WO2016093749A1

WO2016093749A1 - Routing in wireless ad-hoc networks

Info

Publication number: WO2016093749A1
Application number: PCT/SE2014/051471
Authority: WO
Inventors: Petri Jokela; Ari KERÄNEN
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2014-12-09
Filing date: 2014-12-09
Publication date: 2016-06-16

Abstract

There is provided a method for enabling routing in a wireless ad-hoc network. The method is performed by a gateway. The method comprises broadcasting radio signalling to nodes in the wireless ad-hoc network for collecting path information from the gateway to the nodes. The method comprises receiving radio signalling from at least one of the nodes, wherein the received radio signalling comprises an in-packet Bloom Filter representation identifying paths to at least two of the nodes, the at least two nodes thereby becoming routable. There is also presented such a gateway. There is further presented a method for enabling routing in a wireless ad-hoc network as performed by anode, such a node, and computer programs.

Description

ROUTING IN WIRELESS AD-HOC NETWORKS

TECHNICAL FIELD

Embodiments presented herein relate to wireless ad-hoc networks, and particularly to methods, a gateway, a node, computer programs, and a computer program product for routing in wireless ad-hoc networks.

BACKGROUND

In communications networks, there may be a challenge to obtain good performance and capacity for a given communications protocol, its parameters and the physical environment in which the communications network is deployed.

For example, one example of an approach for communications in

communications networks is information-centric networking (ICN). ICN may be regarded as an approach to evolve the Internet infrastructure away from a host-centric paradigm based on perpetual connectivity and the end-to-end principle, to a network architecture in which the focal point is so-called named information (or named content or named data). In this paradigm, connectivity may well be intermittent, end-host and in-network storage can be capitalized upon transparently, as bits in the network and on storage devices have exactly the same value, mobility and multi access are the norm and anycast, multicast, and broadcast are natively supported.

The ICN paradigm thus instead of being based on addressing hosts relies on addressing information and further introduces a concept of scopes. Thereby, instead of defining addresses and paths to resources, hierarchies of scopes and resources within those scopes can be defined. The resources are then allowed to be addressed without the need to define server(s) where those resources are hosted. A simple example of an ICN scope would be lights of a room in a house. These can, for example, be presented as a scope

"house:kitchen:lights" or "house:livingroom:lights". A single resource, say "lighti", may also belong to multiple scopes, e.g.: "house:groundfloor:lighti" and "house:kitchen:lighti". The ICN rendezvous layer will translate the scopes into instructions for the forwarding layer that will in turn forward the queries for a resource to the correct server.

One common way to implement the forwarding layer instructions is called in- packet Bloom Filters (iBFs). In general terms, a Bloom filter is a space- efficient probabilistic data structure that is used to test whether an element is a member of a set or not. With IBFs the rendezvous system combines all link IDs (LIDs) needed to reach the correct host(s) into a Bloom filter that is attached to the packet that is to be forwarded in the ICN network.

The application of in-packet Bloom filters in communications networks is as such known in the art. In general terms, iBF packet forwarding is based on unidirectional LIDs that identify an outgoing link from a node. A set of LIDs are compressed into a Bloom filter to identify a path through the network. A LID is meaningful only at the node, where it is configured on an outgoing interface. The connection technology in the communications networks may be wired or wireless. In general terms, wireless networks may be regarded as easier to physically setup, but the packet routing in wireless network may be more complicated than in wired networks.

The wireless networks may be an ad-hoc network. Routing in such ad-hoc networks may be cumbersome. In general terms, network configuration and routes in ad-hoc networks may change often and the routing information in the nodes may require constant updating. When Internet protocol (IP) based routing is used in ad-hoc networks, middle router routing information must be constantly updated. Current protocols (such as the Open Shortest Path First (OSPF) routing protocol, and the Intermediate System to Intermediate System (IS-IS) routing protocol) are not designed for this kind of fast updates.

Hence, there is a need for improved routing in wireless ad-hoc networks. SUMMARY

An object of embodiments herein is to provide efficient routing in wireless ad-hoc networks.

According to a first aspect there is presented a method for enabling routing in a wireless ad-hoc network. The method is performed by a gateway. The method comprises broadcasting radio signalling to nodes in the wireless ad- hoc network for collecting path information from the gateway to the nodes. The method comprises receiving radio signalling from at least one of the nodes, wherein the received radio signalling comprises an in-packet Bloom Filter (iBF) representation identifying paths to at least two of the nodes, the at least two nodes thereby becoming routable.

Advantageously, this provides efficient routing in wireless ad-hoc networks.

Advantageously, this provides automatic detection of changes in routes and enables new source-routed forwarding paths for packet delivery to be created. Advantageously, changes in network topology do not require changes in routing of the nodes.

Advantageously this supports multicast transmission from the gateway to a set of receiving nodes.

Advantageously, this allows replacing MAC and IP layer addresses with iBF representations acting as more efficient addresses, thus saving addressing overhead. Advantageously, since neither MAC addresses nor network layer addresses are needed, the addressing overhead may be smaller than with traditional addressing (for example depending on the size of the used iBF representations). This is may be particularly advantageous in constrained networks (e.g., IEEE 802.15.4, as developed by the Institute of Electrical and Electronics Engineers (IEEE) Standards Association (IEEE-SA)) where the maximum packet sizes are only around 100 bytes.

According to a second aspect there is presented a gateway for enabling routing in a wireless ad-hoc network. The gateway comprises a processing unit. The processing unit is configured to broadcast radio signalling to nodes in the wireless ad-hoc network for collecting path information from the gateway to the nodes. The processing unit is configured to receive radio signalling from at least one of the nodes, wherein the received radio signalling comprises an in-packet Bloom Filter (iBF) representation identifying paths to at least two of the nodes, the at least two nodes thereby becoming routable.

According to a third aspect there is presented a computer program for enabling routing in a wireless ad-hoc network, the computer program comprising computer program code which, when run on a processing unit of a gateway, causes the processing unit to perform a method according to the first aspect.

