WO2009135522A1

WO2009135522A1 - Methods, apparatuses, system, related computer program product and data structure for network management

Info

Publication number: WO2009135522A1
Application number: PCT/EP2008/055495
Authority: WO
Inventors: Hao Guan; Zhao Zhuyan
Original assignee: Nokia Siemens Networks Oy
Priority date: 2008-05-05
Filing date: 2008-05-05
Publication date: 2009-11-12

Abstract

It is disclosed a method comprising receiving, at a network control element, a plurality of data sub-frames each comprising information related to periodic network monitoring and network topology-related information aggregated by a plurality of network root elements, aggregating, at the network control element, the received network topology-related information, establishing a network topology based on the aggregated network topology-related information periodically, and controlling each one of the plurality of network root elements based on the established network topology; and a method comprising receiving, from the network control element at a network element, network control information indicating a network topology of a plurality of the network elements, and configuring a transmitting portion of at least one transceiver of the network element to one of at least one transceiving state based on the received network control information.

Description

TITLE OF THE INVENTION

METHODS, APPARATUSES, SYSTEM, RELATED COMPUTER PROGRAM PRODUCT AND DATA STRUCTURE FOR NETWORK MANAGEMENT

FIELD OF THE INVENTION

[0001] The present invention relates to network management. More specifically, the present invention relates to methods, apparatuses, a system, a related computer program product and a data structure for network management related e.g. to wireless mesh network using for data backhaul transport. Examples of the present invention may be applicable to the data backhaul transport in rural areas of an emerging market, or may be applicable to municipal wireless networks.

BACKGROUND

[0002] A connectivity network technology may require two components: an access network and a backhaul network. The access network may provide connectivity within a local region and the backhaul network may provide data transport e.g. from a backbone network to the access network. Cellular communication systems may comprise some type of radio access network. The radio access network may allow users of mobile terminals to operate within the network' s service area to communicate with other mobile terminal users and with users of other communication networks, such as the public switched telephone network (PSTN) . In cellular communication systems, the radio access network may comprise at least one base station controller/radio network controller (RNC) and a number of radio base transceiver stations (BTSs) /NodeBs . Each BTS/NodeB may provide coverage over a defined area referred to as a "cell", and may connect to the BSC/RNC e.g. through a landline link, such as Tl/El, fiber cable, or by some line-of-sight wireless link, such as microwave. For municipal wireless networks, such a network may have a flat network structure, but a data backhaul may be needed that enables an access point (AP) to connect with a backbone network.

[0003] The lack of network connectivity in many regions around the world is as much an economic problem as a technological one. This also applies e.g. to rural regions in developing countries with low income levels and low population densities. Currently, there are some low cost access network solutions developed for rural area in emerging markets. However, these solutions omit low capital expenditure (CAPEX) and operational expenditure (OPEX) data transport solutions for covering e.g. the last 20 to 100 km from town to each village, wherein e.g. a fiber cable normally connects the town. On the other hand, traditional connectivity solutions using e.g. fiber-optic networks, satellite and microwave may be ill-suited for such environments. The high infrastructure cost and the long period of time to deploy fiber-optic networks make these technologies economically less appealing and a very risky investment proposition. Additionally, high band-width links may not be necessary in such regions, since many of the applications (e.g. messaging, voice) leveraging the network connectivity have limited bandwidth requirements. E.g. for rural markets with dispersed populations and uncertain demand, network technologies with a low cost of entry may be applied. [0004] There have been solutions directed to solve some of the above deficiencies.

[0005] Fig. 1 shows one such PMP/P2P solution for data backhaul .

[0006] As shown in Fig. 1, a communication system 100 comprises a RNC 101 and an internet protocol (IP) backbone 103 for serving a large area 102. The large area 102 comprises a peer-to-multiple-peer (PMP) /peer-to-peer (P2P) capable center BTS 1021 and nodes 1022-a, ..., 1022-i surrounding the center BTS 1021.

[0007] E.g. worldwide interoperability for microwave access (WiMAX) may be considered as a candidate for wireless backhaul, and fixed WiMAX may define functionalities for P2MP (PMP/P2P) networking. When working at P2MP mode, the center BTS 1021 being e.g. a WiMAX BS may need to provide coverage to the nodes 1022- a,..., 1022-i requiring the data backhaul. E.g. in rural areas, the nodes 1022-a, ..., 1022-i may be located in the large area 102, and the WiMAX BS 1021 providing large area coverage may need an expensive transmitter (TX) chain. At the same time, e.g. the node 1022-d; 1022-i at a cell edge may not obtain the same wide bandwidth as the node 1022-c near the BS. As the node number in the coverage area increases, the WiMAX BS 1021 throughput capability may limit the average bandwidth obtained by each node 1022-a, ..., 1022-i . E.g. WiMAX for wireless backhaul may use a spectrum ranging from 3.5 GHz to 5.8 GHz. Such a spectrum may enable non-line-of-sight (NLOS) transmission, but the NLOS transmission may introduce great link degradation. [0008] As also seen in Fig. 1, e.g. the WiMAX P2MP solution may need, e.g. in rural areas in which the nodes 1022-a, ..., 1022-i are located in the large area 102, an expensive TX chain. Furthermore, the performance in case of NLOS may be poor, and nodes 1022-d, 1022-i far away from the BS 1021 only difficultly obtain a high throughput. Finally, the throughput of the BS 1021 may become a bottleneck when the number of nodes in the cell increases .

[0009] Another solution may reside in a wireless mesh network (WMN) .

[0010] Such a WMN may serve for a purely data backhaul application e.g. because of advanced WMN features such as flexibility, fast deployment, reliability, and auto- configuration. A so-called WMN backhaul focuses on data transport, and the access part may comprise a wireless local area network access point (WLAN AP) . The WMN backhaul may also support a multi access part (such as a global system for mobile communications (GSM) BTS, a wideband code division multiple access (WCDMA) NodeB, a digital video broadcasting terrestrial (DVB-T) BTS etc..) .

[0011] In order to avoid the traditional WMN' s low throughput and long delay, a WMN data backhaul node may use a multi transceiver structure. In such a topology, unlike an ad hoc network which includes hundreds of nodes, the WMN based data backhaul network only consists of a few static nodes which communicate with each other over wireless links. The static nodes may be wireless routers. Among the static nodes, there may be at least one root node which connects with the backbone network (e.g. by fiber, cable, microwave etc..) and the data traffic flow to/from the root node. Such networks can be used provide cost effective and quick installation data backhaul for next generation mobile (NGM) (both GSM and wide band access (WBA) systems) in rural areas, this may help operators to quickly deploy a network e.g. in emerging rural markets.

[0012] Still another approach resides in multi-radio WLAN WMN with a multi-sector antenna. However, this approach focuses on the urban market and municipal wireless network applications.

[0013] Still another approach may reside in a Wifi™-based long distance (WiLD) network which may provide low cost connectivity for rural area in developing countries. However, WiLD networks are comprised of point-to-point wireless links that use high-gain directional antennas (e.g. 24 dBi (i.e. 10 ^• logio (Maximum power of directional antenna/Power of isotropic omni-directional radiator) ) , 8 degree beam-width) with line of sight (LOS) over long distances (e.g. 10-100 km) .

[0014] However, the current WMN solutions for rural area have the following drawbacks.

[0015] Wireless mesh network solution with single radio, single channel and omni-directional antenna

[0016] The channel capacity decreases with the order 0(1/N) as the node number increases (i.e. channel capacity is inverse proportional to number N of nodes) . Likewise, complexity of low efficiency radio channel sharing schemes with huge amount of control signaling increases. Such kind of WMN is difficult to be deployed in rural areas . [0017] Wireless mesh network solution with multi-radio and directional antenna

[0018] In order to increase throughput and to reduce delay, a WMN data backhaul node may use the multi transceiver structure. Each node may be designed to support several simultaneous channels. Through allocating proper orthogonal channels to each radio and antenna direction, each mesh node can receive and transmit data packets independently in different directions without considering the interference from/to other nodes. This multi-channel (multi orthogonal channel), multi-radio (multi transceiver) , and directional antenna structure may yield a performance improvement for WMN in terms of capacity and transmission delay when compared with the WMN having one-channel, one radio and an omni-directional antenna .

[0019] Figs. 2-1 and 2-2 show the communication system 100 comprising the RNC 101 and the large area (not shown) . In turn, the large area comprises a root node 1021 and mesh nodes #1 to #5 1022.

[0020] As shown in Figs 2-1 and 2-2, one of the problems for conversion in data backhaul wireless mesh networks is that a P2P radio link is used for the connection between the mesh nodes 1022. That means that in a certain network topology, although one mesh node 1022 may connect with multiple other mesh nodes 1022, a transceiver of any mesh node 1022 can only connect to the transceiver of the corresponding mesh node 1022. That is, no multiple access technology is used in the radio link.

