JP2008503187A - Method and system for using a smart antenna to install a backhaul network - Google Patents

Abstract

  A method and system for using smart antennas to transmit messages between nodes (102a-102n) is provided. The wireless communication system includes a plurality of nodes (102a to 102n), and each node can be connected to each other. At least some of the nodes are provided with smart antennas (204) configured to generate a plurality of beams (109a-109h). Each node maintains beam configuration information and a list of other nodes that are used to send messages to other nodes. When the source node needs to transmit to the target node, the source node retrieves the beam configuration information and transmits it with a directional beam (109) directed to the target node.

Description

  The present invention relates to wireless communication. More particularly, the present invention relates to a method and system for using a smart antenna to install a backhaul network.

  In a wireless communication system, one of the most important issues is increasing the capacity of the system by reducing interference. Array antennas (also known as smart antennas) have been developed to reduce interference and improve capacity. A smart antenna uses a plurality of antenna elements to generate a directional beam that emits a signal only in a specific direction of azimuth and selectively detects a signal transmitted from the specific direction. With smart antennas, signals can be radiated to a narrow area of service so that wireless communication systems can increase capacity and reduce interference. This can increase the transmission power level of the directional beam without causing excessive interference to other transmitters and receivers such as a wireless transmit / receive unit (WTRU) and the base station, thus reducing the overall system capacity. To increase.

  A wireless communication system typically includes multiple nodes such as a base station and a wireless network controller. The nodes are typically connected to each other by a wired connection such as a mesh network or a cellular network. The nodes communicate with each other and send messages such as backhaul messages.

  However, there are disadvantages to installing a backhaul network by wired connection, as wired connection is expensive, time consuming, and inflexible to network modifications or changes. In particular, mesh networking requires nodes to be connected to each other. When a new node is added to the mesh network, there is a significant burden (in terms of both cost and time) on installing a new connection to the new node for backhaul.

  Accordingly, a need exists for a method and system for installing a cost effective, time consuming and flexible backhaul network.

  The present invention is a method and system for using smart antennas to install a backhaul network. The present invention uses smart antennas to improve intra-cell communication, increase processing power, and form at least part of a flexible backhaul network to carry backhaul data. The present invention is implemented in a wireless communication system that includes a plurality of nodes and each node is connected to each other in a mesh network. At least some of the nodes are provided with one or more smart antennas configured to generate a plurality of directional beams. Each node with one or more smart antennas maintains a list of other nodes with smart antennas and beam directions and configuration information used to send messages to these other nodes. When the source node needs to send backhaul data to the target node, the source node retrieves the beam direction and configuration information for the target node and sends a message with a directional beam directed at the target node.

  The present invention relates to time division duplex (TDD), frequency division duplex (FDD), and time division synchronous code division multiple access (TD-SCDMA), CDMA2000, as applied to Universal Mobile Telecommunication System (UMTS), Any wireless communication, including but not limited to CDMA General, Global System for Mobile Communications (GSM), General Packet Radio System (GPRS), and Enhanced Data Rate (EDGE) for GSM Evolution Applicable to system.

  Hereinafter, the term “WTRU” includes, but is not limited to, user equipment, mobile stations, fixed or mobile subscriber units, pagers, or any other type of equipment that can operate in a wireless environment. When referred to hereafter, the term “node” includes, but is not limited to, a base station, Node B, site controller, access point, or any other type of interface device in a wireless environment.

  FIG. 1 is a block diagram of a network 100 of multiple nodes 102a-n in accordance with the present invention. At least one node, shown diagrammatically as 102n, is connected to the core network 110. The operation of the core network of a wireless communication system is well known to those skilled in the art and is not central to the present invention. Accordingly, the core network 110 is not described in detail here.

  Each node 102a-n serves one or more WTRUs (not shown) located within the service range of the nodes 102a-n. The network 100 may be a mesh network or a cellular network. In the context of the present invention, both mesh and cellular networks transmit backhaul information. However, there are basic differences. Cellular networks typically have fixed network infrastructure and backhaul connections. These connections are typically point-to-point and they do not change. One node sends backhaul data to another node at another location in the network and only to that location.

