile stations, or also with the codebooks used in adjacent cells. Moreover, both uni- and bidirectional backhaul links are considered. The analysis sheds light on the impact of codebook information, decoding delay, and network planning (frequency reuse) on the performance of multicell decoding as enabled by local and finite-capacity backhaul links. Analysis in the high-signal-to-noise ratio (SNR) regime and numerical results validate the main conclusions.

Distributed compression for MIMO coordinated networks with a backhaul constraint

Abstract: We consider the uplink of a backhaul-constrained, MIMO coordinated network. That is, a single-frequency network with N + 1 multi-antenna base stations (BSs) that cooperate in order to decode the users' data, and that are linked by means of a common lossless backhaul, of limited capacity R. To implement the receive cooperation, we propose distributed compression: N BSs, upon receiving their signals, compress them using a multi-source lossy compression code. Then, they send the compressed vectors to a central BS, which performs users' decoding. Distributed Wyner-Ziv coding is proposed to be used, and is designed in this work. The first part of the paper is devoted to a network with a unique multi-antenna user, that transmits a predefined Gaussian space-time codeword. For such a scenario, the "compression noise" covariance at the BSs is optimized, considering the user's achievable rate as the performance metric. In particular, for N = 1 the optimum covariance is derived in closed form, while for N > 1 an iterative algorithm is devised. The second part of the contribution focusses on the multi-user scenario. For it, the achievable rate region is obtained by means of the optimum "compression noise" covariances for sum-rate and weighted sum-rate, respectively.

On Downlink Network MIMO under a Constrained Backhaul and Imperfect Channel Knowledge

Abstract: Next generation mobile communications systems will most likely employ network MIMO in order to mitigate inter-cell interference and improve system fairness and spectral efficiency. Critical issues of such schemes are, however, the large extent of backhaul infrastructure required for the information exchange between cooperating base stations, and the availability of channel knowledge at transmitter and receiver. In this paper, we consider a cooperative downlink transmission under a constrained backhaul, limited channel knowledge at base station and terminal side, and a per-antenna power constraint. We derive inner capacity bounds for different cooperation schemes through uplink/downlink duality and provide numerical results showing the superiority of certain cooperation schemes in terms of rate/backhaul tradeoff for different interference scenarios.

Relay architecture framework

Abstract: Systems and methodologies are described that facilitate providing relay nodes in wireless networks. In particular, cluster nodes, which can be regular eNBs, can provide wireless network access to the relay nodes over a backhaul link, and the relay nodes can offer access to devices or other relay nodes to expand network coverage and/or provide increased throughput. User equipment (UE) relays can function as UEs according to a cluster node such that UE relays receive network addressing and can tunnel communications through the cluster node using the backhaul link. Cell relays can function as a cell of the cluster node, such that transport layer communications terminate at the cluster node. In this regard, cell relays can define transport layers to use in communicating with the cluster nodes over the backhaul and with other devices over a provided access link.

Handover between macrocell and femtocell for UMTS based networks

Abstract: The femtocell networks that use home base station and existing xDSL or other cable line as backhaul connectivity can fulfill the upcoming demand of high data rate for wireless communication system as well as can extend the coverage area. Hence the modified handover procedure for existing networks is needed to support the macrocell/femtocell integrated network. Some modifications of existing network and protocol architecture for the integration of femtocell networks with the existing UMTS based macrocell networks are essential. These modifications change the signal flow for handover procedures due to different 2-tier cell (macrocell and femtocell) environment. The measurement of signal-to-interference ratio parameter should be considered for handover between macrocell and femtocell. A frequent and unnecessary handover is another problem for hierarchical network environment that must be optimized to improve the performance of macrocell/femtocell integrated network. In this paper, firstly we propose the concentrator based and without concentrator based femtocell network architecture. Then we present the signal flow with appropriate parameters for the handover between 3GPP UMTS based macrocell and femtocell networks. A scheme for unnecessary handoff minimization is also presented in this paper. We simulate the proposed handover optimization scheme to validate the performance.

Method and apparatus of communication using subframe between base station and relay

Abstract: Provided is a communication method of a relay station in a wireless communication system, the communication method comprising the steps of configuring subframes dedicated for a backhaul link between a base station and the relay station and receiving a signal from the base station via the subframes dedicated for the backhaul link, wherein access of a legacy mobile station to at least a part of the subframes dedicated for the backhaul link is restricted.