According to a fourth aspect there is presented a method for enabling routing in a wireless ad-hoc network. The method is performed by a node in the wireless ad-hoc network. The method comprises receiving radio signalling for collecting path information from a gateway in the wireless ad-hoc network to the node. The method comprises transmitting radio signalling comprising an in-packet Bloom Filter (iBF) representation identifying a path to the node towards the gateway, the node thereby becoming routable. Advantageously, when the node acts as a forwarder, it does not need to maintain any routing tables or other forwarding state. The node may compare an identifier of its own with the iBF representation in an incoming packet and make a forwarding (re-transmission) decision based on the matching between the identifier and the iBF representation. According to a fifth aspect there is presented a node for enabling routing in a wireless ad-hoc network. The node comprises a processing unit. The processing unit is configured to receive radio signalling for collecting path information from a gateway in the wireless ad-hoc network to the node. The processing unit is configured to transmit radio signalling comprising an in- packet Bloom Filter (iBF) representation identifying a path to the node towards the gateway, the node thereby becoming routable.

According to a sixth aspect there is presented a computer program for enabling routing in a wireless ad-hoc network, the computer program comprising computer program code which, when run on a processing unit of a node, causes the processing unit to perform a method according to the fourth aspect.

According to a seventh aspect there is presented a computer program product comprising a computer program according to at least one of the third aspect and the sixth aspect and a computer readable means on which the computer program is stored.

It is to be noted that any feature of the first, second, third, fourth, fifth, sixth and seventh aspects may be applied to any other aspect, wherever

appropriate. Likewise, any advantage of the first aspect may equally apply to the second, third, fourth, fifth, sixth, and/or seventh aspect, respectively, and vice versa. Other objectives, features and advantages of the enclosed embodiments will be apparent from the following detailed disclosure, from the attached dependent claims as well as from the drawings.

Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the element, apparatus, component, means, step, etc." are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

BRIEF DESCRIPTION OF THE DRAWINGS

The inventive concept is now described, by way of example, with reference to the accompanying drawings, in which: Fig. l is a schematic diagram illustrating a communication network according to embodiments;

Fig. 2a is a schematic diagram showing functional units of a gateway according to an embodiment; Fig. 2b is a schematic diagram showing functional modules of a gateway according to an embodiment;

Fig. 3a is a schematic diagram showing functional units of a node according to an embodiment;

Fig. 3b is a schematic diagram showing functional modules of a node according to an embodiment;

Fig. 4 shows one example of a computer program product comprising computer readable means according to an embodiment;

Figs. 5, 6, 7, and 8 are flowcharts of methods according to embodiments;

Fig. 9 is a schematic illustration of collection of path information according to embodiments;

Fig. 10 is a schematic illustration of matching an identifier to an iBF representation according to embodiments;

Figs. 11(a) and 11(b) are schematic illustrations of packets according to embodiments. DETAILED DESCRIPTION

The inventive concept will now be described more fully hereinafter with reference to the accompanying drawings, in which certain embodiments of the inventive concept are shown. This inventive concept may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the inventive concept to those skilled in the art. Like numbers refer to like elements throughout the description. Any step or feature illustrated by dashed lines should be regarded as optional.

Fig. l is a schematic diagram illustrating a wireless ad-hoc network 10 where embodiments presented herein can be applied. The wireless ad-hoc network to comprises nodes 12a, 12b, 12c, i2d, i2e. Each node i2a-e is configured to transmit and receive signals within a respective coverage region 13a, 13b, 13c, 13d, i3e. Each node i2a-e may be a portable wireless device, such as an Internet-of-Things (IoT) device. The nodes i2a-e may be operatively connected in an ICN network. The ICN network is defined by the coverage regions i3a-e of the nodes i2a-e. In turn, at least one of the nodes i2a-e is operatively connected to an (optional) service network 15 via a gateway 11. The gateway 11 has a coverage region I3f. A Domain Name System (DNS) server 14 (optional), an IP host 16 (optional), which may be an IP node, are also operatively connected to the service network 15. By means of the gateway 11, communication and exchange of data may occur between the nodes i2a-e and the IP host 16. The service network 15 may be an IP network, such as the Internet.

In the ICN network, the nodes i2a-e are addressed by means of iBF representations. Such iBF representations may be provided either for a l-to-i connection (i.e. between the gateway 11 and a node i2a-e in the ICN network) or for a i-to-many connection (i.e. between the gateway 11 and a set of at least two nodes I2a-e in the ICN network). The first type of iBF representations may be used for normal connection between two nodes, and the latter for multicasting traffic to the nodes in the ICN network. It is assume that the ICN network forms a wireless ad-hoc network. The routing in the wireless ad-hoc network utilizes in-packet Bloom Filters (iBFs) instead of traditional media access control (MAC) and network layer identifiers (i.e., MAC and IP addresses). Forwarding Entity Identifiers (FEId; i.e., identity of the node i2a-e) are used because, in general terms, there are no dedicated node-to-node links in the wireless ad-hoc network; all transmissions are (potentially) received by all nodes i2a-e within a certain radio range i3a-e.

At the nodes i2a-e the FEId of the node i2a-e is matched to the arriving packet's iBF when the packet arrives and the nodes i2a-e make a decision if the packet should be processed in this node and/or re-sent out from this node i2a-e. Further details relating thereto will be disclosed below.

Each iBF representation may be an m-bits long bit string. Each FEId may also be m bits long, where k bits have been set to one. The values of m and k can be selected based on properties of the wireless ad-hoc network.

According to one non-limiting example, m=i28, and k=4.

Each node I2a-e may be associated with n FEIds; FEId[o]... FEId[n-i]. Each packet may have a d-value. When the forwarding decision is made at the node i2a-e, the d-value in the packet is used as an index to select the FEId to be used in verification. If the FEId of the node I2a-e (where the FEId has been identified using the d-value of the packet) matches the iBF representation in the packet, the node i2a-e increases the d-value in the packet by one (mod n) and transmits out the packet. Further details relating thereto will be disclosed below.

One purpose of using multiple FEIds is that the forwarded data packet is not forwarded out from the same node i2a-e when the packet is "bouncing back" from the previous node (e.g., first transmitted from node 12a to node I2d and then back from node i2d to node 12a). That is, when node a sends the packet out and it reaches node b, where the iBF matches the FEId, node b will send the packet further out. Because the nodes transmit packets wirelessly, the packet will again reach node a. Now, if only a single FEId is used by the nodes, it would again match the FEId of node a and the packet would again be transmitted out from node a. This is not desirable since it would create a routing loop. If FEIds with e.g. n=8 are used, the d field in the packet header (i.e., the field in the packet that comprises the d-value) is incremented by one (mod 8) on each hop. Thus, if d = 2 when the packet arrives at node a, the packet will be compared with FEId[2] of node a. If this matches the iBF, node a transmits the packet out with d=3. Node b verifies if FEId[3] is included in the iBF representation, and transmits the packet out with d=4 if a match is found. Now, when the packet arrives at node a (since node a is still within the range of node b), node a will attempt to match the iBF representation with FEId[4] since d=4, but FEId[4] was not included in the iBF representation. Thus, node a will drop the packet and avoid a forwarding loop. Further details relating thereto will be disclosed below.