  In the case of a mesh network, the connection between nodes changes, so backhaul data is sent to different nodes for further routing at different times. In particular, in mesh networks, the backhaul connection changes from time to time, so it is important to be able to adjust the smart antenna so that connections to different nodes can be achieved without causing undue interference to other nodes.

  At least some of the nodes 102a-n are provided with at least one smart antenna (as described in detail below), and in addition to normal download transmission to the WTRU and upload reception from the WTRU Thus, the smart antenna is used for backhaul data transmission to the other nodes 102a-n. These nodes 102a-n are capable of generating multiple directional beams and steering the beam in any direction of azimuth.

  The network 100 is expected to include nodes with wired connections and nodes with wireless backhaul connections using smart antennas. Since connections established using smart antennas can be reconfigured and directed to different nodes, they increase the flexibility of the system. However, at least one of the nodes has both a wired connection to the core network 110 and a wireless connection to other nodes, providing an essentially connection between the wired core network and a group of wireless nodes. At least some of the nodes 102a-n may also be provided with the ability to transmit backhaul information via a wired or dedicated connection. A node (such as node 102n) that has both wired and wireless backhaul connections (hereinafter referred to as a hybrid node) is a connection to the wired core network 110. In other words, when a node transmits backhaul information wirelessly with the help of a smart antenna, this backhaul information is finally delivered to the core network 110 via the hybrid node 102n. Thus, the hybrid node 102n can transmit and receive backhaul information to the node over a wireless backhaul connection, while it transmits and receives backhaul information to the core network 110. Therefore, a bridge is formed.

  In one embodiment, nodes 102a-n have a plurality of predetermined beams 109a-h and select one of the plurality of beams 109a-h, as shown in FIG. Specify the direction of transmission or reception. It should be noted that the beams shown in FIG. 4 are given by way of example only, and any number of beams, beam patterns, or any other type of pattern can be realized.

  In an alternative embodiment, each beam 109a-h is generated and directed in real time, rather than selected from a predetermined set of positions.

  Nodes 102a-n provide the best performance in terms of system capacity, data processing capability, interference, etc., with one beam 109a-h direction either dynamically or from multiple available locations. select. Nodes 102a-n are generally fixed at specific locations. Therefore, once the configuration between the beams 109a-h and the two nodes 102a-n is set, the direction and configuration are stored and can be used without modification thereafter. Each node 102a-n can provide two or more beams 109a-h for connection with other nodes 102a-n. This is because the radio environment and traffic load may change on a long-term basis. Thus, each node 102a-n monitors signals received from other nodes 102a-n to dynamically adjust the beam direction and signal configuration to optimize system performance in order to determine the wireless environment.

  An example of the operation of the system is as follows. A first selection node such as node 102a generates a beam and steers it to another selected node such as node 102b. This can be done by adjusting the complex weights applied to the antenna array, as is typically done by a beamforming antenna array. At the same time, node 102a measures the quality of link A to node 102b. Link A quality can be measured as a signal to noise ratio, bit or frame error rate, or some other measurable quality indicator. The transmitting node 102a finds the best antenna beam direction, in this case the best combination of weights that maximizes link quality, and stores both the link quality measurement and the corresponding beam direction (weight). The transmitting node 102a does this for all nearby nodes and stores the corresponding quality and beam information.

  Any node 102a-n can be flexibly and wirelessly connected or disconnected from other nodes 102a-n by selectively directing one or more beams to the other nodes 102a-n. In FIG. 1, the first node 102a transmits a message to the second node 102b using the directional beam A, and transmits to the fourth node 102d using the directional beam B. Directional beams A and B can be controlled independently and can be transmitted simultaneously. Each directional beam A and B is radiated only in a particular direction, so it does not cause excessive interference with other nodes 102a-n or WTRUs.

  FIG. 2 is a block diagram of a node 202 according to the present invention. Node 202 includes smart antenna 204, controller 206, memory 208, and optional wired link 210. The wired link 210 may be a link to the core network 110 or another node. Node 202 implements signal processing algorithms to adapt to multipath along with user mobility, changes in radio frequency environment and co-channel interference. A radio resource management (RRM) function implemented by controller 206 determines how radio resources are allocated within node 202.

