WO2004014025A1

WO2004014025A1 - METHOD AND APPARATUS FOR INCREASED QoS AND REDUCED INTERFERENCE IN MESH ARCHITECTURE RADIO TELECOMMUNICATIONS SYSTEMS

Info

Publication number: WO2004014025A1
Application number: PCT/US2003/024328
Authority: WO
Inventors: Matthew D. Alspaugh; Chris P. Mcintosh
Original assignee: Interwave Communications, Inc.
Priority date: 2002-08-01
Filing date: 2003-08-01
Publication date: 2004-02-12
Also published as: AU2003257158A1

Abstract

Interference is mitigated within a meshed network of radio devices by (30-1, 30-2,……..30-N) dynamically coordinating channel assignments. Link communication quality between radio devices (30-1,30-2,….30-N) is measured for each relevant link (A1,A2,…B1,B2….) in the network (100), point-to-point, point-to-multipoint, and/or multipoint-to-multipoint. Measurement preferably includes reception interference relative to a threshold level, RSSI, BER, peak cell rate, average cell rate, and cell loss ratio. A network management (MNS) system (200) can map various of the link quality measurements to quality parameters (q) associated with packet traffic being carried. The NMS then controls channel assignments among the radio devices (20-1,30-2,…30-N) as needed to promote quality of service (QoS) of packet traffic delivery through the network (100).

Description

METHOD AND APPARATUS FOR INCREASED QoS AND REDUCED

INTERFERENCE IN MESH ARCHITECTURE RADIO

TELECOMMUNICATIONS SYSTEMS

PRIORITY CLAIM TO CO-PENDING APPLICATION Priority is claimed to co-pending U.S. provisional patent application serial number 60/400,926 filed 1 August 2002 entitled "Method and Apparatus for Increased QoS and Reduced Interference in Telecommunications Systems Having a Mesh Radio Architecture".

FIELD OF THE INVENTION The present invention relates generally to telecommunication systems, and more particularly to systems and methods to improvement communication in mesh radio architecture.

BACKGROUND OF THE INVENTION Referring to Fig. 1 , telecommunications systems such a system 10 typically comprise a network 20 that includes a number of radio devices 30-1 , 30-2, ... 30-n, that can be linked via paths A1. A2, ..., B1 , B2, ..., C1 , C2, ..., D1 , D2, to other radio devices within the system. The various radio devices can transmit and receive, and ideally any radio device within network 20 should be able to communicate reliably with any other radio device in the network. Traffic carried by network 20 is commonly in the form of data units commonly referred to as cells or frames, or herein as packets 40. The traffic packets travel through the network from radio device to radio device via linkage paths, typically as determined by a network management system (NMS) 50. Radio 30-1 , for example, may communicate information packets to radio 30-n through any of a variety of path links, for example via link paths A1 , A2, B3, C6, B12, or perhaps instead via link paths C1 , C5, D6, B8, B12, among other possible paths. NMS 50 maintains a set of pre-determined rules and is in communication with the radio devices within a system. NMS 50 can command restructuring of the network as a function of these rules, in an attempt to maintain effective and well functioning linkage paths through the network. In a non-mesh network 20, routing and switching functions, depicted generally by 50, are required.

Often the radio devices 30 are unlicensed, which can be advantageous in that little or no administrative overhead is required with respect to their usage. For example, so-called wireless-fidelity (WiFi) radios can operate in the high MHz region without license. However unlicensed radio devices may be more vulnerable to interference from other such unlicensed devices, perhaps devices such as 60-1 or 60-2 or 60-3 that are unaffiliated with system 10. Whether licensed or unlicensed, it is understood that not all radio devices within the network system necessarily exhibit the same throughput capacity. Further some of the radio devices may be subject to more interference than other radio devices within the network. In addition, the performance of a radio device over a linkage path may be different depending upon whether the radio device is transmitting over that path, or receiving via that path.

As noted above, the locus of linkage paths that defines a route (or interconnection between linked paths) from one radio device to another can be created in a number of ways. The challenge is provide a route (or redundant routes) that will reliably move packet traffic through the network, for example from radio device 30-1 to radio device 30-N in Fig. 1.