The embodiments disclosed herein thus relate to enabling routing in a wireless ad-hoc network 10. In order to obtain such routing there is provided a gateway n, a method performed by the gateway na computer program comprising code, for example in the form of a computer program product, that when run on a processing unit of the gateway n causes the processing unit to perform the method. In order to obtain such routing there is further provided a node i2a-e, a method performed by the i2a-e, and a computer program comprising code, for example in the form of a computer program product, that when run on a processing unit of the i2a-e, causes the processing unit to perform the method.

Fig. 2a schematically illustrates, in terms of a number of functional units, the components of a gateway 11 according to an embodiment. A processing unit 21 is provided using any combination of one or more of a suitable central processing unit (CPU), multiprocessor, microcontroller, digital signal processor (DSP), application specific integrated circuit (ASIC), field programmable gate arrays (FPGA) etc., capable of executing software instructions stored in a computer program product 41a (as in Fig. 4), e.g. in the form of a storage medium 23. Thus the processing unit 21 is thereby arranged to execute methods as herein disclosed. The storage medium 23 may also comprise persistent storage, which, for example, can be any single one or combination of magnetic memory, optical memory, solid state memory or even remotely mounted memory. The gateway 11 may further comprise a communications interface 22 for communications with at least one node i2a-e and entities of, and operatively connected to, the service network 15. As such the communications interface 22 may comprise one or more transmitters and receivers, comprising analogue and digital

components and a suitable number of antennas for radio communications and ports for wireline communications. The processing unit 21 controls the general operation of the gateway 11 e.g. by sending data and control signals to the communications interface 22 and the storage medium 23, by receiving data and reports from the communications interface 22, and by retrieving data and instructions from the storage medium 23. Other components, as well as the related functionality, of the gateway 11 are omitted in order not to obscure the concepts presented herein.

Fig. 2b schematically illustrates, in terms of a number of functional modules, the components of a gateway 11 according to an embodiment. The gateway 11 of Fig. 2b comprises a number of functional modules; such as a transmit and/or receive module 21a configured to perform below steps S102, S104, S110. The gateway 11 of Fig. 2b may further comprises a number of optional functional modules, such as any of a repeat module 21b configured to perform below step S112, a store module 21c configured to perform below step S06, and a retrieve module 2id configured to perform below step S108. The functionality of each functional module 2ia-d will be further disclosed below in the context of which the functional modules 2ia-d may be used. In general terms, each functional module 2ia-d may be implemented in hardware or in software. Preferably, one or more or all functional modules 2ia-d may be implemented by the processing unit 21, possibly in cooperation with functional units 22 and/or 23. The processing unit 21 may thus be arranged to from the storage medium 23 fetch instructions as provided by a functional module 2ia-d and to execute these instructions, thereby performing any steps as will be disclosed hereinafter.

Fig. 3a schematically illustrates, in terms of a number of functional units, the components of a node I2a-e according to an embodiment. A processing unit 31 is provided using any combination of one or more of a suitable central processing unit (CPU), multiprocessor, microcontroller, digital signal processor (DSP), application specific integrated circuit (ASIC), field programmable gate arrays (FPGA) etc., capable of executing software instructions stored in a computer program product 41b (as in Fig. 4), e.g. in the form of a storage medium 33. Thus the processing unit 31 is thereby arranged to execute methods as herein disclosed. The storage medium 33 may also comprise persistent storage, which, for example, can be any single one or combination of magnetic memory, optical memory, solid state memory or even remotely mounted memory. The node I2a-e may further comprise a communications interface 32 for communications with another node i2a-e and the gateway 11. As such the communications interface 32 may comprise one or more transmitters and receivers, comprising analogue and digital components and a suitable number of antennas for radio

communications and (optionally) ports for wireline communications. The processing unit 31 controls the general operation of the node i2a-e e.g. by sending data and control signals to the communications interface 32 and the storage medium 33, by receiving data and reports from the communications interface 32, and by retrieving data and instructions from the storage medium 33. Other components, as well as the related functionality, of the node i2a-e are omitted in order not to obscure the concepts presented herein.

Fig. 3b schematically illustrates, in terms of a number of functional modules, the components of a node i2a-e according to an embodiment. The node i2a-e of Fig. 3b comprises a number of functional modules; such as a transmit and/or receive module 31a configured to perform below steps S202, S204, S210, S216, S222. The node I2a-e of Fig. 3b may further comprises a number of optional functional modules, such as any of a determine module 31b configured to perform below step S206, a store module 31c configured to perform below step S208, a check module 3id configured to perform below step S212, an increase module 3ie configured to perform below steps S214, S220, and a detect module 3if configured to perform below step S218. The functionality of each functional module 3ia-f will be further disclosed below in the context of which the functional modules 3ia-f may be used. In general terms, each functional module 3ia-f may be implemented in hardware or in software. Preferably, one or more or all functional modules 3ia-f may be implemented by the processing unit 31, possibly in cooperation with functional units 32 and/or 33. The processing unit 31 may thus be arranged to from the storage medium 33 fetch instructions as provided by a functional module 3ia-f and to execute these instructions, thereby performing any steps as will be disclosed hereinafter.

Fig. 4 shows one example of a computer program product 41a, 41b

comprising computer readable means 43. On this computer readable means 43, a computer program 42a can be stored, which computer program 42a can cause the processing unit 21 and thereto operatively coupled entities and devices, such as the communications interface 22 and the storage medium 23, to execute methods according to embodiments described herein. The computer program 42a and/or computer program product 41a may thus provide means for performing any steps of the gateway 11 as herein disclosed. On this computer readable means 43, a computer program 42b can be stored, which computer program 42b can cause the processing unit 31 and thereto operatively coupled entities and devices, such as the communications interface 32 and the storage medium 33, to execute methods according to embodiments described herein. The computer program 42b and/or computer program product 41b may thus provide means for performing any steps of the node i2a-e as herein disclosed.