[0021] Fig. 2-1 shows an exemplary mesh network. Each mesh node 1022 may have an antenna array, which may be composed e.g. of six 60 degree antennas that deliver 360 converge. Furthermore, each (radio) transceiver is configured with a corresponding antenna element. In Fig, 2-1, mesh node #3 1022 and mesh node #4 1022 may correspond to the same antenna beam of mesh node #2 1022. However, mesh node #3 1022 and mesh node #4 1022 cannot directly connect with the mesh node #2 1022 at the same time due to P2P radio link limitation.

[0022] As shown in Fig. 2-2, mesh node #4 1022 has to connect with mesh node #3 1022 in order to access the network. However, this may render the network topology less flexible. Such a network topology may introduce additional hop and mesh node throughput degradation.

[0023] Fig. 3 shows two large areas 102-a, 102-b neighboring each other. Each large area 102-a, 102-b comprises an own network as shown in Fig. 2-2. A first node cluster in the large area 102-a comprises the root node #1 1021 and the mesh nodes #1 to #5 1022, and a second node cluster in the large area 102-b comprises the root node #2 1021 and the mesh nodes #6 to #10 1022.

[0024] As shown in Fig. 3, another problem for conversion of data backhaul wireless mesh networks is that the first and second node clusters belong to different root nodes run independently. In Fig. 3, the 2 root nodes 1021 exit in the areas 102-a, 102b, respectively, in order to improve the WMN coverage and capacity.

[0025] However, the root nodes 1021 operate independently, connect with the backbone network 103 separately and do not have any neighbor WMN cluster- related information, such as the topology and mesh nodes status. The neighborhood mesh nodes 1022 which belong to different root nodes 1021 cannot communicate with each other. That is, e.g. in the case a link between root node #1 1021 and mesh node #1 1022 is unavailable, data traffic of mesh node #1 1021 cannot be transmitted to root node #2 1022 through mesh node #8 1022 and mesh node #7 1022. This makes the network topology less flexible and lacks redundancy.

[0026] In consideration of the above, it is an object of examples of the present invention to overcome one or more of the above drawbacks. In particular, examples of the present invention provide methods, apparatuses, a system, a related computer program product and a data structure for network management.

[0027] According to an example of the present invention, in a first aspect, this object is for example achieved by a method comprising: receiving, at a network control element, a plurality of data sub-frames each comprising information related to periodic network monitoring and network topology-related information aggregated by a plurality of network root elements; aggregating, at the network control element, the received network topology-related information; establishing a network topology based on the aggregated network topology-related information periodically; and controlling each one of the plurality of network root elements based on the established network topology.

[0028] According to further refinements of the invention as defined under the above first aspect, the method further comprises routing each of a plurality of received data packets to an intended one of the plurality of network root elements based on the established network topology; the routing further comprises creating a routing table; the network topology-related information comprises status information of each one of network traffic elements;

- the status information comprise at least one of a traffic condition, a used channel, a quality of the used channel, a preamble, an antenna direction and a transmit sub-frame time; the controlling further comprises exchanging the aggregated network topology-related information among each one of the plurality of network root elements.

[0029] According to an example of the present invention, in a second aspect, this object is for example achieved by a method comprising: receiving, from a network control element at a network element, network control information indicating a network topology of a plurality of the network elements; and configuring a transmitting portion of at least one transceiver of the network element to one of at least one transceiving state based on the received network control information .

[0030] According to an example of the present invention, in a third aspect, this object is for example achieved by a method comprising: receiving, from a network control element at a network element, network control information indicating a network topology of a plurality of the network elements; and configuring a receiving portion of at least one transceiver of the network element to one of at least one transceiving state based on the received network control information .

[0031] According to further refinements of the invention as defined under the above second and third aspects,

- the receiving is performed based on one of fixed or mobile worldwide interoperability for microwave access and fixed or mobile worldwide interoperability for microwave access in time division multiple access mode;

- the receiving is performed based on one of fixed or mobile worldwide interoperability for microwave access time division duplex and fixed or mobile worldwide interoperability for microwave access in time division multiple access mode;

- the configuring is further based on one of adding a network element, deleting a network element and connection relationships between the network elements.

[0032] According to an example of the present invention, in a fourth aspect, this object is for example achieved by a method comprising: transmitting according to the second aspect; and receiving according to the third aspect.

[0033] According to further refinements of the invention as defined under the above fourth aspect, the transmitting and receiving is performed by utilization of multi-radio multi-channel directional antennas;

- the method further comprises allocating at least one orthogonal channel to each radio and antenna direction. [0034] According to further refinements of the invention as defined under the above second to fourth aspects,

- the transceiving state comprises at least one of a first transceiving state being a base station state from a parent node element to at least one child node element, a second transceiving state being a subscriber state from the at least one child node element to the parent node element, a third transceiving state being a free-base station state in which the network element is not connected to any other network element, and a fourth transceiving state comprising the parent node element in the third transceiving state and the at least one child node element in the second transceiving state, wherein the parent node element and the at least one child node element effect a network measurement without data flow during a measurement frame.

[0035] According to further refinements of the invention as defined under the above first to fourth aspects,

- the network topology is changed depending on at least one of addition of a network element, failure of an existing network element, a channel condition and traffic flow.

[0036] According to an example of the present invention, in a fifth aspect, this object is for example achieved by an apparatus comprising: means for receiving, at a network control element, a plurality of data sub-frames each comprising information related to periodic network monitoring and network topology-related information aggregated by a plurality of network root elements; means for aggregating, at the network control element, the network topology-related information received by the means for receiving; means for establishing periodically a network topology based on the network topology-related information aggregated by the means for aggregating; and means for controlling each one of the plurality of network root elements based on the network topology established by the means for establishing.

[0037] According to further refinements of the invention as defined under the above fifth aspect,

- the network control element is constituted by a root network controller;

- the network control element is configured for gateway functionality with one of a synchronous digital hierarchy backbone and an internet protocol backbone; the network control element is configured for a synchronous digital hierarchy add-drop multiplexer functionality in case of the synchronous digital hierarchy backbone;

- the means for controlling further comprises means for routing each of a plurality of received data packets to an intended one of the at least one network root element based on the network topology; the means for routing further comprises means for creating a routing table; the network topology-related information comprise status information of each one of network traffic elements;

- the status information comprise at least one of a traffic condition, a used channel, a quality of the used channel, a preamble, an antenna direction and a transmit sub-frame time;

- the apparatus further comprises means for exchanging the aggregated network topology-related information among each one of the plurality of network root elements;

- the network control element is co-located with one of the plurality of network root elements;

- a connection between the network control element and the co-located network root element is provided by a high bandwidth communication interface;

- the high bandwidth communication interface is one of a fiber cable and a microwave link;

- the apparatus is constituted by a processing means or module for a root network controller.

[0038] According to an example of the present invention, in a sixth aspect, this object is for example achieved by an apparatus comprising: means for receiving, from a network control element at a network element, network control information indicating a network topology of a plurality of the network elements; and means for configuring a transmitting portion of at least one transceiver of the network element to one of at least one transceiving state based on the network control information received by the means for receiving.

[0039] According to an example of the present invention, in a seventh aspect, this object is for example achieved by an apparatus comprising: means for receiving, from a network control element at a network element, network control information indicating a network topology of a plurality of the network elements; and means for configuring a receiving portion of at least one transceiver of the network element to one of at least one transceiving state based on the network control information received by the means for receiving.

[0040] According to further refinements of the invention as defined under the above sixth and seventh aspects, - the means for receiving is configured to receive based on one of fixed or mobile worldwide interoperability for microwave access and fixed or mobile worldwide interoperability for microwave access in time division multiple access mode;

- the means for configuring is further configured to configure based on one of adding a network element, deleting a network element and connection relationships between the network elements;

[0041] According to an example of the present invention, in an eighth aspect, this object is for example achieved by an apparatus comprising: the means of the apparatus according to the sixth aspect; and the means of the apparatus according to the seventh aspect.

[0042] According to further refinements of the invention as defined under the above sixth to eighth aspects,

- the network topology is changed depending on at least one of addition of a network element, failure of an existing network element, a channel condition and a traffic flow;

- the transmitting portion and the receiving portion of the at least one transceiver are configured, by the means for configuring, to use multi-radio multi-channel directional antennas; the apparatus further comprises multiple radio frequency front-end chips and baseband processing modules for providing multi-channels; the transceiving state comprises one of a first transceiving state being a base station state from a parent node element to at least one child node element, a second transceiving state being a subscriber state from the at least one child node element to the parent node element, a third transceiving state being a free-base station state in which the network element is not connected to any other network element, and a fourth transceiving state comprising the parent node element in the third transceiving state and the at least one child node element in the second transceiving state, wherein the parent node element and the at least one child node element effect a network measurement without data flow during a measurement frame;

- the network element is a root node element and the at least one transceiver is configured to the first transceiving state by the means for configuring;

- the network element is one of a branch node element and a leaf node element, and the at least one transceiver is configured, by the means for configuring, to one of the first to fourth transceiving states based on the network topology;

- the apparatus further comprises means for allocating at least one orthogonal channel to each radio and antenna direction;

- the network topology is constituted by a network tree- topology;

- the network elements each comprise a multi transceiver structure; each transceiver is configured with a directional antenna;

- the apparatus is constituted by a processing means or module for at least one of a root node element, a branch node element and a leaf node element.

