WO2002023829A1

WO2002023829A1 - Telecommunications networks and methods

Info

Publication number: WO2002023829A1
Application number: PCT/GB2001/004058
Authority: WO
Inventors: Keith Edward Mayes; Rajadurai Vijithan; Arulalingam Arulkkumaran; Alan Law
Original assignee: Vodafone Group Plc
Priority date: 2000-09-12
Filing date: 2001-09-10
Publication date: 2002-03-21
Also published as: AU2001286068A1; GB2367208A; GB2367208B; DE60133397T2; GB2366951B; DE60133397D1; GB0025910D0; GB2366951A; GB0022335D0

Abstract

A multi-hop wireless network for transmitting data packets between a concentration point (CP) and one of a plurality of radio transceiving nodes (e.g. R1...R6, Y1...Y4) is described. Each node is allocated to a particular region which is spatially positioned relative to the concentration point (CP) such as a base station. The allocation of each node to a particular region may be carried out according to the distance of thenode from the concentration point (CP), by distance measurements carried out by the node itself or by the concentration point (CP), or may be allocated according to its allocated region. Data transmission, for data to be transmitted from a particular node to the concentration point (CP) or in the reverse direction, is carried out according to predetermined rules, and in accordance with these rules each node receiving data for onward transmission may be constrained to transmit the data only to a node in the adjacent region.

Description

TELECOMMUNICATION NETWORKS AND METHODS

The invention relates to a method for routeing data in a wireless network for transmission

between two spaced radio transceiving nodes in the network, one of the nodes being a

concentration point and the other node being a selectable one of a plurality of the ^"nodes

spatially positioned with reference to the concentration point, by means of a plurality of

hops involving at least one intermediate one of the nodes. The invention also relates to

a wireless telecommunication network, comprising a plurality of radio transceiving nodes,

and routeing means for routeing data for transmission between two of the nodes one of

which is a concentration point in the network and the other of which is a selectable one

of a plurality of the nodes spatially positioned with reference to the concentration point,

the routeing means routeing the data between the two nodes by the means of a plurality

of hops involving at least one intermediate one of the nodes.

Such a method and such a network are shown for example in GB-A-2 291 564. In this

method and network, transmission between a mobile terminal and a base station can take

place via a second mobile terminal if the first mobile terminal is out of range of the base

station, the selection of the second mobile station being carried out using measurements

of signal level at the time of transmission.

According to the invention, the method as first set forth above is characterised in that before the transmission each node is allocated to a particular one of a plurality of regions

which are differently spatially positioned relative to the concentration point, and in that

at least one of the hops is constrained to start in one of the regions and end in another of

the regions.

According to the invention, also, the network as first set forth above is characterised by

means operative before the transmission to allocate each of the nodes to a particular one

of a plurality of regions which are differently spatially positioned relative to the

concentration point, and constraining means for constraining at least one of the hops to

start in one of the regions and end in another of the regions.

Telecommunication networks and methods according to the invention will now be

described, by way of example only, with reference to the accompanying diagrammatic

drawings in which:

Figure 1 shows one of the networks;

Figure 2 shows part of a node or mobile terminal in the network of Figure 1; and

Figure 3 shows part of a concentration point or base station in the networks of Figure 1.

The telecommunication network to be described is in the form of a wireless network, which may be a cellular network, in which packet data is transmitted from a source node

in the network to a destination node. The network comprises one node in the form of a

concentration or inner point which may be a base station, and a plurality of other nodes

spaced away from and around the concentration point. The nodes may be radio

transceivers of any suitable type. The nodes spaced around the concentration point may,

for example, be represented by mobile terminals such as cellular telephone handsets. The

source node may be any of the distributed nodes in the network and the destination node

is then the base station or concentration point. Instead, however, the concentration point

may be the source node, transmitting data to a destination node comprising one of the

hand sets. Data is transmitted by hopping - that is, data is communicated between the

source node and the destination node in a series of hops, in which the data is received by

an intermediate node and then transmitted to another node, this process continuing until

the data reaches the destination node. Such a hopping technique minimises the

transmission power required and thus reduces the possibility of radio interference - as

compared with an attempt to transmit the data between source and destination nodes in

a single transmission.