A further challenge is provide routes that subject the packet traffic being carried to an acceptable level of interference, including interference from radio devices within and without the network. By acceptable level of interference it is meant that traffic packets 40' arriving at a destination radio device 30-N within network 20 should provide sufficient quality data that the message being communicated is still intelligible. Thus packets 40' output from system 10 should be sufficiently identical to incoming packets 40 to be useful. One measure of acceptability of information is quality of service (QoS). Acceptable QoS for human voice transmission might be an error rate of 10^"6, whereas for digital files, QoS might be on the order of 10^"10, e.g., acceptable error is very small compared to what is acceptable for human voice communication.

So-called channel agile networks attempt to mitigate device-to-device interference by having various of the radio devices change channels (e.g., frequencies) as necessary. As such, channel agile radio devices 30 can be disadvantageous or counterproductive for use in a mesh network, as such networks will have established rules implementing an overall channel plan to mitigate interference among the meshed radio devices. In some radio architecture, especially non-meshed architecture system 10 may include monitored so-called hot-standby radios, e.g., 30'-3, 30'-4, in an attempt to improve link availability and reliability. However having to provide and maintain redundant radio devices is an expensive and inefficient technique that can be avoided by using a mesh network configuration.

There is a need for a system and method for use with meshed architecture enabling channel assignments among radio devices to be dynamically managed and coordinates so as to mitigate interference, including interference from devices within and without the network, and including effects of atmospheric conditions upon reception.

Further there is a need for a system and method whereby quality of service (QoS) can be enhanced for packet switched communications over radio transport links, using measurements of dynamic radio transport link quality.

The present invention provides such systems and methods.

SUMMARY OF THE INVENTION

The present invention mitigates interference in a meshed architecture network of radio devices by dynamically coordinating channel assignments among the radio devices. At least one measure of link communication quality between radio devices is measured for each relevant link in the network. Alternatively the link definitions can be made from point-to-multipoint devices, and/or multipoint-to-multipoint. Link communication quality preferably includes at least one parameter from a group including reception interference relative to a threshold level, received signal strength indication (RSSI), uncorrected bit or byte error rate (BER), peak cell rate, average cell rate, and cell loss ratio.

Associated with the mesh architecture network of radio devices is a network management system (NMS) that can reconfigure channel linkage paths between the devices. The radio devices communicate the link quality measurement parameter data to the NMS, which preferably maps any or all of these parameters to quality parameters associated with packet traffic being carried. Using various mapping opportunities, the NMS can intelligently command and control channel assignments among the radio devices as needed to promote quality of service (QoS) of packet traffic delivery through the network.

Other features and advantages of the invention will appear from the following description in which the preferred embodiments have been set forth in detail, in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a network system to communicate packets of information between radio devices, according to the prior art;

FIG. 2 is a block diagram of a mesh architecture network system to communicate packets of information between radio devices using link paths that are dynamically selected to maintain quality of transmission, according to the present invention; and

FIG. 3 is a block diagram showing a preferred implementation of a method to carry practice the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Fig. 2 is a block diagram of a mesh architecture network system 100, according to the present invention. Meshed system 100 includes a network 200 of radio devices 30-1, 30-2, ... 30-N that may be interconnected for communication via any combination of links A1, A2 ..., B1, B2, ..., defined between radio devices. Thus if incoming traffic packet is received by device 30-1 , the packet may be routed to radio device 30-N by any combination of path linkages definable between the two devices. The challenge is for NMS 200 to dynamically make the best decision as to which path linkages to use at any given time.

It is seen in Fig. 2 that associated with each point-to-point path linkage is a linkage quality parameter q. Thus path A1 , definable between radio devices 30-1 and 30-2 is characterized by linkage quality parameter qA1. Similarly linkage path A2 is characterized by linkage quality parameter qA2, and so on for every linkage path definable within the mesh architecture network shown.

The various linkage quality parameters q typically vary with time, with atmospheric conditions (which can affect reliability of radio transmission and radio reception), with the transmission and reception characteristics of each radio device, and so forth. Note that qA1 may have one value for transmission from device 30-1 to device 30-2, and another value for transmission from device 30-2 to device 30-1 , since the send-receive characteristics and/or frequencies can differ from device to device.