[0043] According to further refinements of the invention as defined under the above fifth to eighth aspects,

- at least one, or more of means for receiving, means for aggregating, means for establishing, means for controlling, means for routing, means for creating, means for exchanging, means for configuring, means for allocating and the apparatus is implemented as a chipset or module.

[0044] According to an example of the present invention, in a ninth aspect, this object is for example achieved by a system comprising: an apparatus according to the fifth aspect being a root network controller; and a plurality of network elements being one of a root node element, a branch node element and a leaf node element, each comprising a transceiver controlled by an apparatus according to the sixth to eighth aspects.

[0045] According to an example of the present invention, in a tenth aspect, this object is for example achieved by a data structure comprising: means for conveying, to an apparatus according to the eighth aspect, a plurality of data sub-frames each comprising information related to periodic network monitoring and network topology-related information aggregated by a plurality of the network root elements.

[0046] According to further refinements of the invention as defined under the above tenth aspect, the transmission direction from the at least one network root node to the network control element is an uplink, and the network control element constitutes a parent node element and the plurality of network root elements constitute child node elements; the means for conveying are constituted by a frame interval, and the data sub-frames are uplink sub-frames comprised in the frame interval; the uplink sub-frame is preceded by a transmit turnaround gap and is followed by a receive turnaround gap; the uplink sub-frame comprises an initial ranging contention slot, a periodic ranging contention slot comprising the information related to periodic network monitoring, and a plurality of uplink physical protocol data units comprising the network topology-related information;

- the plurality of uplink physical protocol data units is shared according to the number of child node elements;

- the transmission direction from the network control element to the plurality of root node elements is a downlink, and if the number of child nodes is zero, information sent on the downlink only comprises a preamble and a frame control header; at least no uplink bursts are transmitted on the uplink;

- the means for conveying is configured to convey based on one of a fixed worldwide interoperability for microwave access time division duplex structure and a mobile worldwide interoperability for microwave access time division duplex structure.

[0047] According to an example of the present invention, in an eleventh aspect, this object is for example achieved by a computer program product comprising code means for performing methods steps of a method according to any one the first to fourth aspects, when run on a processing means or module.

[0048] In this connection, it has to be pointed out that examples of the present invention enable one or more of the following:

- Providing a suitable solution for satisfying the data backhaul requirement e.g. in the rural areas of emerging market s .

- Providing an affordable networking technology. So, low CAPEX and OPEX are crucial for the success of the scenario. Therefore, a cheap self-configurable network, which allows fast network deployment and low operational costs, is provided.

Balancing coverage against capacity. High band-width links may not be necessary in rural regions, especially at beginning of network deployment. In rural areas, e.g. a macro GSM BTS may be configured e.g. with 2 El cables, which means that data backhaul may sufficiently provide around 4 Mbps both in uplink and downlink.

Providing a low power infrastructure. Such an infrastructure is applicable in an area without power plant. Furthermore, such a low power infrastructure may yield the opportunity to use clean energy such as solar energy or wind energy.

Coping with LOS requirements. This is applicable, since many non-connected villages may be located e.g. in mountainous or hilly areas. In such an area, it is difficult to find a line of sight between the access infrastructure in the village and e.g. the already wired location (town) . Furthermore, such a solution may consider how to obviate obstacles.

- Coping with lack of predictability of traffic demand. In rural areas, especially at beginning of network deployment, the traffic demand is difficult to forecast. The data backhaul network may be scalable, this means that addition of capacity and range extension may be simple and cost efficient. Then the network can grow with the business.

BRIEF DESCRIPTION OF THE DRAWINGS [0049] Embodiments of the present invention are described herein below with reference to the accompanying drawings, in which:

[0050] Fig. 1 shows the above-described PMP/P2P solution for data backhaul;

[0051] Figs. 2-1 and 2-2 show the above-described conversion wireless mesh network solution for data backhaul;

[0052] Fig. 3 shows another example of the above- described conversion wireless mesh network solution for data backhaul;

[0053] Fig. 4 shows a data backhaul wireless mesh network architecture according to an example of the present invention;

[0054] Fig. 5 shows an example of a data backhaul wireless mesh network according to an example of the present invention;

[0055] Fig. 6 shows an example of the present invention related to a multi-channel, multi-radio, directional antenna;

[0056] Fig. 7 shows a structure of a root node controller according to an example of the present invention;

[0057] Fig. 8 shows a processing module of the root node controller according to an example of the present invention; [0058] Fig. 9 shows a method e.g. for controlling the processing module of the root node controller according to an example of the present invention;

[0059] Fig. 10 shows a mesh node structure e.g. for root nodes, branch nodes and leaf nodes according to an example of the present invention;

[0060] Fig. 11 shows a processing module of the root nodes, branch nodes and/or leaf nodes according to an example of the present invention;

[0061] Fig. 12 shows a method e.g. for controlling the processing module of the root nodes, branch nodes and/or leaf nodes according to an example of the present invention;

[0062] Fig. 13 shows a structure of a line interface module according to an example of the present invention;

[0063] Fig. 14 shows a transceiver according to an example of the present invention from a structural viewpoint;

[0064] Fig. 15 shows the transceiver according to an example of the present invention from a state automaton viewpoint;

[0065] Fig. 16 shows a data structure according to an example of the present invention;

[0066] Fig. 17 shows a mesh node protocol stack according to an example of the present invention; and [0067] Fig. 18 shows a wireless mesh network solution for data backhaul according to an example of the present invention .

DETAILED DESCRIPTION OF THE PRESENT INVENTION

[0068] Embodiments of the present invention are described herein below by way of example with reference to the accompanying drawings .

[0069] It is to be noted that for this description, the terms "root network controller; mesh node or root node, branch node and leaf node; UL sub-frame; periodic ranging contention slot and UL physical protocol data unit" are examples for "network control element; network element; data sub-frame; information related to periodic network monitoring and network topology-related information", respectively, without restricting the latter-named terms to the special technical or implementation details imposed to the first-named terms.

[0070] Fig. 4 shows an architecture of the data backhaul WMN according to an example of the present invention. In order to provide data backhaul e.g. for GSM/WBA in a rural area, as shown in Fig. 4, a data backhaul WMN system 200 may comprise a RC (Root Controller) 201-A, one or more RNs (Root Nodes) 2011-a, ..., 2011-c, and a plurality of LNs (leaf Nodes) 2013-a, ..., 2013-g and BNs (Branch Nodes) 2012-a, ..., 2012-e . The network may be organized as tree structure.

[0071] The RC 201-A may constitute the aggregation point of the RNs 2011, and each RN 2011 may be the aggregation point of the LNs 2013 and BNs 2012. The RC 201-A may have two main functions.

[0072] The first function of the RC 201-A may be to act as a gateway between data backhaul WMN and a backbone network 203, which can be a synchronous digital hierarchy (SDH) backbone or an IP backbone. In case the RC 201-A connects with a SDH circle, the RC 201-A may provide the function of a SDH add-drop multiplexer.

[0073] The second function of the RC 201-A may reside in serving as the aggregation point of the RNs 2011. One or more RNs 2011 may be connected to the backbone 203 through the RC 201-A. Each RN 2011 may periodically report to the RC 201-A the topology structure related to the RN 2011 and the status of mesh nodes 2011, 2012, 2013 in the network topology. Then, the RC 201-A may hold information on the status and topology of all mesh nodes

2011, 2012, 2013.

[0074] In case that more than one RN 2011 is connected with the RC 201-A, the RC 201-A may route, for data packets received from the backbone network 203, the data packets to the intended RN 2011 and/or the mesh node(s)

2012, 2013 belonging to the RN 2011 in the area. Through monitoring the status of the RN(s) 2011, the RC 201-A may hold information on the total network topology and on the work status of each mesh node in the area. The status may include mesh node traffic condition, channel quality, etc .

[0075] Furthermore, the RC 201-A may help the RNs 2011 to exchange these information. Then, also each RN 2011 may hold information on the neighboring RN 2011 cluster condition (s) . Such information may be used to assist e.g. in a mesh node 2012, 2013 handover between neighboring RN 2 0 1 1 clus ters .

[0076] Furthermore, the RN 2011 may be the aggregation point of a network tree organized by LNs 2013 and BNs 2012. The RN 2011 may have an important role in the network 200.

[0077] The first function of the RN 2011 may reside in maintaining the tree structure/topology, i.e. adding, deleting a LN 2013/BN 2012 in the tree structure and deciding on connection relationships.

[0078] The second function of the RN 2011 may reside in providing data traffic for the mesh nodes 2012, 2013 in the tree. For example, the RN 2011 may be connected to the RC 201-A with a high bandwidth communication interface, such as a fiber cable or a microwave link. When the mesh node number increases in an area, multiple RNs 2011 may be used to enhance redundancy and load balance. The RC 201-A may be co-located with a RN 2011 in the area.