  Smart antenna 204 includes a plurality of antenna elements (not shown) for generating a plurality of directional beams under the control of controller 206. Each beam functions as a wireless connection between node 202 and other nodes. As described above, since node 202 is typically fixed at a particular location, the beam direction and configuration between the two nodes can be predetermined and stored in memory 208. Memory 208 maintains a list of beam directions and configuration information for other nodes and each of these other nodes. When the node 202 needs to send a message, such as backhaul data, to another node, the controller 206 retrieves the corresponding beam direction and configuration information from the memory 208 and sends the directional beam steered in a particular direction. Generate and send a message using the beam.

  In the case of hybrid node 102n, this process continues with the establishment of a wireless connection with other nodes with the help of smart antenna 204. When the hybrid node 102n establishes a backhaul connection to the core network or other nodes, the wired link 210 is physically fixed and always provides a connection between the same two nodes, so configuration information or beam selection Does not exist.

  According to the present invention, the smart antenna 204 preferably has multi-beam capability and each beam can be used independently. Node 202 generates two or more directional beams to transmit backhaul data to multiple other nodes simultaneously. Since the same frequency can be reused for two or more directional beams within the same service range, the system capacity is substantially increased.

  Some nodes have several beams combined together. This is advantageous for changing connections and adapting dynamically to changes within a wireless environment. For example, two beams are provided for connection between two nodes. If one beam experiences excessive interference, the node can switch to another beam for message transmission.

  The use of the smart antenna allows the construction of a flexible backhaul link between nodes. Each node is configured to generate multiple directional beams and can be steered in either direction of azimuth so that when a new node is added to the network 100, the existing A node can establish a new connection to the new node by simply setting a new beam direction and configuration directed to the new node. In addition, when an existing node is removed from the network 100, the node simply needs to delete the configuration and beam direction for the removed node from the memory 208. The present invention additionally installs or removes unnecessary equipment to establish or remove connections between nodes. It should be noted that the present invention can be implemented in either a mesh network or a cellular network.

  One of the strengths of mesh networking is the ability to create and delete new links between nodes, depending on multiple factors including traffic load, interference, and individual node performance. As shown in FIG. 1, the plurality of nodes 102a-n are coupled to each other using smart antennas. The lines between nodes 102a-n in FIG. 1 indicate possible links A-F. Control can be centralized so that at least one node can function as a control node for controlling connections between nodes. Alternatively, control can be decentralized, where control is distributed across some or all nodes. If one node is designated as the control node, this control node collects information about the traffic state and performance of each node and the best traffic for sending messages from one node to another Determine the route.

  Each node 102a-n preferably transmits one or more beacon signals in its one or more beams. These provide useful information about network operation. For example, the beacon signal transmits the current power level, traffic level, interference level, and other parameters. The beacon signal can also include access priority, security, identification, and other varying types of access control and security control information. The beacon signal is measured periodically or aperiodically, and the parameters are used as a basis for adjusting the connection between nodes to find the maximum efficiency traffic route. Forming at least part of a backhaul connection wirelessly by using a smart antenna according to the present invention allows flexibility and eliminates unnecessary time and expense for establishing and adjusting connections between nodes. Can be reduced.

  For example, as shown in FIG. 1, if the traffic load between the second node 102b and the fourth node 102d is too heavy, the other nodes read the beacon signals of the nodes 102b, d as described in detail later. As a result, the traffic state between the two nodes 102b and 102d is recognized. If the first node 102a wishes to deliver traffic to the fifth node 102e, if possible, it avoids the second and fourth nodes 102b, d and substitutes traffic through the Nth node 102n. Routing.

  The present invention not only has the advantage of providing a flexible wireless mesh network, but the backhaul information (typically transmitted via wire) is also the same flexible link via a smart antenna. Will now be sent via. This type of realization of a dual-use smart antenna scheme according to the present invention results in significant benefits over current wireless communication systems.