In such a multi-hop network, however, it is necessary to provide a mechanism by which

each node selects the next node in the transmission path so as to maximise efficiency of

data transmission - thus ensuring that each hop carries the data forward to the destination

node in the most efficient direction. For example, if a node simply transmits the data to

the intermediate node nearest to it, a very large number of nodes in the network may be involved in the data transmission path to the destination node, considerable increasing the

traffic density in the network and reducing its capacity and without necessarily

transmitting the data quickly and efficiently.

In accordance with the invention, each node is allocated to a respective region, the regions

being spatially arranged with respect to each other. Each region may contain a plurality

of the nodes. Each region is given an individual identity (for example, the regions can be

colour-coded so that there is a "red" region, a "yellow" region and a "green" region). Each

node is given a "tag" which identifies the region to which it belongs. Thus, in the

example being considered, each node will be given a red, yellow or green tag. The

regions are spatially arranged with respect to the concentration point or base station so

that a first region includes the concentration point and the other regions are successively

spaced at greater distances from the first region. For example, the regions may be

arranged so that each one embraces or surrounds the next region nearer to the

concentration point. As a specific example of this arrangement, the regions can be

concentric. The regions are normally contiguous.

When the regions have been set up in this way, so that each node has been tagged

according to the region in which it is situated, it is then possible to set up rules to control

the transmission of data within the network. More specifically, for example, a node in a

particular region may be arranged to have data communication only with a node in the

next adjacent region - thus excluding communication with another node in the same region or with a node in a region spaced beyond the adjacent region. In this way, data

transmission in the network can be expedited.

Figure 1 shows a network arranged into three regions; a green region 1, a yellow region

2 and a red region 3. Region 1 contains the concentration point (CP) or base station.

Regions 2 and 3 are arranged successively and concentrically around region 1. Such a

concentric arrangement is shown by way of example only. The regions could have any

suitable shape. In this example, the radius or effective size of the regions increases as

their distance from the CP increases.

The CP is always involved in data transmission. Messages may or may not be intended

for the CP or may or may not be originated by the CP but in general they always pass

through the CP.

The Figure shows a node Gl in the green region 1, nodes Y1,Y2,Y3,Y4 in the yellow

region 2, and nodes R1,R2,R3,R4,R5 and R6 in the red region 3. There may, of course,

be many more nodes.

As will be described in more detail below, when data is to be transmitted from a node in

the red region 3 to the CP in region 1 , the source node in the red region 3 will transmit the

data in a first hop to a node in the yellow region 2 which will then in turn transmit the

data in a second hop to the CP in region 1. Similarly, when data is to be transmitted from the CP to a node in the red region 3, the CP will transmit the data in the first hop to a node

in the yellow region 2 which will then transmit the data in the second hop to the

destination node in the region 3.

In order for the system to operate, it is necessary initially for each node to be assigned to,

or to assign itself to, a particular one of the regions. This assignment process can be

carried out in several different ways.

(a) The node can determine its own spatial position relative to the CP or base

station and can then assign itself to a particular region.

(b) The CP can determine the relative positions of the individual nodes and

then assign them to particular regions.

Each node can determine its own position relative to the CP in a number of different

ways. For example, as shown in Figure 2, it can comprise allocating means 10 which

transmits a signal to the CP and determines its distance from the CP from a reply signal

returned by the CP (assuming a particular radio path loss model). Instead, it can

determine its distance from the CP by utilising broadcast transmissions from the CP

(again assuming a particular radio path loss model). Another possibility is for each node

to use an external method to determine its position e.g. using GPS signals.

Figure 3 shows how the CP can contain allocating means 12 which transmits signals to / all the nodes and receives reply signals from which it determines their respective

distances from itself (again assuming a particular radio path loss model). In this way, it

allocates the nodes to their respective regions.

The sizes, shapes, and relative spatial positions of the regions need not be constant. For

example, they can be changed or modified dynamically, and the tags on the individual

nodes altered accordingly, in accordance with changing interference patterns.