[0079] Both the BNs 2012 and LNs 2013 in the tree may function as traffic data router. The difference between LNs 2013 and BNs 2012 may be that the BNs 2012 do not consume/generate the data traffic, while the LNs 2013 do consume/generate the data traffic. Furthermore, the BNs

2012 may be used for overcoming path loss, thus extending transmitting distance and adding to linkage. The LNs 2013 may be the node(s) connected with an access unit such as WLAN AP and GSM BTS.

[0080] Since the data backhaul WMN network may be organized as tree structure, each mesh node 2011, 2012,

2013 in the tree may only have one parent node. Conversely, each mesh node 201, 2012, 2013 may act as parent node for one or more child nodes.

[0081] If a data packet arrives at the RC 201-A, the RC 201-A may transmit the data packet to the intended RN 2011 e.g. according to a routing table. The data packet may then be routed through the tree, wherein each node 2011, 2012, 2013 may determine whether the data packet carries a local address. If so, the data packet may be passed to local processing. If the data packet is not intended for the node, the data packet may be checked against the routing table, and the data packet may be routed to the intended child node. Conversely, the packet data may be routed from a LN 2013 in the tree back through any intervening parent node 2012, 2013 to reach the RN 2011, which RN 2011 then may pass the data packet to the backbone network 203.

[0082] Fig. 5 shows an example of data backhaul wireless mesh network according to an example of the present invention .

[0083] In Fig. 5, dotted lines represent an active wireless connection, dashed lines represent a potential wireless connection and solid lines represent a connection between the RN 2011 and the RC 201-A. The latter connection may be a fiber cable or a microwave link.

[0084] As derivable from Fig. 5, each LN 2013 may have multiple routes to reach a RN 2011. The RN 2011 may control the tree topology. There may be many tree topologies existing for a few static nodes. The RN 2011 may select or change the tree topology e.g. according to channel condition or traffic flow. Furthermore, e.g. in case of a node failure or of addition of a new node, the RN 2011 may modify the tree topology according to the change .

[0085] At the beginning, only one RN 2011 may exist in the area. When the network becomes more and more loaded, the situation can be relieved by providing another RN 2011 with a new wide bandwidth link to the backbone network 203. This may divide the mesh network into more trees and increase system capacity.

[0086] Fig. 6 shows an example of the present invention related to a multi-channel, multi-radio, directional antenna. Use of such an antenna may increase mesh node throughput and reduce traffic delay.

[0087] Each RN 2011, BN 2012 and LN 2013 is designed to support several simultaneous channels using e.g. multiple parallel radio frequency (RF) front-end chips and baseband processing modules. Furthermore, each data backhaul node may be configured with an antenna array which is composed of multi antenna elements, such as e.g. three 120 degree antennas (as shown in Fig. 6) or six 60 degree antennas (not shown) delivering 360 degree converge. Each sectorized antenna may focus energy in a directional horizontal beam (such as 120 degree/60 degree) e.g. for obtaining greater signal strength and significantly longer range than omni-directional antennas. The directional capabilities of the antenna array may also permit a more effective utilization of available spectrum by allowing simultaneous communication between nodes 2011, 2012, 2013 in neighboring areas.

[0088] As can be seen in Fig. 6, spatial reuse may be realized through allocating proper orthogonal channels to each radio and antenna direction. In order to realize simultaneous data transmission/reception in different directions, each mesh node 2011, 2012, 2013 may have several radio transceivers (to be described later) . The number of radio transceivers may be same as or less than the number of antenna elements. In case the number of antennas is equal to the number of radio transceivers behind each antenna element, there may be a responding (e.g. 802.16) radio transceiver. In case the number of transceivers is less than the number of antenna elements, a switch may be used to configure the transceiver to an antenna element pointing in a given direction according to network topology requirements.

[0089] As can further be seen in Fig. 6, combined with directional antenna technology, effective spatial and spectral reuse can be realized, such as allocating proper orthogonal channels to each radio and antenna direction. Multi-channel (i.e. multiple orthogonal channels) may be realized by using any access technique such as frequency division multiple access (FDMA) , time division multiple access (TDMA) , code division multiple access (CDMA) , orthogonal frequency division multiple access (OFDMA) or hybrids which use one or more of these techniques in combination. In the example shown in Fig. 6, an orthogonal channel may be realized by using frequency division multiplexing (FDM) . Furthermore, different frequency bands may be allocated for each orthogonal channel used in the system. In data backhaul WMN, e.g. fixed WiMAX time division duplex (TDD) may be used for the radio link. Furthermore, a fixed/mobile WiMAX TDD mode may used to divide Uplink and Downlink e.g. of each hop. In addition, fixed WiMAX TDMA may be used for user multiplexing . [0090] As further shown in Fig. 6, in case a transceiver is only connected to one node 2011, 2012, 2013, then a P2P mode may be used. In case a transceiver is connected to more than one node, then e.g. fixed WiMAX TDMA may used for the connection.

[0091] Fig. 7 shows a structure of the root node controller 201-A according to an example of the present invention .

[0092] According to this structure, the RC 201-A may comprise a processing module 201-1, an optical module 201-2, a time division multiplex (TDM) interface 201-3 for connecting to the backbone network 203, a frame processor 201-41, an ethernet interface 201-42, a RN switch 201 and a microwave, a fiber cable or a ethernet cable 201-6.

[0093] The RC 201-A may function as in a SDH add-drop multiplexer role. Then, e.g. the data from the backbone network 203 may be transferred to an (IP) data packet. Then, the data packet may be transmitted to the root node 2011. In case the RC 201-A is connected to more than one root node 2011, the RC 201-A may have to decide which root node 2011 the data packet is to be transmitted to. Since the RC 201-A may hold information on the topology of the area and on which mesh node 2011, 2012, 2013 is connected to which root node 2011, 2012, 2013, the RC 201-A has means to decide to which root node 2011 the data packet should be transmitted to firstly. If the RC 201-A is co-located with one of the root nodes 2011, an ethernet cable 201-6 may used to communication between the RC 201-A and the RN 2011. If the root node 2011 is located far away from the RC 201-A, then e.g. microwave or a fiber cable 201-6 may be used for data packet transmission .

[0094] Fig. 8 shows embodiments of a processing module 201-1 of the RC 201-A for network management according to an example of the present invention. Within Fig. 8, for ease of description, means or portions which may provide main functionalities are depicted with solid functional blocks or arrows and a normal font, while means or portions which may provide optional functions are depicted with dashed functional blocks or arrows and an italic font.

[0095] The processing module 201-1 may comprise a CPU (or core functionality CF) 201-11, a memory 201-12, an optional transmitter (or means for transmitting) 201-13, a receiver (or means for receiving) 201-14, an aggregator (or means for aggregating) 201-15, an establisher (or means for establishing) 201-16, a controller (or means for controlling) 201-17, an optional router (or means for routing) 201-18, an optional creator (or means for creating) 201-19 and an optional exchanger (or means for exchanging) 201-110.

[0096] Furthermore, as indicated by the dashed extension of the functional block of the CPU 201-11, the means for aggregating 201-15, the means for establishing 201-16, the means for controlling 201-17, the means for routing 201-18, the means for creating 201-19 and the means for exchanging 201-110 may be functionalities running on the CPU 201-11 or may alternatively be separate functional entities or means. In addition, as an optional feature, the means for receiving 201-14 may also constitute, partly or as a whole, a sub-functionality of the CPU 201- 11, as indicated by the functional blocks of the means for receiving being (partly) superimposed on the functional block of the CPU 201-11. The same applies to the optional means for transmitting 201-13, which may be comprise the sub-functionalities of the RN switch 201-5 and the microwave, fiber cable or ethernet cable 201-6.

[0097] The CPU 201-11 may be configured to process various data inputs and to control the functions of the memory 201-12, the means for transmitting 201-13 and the means for receiving 201-14 (and the means for aggregating 201-15, the means for establishing 201-16, the means for controlling 201-17, the means for routing 201-18, the means for creating 201-19 and the means for exchanging 201-110) . The memory 201-12 may serve e.g. for storing code means for carrying out e.g. a method according to an example of the present invention, when run e.g. on the CPU 201-11.

[0098] Thus, e.g. the means for receiving 201-14 of the processing module 201-1 may perform receiving, at a network control element (e.g. RC 201-A as parent), a plurality of data sub-frames (e.g. UL sub-frames 302-c) each comprising information (e.g. periodic ranging contention slot 303-c) related to periodic network monitoring and network topology-related information (e.g. UL physical protocol data unit 303-d) aggregated by a plurality of network root elements (e.g. RNs 2011-a/b/c) .

[0099] Then, e.g. the means for aggregating 201-15 of the processing module 201-1 may perform, at the network control element (e.g. RC 201-A), the network topology- related information received by the means for receiving.

[00100] Then, e.g. the means for establishing 201-16 of the processing module 201-1 may perform establishing periodically a network topology based on the network topology-related information aggregated by the means for aggregating.