The value of q preferably is attained from information available at the radio devices defining the end points of the associated linkage path, e.g., devices 30-1 and 30-2 for path A1 and associated quality parameter qAl However q values may be assigned not merely point-to-point paths (e.g., for only path A1 between devices 30-1 , 30-2), but for point-to-multipoint paths (e.g., perhaps path A1 and path C1 from device 30-1 to device 30-6), or for multipoint-to- multipoint paths (e.g., perhaps path A1 , A2, A3 and C1, C5, linking devices 30-1 , 30-3, 30-3, and devices 30-1 , 30-6, 30-11). Under some system operating conditions point-to-point quality information may be sufficient, while other system operating conditions may best be measured otherwise.

Each linkage quality parameter q (be it point-to-point, point-to-multipoint, multipoint-to-multipoint) will take into account at least one factor from a list of several factors. The factor list preferably includes whether interference exceeding a threshold strength is now being received, present received signal strength indication (RSSI), present uncorrected incoming bit or byte error rate (BER) in the traffic flow not accompanied by a drop in RSSI, peak cell rate, average cell rate, and cell loss ratio. Those skilled in the art will recognize that in network 100 or within a given radio device 20, the cell loss ratio is (1- x/y), where y is the number of cells (or packet units) that arrive in an interval at the ingress of the network or radio device, and x is the number of these y cells that leave at the egress of the network or radio device.

The various q data are communicated from the radio devices 30 to NMS 200, preferably wirelessly (as indicated in Fig. 2 by the jagged arrowed line pointing into the NMS. The NMS considers the received q data and will determine how best to define the communications channels or links to best output packets 40' such that network 200 exhibits a preferably high quality of service (QoS). Since the configuration of system 100 preferably is mesh architecture, it can be counterproductive to allow individual radio devices 30

Preferably the NMS maintains at least one set of rules specific to each mesh design for system 100 to guide assignment of a communication channel for new radio link(s) as needed. Typically such assignment is based upon channel location within the mesh network.

Thus by way of example, assume that radio device 30-3 determines that it is presently receiving interference above an acceptable threshold. Under NMS rules, device 30-3 should be taken temporarily out of service. Communication from radio device 30-3 to NMS 200 is preferably wireless (shown in Fig. 2 as a zig-zag arrowed line pointing towards NMS 200), and may be in the form of a simple network management protocol (SNMP) trap. While radio device 30-2 is out-of-service, NMS 200 reroutes packet traffic over other paths within meshed network 200. Preferably radio device 30-3 will use this out-of- service time to evaluate other channels or frequencies and will report a prioritized list of best channels to NMS 200. The NMS evaluates the effect of potential channel changes (e.g., suggested by device 30-3) upon adjacent radio devices within the meshed network. Further, the NMS can determine whether such adjacent radio devices should also change channels to decrease their being affected by a channel change associated with radio 30-3. In this exemplary fashion, NMS 200 can intelligently dynamically reconfigure the packet traffic path through the meshed network such that acceptably good QoS is promoted.

Preferably the NMS causes affected radio devices (e.g., radio device 30-2 in the above example) to go out-of- service sequentially, one at a time, and to locally check alternate channels. The NMS preferably applies an algorithmic method, perhaps linear programming, in its reassignment of channels to the group of affected radio devices to minimize interference to each radio device. Such channel reassignment preferably is implemented wireless by SNMP messages from the NMS to the radio devices, and is denoted in Fig. 2 by the arrowed zig-zag line pointing away from the NMS. Preferably the NMS can also generate reports or the like for use by persons operating network 200 such that sources of the interference may be manually identified and possibly mitigated. Note that the above-described procedure enables a mechanism to deal with point-to-point, point-to-multipoint, and multipoint-to-multipoint link quality within network 200, to avoid bad or congested links, and to ensure good QoS in reliably transporting traffic packets. This level of control is advantageous, especially when compared to prior art approaches that perhaps implement routing algorithms to try and deal only with end-to-end QoS, e.g., from input to output of a network. Asynchronous transfer mode private network node interface (ATM PNNI) protocols can provide mechanisms (e.g., "Hello Protocol") to evaluate link availability and to force routing modification when a link is lost. Such mechanisms can determine the state of a link and can determine changes to ATM specific resource availability information group (RAIG), which includes parameters such as peak cell rate, available cell rate, cell loss ratio, etc..