Although the regions are located spatially with respect to each other, they need not be

geographically fixed; for example, they could be regions within a moving environment

such as on a train or ship.

Each node may be capable of fransndtting information to, and receiving information from,

all the nodes in the same region and at least one other node in the neighbouring region.

Figure 2 shows how each node includes hop constraining means 11 which controls how

the node transmits data to the next node.

If a node finds that it cannot transmit data to a node in the next region, it will then

transmit to a node in the same region. It can select this node according to a number of

different possible rules. It may simply transmit to the closest node. If that node can then

successfully dispose of the data (by transmitting to the next region or, possibly, by transmitting to another node in the same region if transmission to the next region is not

possible), then the originating node will have completed its task. However, if the node

receiving the data from the originating node cannot successfully transmit the data to an

onward node, it will inform the originating node which will then attempt transmission via

another node. Such an arrangement is more satisfactory than arrangements in which the

originating node sends out data indiscriminately.

There may be one or more dedicated nodes in each region for receiving data from another

region and for onward-transmitting it. Alternatively, a node in one region could select a

particular node in the next region to receive transmissions, such as in accordance with

information previously transmitted to it. Another possibility would be for a node in one

region to broadcast-transmit to all the nodes in the next region, the first one in the second

region to transmit the data to the next region disabling transmission from the others.

Preferably, the sizes of the regions decrease in the direction towards the CP. This ensures

that the lengths of the hops decrease for data transmitted towards the CP and increase for

data transmitted away from the CP. This is advantageous because it optimises the

capacity in the network.

In a more specific example, a frequency division duplex (FDD) system can be used for

routeing packets between source and destination nodes in the network. An FDD system

requires the use of two different RF carriers, at one frequency for transmitting data and at a second frequency for receiving data. By alternating the transmitting frequencies for

the successively arranged regions, and similarly alternating the receiving frequencies for

the successively arranged regions, it can be ensured that each node can only transmit data

to a node in the next region. For example, the respective transmitting and receiving

carrier frequencies can be arranged in the following way:-

If data is to be transmitted from a source node in the red region 3 to the CP in the green

region 1, it will be initially transmitted at frequency fl. It therefore cannot be received

by any of the other nodes in the red region 3 but will be received by a particular node in

the yellow region 2 - because the nodes in this region have fl as their receiving frequency.

The node in the yellow region 2 which receives the data then re-transmits it with- the

transmitting frequency £2 so that it will be received by the CP in the green region 1 which

has receiving frequency f2.

Other transmission and receiving systems (e.g. TDD) can be used instead of FDD, of

course. The particular transmission/receiving system does not control the routeing of

data. The nodes in different regions may be arranged to provide different services - for

example, all the nodes in the red region 3 could have a higher data rate.

Claims

1. A method for routeing data in a wireless network for transmission between two

spaced radio transceiving nodes in the network, one of the nodes being a concentration

point (CP) and the other node being a selectable one of a plurality of the nodes (G1,Y1...,

RI...) spatially positioned with reference to the concentration point (CP), by means of a

plurality of hops involving at least one intermediate one of the nodes (G1,Y1..., RI...),

characterised in that before the transmission each node (G1,Y1..., RI ...) is allocated to a

particular one of a plurality of regions (1,2,3) which are differently spatially positioned

relative to the concentration point (CP), and in that at least one of the hops is constrained

to start in one of the regions (1,2,3) and end in another of the regions (1,2,3).

2. A method according to claim 1 , characterised in that the or each constrained hop

is a hop from one region (1,2,3) to the adjacent spatially positioned region (1,2,3).

3. A method according to claim 2, characterised in that the regions (1,2,3) are

successively spaced further away from the concentration point (CP).

4. A method according to claim 3, characterised in that there are at least two regions

(2,3) spaced outwardly of the region (1) containing the concentration point (CP), the first

one (2) of these embracing the region (1) containing the concentration point (CP) and the

second one (3) embracing the first region (2).

5. A method according to claim 4, characterised in that the regions (1,2,3) are

arranged concentrically.