[00101] And, e.g. the means for controlling 201-17 of the processing module 201-1 may perform controlling each one of the plurality of network root elements (RNs 2011) based on the network topology established by the means for establishing.

[00102] According to further developments of the processing module according to an example of the present invention, the network control element may be constituted by a root network controller. Furthermore, the network control element may be configured for gateway functionality with a synchronous digital hierarchy backbone or an internet protocol backbone. In addition, the network control element may be configured for a synchronous digital hierarchy add-drop multiplexer functionality in case of the synchronous digital hierarchy backbone.

[00103] Furthermore, the means for controlling may further comprise means for routing 201-18 which routes each of a plurality of received data packets to an intended one of the at least one network root element (e.g. RNs 2011) based on the network topology. And, the means for routing may further comprise the means for creating 201-19 which creates a routing table. Further, the network topology-related information may comprise status information of each one of network traffic elements (e.g. BN 2012, LN 2013) and/or may comprise a traffic condition, a used channel, a quality of the used channel, a preamble, an antenna direction and/or a transmit sub-frame time. [00104] In addition, the processing module according to an example of the present invention may further comprise the means for exchanging 201-110 which exchanges the aggregated network topology-related information among each one of the plurality of network root elements.

[00105] Finally, the network control element may be co- located with one of the plurality of network root elements. A connection between the network control element and the co-located network root element may be provided by a high bandwidth communication interface which may be a fiber cable or a microwave link.

[00106] Fig. 9 shows a method for the processing module 201-1 according to an example of the present invention for network management. Signaling between elements is indicated in horizontal direction, while time aspects between signaling may be reflected in the vertical arrangement of the signaling sequence as well as in the sequence numbers. It is to be noted that the time aspects indicated in Fig. 9 do not necessarily restrict any one of the method steps shown to the step sequence outlined. This applies in particular to method steps that are functionally disjunctive with each other, e.g. optional step Sl-6 may also be performed at another time. Within Fig. 9, for ease of description, means or portions which may provide main functionalities are depicted with solid functional blocks or arrows and a normal font, while means or portions which may provide optional functions are depicted with dashed functional blocks or arrows and an italic font.

[00107] In step Sl-I, e.g. the means for receiving 201-14 may perform receiving, at a network control element (RC 201-A as parent), a plurality of data sub-frames (e.g. UL sub-frames 302-c) each comprising information (e.g. periodic ranging contention slot 303-c) related to periodic network monitoring and network topology-related information (e.g. UL physical protocol data unit 303-d) aggregated by a plurality of network root elements (e.g. RNs 2011-a/b/c) .

[00108] In step Sl-2, e.g. the means for aggregating 201-

15 may perform aggregating, at the network control element, the received network topology-related information .

[00109] In step Sl-3, e.g. the means for establishing 201-16 may perform establishing a network topology based on the aggregated network topology-related information periodically.

[00110] And, in step Sl-2, e.g. the means for controlling 201-17 may perform controlling each one of the plurality of network root elements based on the established network topology.

[00111] According to further developments of the method for the processing module 201-1, the method may further comprise, as optional step Sl-6, routing each of a plurality of received data packets to an intended one of the plurality of network root elements based on the established network topology. In addition, the routing may further comprise, as optional step Sl-7, creating a routing table. Furthermore, the network topology-related information may comprise status information of each one of network traffic elements (BN 2012, LN 2013) . And, the status information may comprise at least one of a traffic condition, a used channel, a quality of the used channel, a preamble, an antenna direction and a transmit sub-frame time. Further, the controlling may further comprise, as an optional step Sl-5, exchanging the aggregated network topology-related information among each one of the plurality of network root elements.

[00112] Fig. 10 shows a mesh node structure e.g. for root nodes 2011, branch nodes 2012 and leaf nodes 2013 according to an example of the present invention. The mesh node may comprise the processing module 204-1, at least one radio transceiver 204-2 and a corresponding antenna 204-3, an optional line interface 204-4 for connection with access devices, an optional interface 204-5 and a synchronization and clock module 204-6.

[00113] For the root node 2011, the interface 204-5 with the root node controller 201-A may be disposed. The radio transceiver 204-2 may process e.g. the fixed WiMAX RF and baseband signal of a wireless link. In this example, each radio transceiver 204-2 may be configured corresponding to a fixed antenna element of antenna (arrays) 204-3, which may be composed of multi-antenna elements, such as three 120 degree antennas or eight 60 degree antennas that deliver 360 degree coverage.

[00114] The processing module 204-1 may comprise at least one micro processor for MAC layer and IP layer processing and routing. When the processing module 204-1 receives a data packet from one radio transceiver 204-2, the module 204-1 firstly checks if the data packet carries a local address. If so, the processing module 204-1 may process the packet locally. If the packet is not intended for the receiving node, the processing module 204-1 may check a routing table, and route the data packet to the intended child node (downlink) / parent node (uplink) using the corresponding transceiver 204-2. Since the processing module 204-1 may process and route the data packet in a local mesh node, the processing time may be very fast compared with the data packet transmission and processing time in the radio transceiver 204-2. The processing module 204-1 may also be used to control the radio transceiver 204-2 according to a system configuration, such as used channel, frame structure and transmit and receiver time etc.

[00115] If the mesh node is a LN 2013, the line interface 204-4 may provide the interface between mesh node and the access devices which may use the mesh data backhaul . The access devices may be a WLAN AP, GSM BTS, WCDMA NodeB, DVB-T BTS etc. The line interface 204-4 may be ethernet, Tl/El etc.

[00116] The Synchronization and clock module 204-6 may provide a high accuracy clock and synchronize the mesh node with a system clock. Any synchronization method such as GPS or TDM over IP, may be used.

[00117] Fig. 11 shows embodiments of the processing module 204-1 of the mesh nodes 2011, 2012, 2013 for network management according to an example of the present invention. Within Fig. 11, for ease of description, means or portions which may provide main functionalities are depicted with solid functional blocks or arrows and a normal font, while means or portions which may provide optional functions are depicted with dashed functional blocks or arrows and an italic font.

[0100] The processing module 204-1 may comprise a CPU (or core functionality CF) 204-11, a memory 204-12, an optional transmitter (or means for transmitting) 204-13, a receiver (or means for receiving) 204-14, a configurator (or means for configuring) 204-15 and an optional allocator (or means for allocating) 204-16.

[0101] Furthermore, as indicated by the dashed extension of the functional block of the CPU 204-11, the means for configuring 204-15 and the means for allocating 204-16 may be functionalities running on the CPU 204-11 or may alternatively be separate functional entities or means. In addition, as an optional feature, the means for receiving 204-14 may also constitute, partly or as a whole, a sub-functionality of the CPU 204-11, as indicated by the functional blocks of the means for receiving being (partly) superimposed on the functional block of the CPU 204-11.

[0102] The CPU 201-11 may be configured to process various data inputs and to control the functions of the memory 204-12, the means for transmitting 204-13 and the means for receiving 204-14 (and the means for configuring 204-15 and the means for allocating 204-16) . The memory 204-12 may serve e.g. for storing code means for carrying out e.g. a method according to an example of the present invention, when run e.g. on the CPU 204-11.

[0103] According to the processing module 204-1 according to an example of the present invention e.g. for controlling a transmitter portion of transceiver (s) 204- 2, e.g. the means for receiving 204-14 may be configured to receive, from a network control element (e.g. RC 201- A) at a network element (e.g. RN 2011, BN 2012, LN 2013), network control information indicating a network topology of a plurality of the network elements (e.g. RN, BN, LN) .

[0104] And, e.g. the means for configuring 204-15 may be configured to configure a receiving portion of at least one transceiver of the network element to one of at least one transceiving state based on the network control information received by the means for receiving.

[0105] According to developments of the processing module 204-1 according to an example of the present invention e.g. for controlling a transmitter portion of transceiver (s) 204-2, the means for receiving may be configured to receive based on fixed/mobile worldwide interoperability for microwave access (e.g. 802.16d/802.16e) and fixed worldwide interoperability for microwave access in time division multiple access mode. Also, the means for configuring may further be configured to configure based on one of adding a network element, deleting a network element and connection relationships between the network elements.

[0106] In addition, the above processing modules according to examples of the present invention for controlling the transmitting/receiving portions of the transceivers 204-2 may be summarized to a processing module for controlling the entire transceiver 204-2.

[0107] Furthermore, as a further development, the network topology may be changed depending on at least one of addition of a network element, failure of an existing network element, a channel condition and a traffic flow.

[0108] Furthermore, the transmitting portion and the receiving portion of the at least one transceiver may be configured, by the means for configuring, to use multi- radio multi-channel directional antennas. And, the processing module 204-1 may further comprise multiple RF front-end chips and baseband processing modules for providing multi-channels.