But in mesh architecture implemented with radio devices, such as exemplified by Fig. 2, changes in radio link performance due to atmospheric conditions, radio interference, and path obstructions will affect the above-noted resource availability parameters. Further such changes can ultimately affect the upstate or down-state of the link itself. Advantageously the ability of the present invention to provide point-to-point measurement parameters (q) offers many other indications, including receive signal strength indication (RSSI) and uncorrected bit error rate (BER). These RSSI and BER parameters can be more efficient indications of link performance than RAIG parameters, and can better contribute to enhanced QoS. In Fig. 3, method step 400 includes the providing of such link quality measurement parameter(s) to NMS 200.

As shown in Fig. 2, preferably within NMS 200 mappings occur in which at least one of such proxy indications (e.g., RSSI, BER) is mapped into the RAIG information. The mapping preferably can use deterministic mechanisms appropriate to the equipment implementing the various radio devices 30. For example, an uncorrected BER value may be mapped to the cell loss ratio (CLR) component of the RAIG. Such mapping would have the effect of forcing traffic for which CLR might be important off one link and through other parts of the network. Although CLR may not be the most ideal metric for errored cells, in practice CLR can be a good proxy metric to more efficiently route traffic cells through appropriate link paths within network 200. In Fig. 3, method step 410 depicts generically such mapping(s).

Further, hysteresis can be added to the algorithm used to implement mapping. The result can be a smoothing out of time variations in the performance of radio devices 30 such that excessive numbers of RAIG updates (PNNI topology state elements) are not exchanged.

At least one mechanism to map radio device specific elements to the ATM RAIG elements preferably is implemented using at least one of SNMP, common management information protocol (CMIP), or common object broker architecture (COBRA) management information bases (MIBs) associated with the hardware used to implement radio devices 30 and their associated device switches.

Preferably using such mechanisms, part of the switch control software associated with the radio devices will periodically examine the radio device MIB. Link quality parameter indications such as RSSI and BER can then be mapped into the RAIG parameters in the PNNI MIB. In this fashion, NMS 200 can force an update to the link configuration or topology of network 200. Consider now an example of IP traffic carried over the radio device links in network 200. In this example, radio device specific elements can be mapped into at least one of the multiprotocol label switching (MPLS) field, the differentiated services (DiffServ) field, the resource reservation protocol (RSVP) field, or the call admission control (CAC) field in the mapping algorithm. In a more advanced embodiment that can provide a third generation universal mobile telecommunications system (UMTS) radio network, the radio access bearer QoS parameters communicated by the RNC could be modified based upon radio link information. As shown in Fig. 3 by method step 420, NMS 200 can intelligently command network 200 to reconfigure as needed to promote good QoS throughout the network. As noted, reconfiguration decisions are intelligently made not merely on an end-to-end basis as in the prior art, but based upon point-to-point, point- to-multipoint, and/or multipoint-to-multipoint quality parameters.

Although the preferred embodiments have been described with respect to a meshed network of wireless point-to-point devices, it will be appreciated that the present invention could also be implemented using fiber optic or other transport links as well.

Modifications and variations may be made to the disclosed embodiments without departing from the subject and spirit of the invention as defined by the following claims.

Claims

WHAT IS CLAIMED IS:

1. A communication system to carry packet traffic, comprising: a plurality of radio devices configurable in a network to carry said packet traffic from at least a first of said devices to at least a second of said devices via traffic links definable between said devices; means for defining at least one link quality measurement parameter for at least some of said traffic links in said network; means for mapping at least one said link quality measurement parameter to a quality parameter associated with said packet traffic carried by said network; and means, coupled to said means for mapping, for reconfiguring at least one of said traffic links to promote quality of carrying of said packet traffic through said network.

2. The communication system of claim 1, wherein said network is configured as a mesh architecture.

3. The communication system of claim 1 , wherein at least one said link quality measurement parameter is associated with a link selected from a group consisting of (a) a link defined point-to-point between two of said devices, (b) a link defined point-to-multipoint between several of said devices, and (c) a link defined multipoint-to-multipoint between several of said devices.

4. The communication system of claim 1 , wherein at least one of said means for mapping and said means for reconfiguring includes a network management system.