Enterprise mobile network for providing cellular wireless service using licensed radio frequency spectrum and internet protocol backhaul

Abstract: One embodiment is directed to an enterprise mobile network for providing wireless service within a coverage area associated with an enterprise using licensed radio frequency spectrum. The enterprise mobile network includes a base station subsystem deployed on a premises of the enterprise to provide wireless capacity within the coverage area using the licensed radio frequency spectrum. The enterprise mobile network further includes a mobile switching subsystem deployed in an office of a service provider that operates a public land mobile network. The mobile switching subsystem is communicatively coupled to the public land mobile network. The base station subsystem is communicatively coupled to the mobile switching subsystem using an Internet Protocol (IP) network. The mobile switching subsystem is configured to function as a mobile switching center (MSC) and visitor location register (VLR) for roaming subscribers and local subscribers of the enterprise. The mobile switching subsystem is configured to function as a home location register (HLR) and gateway mobile switching center (GMSC) for local subscribers of the enterprise.

Serving base station selection using backhaul quality information

Abstract: Techniques for selecting a serving base station for a terminal by taking into consideration the backhaul quality of candidate base stations are described. In one design, a base station may determine backhaul quality information indicative of its current backhaul quality. The base station may send the backhaul quality information, e.g., in an overhead message sent over the air to terminals or in a backhaul message sent to neighbor base stations or a network controller. A server selection entity may receive backhaul quality information for at least one candidate base station for the terminal. The server selection entity may also determine at least one metric for each candidate base station. The server selection entity may then select the serving base station for the terminal based on the backhaul quality information and the at least one metric for the at least one candidate base station.

Self Organizing Network

Abstract: A method for implementing a self organizing network includes establishing a connection between a femto base station and a network access device operable to provide the femto base station with Internet access. The method also includes establishing a backhaul connection between the femto base station and a wireless service provider's network via the Internet. The method further includes establishing a wireless connection with one or more endpoints via a radio frequency (RF) channel. The method additionally includes transmitting, from the femto base station to the wireless service provider's network, neighborhood RF interference information via the backhaul connection. The method also includes receiving RF channel re-provisioning information from the wireless service provider's network and re-provisioning the RF channel. The method further includes participating in a hand-off procedure to hand-off the endpoints to the re-provisioned RF channel.

Hybrid wireless-optical broadband access network(woban) : prototype development and research challenges

Abstract: The hybrid wireless-optical broadband access network is emerging as a promising technology to provide economical and scalable broadband Internet access. In this cross-domain network architecture, end users receive broadband services through a wireless, mesh front end that is connected to the optical backhaul through gateway nodes. In this article, we present the architecture and functional characteristics of a WOBAN prototype built in the Networks Lab at UC Davis. We discuss research challenges for hybrid networks based on our experimental observations.

Mobile devices with femto cell functionality

Abstract: Aspects describe communications environments in which femtocell capability is provided to devices within the communications network. A non-femto enabled device and/or a femto enabled device can communicate with a femto enabled device in the same geographical area for femto-enabled peer-to-peer communication. Two non-femto enabled devices can be provided femto functionality through utilization of a femto enabled device, which operates as a hub between the two devices. Other aspects relate to enhanced position determination, adaptive coverage enhancement, local mobile networks, open access femtocells without a backhaul, and local broadcast of media though utilization of femto enabled devices.

Opportunistic relay scheduling in wireless communications

Abstract: Systems and methodologies are described that facilitate providing opportunistic relay node communication based on scheduling of other communications in a wireless network. In particular, a relay node can maintain a backhaul link with an access point and an access link with a mobile device to facilitate communicating information therebetween. Time slots during which the backhaul link is active can be determined and avoided during scheduling access link communications with the mobile device. Furthermore, resource assignments from the access point to the mobile device can be monitored and decoded such that time slots associated therewith can also be determined and avoided. Thus, the relay node can communicate with mobile devices in time slots where the backhaul link is inactive and/or the mobile devices are not occupied communicating directly with the access point.

Femtocell versus WiFi - A survey and comparison of architecture and performance

Abstract: Femtocells use common cellular air access technologies, but claim to improve system capacity according to Shannon's law by reducing distance between transmitter and receiver and thus improving the signal-to-noise ratio (SNR). Femtocells, however, use the IP Network as backhaul architecture instead of the conventional cellular network infrastructure. Thus, femtocell and WiFi infrastructure networks have a lot in common. This raises a curiosity whether femtocell technology would replace existing WiFi technology. This can be answered only by carefully analyzing the similarities and differences between the two technologies. This paper provides a technical comparison between femtocells and WiFi in terms of architecture, operation and standards.

Active set modification to release backhaul capacity

Abstract: System(s), method(s), and device(s) that enable release of backhaul capacity associated with base stations are presented. During soft handover, a communication device can have its connection maintained with more than one base station. A link controller component can identify a radio link having the highest quality and can determine the relative backhaul load of each base station communicating with the communication device. The link controller component determines whether the base station having the highest radio link quality is experiencing the heaviest backhaul load relative to the other base stations. If the base station with the highest link quality does not also have the heaviest backhaul load, the link controller component identifies the base station having the heaviest backhaul load and the identified base station can have its status modified with respect to the communication device for a desired period of time, in accordance with predefined status modification criteria.