In the example of Fig. 4, the computer program product 41a, 41b is illustrated as an optical disc, such as a CD (compact disc) or a DVD (digital versatile disc) or a Blu-Ray disc. The computer program product 41a, 41b could also be embodied as a memory, such as a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM), or an electrically erasable programmable read-only memory (EEPROM) and more particularly as a non-volatile storage medium of a device in an external memory such as a USB (Universal Serial Bus) memory or a Flash memory, such as a compact Flash memory. Thus, while the computer program 42a, 42b is here schematically shown as a track on the depicted optical disk, the computer program 42a, 42b can be stored in any way which is suitable for the computer program product 41a, 41b. Figs. 5 and 6 are flow charts illustrating embodiments of methods for enabling routing in a wireless ad-hoc network 10 as performed by the gateway 11. Figs. 7 and 8 are flow charts illustrating embodiments of methods for enabling routing in a wireless ad-hoc network 10 as performed by the node i2a-e. The methods are advantageously provided as computer programs 42a, 42b.

Reference is now made to Fig. 5 illustrating a method for enabling routing in a wireless ad-hoc network 10 as performed by the gateway 11 according to an embodiment. In order to make the nodes i2a-e routable the gateway 11 needs to have access to information which describes how communication from the gateway 11 can reach the nodes i2a-e in the wireless ad-hoc network 10. The gateway 11 is therefore configured to, in a step S102, broadcast radio signalling to nodes I2a-e in the wireless ad-hoc network 10 for collecting path information from the gateway 11 to the nodes i2a-e.

Not all nodes i2a-e may directly receive this broadcast radio signalling.

However, as will be further disclosed below, a node i2a-e receiving this broadcast radio signalling may forward it to another node i2a-e. It is therefore assumed that this broadcast radio signalling is received by at least one of the nodes i2a-e. As will be further disclosed below with reference to Fig. 7, the at least one node i2a-e receiving the broadcast radio signalling responds to the gateway 11. The gateway 11 is thus configured to, in a step S104, receive radio signalling from at least one of the nodes i2a-e. The received radio signalling comprises an in-packet Bloom Filter (iBF) representation identifying paths to at least two of the nodes i2a-e. The at least two nodes i2a-e thereby become routable. In this respect, the radio signalling may in step S104 be directly received from only one of the nodes i2a-e, but the received radio signalling comprises an iBF representation identifying paths to at least two nodes i2a-e. One reason for this is that the response transmitted by the at least one node i2a-e receiving the broadcast radio signalling may be received not only by the gateway 11 but also by at least one other node i2a-e. This at least one other node i2a-e may then , in turn, respond to its own received radio signalling by transmitting further radio signalling where its own iBF representation is added to the iBF representation already comprised in the received radio signalling. The information of this further radio signalling is eventually received by the gateway 11, possibly by means of being forwarded by other nodes i2a-e. This will be further explained below.

Embodiments relating to further details of enabling routing in a wireless ad- hoc network 10 will now be disclosed. The iBF representation may identify at least one path to each one of the nodes i2a-e.

Some embodiments presented herein relate to creating paths to the gateway 11. Different examples relating thereto will now be described in turn.

The broadcast radio signalling may be a path-setup request. The path-setup request may be sent with a specific iBF representation in the packet. That is, the broadcasted radio signalling may be sent in packets comprising a specific bit pattern. The specific bit pattern may thus be the specific iBF

representation.

Further, each transmitted packet may comprise a serial number. That is, the broadcasted radio signalling may be sent in packets comprising a serial number. Each serial number may represent a unique occurrence of the broadcasted radio signalling. However, since the serial number may take a value in a set of limited values, it could be so that when the serial number has reached the highest value in this set, the next serial value will again take the lowest value in this set. Each packet may therefore also comprise a Time-to- Live (TTL) field, see below. Such a TTL field may be used to avoid

simultaneous occurrences of the same serial number from different generations of serial numbers, assuming that the TTL is shorter than the expected time duration for cycling through one generation of serial numbers. Reference is now made to Fig. 6 illustrating methods for enabling routing in a wireless ad-hoc network 10 as performed by the gateway 11 according to further embodiments.

Some embodiments presented herein relate to registration of a node i2a-e in the gateway 11, where the iBF representation is collected from the gateway 11 to the node i2a-e. Different examples relating thereto will now be described in turn.

The iBF representation received by the gateway 11 may comprise identifiers and index values. That is, the received radio signalling may further comprise identifiers of the nodes i2a-e and index values used by the nodes i2a-e. The index values may correspond to the above disclosed d-values.

Some embodiments presented herein relate to transmission of data from the gateway 11 to a node i2a-e. Different examples relating thereto will now be described in turn. The gateway 11 may store the node identifier together with the collected iBF representation; all the added iBF representations may be required to have the same initial index value (i.e., d-value) stored at the gateway. Hence, the gateway 11 may be configured to, in an optional step S106, store the received iBF representation, the identifiers and at least one of the index values. The gateway 11 may uses stored iBF representations to transmit data to a specific node i2a-e in the wireless ad-hoc network 11. Hence, the gateway 11 may be configured to, in an optional step S108, retrieve the stored iBF representation of at least one of said nodes (12a, 12b, 12c, i2d, i2e) in said wireless ad-hoc network (10). The gateway 11 may then be configured to, in an optional step S110, transmit further radio signalling to said at least one of the nodes i2a-e, wherein the further radio signalling comprises the stored iBF representation. When the gateway 11 sends multicast packet towards multiple nodes i2a-e, the packet has only one index value. That is the further radio signalling, as transmitted in step S110, may comprise one of the (stored) index values.

The gateway 11 may combine set of nodes i2a-e into one single iBF

representation by performing a logical OR operation between the iBF representations. That is, the further radio signalling, as transmitted in step S110, may comprise at least two stored iBF representations being represented by a result of a bitwise logical OR operation between the at least two stored iBF representations. The gateway 11 may transmit configuration information to the set of nodes i2a-e. Hence, the further radio signalling, as transmitted in step S110, may comprise configuration information.

Some embodiments presented herein relate to enabling identification of packet at receivers of the packet. Different examples relating thereto will now be described in turn.