[0109] Furthermore, the transceiving state may comprise a first transceiving state (e.g. BS state) being a base station state from a parent node element to at least one child node element, a second transceiving state (e.g. SS state) being a subscriber state from the at least one child node element to the parent node element, a third transceiving state (e.g. free BS state) being a free-base station state in which the network element is not connected to any other network element, or a fourth transceiving state (e.g. measure) comprising the parent node element in the third transceiving state and the at least one child node element in the second transceiving state, wherein the parent node element and the at least one child node element effect a network measurement without data flow during a measurement frame. Furthermore, the network element may be a root node element 2011 and the at least one transceiver 204-2 may be configured to the first transceiving state by the means for configuring. In addition, the network element may be a branch node element 2012 or a leaf node element 2013, and the at least one transceiver 204-2 may be configured, by the means for configuring, to one of the first to fourth transceiving states based on the network topology.

[0110] Furthermore, the processing module 204-1 may further comprise the means for allocating 204-16 at least one orthogonal channel to each radio and antenna direction. The network topology may constituted by a network tree-topology. Further, the network elements may each comprise a multi transceiver structure, wherein each transceiver may be configured with a directional antenna. [0111] Fig. 12 shows methods for the processing module (s) 204-1 according to an example of the present invention for network management. Signaling between elements is indicated in horizontal direction, while time aspects between signaling may be reflected in the vertical arrangement of the signaling sequence as well as in the sequence numbers. It is to be noted that the time aspects indicated in Fig. 12 do not necessarily restrict any one of the method steps shown to the step sequence outlined. This applies in particular to method steps that are functionally disjunctive with each other, e.g. optional step S2-3 may also be performed at another time. Within Fig. 12, for ease of description, means or portions which may provide main functionalities are depicted with solid functional blocks or arrows and a normal font, while means or portions which may provide optional functions are depicted with dashed functional blocks or arrows and an italic font.

[0112] As already described hereinabove with reference to Fig. 11, according to examples of the present invention, there may be a method for controlling the transmitting portion of the transceiver 204-2, a method for controlling the receiving portion of the transceiver 204- 2 and a method for controlling the entire transceiver 204-2.

[0113] Accordingly, in step S2-1 of all 3 methods, e.g. the means for receiving 204-14 may perform receiving, from a network control element (e.g. RC 201-A) at a network element (e.g. RN, BN, LN), network control information indicating a network topology of a plurality of the network elements (e.g. RN, BN, LN) . [0114] And, in step S2-2, e.g. the means for configuring 204-15 may perform configuring a transmitting/receiving portion (or the entire transceiver) of at least one transceiver of the network element to one of at least one transceiving state based on the received network control information .

[0115] According to developments of all 3 methods according to examples of the present invention, the receiving may be performed based on fixed/mobile worldwide interoperability for microwave access (time division duplex) (e.g. 802.16d/e) or fixed worldwide interoperability for microwave access in time division multiple access mode (in time division duplex mode) .

[0116] In addition, the configuring may further be based on adding a network element, deleting a network element or connection relationships between the network elements. Furthermore, the transmitting and receiving (in the transceiving method) may be performed by utilization of multi-radio multi-channel directional antennas. In addition, the transceiving method may further comprise, as an optional step S2-3, allocating at least one orthogonal channel to each radio and antenna direction.

[0117] Furthermore, the transceiving state may comprise a first transceiving state (e.g. BS state) being a base station state from a parent node element to at least one child node element, a second transceiving state (e.g. SS state) being a subscriber state from the at least one child node element to the parent node element, a third transceiving state (e.g. free BS state) being a free-base station state in which the network element is not connected to any other network element, or a fourth transceiving state (e.g. measure state) comprising the parent node element in the third transceiving state and the at least one child node element in the second transceiving state, wherein the parent node element and the at least one child node element effect a network measurement without data flow during a measurement frame.

[0118] Finally, the network topology may be changed depending on addition of a network element, failure of an existing network element, a channel condition and/or traffic flow.

[0119] Fig. 13 shows a structure of a line interface module 201-4 according to an example of the present invention. In case access devices need e.g. a TDM based interface, an ethernet interface 201-41 TDM interface 201-43 and frame processing 201-42 transaction is performed by the line interface module 201-4.

[0120] Figs. 14 and 15 show a transceiver according to an example of the present invention from both a structural and a state automaton viewpoint.

[0121] As shown in Fig. 14 (and described hereinabove) , the transceiver 201-2 may comprise a transmitter (portion) and a receiver (portion) . It is to be noted that sections being labeled with "^-1" _may constitute functions inverse to the functions performed by the corresponding section without "^-1" (e.g. 202-25^'1 may be the inverse function of 202-25) .

[0122] The transmitter portion may receive binary input data, which may be fed, (substantially) in this order, to a coding section 201-21, an interleaving section 202-22, a quadrature amplitude modulation (QAM) mapping section 202-23, a pilot insertion section 202-24, a supplementary/polling (S/P) section 202-25, an inverse fast Fourier transformation (IFFT) section 202, a polling/supplementary (P/S) section 202-25^'1, an add contention period (CP) and windowing section 202-27, a digital-to-analog converter (DAC) section 202-28 and finally to a radio frequency transmission (RF TX) section 202-29.

[0123] Then, the binary input data having undergone sections 202-21 to 202-29 may be sent via the channel 202-210.

[0124] Then, the data may be received by the receiver portion. That is, the data may be fed, (substantially) in this order, to a RF receiver (RX) section 202-29^"1, an analog-to-digital converter (ADC) section 202-28^'1, a timing frequency synchronization section and a remove CP section 202-27^"1, a S/P section 202-25^"1, a fast Fourier transformation (FFT) section 202-26^"1, a P/S section 202- 25, a channel correction section 202-24^"1, a QAM de- mapping section 202-23^'1, a de-interleaving section 202- 22^"1 and a de-coding section 202-21^"1.

[0125] Afterwards, the binary output data should be (substantially) identical to the binary input data.

[0126] As shown in Fig. 15 (and described hereinabove) , since the data backhaul WMN may be organized as a tree structure, each mesh node in the tree may only have one parent node at a time. Conversely, each node may act as parent node for one or more children node. As the tree structure should change according to an environmental change, such as adding a new node in the tree, deleting a node of the tree and change the tree topology according to the channel status, each transceiver 201-2 should work either as a base station (BS) or a subscriber station (SS) . All transceivers of the RNs 2011 may function at the BS state. The transceivers of LNs 2013 and BNs 2012 may have 4 states, namely SS, BS, free BS (fBS) and measure states.

[0127] If the transceiver 201-2 of a given parent node is used to connect with the transceiver 201-1 of the corresponding child node(s), the transceiver 201-2 may be in the BS state. Conversely, the transceiver 201-2 of the corresponding child node(s) is in the SS state. For LNs 2013 and BNs 2012, some transceivers 201-2 may be in the BS state and some different transceivers 201-2 in the SS state according to tree topology.

[0128] In case a transceiver 201-2 of a mesh node 2011, 2012, 2013 is free (i.e. not used to connect with any other node), the transceiver 201-2 may (e.g. by default) be in the free BS state. In the free BS state, the transceiver 201-2 may only send the preamble and a frame control header (FCH) part e.g. of the DL frame to avoid interference .

[0129] For the data backhaul WMN, the tree topology may be adjusted according to the channel status, the child node may continue monitoring the channel status of possible parent node(s) and find the proper parent node according to the measurement results. To realize the measurement, the RN 2011 may provide the LN 2013, BN 2012 with the information of neighboring node(s) (e.g. preamble pattern, frequency, antenna direction) . The RN 2011 may also notify the LN, BN frame for measurement. In the frame for measurement, no data flow may be transmitted between the node and the corresponding parent node for the transceiver 201-2 in the SS state. For the transceiver 201-2 in the free BS state, the transceiver 201-2 may perform the measurement according to the requirement of the RN 2011. In the frame for measurement, the transceiver 201-2 may be in the measure state.

[0130] Fig. 16 shows a data structure according to an example of the present invention. That is, a data structure may comprise means for conveying (e.g. data frame 301), to an apparatus such as the above-described processing module 204-1 for controlling the transceiver (s) 204-2,, a plurality of data sub-frames

(e.g. UL sub-frame 302-c) each comprising information

(e.g. periodic ranging contention slot 303-c) related to periodic network monitoring and network topology-related information (e.g. UL physical protocol data unit 303-d) aggregated by a plurality of the network root elements

(e.g. RNs 2011-a/b/c) .

[0131] As for further developments of the data structure according to an example of the present invention, the transmission direction from the at least one network root node to the network control element may be an uplink, and the network control element may constitutes a parent node element and the plurality of network root elements may constitute child node elements.

[0132] Furthermore, the means for conveying may be constituted by a frame interval (301), and the data sub- frames may be uplink sub-frames comprised in the frame interval (301) . Furthermore, the uplink sub-frame may be preceded by a transmit turnaround gap and may be followed by a receive turnaround gap. In addition, the uplink sub- frame may comprise an initial ranging contention slot (303-b) , a periodic ranging contention slot (303-c) comprising the information related to periodic network monitoring, and a plurality of uplink physical protocol data units (303-d) comprising the network topology- related information. Further, the plurality of uplink physical protocol data units may be shared according to the number of child node elements.