Determining backhaul bandwidth requirements for network MIMO

Abstract: In systems employing coordinated base station transmission and reception (also known as network MIMO), information needs to be shared among clusters of coordinated bases. This information includes coherent channel state information, user data, and baseband received signals. The cost of leasing and maintaining a reliable backhaul to share this information will be the dominant operational expense for cellular systems with network MIMO. In this paper we analyze the bandwidth requirements for sharing information among coordinated bases for network MIMO as a function of the coordination cluster size and channel characteristics. We find that for moderate Doppler speeds, the channel state information is a negligible fraction of the overall backhaul bandwidth. We also show that sending linearly quantized baseband signals over the backhaul achieves a significant fraction of ideal unquantized sum rate performance for uplink network MIMO based on zero-forcing.

Is microwave backhaul up to the 4G task

Abstract: With the evolution toward the fourth generation of mobile networks, the backhaul network that portion of the network infrastructure that provides interconnectivity between the base stations and the core network is expected to come under intense pressure as capacity requirements increase to support new mobile broadband services. As a key technology used in backhaul networks around the world, point-to-point microwave is rapidly evolving to support this increasing capacity demand, improve network efficiency, and allow operators to reduce network operational costs. This article details how recent developments in the microwave industry support both the lowest cost per Mb/s transport and also the maximum Mb/s/MHz. These developments embrace the dramatic shift to support Internet protocol (IP) network convergence, including the key features to enable link capacities not previously seen in the industry, and the new methods developed to enable every last drop to be squeezed out of the finite resource that is the available frequency spectrum.

On Uplink Network MIMO under a Constrained Backhaul and Imperfect Channel Knowledge

Abstract: It is known that next generation mobile communications systems will most likely employ multi-cell signal processing - often referred to as network MIMO - in order to improve spectral efficiency and fairness. Many publications exist that predict strong achievable rate improvements, but usually neglecting various practical issues connected to network MIMO. In this paper, we analyse the impact of a constrained backhaul infrastructure and imperfect channel knowledge on uplink network MIMO from an information theoretical point of view. Especially the latter aspect leads to the fact that the channel conditions for which network MIMO is reasonably beneficial are strongly constrained. We observe different base station cooperation schemes in scenarios of maximal 3 base stations and 3 terminals, provide simulation results, and discuss the practicability of the discussed schemes and the implications of our results.

Method for routing via access terminals

Abstract: An access-terminal routing methodology is provided that may be used to enable a wireless, meshed backhaul between base stations using existing wireless-access resources (time, bandwidth, code-space, power), protocols, and base station infrastructure. Accordingly, the invention provides a means to extend the coverage of existing networks by adding standalone base stations without wired or specialized wireless backhaul.

Gateway Selection in Backbone Wireless Mesh Networks

Abstract: IEEE 802.11-based backbone mesh networks comprise of static Wireless Mesh Routers (WMRs) which create a wireless multihop backbone to provide high-speed last-mile wireless Internet access to communities. Specialized WMRs called Gateways provide the interconnection between the mesh network and fixed IP networks. Mesh routers perform backhaul routing and may additionally serve as Access Points (APs) for clients. Their main task is to maintain backhaul mesh connectivity and find routes to gateways for clients. An important research problem which has received little attention is the optimal selection of gateway and the route to that gateway by mesh routers within the mesh backbone. We propose an efficient gateway and route selection scheme for backbone mesh networks which can be adopted for upcoming 802.11s mesh standard [1] with minimal changes. Gateway load, route interference and path quality metrics are used to select the best available gateway and the route to that gateway. Simulation results show improved performance compared to schemes using nearest gateway, gateway load metric or the ETX [2] metric for gateway selection.

CaDAR: An Efficient Routing Algorithm for a Wireless–Optical Broadband Access Network (WOBAN)

Abstract: A wireless-optical broadband access network (WOBAN) is a combination of wireless and optical network segments to optimize the cost and performance of an access network. A WOBAN's optical backhaul enables it to support high capacity, while its wireless front end [also called a wireless mesh network (WMN)] enables its users to have untethered access. Wireless nodes collect traffic from end users and carry them to the optical part of a WOBAN, possibly using multiple hops, but the traffic also experiences delay at each wireless node. The finite radio capacity at each wireless node limits the capacity on each outgoing link from a wireless node of a WOBAN. Thus, delay and capacity limitation in the WMN of a WOBAN are major constraints. We design a capacity- and delay-aware routing scheme, called CaDAR, to minimize the delay and increase the throughput in the WMN of a WOBAN. Our analysis shows that CaDAR is an efficient routing scheme for WOBAN that can support much higher load and has lower system delay than other approaches (IEEE Network, vol. 22, no. 3, p. 20, 2008) because of better load-balanced routing.