Each node i2a-e may include the node's identifier in the packet separately. That is, the further radio signalling, as transmitted in step S110, may comprise one explicit identifier for each one of the at least one of the nodes i2a-e. Each node i2a-e may have a specific Id that can be included in the forwarding iBF representation. That is, the iBF representation may comprise identifiers for all of the at least one of said nodes i2a-e.

Some embodiments presented herein relate to implementing iBF addressing with IEEE 802.15.4. Different examples relating thereto will now be described in turn. Particularly, the received radio signalling may be received using IEEE 802.15.4 radio. The iBF representation may be provided in a media access control (MAC) address field (or fields) of the IEEE 802.15.4 packets. Some embodiments presented herein relate to repeating the procedure periodically to cope with changes in network topology. Particularly, the gateway 11 may be configured to, in an optional step S112, periodically repeat at least the step S02 of broadcasting radio signalling and the step S104 of receiving radio signalling. The gateway 11 may further be configured to periodically repeat any further steps as herein performed by the gateway 11.

Reference is now made to Fig. 7 illustrating a method for enabling routing in a wireless ad-hoc network 10 as performed by the node i2a-e according to an embodiment. As noted above with reference to Fig. 5 the gateway 11 in a step S102 transmits radio signalling. This radio signalling is received by at least one of the nodes i2a-e. It is assumed that the radio signalling is received at least by node 12a. Thus, the node 12a is configured to, in a step S202, receive radio signalling for collecting path information from a gateway 11 in the wireless ad-hoc network 10 to the node 12a.

The node 12a responds to this received radio signalling by transmitting radio signalling. Thus, the node 12a is configured to, in a step S204, transmit radio signalling comprising an in-packet Bloom Filter (iBF) representation identifying a path to the node 12a towards the gateway 11. The node 12a is thereby routable. Either this radio signalling is directly received by the gateway 11, or this radio signalling is received by another node, say node 12b, which another node may add an iBF representation identifying a path to this another node to the iBF representation of the node 12a before forwarding the radio signalling, and so on, the radio signalling thus eventually reaching the gateway 11. In any of these two cases, information as transmitted by the node 12a in step S204 eventually reaches the gateway 11, and thus, in both these case the node 12a is made routable.

Embodiments relating to further details of enabling routing in a wireless ad- hoc network 10 will now be disclosed. l8

As disclosed above, the radio signalling received in step S202 may comprise a further iBF representation identifying a further path to at least one further node 12b in the wireless ad-hoc network 10. The radio signalling as transmitted in step S204 may then comprise the iBF representation and the further iBF representation.

As disclosed above, the radio signalling received in step S202 may comprise an identity of the gateway 11.

As disclosed above, the radio signalling received in step S202 may comprise a serial number. Reference is now made to Fig. 8 illustrating methods for enabling routing in a wireless ad-hoc network 10 as performed by the node i2a-e according to further embodiments.

As noted above, some embodiments presented herein relate to creating paths to the gateway 11. Different examples relating thereto will now be described in turn.

The node 12a may check if it already has an iBF representation stored leading towards the gateway 11 identified with the gateway identifier in the packet. If not previously stored, the node 12a may then store identifier, the

corresponding serial number, the iBF representation, and index value. The radio signalling received in step S202 may comprise an index value. As noted above, the index value may correspond to the d-value. The node 12a may be configured to, in an optional step S206, determine whether the node 12a previously has received radio signalling from the gateway 11 or not by checking if the identity has previously been stored by the node. The node 12a may then be configured to, in an optional step S208 store the identity, the serial number, and the index value if not previously stored.

The node 12 may add its own identifier in the packet. The radio signalling transmitted in step S204 may thus comprise an identifier of said node 12a. The identifier may be the FEId of the node 12a. The FEId may by the node 12a be selected using the index value from the incoming packet. That is, the radio signalling received in step S204 may comprise an index value. The identifier may then be selected from a set of identifiers available to the node 12a, wherein the node 12a selects the identifier based on the index value. The identifier may be added to the iBF field in the packet using a bitwise logical OR operation. That is, the radio signalling received in step S202 may comprise an iBF representation, and the identifier may be added to the radio signalling transmitted in step S204 using a bitwise logical OR operation on the iBF representation in the received radio signalling. Some embodiments presented herein relate to transmission of data from the node i2a-e to the gateway 11. Different examples relating thereto will now be described in turn.

When the node 12a transmits a packet to the gateway 11, the node 12a may match the iBF representation in the packet to the identifier indexed with the index value in the packet. Particularly, the node 12a may be configured to, in an optional step S210, receive further radio signalling from a first node 12b in the wireless ad-hoc network 10. The said further radio signalling may comprise an iBF representation and an index value. The node 12a may then be configured to, in an optional step S212, check if the iBF representation matches an identifier of the node 12a or not. The identifier may be selected from a set of identifiers available to the node 12a. The identifier may be selected based on the index value.

The iBF representation and the identifier may be bitwise logically AND-ed and if the result is the identifier, there is a match. That is, the iBF

representation may match the identifier only if a bitwise logical AND operation between the iBF representation and the identifier is equal to the identifier.

The index value may (if there is a match) then be increased by one (mod n) and the packet be transmitted out from the node 12a. Thus, the node 12a may then be configured to, in an optional step S214, increase the index value by one; and, in an optional step S216, transmit further radio signalling, wherein the further radio signalling comprises the iBF representation and the increased index value.

If the node 12 detects that it has a silent neighbour node (i.e., a node that does not transmit when expected to transmit) the node 12a may skip the next hop node by retransmitting the same packet but increasing the index value by two instead of one. Thus, the node 12a may be configured to, in an optional step S218, detect lack of reception of further radio signalling from a second node i2d in the wireless ad-hoc network 10. The node 12a may then be configured to, in an optional step S220, in response thereto, further increase the index value by one; an, in an optional step S222, re-transmit the transmitted further radio signalling, wherein the re-transmitted radio signalling comprises the iBF representation and the further increased index value. As noted above, some embodiments presented herein relate to registration of a node i2a-e in the gateway 11, where the iBF representation is collected from the gateway 11 to the node i2a-e. Different examples relating thereto will now be described in turn.

The radio signalling transmitted in step S204 may comprise registration information of the node 12a. The registration information may comprise an iBF representation from the node 12a towards the gateway 11, and an identity of the node 12a.

Some embodiments presented herein relate to handling false positives. For example, each packet may have a Time-to-Live field. Hence, the radio signalling received in step S102 may comprise a time-to-live indicator.