[0133] In this respect, the transmission direction from the network control element to the plurality of root node elements may be a downlink, and if the number of child nodes is zero, information sent on the downlink may only comprise a preamble (304-a) and a frame control header (304-b) . Further, at least no uplink bursts (304-e) may be transmitted on the uplink.

[0134] Finally, the means for conveying may be configured to convey based on a fixed worldwide interoperability for microwave access time division duplex structure or a mobile worldwide interoperability for microwave access time division duplex structure.

[0135] To sum up, according to Fig. 16, each frame interval 301 may consist of DL sub-frames 302-a and UL sub frames 302-c. In each TDD frame, the UL/DL sub frames may be separated by guard times such as the transmit turnaround gap (TTG) 302-b and the receive turnaround gap (RTG) 302-d. A DL sub frame may comprise a single PHY PDU 303-a. (Here, the DL may be the direction from parent node to children node) . Each DL PHY PDU 303-a may comprise a long preamble 304-a followed by the frame control header (FCH) 304-b and multiple DL bursts 304-c. The first DL Burst 304-c may contain broadcast messages like the DL-mobile application part (MAP) 305-a and the UL-MAP 305-b. The DL-MAP 305-a may contain a location and profile of the following bursts 304-c. The UL-MAP 305-b may contain physical parameters and start time for UL PHY bursts 303-d. The UL sub-frame 302-c may comprise contention intervals for initial 303-b and periodic 303-c ranging and one or more UL PHY PDUs 303-d. (here, the UL may be the direction from children node to parent) . In the P2P case, only one child node may connect to a transceiver 201-2 of the corresponding parent node, and all radio resources are located to the child node. In the P2MP case, more than one child node may connect to a transceiver 201-2 of the corresponding parent node, and the radio resources (e.g. time slots) are shared between the child nodes. Each child mesh node connected with the same transceiver 201-2 of the parent mesh node may transmit a separate UL PHY PDU 303-d to the parent mesh node. The UL PHY PDU 303-d may consist of a short preamble 304-d followed by the UL burst 304-e.

[0136] Fig. 17 shows a mesh node protocol stack according to an example of the present invention. The protocol stack may include 4 layers. Some functions e.g. of fixed/mobile WiMAX (e.g. 802.16d/e) physical layer may be located in the transceiver (s) 201-2, and some functions of the physical layer may be located in the above-described processing modules. Medium access control (MAC) -R (MAC layer for radio) may manage and maintain the fixed/mobile WiMAX radio link. The functions are defined by fixed/mobile WiMAX specification (e.g. 802.16d/e), and the functions include fixed/mobile WiMAX system acquisition and ranging, support P2P and P2MP operation, resource allocation, quality-of-service (QoS) management and admission request (ARQ) . The MAC-M may be the MAC layer for mesh. The functions of MAC-M may be to manage the wireless mesh network. The functions may include: tree topology control, routing table update and routing. The MAC layer may provide interface e.g. to the IP layer and IP based applications supported.

[0137] Fig. 18 shows a possible effect of a wireless mesh network solution for data backhaul according to an example of the present invention. In case a mesh node #1 2022 belonging to the Root Node #1 2021 intends to connect to a neighboring mesh node #8 2021 belonging to another RN root node #2 2022, the RC 201-A or the root node #1 2021 may provide mesh node #1 2021 with the information of mesh node #8 2021 (such as preamble, used channel, antenna direction, TX sub-frame time etc.), and mesh node #1 2022 may use the information for measurement .

[0138] Furthermore, at least one of, or more of the means for receiving 201-14; 204-14, means for aggregating 201- 15, means for establishing 201-16, means for controlling 201-17, means for routing 201-18, means for creating 201- 19, means for exchanging 201-110, means for configuring 204-15, means for allocating 204-16, or the processing modules 201-1; 204-1 or the respective functionalities carried out, may be implemented as a chipset or module.

[0139] Finally, the present invention also relates to a system which may comprise the above-described a root network controller (processing module 201-1), and a plurality root node elements, branch node elements or a leaf node elements, each comprising a transceiver controlled by a processing module 204-1.

[0140] Without being restricted to the details following in this section, the embodiment of the present invention may be summarized as follows:

It is defined a new WMN architecture which uses e.g. 802.16d/e as radio link to provide cost effective data backhaul for the NGM (both GSM&WBA system) in rural areas. Each mesh node and root node may use multi- transceiver structure, wherein each transceiver may be configured with a directional antenna. Through allocating proper orthogonal channels to each radio and antenna direction, each mesh node can receive and transmit packet independently in different directions without considering the interference from/to other nodes. 802.16d/e radio may be used for the radio link. When a transceiver needs to connect two nodes in the same direction, e.g. 802.16d/e time division multiple access (TDMA) mode may be used. A new device RC (root node controller) is introduced in the network architecture, which makes the neighboring root node clusters cooperate together.

[0141] [Further embodiments]

[0142] For the purpose of the present invention as described herein above, it should be noted that

- an access technology may be any technology by means of which a user equipment can access an access network (or base station, respectively) . Any present or future technology, such as WiMAX (Worldwide Interoperability for Microwave Access) or WLAN (Wireless Local Access Network) , BlueTooth, Infrared, and the like may be used; although the above technologies are mostly wireless access technologies, e.g. in different radio spectra, access technology in the sense of the present invention may also imply wirebound technologies, e.g. IP based access technologies like cable networks or fixed line.

- a network may be any device, unit or means by which a station entity or other user equipment may connect to and/or utilize services offered by the access network; such services include, among others, data and/or (audio-) visual communication, data download etc.; - generally, the present invention may be applicable in those network/user equipment environments relying on a data packet based transmission scheme according to which data are transmitted in data packets and which are, for example, based on the Internet Protocol IP. The present invention is, however, not limited thereto, and any other present or future IP or mobile IP (MIP) version, or, more generally, a protocol following similar principles as

(M) IPv4/6, is also applicable;

- a user equipment may be any device, unit or means by which a system user may experience services from an access network;

- method steps likely to be implemented as software code portions and being run using a processor at a network element or terminal (as examples of devices, apparatuses and/or modules thereof, or as examples of entities including apparatuses and/or modules therefore) , are software code independent and can be specified using any known or future developed programming language as long as the functionality defined by the method steps is preserved; generally, any method step is suitable to be implemented as software or by hardware without changing the idea of the invention in terms of the functionality implemented;

- method steps and/or devices, units or means likely to be implemented as hardware components at the MSS and/or the MGW, or any module (s) thereof, are hardware independent and can be implemented using any known or future developed hardware technology or any hybrids of these, such as MOS (Metal Oxide Semiconductor) , CMOS (Complementary MOS) , BiMOS (Bipolar MOS) , BiCMOS (Bipolar

CMOS), ECL (Emitter Coupled Logic), TTL (Transistor- Transistor Logic), etc., using for example ASIC (Application Specific IC (Integrated Circuit)) components, FPGA (Field-programmable Gate Arrays) components, CPLD (Complex Programmable Logic Device) components or DSP (Digital Signal Processor) components; in addition, any method steps and/or devices, units or means likely to be implemented as software components may alternatively be based on any security architecture capable e.g. of authentication, authorization, keying and/or traffic protection;

- devices, units or means (e.g. processing modules) can be implemented as individual devices, units or means, but this does not exclude that they are implemented in a distributed fashion throughout the system, as long as the functionality of the device, unit or means is preserved; an apparatus may be represented by a semiconductor chip, a chipset, or a (hardware) module comprising such chip or chipset; this, however, does not exclude the possibility that a functionality of an apparatus or module, instead of being hardware implemented, be implemented as software in a (software) module such as a computer program or a computer program product comprising executable software code portions for execution/being run on a processor;

- a device may be regarded as an apparatus or as an assembly of more than one apparatus, whether functionally in cooperation with each other or functionally independently of each other but in a same device housing, for example.

[0143] Although the present invention has been described herein before with reference to particular embodiments thereof, the present invention is not limited thereto and various modification can be made thereto.

Claims

CLAIMS :

1. A method, comprising: receiving, at a network control element, a plurality of data sub-frames each comprising information related to periodic network monitoring and network topology-related information aggregated by a plurality of network root elements; aggregating, at the network control element, the received network topology-related information; establishing a network topology based on the aggregated network topology-related information periodically; and controlling each one of the plurality of network root elements based on the established network topology.

2. The method according to claim 1, further comprising routing each of a plurality of received data packets to an intended one of the plurality of network root elements based on the established network topology.

3. The method according to claim 2, wherein the routing further comprises creating a routing table.

4. The method according to claim 1, wherein the network topology-related information comprises status information of each one of network traffic elements.

5. The method according to claim 4, wherein the status information comprise at least one of a traffic condition, a used channel, a quality of the used channel, a preamble, an antenna direction and a transmit sub-frame time .

6. The method according to any one of claims 1 to 5, wherein the controlling further comprises exchanging the aggregated network topology-related information among each one of the plurality of network root elements.