Jamming graph and its application in network resource assignment

Abstract: A wireless communication network uses backhaul negotiation based upon static and dynamic resource assignment on jamming graphs. Static reuse factor design methods including fractional frequency reuse (FFR) are addressed. The jamming graph is used to summarize the interfering relationship between transmitters (nodes in the jamming graph). Negotiation-based algorithm is used to arrive at a static resource assignment so that a large reuse factor can be achieved while jamming scenario can be avoided. As a result of such algorithm, each transmitter is assigned some resources, over which traffic transmission can be done instantaneously to reduce the packet delay for short packets. Based on the result of static resource negotiation algorithm, a dynamic resource algorithm can be run, such that the resources assigned to different nodes can be share in a bursty traffic scenario to further reduce packet delay for larger packet size cases, while jamming be also avoided.

Method and apparatus for transmitting reference signal performed by relay station in wireless communication system

Abstract: A method of transmitting a reference signal performed by a Relay Station (RS) in a wireless communication system comprises allocating a guard time in the front of a backhaul subframe or the end of the backhaul subframe, the backhaul subframe comprising a plurality of slots, each of the plurality of slots comprising a plurality of Orthogonal Frequency Division Multiplexing (OFDM) symbols, and the guard time being a time interval for switching between an access link and a backhaul link, and transmitting a Demodulation Reference Signal (DMRS) to a Base Station (BS) in an OFDM symbol of the backhaul subframe. The OFDM symbol for the DMRS is not overlapped with the guard time.

Serving base station selection based on backhaul capability

Abstract: Techniques for selecting a serving base station for a terminal by taking into account backhaul capability are described. The terminal may be within the coverage of multiple base stations, which may be of different types and may have different backhaul capabilities. One of the base stations may be selected as a serving base station for the terminal based on the backhaul capabilities of these base stations. The serving base station may also be selected based on additional criteria such as data or delay requirements of the terminal, transmit power capability of the terminal, characteristics of data for the terminal, etc.

Architecture to integrate multiple PONs with long reach DWDM backhaul

Abstract: This paper demonstrates the feasibility of an architecture that consolidates a number of deployed Passive Optical Network (PON) infrastructures into a long-reach, high-split ratio system which further increases equipment sharing between users. The demonstrated system allows the use of uncooled lasers with possible wavelength drift across a CWDM band (20 nm) with optical amplification and narrow optical filtering with no performance degradation. A complete study of potential implementations was performed with experimental results showing that a target performance of 10-10 could be achieved over 120 km of standard fiber with transmitter wavelengths from 1542 to 1558 nm and DWDM backhaul wavelengths from 1520 to 1535 nm. This gives the potential to support up to 2560 users.

Customer supported automatic meter reading method

Abstract: A method is described in which an automatic metering reading (AMR) method is implemented in the utility distribution system. The AMR method comprises a mesh network in which selected customers of the utility company support the network by providing collocated internet access points via the customer's existing internet connections; thus providing AMR data “backhaul”, thereby minimizing the need for the utility to build and deploy all the access points needed to populate the mesh infrastructure network. This customer access point for which the customer is remunerated, in whole or in part by the utility, allows the utility to develop and implement all the network elements to meet the utility AMR needs at a much lower cost. The customer-supported method can allow the utility to efficiently and effectively service its metering needs via the global communications network without a major investment in hardware, software and personnel.

The case for free space

Abstract: This article discusses the prospect of free- space optical links (FSOLs) in relation to backhaul applications as well as its technology trend, including the recent development of radio on free-space optical links (RoFSOLs). Here, we consider how FSOLs act as useful transport media, focusing on practical experience in mobile backhaul networks. We refer to studies on FSOL conducted by the International Telecommunications Union (ITU) from the viewpoint of the possible exploitation of the frequency bands above 3,000 GHz, which are outside the scope of the current Radio Regulations.

Method and apparatus for routing of a bearer path in an internet protocol multimedia subsystem-based communication system

Abstract: A communication system (100) routes a bearer path of a communication session between an originating Node B (112) and a terminating Node B (e.g., Node B 122) via an X2 interface (116), bypassing an IMS core network (152), while continuing to route the signaling path to an IMS network (150), thereby allowing the IMS network to retain control of the bearer path while avoiding delay, potential for bearer stream data loss and jitter, and additional backhaul capacity requirements that result from routing the bearer path between the originating and terminating Node Bs via the IMS core network. In determining whether the bearer path may bypass the IMS core network, the communication system determines whether IMS core network bearer associated services are required for the communication session such that a bearer path of the call will need to be routed to the IMS core network in order to provide such services.