  FIG. 3 is a flow diagram of a method 300 for using a smart antenna to transmit messages between nodes according to the present invention. At least a portion of the node is provided with at least one smart antenna configured to generate a plurality of directional beams and steer independently of azimuth (step 302). Each beam is used as a wireless connection to other nodes in addition to the normal traffic for downloading to and uploading from the WTRU. Each node maintains a list of configuration information and beam directions used for transmission to other nodes and other nodes. Steps 302 and 304 are typically performed in reconfiguring the system to set up the system or accept or delete nodes, and typically do not need to be formed during normal operation. When the source node needs to transmit to the target node, the source node retrieves configuration information and beam direction for the target node from memory and uses the configuration information and beam direction to generate a directional beam (step 306). ). Once a node is selected for backhaul data transmission based on other considerations such as link quality and traffic density, the transmitting node selects a beam direction (weight) from the list and sends it to the antenna Apply.

  As the environment changes and the beam direction needs to be adjusted, the process of measuring link quality and storing related information will need to be done periodically. Then, the source node transmits the generated directional beam to the target node (step 308).

  In optional steps, changes in the network occur where new nodes are added to the network, existing nodes are removed from the network, or where radio frequency or other conditions change. In response to the change, the other nodes update the list of beam direction and configuration information to reflect the change (step 310).

  Although the features and elements of the invention have been described in preferred embodiments in specific combinations, each feature or element can be used alone without other features and elements in the preferred embodiments, and It can be used in various combinations with or without other features and elements of the present invention.

1 is a block diagram of a multi-node network according to the present invention. FIG. FIG. 3 is a block diagram of a node made in accordance with the present invention. FIG. 4 is a flow diagram of a method for using a smart antenna for message transmission between nodes according to the present invention. FIG. 4 is an example of a beam pattern generated by a node according to the present invention.

Claims (17)

A wireless communication system including a plurality of nodes, each node connected to at least one nearby node, each node comprising:
A smart antenna for generating multiple directional beams;
A memory for storing a list of nearby nodes having connection and beam configuration information used to send messages to nearby nodes;
A controller that selects a specific directional beam for transmitting a specific message to another node and independently controls each of the plurality of directional beams;
A wireless communication system comprising:   The controller of claim 1, wherein the controller obtains information about traffic load conditions and the capabilities of nearby nodes and selects an appropriate path for sending a message to another node based on the information. System.   The system of claim 1, wherein the plurality of nodes includes a mesh network.   The system of claim 1, wherein the plurality of nodes includes a cellular network.   The node according to claim 1, wherein one of a plurality of nodes is designated as a control node, and the control node collects information on the capability and traffic load state of each node and controls the routing in each node. The described system.   Each node transmits a beacon signal carrying a beacon message to a nearby node, and each node uses the beacon message to select an appropriate path for transmitting the message to other nodes. Item 4. The system according to Item 1.   The system of claim 6, wherein the beacon message includes power level, traffic level, interference level, access priority, security, identification, and other access control and security control information.   The system of claim 1, wherein each node is connected using two or more beams, whereby the beams are switched to fit between the beams provided for the connection. A method of using a smart antenna in a wireless communication system including a plurality of nodes, each of at least two nodes of the plurality of nodes having a smart antenna, the smart antenna for connecting to at least one nearby node Generating at least one directional beam, the method comprising:
Measuring and storing a list of nearby nodes with connection and beam direction and configuration information used to send messages to nearby nodes;
Generating a directional beam for transmitting a specific message to the target node according to the beam direction and configuration information;
Transmitting the message to the target node by the generated directional beam;
A method comprising the steps of:   The method of claim 9, further comprising the step of updating the list to reflect network changes or modifications.   10. The method of claim 9, further comprising the step of obtaining information regarding traffic load conditions and capabilities of nearby nodes and selecting an appropriate path for sending a message to another node based on the information. The method described.   The method of claim 9, wherein the plurality of nodes comprises a mesh network.   The method of claim 9, wherein the plurality of nodes comprises a cellular network.   10. A node in the plurality of nodes is designated as a control node, wherein the control node collects information about each node's capabilities and traffic load conditions and controls routing at each node. the method of.   Each node transmits a beacon signal carrying a beacon message to a nearby node, and each node uses the beacon message to select an appropriate path for transmitting the message to other nodes. Item 10. The method according to Item 9.   The method of claim 15, wherein the beacon message includes power level, interference level, traffic level, access priority, security, identification, and other access control and security control information.   10. The method of claim 9, wherein each node is connected using two or more beams, whereby the beams are switched to fit between the beams provided for the connection.

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