5. The communication system of claim 1 , wherein said link quality measurement parameter includes at least one parameter selected from a group consisting of (a) reception interference relative to a threshold level, (b) received signal strength indication, (c) uncorrected bit error rate, (d) peak packet traffic cell rate, (e) average packet traffic cell rate, and (f) packet traffic cell loss ratio.

6. The communication system of claim 1 , wherein said means for mapping maps at least one proxy indicator associated with said link quality measurement parameter into at least one resource availability information group parameter.

7. The communication system of claim 1 , wherein said means for mapping provides hysteresis to smooth-out time variations in measured performance of said radio devices.

8. The communication system of claim 1 , wherein information carried via said traffic links has at least one protocol selected from a group consisting of (a) asynchronous transfer mode protocol, (b) asynchronous transfer mode private network node interface protocol, and (c) an IP protocol.

9. The communication system of claim 8, wherein said means for mapping maps at least one said link quality measurement parameters into a parameter associated with a said asynchronous transfer mode protocol.

10. The communication system of claim 8, wherein said means for mapping maps appropriate to said radio devices in at least one manner selected from a group consisting of (a) mapping is deterministic, (b) mapping is into a multiprotocol label switching field, (c) mapping is into a differentiated services field, (d) mapping is into a resource reservation protocol field, (e) mapping is into a call admission control field, (f) mapping is via management information bases associated with said radio devices, (g) mapping is into an asynchronous transfer mode private network node interface protocol via simple network management protocol management, (h) mapping is communicated with a simple network management protocol, (I) mapping is communicated with a common management information protocol, and G) mapping is carried out using common object broker architecture management information bases.

11. A method to improve quality of service through a communication system that includes a plurality of radio devices configurable in a network to carry packet traffic from at least a first of said devices to at least a second of said devices via traffic links definable between said devices, the method comprising the following steps:

(a) defining at least one link quality measurement parameter for at least some of said traffic links in said network;

(b) mapping at least one said link quality measurement parameter to a quality parameter associated with said packet traffic carried by said network; and

(c) reconfiguring at least one of said traffic links to promote quality of carrying of said packet traffic through said network.

12. The method of claim 11 , wherein said network is configured as a mesh architecture, and wherein at step (a) said link quality measurement parameter includes at least one of (I) a parameter associated with a link defined point-to-point between two of said devices, (ii) a parameter associated with a link defined point-to-multipoint between several of said devices, and (iii) a parameter associated with a link defined multipoint-to-multipoint between several of said devices.

13. The method of claim 11 , wherein at least one of step (b) and step (c) is controlled by a network management system.

14. The method of claim 11 , wherein at step (a) said link quality measurement parameter includes at least one parameter selected from a group consisting of (I) reception interference relative to a threshold level, (ii) received signal strength indication, (iii) uncorrected bit error rate, (iv) peak packet traffic cell rate, (v) average packet traffic cell rate, and (vi) packet traffic cell loss ratio.

15. The method of claim 11 , wherein step (b) includes mapping at least one proxy indicator associated with said link quality measurement parameter into at least one resource availability information group parameter.

16. The method of claim 11 , wherein step (b) includes smoothing-out variations in measured performance of said radio devices.

17. The method of claim 11 , wherein information carried via said traffic links has at least one protocol selected from a group consisting of (I) asynchronous transfer mode protocol, (ii) asynchronous transfer mode private network node interface protocol, and (iii) an IP protocol.

18. The method of claim 11 , wherein step (b) includes mapping appropriate to said radio devices in at least one manner selected from a group consisting of a) mapping is deterministic, (b) mapping is into a multiprotocol label switching field, (c) mapping is into a differentiated services field, (d) mapping is into a resource reservation protocol field, (e) mapping is into a call admission control field, (f) mapping is via management information bases associated with said radio devices, (g) mapping is into an asynchronous transfer mode private network node interface protocol via simple network management protocol management, (h) mapping is communicated with a simple network management protocol, (I) mapping is communicated with a common management information protocol, and (j) mapping is carried out using common object broker architecture management information bases.

19. The method of claim 11 , wherein said network carries third generation radio access bearer traffic.

20. The method of claim 11 , wherein said method is on-going such that said network can be dynamically continuously reconfigured as needed.