As noted above, some embodiments presented herein relate to implementing iBF addressing with IEEE 802.15.4. That is, the node 12 may transmit the radio signalling in step S204 using IEEE 802.15.4 packets, wherein the iBF representation is provided in a MAC address field of the IEEE 802.15.4 packets. Particular embodiments based on at least some of the above disclosed embodiments will now be disclosed.

Further details of creating paths to the gateway 11 will now be disclosed.

The gateway 11 may (periodic) transmit path-setup requests, by means of the radio signalling broadcasted in step S102, towards the nodes i2a-e. These requests may be transmitted with a specific iBF representation in the packet (e.g. all ones, or some other specific bit-pattern) so that all nodes i2a-e receiving the packet know that this is a path-setup packet that should be processed in all nodes i2a-e. The packets may also comprise a serial number that by the nodes i2a-e is used to detect different generations of path-setup requests. One purpose of the packet of this broadcasted radio signalling is to collect path information so that any node i2a-e receiving such a packet may acquire an iBF representation that may be used to deliver packets from the nodes i2a-e to the gateway 11. Each node i2a-e receiving the path-setup packet may take two actions. These actions will be described next.

First, the node i2a-e may check if it already has an iBF representation stored leading towards that gateway 11 identified with the gateway identifier in the packet. If the iBF representation does not exist, the node i2a-e stores this identifier with the corresponding serial number, iBF representation, and index value for future use. The node I2a-e may then use this iBF

representation with the index value if the node i2a-e needs to transmit information to the gateway 11 (or to the service network 15 via the gateway 11). The serial number may be used by the node i2a-e to determine that a new path-setup message is coming. The iBF representation that has an old serial number is typically not needed, because it is possible that the topology of the wireless ad-hoc network 10 has changed and is no longer valid. Thus, the collected iBF representation from a path-setup message with a newer serial number may be stored by the node i2a-e. If the received iBF representation is the first one received for this serial number the iBF representation may always be stored by the node I2a-e. However, if an iBF representation with this serial number already has been stored by the node i2a-e, the node i2a-e may try to select the best one of these two. There may be different criterions which iBF representation should be selected as the best. For example, each iBF representation may have been transmitted at the same time from the gateway n but have taken a different path towards the node i2a-e. One way to select the best iBF representation is for the node i2a-e to count the number of ones (is) in the iBF representation and select the iBF representation with least number of ones. Less number of ones may indicate that the path from the gateway n is shorter. Alternatively, the path-setup message may contain a hop-count counter to detect short paths. However, counting the number of ones in the iBF representation may result in smaller packets, which may be desirable in resource constrained wireless ad-hoc networks n. Second, the node i2a-e may add its own identifier in the packet. The node i2a-e may select the identifier that the node i2a-e inserts it in the iBF collection field using the index value from the incoming packet decreased by one (mod n) as the index value. The node i2a-e may add the identifier to the iBF field in the packet using a bitwise logical OR operation. The node i2a-e may transmit the packet out from the node i2a-e with the decreased index value. As noted above, the identifier may be the FEId and the index value may be the d-value.

This is illustrated in Fig. 9. Fig. 9 is a schematic illustration of how path information may be collected from the nods i2a-e towards the gateway 11. According to this illustrative example, the gateway 11 has broadcasted, as in step S102, a path-setup request, Path-setup[to=broadcast; IDGW=GWI;

ser=i4; coll=iBF_t0Gw; d=2], where "to" represents where the packet is transmitted to, "IDGW" represents an identity of the gateway 11, "ser" is the serial number of the path-setup packet, "coll" is the field in the packet where the path, by means of an iBF representation, to the gateway 11 is collected, and "d" is the index value to be used by the node i2a-e receiving the packet to match to its identifier, FEId. The node i2a-e receiving the packet adds the iBF representation 011000110100 of the incoming packet and the identifier with index value d=2, i.e., to FEId[2] by performing a bitwise logic OR operation between the iBF representation and FEId[2] . The resulting iBF representation 011010110110 is included in the field iBFtoowof the packet. The node I2a-e further compares the iBFtoowto previously stored BFtoow for the same serial number by comparing the number of ones (is) in the iBFtoow and keeps the iBFtoow with the least number of ones (is). The node i2a-e receiving the path-setup request then forwards the received packet with an updated d-value (i.e., where the d-value is decreased by one) and updated iBF representation, iBFtoow.

Further details of the node i2a-e transmitting data to the gateway 11 will now be disclosed.

Once a node i2a-e has received an iBF representation comprising a path to the gateway 11, the node I2a-e may start transmitting information to the gateway 11 using this iBF representation. When the node I2a-e transmits a packet to the gateway 11, all nodes i2a-e that receive the packet will verify if their identifier (such as the FEId) has been included in the packet's iBF representation.

The node I2a-e matches the iBF representation in the incoming packet to the identifier indexed with the index value (such as the d-value) in the packet. The matching may be accomplished by the node i2a-e performing a bitwise logical AND-operation between the iBF representation and the identifier and if the result is the identifier (for the used index value), there is a match. In this case the index value is increased by one (mod n) and the packet is transmitted out from the node I2a-e. However, if there is no match, the packet is dropped. This process is performed at all nodes i2a-e receiving the packet until the packet reaches the gateway 11 from where the data in the packet may be delivered further to the service network 15.

If a node 12a detects that a neighboring node i2a-e that used to be the next hop in an iBF representation is no longer forwarding packets (e.g., the node 12b has run out of power or is temporarily under high load), and there is no alternative route available, the node 12a may attempt to skip the next hop node 12b by retransmitting the same packet but increasing the index value by two instead of one. In addition, the node 12a may need to increase the power used for the wireless transmission in order to reach a node 12c further away. If a next-hop node 12c receives this packet, the packet looks identical to a packet sent by the unresponsive node 12b and is therefore forwarded by the node 12c just like any other packet.

This is illustrated in Fig. 10. Fig. 10 is a schematic illustration of how the node i2a-e receiving the packet matches its identifier to the iBF

representation of the packet. According to this illustrative example, the gateway 11, or another node i2a-e, has transmitted a data message, Data- packet[to= iBFtoow; d=2], where "to" represents where the packet is transmitted to, and "d" is the index value to be used by the node i2a-e receiving the packet to match to its identifier, FEId. The node I2a-e receiving the packet matches the iBF representation 001010110010 of the incoming packet with the identifier with index value d=2, i.e., to FEId[2] by performing a bitwise logic AND operation between the iBF representation iBFtoow and FEId[2]. The resulting iBF representation 011010110110 is identical to

FEId[2] and hence there is a match. The node i2a-e receiving the data message therefore forwards the received packet with an updated d-value (i.e., where the d-value is increased by one).