7. A method, comprising: receiving, from a network control element at a network element, network control information indicating a network topology of a plurality of the network elements; and configuring a transmitting portion of at least one transceiver of the network element to one of at least one transceiving state based on the received network control information .

8. A method, comprising: receiving, from a network control element at a network element, network control information indicating a network topology of a plurality of the network elements; and configuring a receiving portion of at least one transceiver of the network element to one of at least one transceiving state based on the received network control information .

9. The method according to claims 7 or 8, wherein the receiving is performed based on one of fixed or mobile worldwide interoperability for microwave access and fixed or mobile worldwide interoperability for microwave access in time division multiple access mode.

10. The method according to claims 7 or 8, wherein the receiving is performed based on one of fixed or mobile worldwide interoperability for microwave access time division duplex and fixed or mobile worldwide interoperability for microwave access in time division multiple access mode.

11. The method according to any one of claims 7 to 10, wherein the configuring is further based on one of adding a network element, deleting a network element and connection relationships between the network elements.

12. A method, comprising: transmitting according to any one of claims 7 and 9 to 11; and receiving according to any one of claims 8 to 11.

13. The method according to claim 12, wherein the transmitting and receiving is performed by utilization of multi-radio multi-channel directional antennas.

14. The method according to claim 12, further comprising allocating at least one orthogonal channel to each radio and antenna direction.

15. The method according to any one of claims 7 to 14, wherein the transceiving state comprises at least one of: a first transceiving state being a base station state from a parent node element to at least one child node element; a second transceiving state being a subscriber state from the at least one child node element to the parent node element; a third transceiving state being a free-base station state in which the network element is not connected to any other network element; and a fourth transceiving state comprising the parent node element in the third transceiving state and the at least one child node element in the second transceiving state, wherein the parent node element and the at least one child node element effect a network measurement without data flow during a measurement frame.

16. The method according to any one of claims 1 to 15, wherein the network topology is changed depending on at least one of addition of a network element, failure of an existing network element, a channel condition and traffic flow.

17. An apparatus, comprising: means for receiving, at a network control element, a plurality of data sub-frames each comprising information related to periodic network monitoring and network topology-related information aggregated by a plurality of network root elements; means for aggregating, at the network control element, the network topology-related information received by the means for receiving; means for establishing periodically a network topology based on the network topology-related information aggregated by the means for aggregating; and means for controlling each one of the plurality of network root elements based on the network topology established by the means for establishing.

18. The apparatus according to claim 17, wherein the network control element is constituted by a root network controller .

19. The apparatus according to claim 18, wherein the network control element is configured for gateway functionality with one of a synchronous digital hierarchy backbone and an internet protocol backbone.

20. The apparatus according to claim 19, wherein the network control element is configured for a synchronous digital hierarchy add-drop multiplexer functionality in case of the synchronous digital hierarchy backbone.

21. The apparatus according to claim 17, wherein the means for controlling further comprises means for routing each of a plurality of received data packets to an intended one of the at least one network root element based on the network topology.

22. The apparatus according to claim 21, wherein the means for routing further comprises means for creating a routing table.

23. The apparatus according to any one of claims 17 to 22, wherein the network topology-related information comprise status information of each one of network traffic elements.

24. The apparatus according to claim 23, wherein the status information comprise at least one of a traffic condition, a used channel, a quality of the used channel, a preamble, an antenna direction and a transmit sub-frame time .

25. The apparatus according to any one of claims 17 to

24, further comprising means for exchanging the aggregated network topology-related information among each one of the plurality of network root elements.

26. The apparatus according to any one of claims 17 to

25, wherein the network control element is co-located with one of the plurality of network root elements.

27. The apparatus according to claim 26, wherein a connection between the network control element and the co-located network root element is provided by a high bandwidth communication interface.

28. The apparatus according to claim 27, wherein the high bandwidth communication interface is one of a fiber cable and a microwave link.

29. An apparatus, comprising: means for receiving, from a network control element at a network element, network control information indicating a network topology of a plurality of the network elements; and means for configuring a transmitting portion of at least one transceiver of the network element to one of at least one transceiving state based on the network control information received by the means for receiving.

30. An apparatus, comprising: means for receiving, from a network control element at a network element, network control information indicating a network topology of a plurality of the network elements; and means for configuring a receiving portion of at least one transceiver of the network element to one of at least one transceiving state based on the network control information received by the means for receiving.

31. The apparatus according to claims 29 or 30, wherein the means for receiving is configured to receive based on one of fixed or mobile worldwide interoperability for microwave access and fixed or mobile worldwide interoperability for microwave access in time division multiple access mode.

32. The apparatus according to claims 29 or 30, wherein the means for configuring is further configured to configure based on one of adding a network element, deleting a network element and connection relationships between the network elements.

33. An apparatus, comprising: the means of the apparatus according to claim 29, 31 and 32; and the means of the apparatus according to claims 30 to 32.

34. The apparatus according to any one of claims 29 to

33, wherein the network topology is changed depending on at least one of addition of a network element, failure of an existing network element, a channel condition and a traffic flow.

35. The apparatus according to any one of claims 29 to

34, wherein the transmitting portion and the receiving portion of the at least one transceiver are configured, by the means for configuring, to use multi-radio multichannel directional antennas.

36. The apparatus according to claim 35, further comprising multiple radio frequency front-end chips and baseband processing modules for providing multi-channels.

37. The apparatus according to any one of claims 29 to 36, wherein the transceiving state comprises one of: a first transceiving state being a base station state from a parent node element to at least one child node element; a second transceiving state being a subscriber state from the at least one child node element to the parent node element; a third transceiving state being a free-base station state in which the network element is not connected to any other network element; and a fourth transceiving state comprising the parent node element in the third transceiving state and the at least one child node element in the second transceiving state, wherein the parent node element and the at least one child node element effect a network measurement without data flow during a measurement frame.

38. The apparatus according to claim 37, wherein the network element is a root node element and the at least one transceiver is configured to the first transceiving state by the means for configuring.

39. The apparatus according to claim 37, wherein the network element is one of a branch node element and a leaf node element, and the at least one transceiver is configured, by the means for configuring, to one of the first to fourth transceiving states based on the network topology.

40. The apparatus according to any one of claims 29 to

39, further comprising means for allocating at least one orthogonal channel to each radio and antenna direction.

41. The apparatus according to any one of claims 29 to

40, wherein the network topology is constituted by a network tree-topology.

42. The apparatus according to any one of claims 29 to

41, wherein the network elements each comprise a multi transceiver structure.

43. The apparatus according to any one of claims 29 to

42, wherein each transceiver is configured with a directional antenna.

44. The apparatus according to any one of claims 17 to 28, wherein the apparatus is constituted by a processing means or module for a root network controller.

45. The apparatus according to any one of claims 29 to

43, wherein the apparatus is constituted by a processing means or module for at least one of a root node element, a branch node element and a leaf node element.

46. The apparatus according to any one of claims 17 to 45, wherein at least one, or more of means for receiving, means for aggregating, means for establishing, means for controlling, means for routing, means for creating, means for exchanging, means for configuring, means for allocating and the apparatus is implemented as a chipset or module.

47. A system, comprising: an apparatus according to claims 17 to 28 and 44 being a root network controller; and a plurality of network elements being one of a root node element, a branch node element and a leaf node element, each comprising a transceiver controlled by an apparatus according to claims 29 to 43.

48. A data structure, comprising: means for conveying, to an apparatus according to claim 33, a plurality of data sub-frames each comprising information related to periodic network monitoring and network topology-related information aggregated by a plurality of the network root elements.

49. The data structure according to claim 48, wherein the transmission direction from the at least one network root node to the network control element is an uplink, and the network control element constitutes a parent node element and the plurality of network root elements constitute child node elements.

50. The data structure according to claim 49, wherein the means for conveying are constituted by a frame interval, and the data sub-frames are uplink sub-frames comprised in the frame interval .

51. The data structure according to claim 50, wherein the uplink sub-frame is preceded by a transmit turnaround gap and is followed by a receive turnaround gap.

52. The data structure according to claim 50, wherein the uplink sub-frame comprises an initial ranging contention slot, a periodic ranging contention slot comprising the information related to periodic network monitoring, and a plurality of uplink physical protocol data units comprising the network topology-related information.

53. The data structure according to claim 52, wherein the plurality of uplink physical protocol data units is shared according to the number of child node elements.

54. The data structure according to any of claims 49 to 53, wherein the transmission direction from the network control element to the plurality of root node elements is a downlink, and if the number of child nodes is zero, information sent on the downlink only comprises a preamble and a frame control header.

55. The data structure according to claim 54, wherein at least no uplink bursts are transmitted on the uplink.

56. The data structure according to any one of claims 48 to 55, wherein the means for conveying is configured to convey based on one of a fixed worldwide interoperability for microwave access time division duplex structure and a mobile worldwide interoperability for microwave access time division duplex structure.

57. A computer program product comprising code means for performing methods steps of a method according to any one of claims 1 to 16, when run on a processing means or module .