6. A method according to any preceding claim, characterised in that each node

(G1,Y1..., RI...) itself determines its region (1,2,3).

7. A method according to claim 6, characterised in that each node (G1,Y1..., RI...)

determines its region (1,2,3) by exchanging signals with the concentration point (CP)

and/or others of the nodes (1,2,3).

8. A method according to claim 6, characterised in that each node (G1,Y1..., RI...)

determines its region (1,2,3) by reference to signals from outside the network, such as

GPS signals.

9. A method according to any one of claims 1 to 5, characterised in that the

concentration point (CP) determines the position of the respective nodes (G1,Y1..., RI...)

and itself allocates them to particular ones of the regions (1,2,3) itself.

10. A method according to any preceding claim, characterised in that the sizes of the

regions (1,2,3) are allocated and changed dynamically.

11. A method according to any preceding claim, characterised in that data is

transmitted and received using a frequency division duplex system in which the

transmitting and receiving carrier frequencies for a node (G1,Y1..., RI...) in one of the

regions (1,2,3) are the same as the receiving and transmitting carrier frequencies,

respectively, for a node (G1,Y1..., RI...) in the adjacent region (1,2,3).

12. A method according to any preceding claim, characterised in that the length of a

constrained hop closer to the concentration point (CP) is less than the length of a

constrained hop further from the concentration point (CP).

13. A wireless telecommunication network, comprising a plurality of radio

transceiving nodes A, and routeing means for routeing data for transmission between two

of the nodes (Gl ,Y1...., RI ....) one of which is a concentration point (CP) in the network

and the other of which is a selectable one of a plurality of the nodes (Gl ,Y1...., RI ....)

spatially positioned with reference to the concentration point (CP), the routeing means

routeing the data between the two nodes (Gl ,Y1...., RI ....) by the means of a plurality

of hops involving at least one intermediate one of the nodes (G1,Y1....₅ RI....),

characterised by means operative before the transmission to allocate each of the nodes

(G1,Y1...., RI ....) to a particular one of a plurality of regions (1,2,3) which are

differently spatially positioned relative to the concentration point (CP), and constraining

means for constraining at least one of the hops to start in one of the regions (1,2,3) and

end in another of the regions (1,2,3).

14. A network according to claim 13, characterised in that the constraining means

constrains the or each constrained hop to be a hop from one region (1,2,3) to the adjacent

region (1,2,3).

15. A network according to claim 14, characterised in that the regions (1,2,3) are

successively spaced further away from the concenfration point (CP).

16. A network according to claim 15, characterised in that there are at least two

regions (1,2,3) spaced outwardly of the region (1) containing the concentration point

(CP), the first one (2) of these embracing the region (1) containing the concentration point

(CP) and the second one (3) embracing the first region (2).

17. A network according to claim 16, characterised in that the regions (1,2,3) are

arranged concentrically.

18. A network according to any one of claims 13 to 17, characterised in that each node

(G1,Y1...., RI....) comprises means for allocating itself to its region (1,2,3).

19. A network according to claim 18, characterised in that each node (G1,Y1....,

RI ....) allocates itself to its region (1,2,3) by exchanging signals with the concentration

point (CP) and/or others of the nodes (Gl ,Y1...., RI ....).

20. A network according to claim 18, characterised in that each node (G1,Y1....,

RI ....) allocates itself to its region (1,2,3) by reference to signals from outside the

network, such as GPS signals.

21. A network according to any one of claims 13 to 17, characterised in that the

concenfration point (CP) includes means for determining the position of the respective

nodes (G1,Y1...., RI ....) and allocating them to particular ones of the regions (1,2,3)

itself.

22. A network according to any one of claims 13 to 21, characterised in that data is

transmitted and received using a frequency division duplex system in which the

transmitting and receiving carrier frequencies for a node (G1,Y1...., RI ....) in one of the

respectively, for a node (Gl ,Y1...., RI ....) in the adjacent region (1 ,2,3).

23. A network according to any other one of claims 13 to 22, characterised in that the

length of a constrained hop closer to the concentration point (CP) is less than the length

of a constrained hop further from the concentration point (CP).