Further details of registering the node 12a in the gateway 11 and / or collecting the iBF representation from the gateway 11 to the node 12a will now be disclosed.

According to embodiments the gateway 11 requires nodes i2a-e to register themselves. The registration process as such is out of the scope of this disclosure. A node i2a-e may initiate the registration process once it has received iBF representation for the gateway 11, for example in the form of the above disclosed path-setup request, by transmitting a reverse-path-setup message to the gateway 11 using the received iBF representation. In the reverse-path-setup message, the nodes i2a-e may collect the reverse path information that the gateway 11 may use to transmit data towards the node i2a-e. The reverse-path-setup packet may be similar to the path-setup packet, with the following differences: the to-field comprises the iBF representation from the registering node i2a-e to the gateway 11, the node Id field comprises the identifier of the registering node i2a-e, the collector field and the index value field operate in a similar way as with the path-setup, and a serial number is not necessary. When the nodes I2a-e forward the packet towards the gateway 11, all nodes i2a-e receiving the packet insert their identifier in the collecting field, where the identifier is indexed with the index value of the packet decreased by one, and transmit the packet further out with the decreased index value. This is a similar process as is performed for the path- setup packet.

When the gateway 11 receives the reverse-path-setup packet, it stores the identifier of the node i2a-e together with the index value and the collected iBF representation. The nodes i2a-e may be required to transmit the reverse- path-setup packet if a change in the network topology is detected. Further, because the packet may be regarded as being forwarded using strict source routing, it may be required that the reverse-path-setup is transmitted from the node i2a-e to the gateway 11 when the iBF representation towards the gateway 11 changes, e.g. when the node i2a-e receives a path-setup message from the gateway 11 with a new iBF representation.

The node i2a-e may transmit the reverse-path-setup packet using the index value n(max) - index value stored for the iBF representation to the gateway 11. With that iBF representation, the packet takes the same route to the gateway 11 as it took from the gateway 11 to the node i2a-e. Selecting n(max) - stored index value means that when the setup packet arrives at the gateway, the index value is zero. Thus, all values in the iBF representation to node i2a-e for all nodes i2a-e may have the same initial index value, such as the value zero (o), at the gateway 11. One purpose of having the same initial index value at the gateway 11 is to enable multicast support towards the nodes i2a-e. Further details of the gateway 11 transmitting data to the node i2a-e will now be disclosed.

The gateway 11 may use the stored iBF representations to transmit data to a specific node i2a-e in the wireless ad-hoc network 10. The gateway 11 may also combine a set of destination nodes i2a-e into one single iBF

representation by performing a logical OR operation on the individual iBF representations of the individual nodes i2a-e. This forms a multicast tree from the gateway 11 to all the selected destination nodes i2a-e. This procedure may be used to transmit e.g. configuration information to a set of nodes i2a-e.

To support this procedure, all the added iBF representations may be required to have the same initial index value stored at the gateway 11. As disclosed above, this may be accomplished when the reverse-path-setup packet is transmitted from the node i2a-e towards the gateway 11. When the gateway 11 transits a multicast packet towards multiple nodes i2a-e, the packet has only one index value that must be initially correct to all the included individual iBF representations so that all the nodes I2a-e match the iBF representation of the packet with the correctly indexed identifier.

Care should be taken when multiple iBFs are merged into one; the number of ones (is) in the transmitted iBF representation may increase such that the possibility for false routing decisions in the network increases.

Further details of handling false positives will now be disclosed.

With iBF representations, there is possibility of having false positive forwarding decisions. However, if the wireless ad-hoc network 10 is relatively small (i.e., comprising a limited number of nodes i2a-e), it is possible to avoid all false positive forwarding decisions. Using the herein disclosed embodiments of including index values in the packets and at the nodes comparing the iBF representation of incoming packets with its identifier indexed by the index value reduces the possibility for false positives as well as reducing the risk of packets being bounced back and forth between two forwarding nodes i2a-e since the index value changes fat each hop.

Further, the packets may comprise a Time-to-Live (TTL) field. The

transmitter (node i2a-e or gateway 11) sets the TTL field to an initial value and each forwarding node i2a-e receiving the packet decreases the TTL field by one. Once the TTL value reaches zero, the packet is dropped. While the use of TTL values could be used for breaking routing loops, using the herein disclosed embodiments of including index values in the packets may be more effective in order to reducing the possibility of having false positive

forwarding decisions since loops are generally broken before they even form. Using these mechanisms together may mitigate loops altogether.

Further details of identifying the packet at the receiver of the packet will now be disclosed.

When a packet reaches the destination node i2a-e, the destination node i2a-e must be able to identify that it indeed is the destination node i2a-e of the packet (or one of the destination nodes i2a-e in case of multicast

transmission). Two alternatives for the destination node I2a-e to identify that it indeed is the destination node i2a-e of the packet will be disclosed next.

In a first example, the transmitting node i2a-e or gateway 11 includes an identity of the destination node i2a-e in the packet separately. According to this first example, the iBF representation comprises only the path

information. Each node I2a-e receiving the packet must then verify the actual destination identity in the packet to determine whether or not it is one of the intended receivers of the packet. If the receiving node i2a-e is one of the intended receivers of the packet, the receiving node i2a-e processes the packet. The receiving node i2a-e also verifies the identifier, if the packet has to be transmitted further out from receiving node I2a-e. This is illustrated in Fig. 11(a). Fig. 11(a) is a schematic illustration of a packet comprising an iBF representation "iBF_path", destination identities "Dstldi", "Dstldn", and data "Data". In a second example, each node i2a-e has a specific identity that can be included in the forwarding iBF representation. According to this second example, each node i2a-e maintains a Destination Node Identifier (DNId) that may be similar to the identifiers, i.e. it may be m bits long and may have k bits set to one. Each entity initiating either the path-setup (the entity being the gateway 11) or the reverse-path-setup (the entity being a node i2a-e) may then include the DNId as the initial value in the field collecting the iBF representation. This is illustrated in Fig. 11(b). Fig. 11(b) is a schematic illustration of a packet comprising an iBF representation "iBF_path+DNid(i-n)", and data "Data".

When a node i2a-e receives a packet, it makes the verification of the identifier as described above and also verifies from the iBF representation whether its own DNId has been included or not. In case of multicast, it is possible that both match, in which case the received packet is both

transmitted out from the receiving node i2a-e and processed locally in the receiving node i2a-e.

Further details of implementing iBF addressing with IEEE 802.15.4 will now be disclosed.

IEEE 802.15.4 is currently a common used physical and MAC layer protocol for low-rate wireless Personal Area Networks (PANs). The payload of IEEE 802.15.4 physical layer frames is only 127 bytes and hence efficient addressing is important for efficient operation. The iBF representation based forwarding of packets disclosed herein provides such effective addressing.

Since the MAC addresses are no longer needed for forwarding, these fields may be used to comprise the iBF representation in IEEE 802.15.4 data frames. One of the reserved bits (7-9 or 12-13) of the IEEE 802.15.4 Frame Control octets or the reserved addressing mode (boi) may be used to indicate that the addressing mode is based on iBF representation. Alternatively, the currently forbidden addressing mode (where both destination and source MAC addresses are elided) could be used for indicating that some other network specific addressing mode (such as based on iBF representation) is used in this PAN. In such cases the iBF representation(s) may be comprised e.g., in the beginning of the payload part of the frame.

In summary, in-packet Bloom filter forwarding and in-packet Bloom filters (iBFs) are proposed to, instead of traditional MAC and network layer addresses, be used for enabling routing in the wireless ad-hoc network 10 to create suitable forwarding identifiers that can be changed automatically when the network topology changes. First, the gateway 11 may broadcast packets that are used to collect iBF representations leading from a node i2a-e to the gateway 11. Second, each node i2a-e may register itself to the gateway 11. The nodes i2a-e may use the received iBF representation to deliver the

registration to the gateway 11. During the registration packet delivery, the reverse path is collected in the packet, and the gateway 11 acquires the iBF representation comprising the path to that node i2a-e. The gateway 11 may store the node identifier together with the collected iBF representation and may then communicate with the node I2a-e using this iBF representation. This procedure may be repeated periodically to cope with any changes in the network topology. Furthermore, routing loops that would be generated if naive iBF routing was used may be avoided by using the herein disclosed processes using index values and identifiers.

The inventive concept has mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the inventive concept, as defined by the appended patent claims.

Claims

1. A method for enabling routing in a wireless ad-hoc network (10), the method being performed by a gateway (11), comprising the steps of:

broadcasting (S102) radio signalling to nodes (12a, 12b, 12c, i2d, i2e) in said wireless ad-hoc network (10) for collecting path information from said gateway (11) to said nodes; and

receiving (S104) radio signalling from at least one of said nodes (12a, 12b, 12c, i2d, i2e), wherein said received radio signalling comprises an in- packet Bloom Filter, iBF, representation identifying paths to at least two of said nodes (12a, 12b, 12c, i2d, i2e), said at least two nodes (12a, 12b, 12c, i2d, i2e) thereby becoming routable.

2. The method according to claim 1, wherein said iBF representation identifies at least one path to each one of said nodes (12a, 12b, 12c, i2d, i2e).

3. The method according to claim 1, wherein said broadcasted radio signalling is sent in packets comprising a serial number, each serial number representing an occurrence of said broadcasted radio signalling.

4. The method according to claim 1, wherein said received radio signalling further comprises identifiers of said nodes (12a, 12b, 12c, i2d, i2e) and index values used by said nodes (12a, 12b, 12c, i2d, i2e) to match said iBF representation to an identifier of said nodes (12a, 12b, 12c, i2d, i2e).

5. The method according to claim 4, further comprising:

storing (S106) said iBF representation, said identifiers and at least one of said index values.

6. The method according to claim 5, further comprising:

retrieving (S108) said stored iBF representation of at least one of said nodes (12a, 12b, 12c, i2d, i2e) in said wireless ad-hoc network (10); and

transmitting (S110) further radio signalling to said at least one of said nodes (12a, 12b, 12c, i2d, i2e), wherein said further radio signalling comprises said stored iBF representation.

7. The method according to claim 6, wherein said further radio signalling comprises at least two stored iBF representations being represented by a result of a bitwise logical OR operation between said at least two stored iBF representations.

8. The method according to claim 6, or 7, wherein said further radio signalling comprises one explicit identifier for each one of said at least one of said nodes (12a, 12b, 12c, i2d, i2e).

9. The method according to claim 6, or 7, wherein said iBF representation comprises identifiers for all of said at least one of said nodes (12a, 12b, 12c, i2d, i2e).

10. A method for enabling routing in a wireless ad-hoc network (10), the method being performed by a node (12a) in said wireless ad-hoc network (10), comprising the steps of:

receiving (S202) radio signalling for collecting path information from a gateway (11) in said wireless ad-hoc network (10) to said node; and

transmitting (S204) radio signalling comprising an in-packet Bloom Filter, iBF, representation identifying a path to said node (12a) towards said gateway (11), said node (12a) thereby becoming routable.

11. The method according to claim 10, wherein said received radio signalling comprises a further iBF representation identifying a further path to at least one further node (12b) in said wireless ad-hoc network (10), and wherein said transmitted radio signalling comprises said iBF representation and said further iBF representation.

12. The method according to claim 10, wherein said received radio signalling comprises an identity of said gateway (11).

13. The method according to claim 10, wherein said received radio signalling comprises a serial number.

14. The method according to claim 12 and 13, wherein said received radio signalling comprises an index value, said method further comprising: determining (S206) whether said node (12a) previously has received radio signalling from said gateway (11) or not by checking if said identity has previously been stored by said node; and if not previously stored:

storing (S208) said identity, said serial number, and said index value.

15. The method according to claim 10, wherein said transmitted radio signalling comprises an identifier of said node (12a).

16. The method according to claim 15, wherein said received radio signalling comprises an index value, and wherein said identifier is selected from a set of identifiers available to said node (12a), and wherein said identifier is selected based on said index value.

17. The method according to claim 15 or 16, wherein said received radio signalling comprises an iBF representation, and wherein said identifier is added to said transmitted radio signalling using a bitwise logical OR operation on said iBF representation in said received radio signalling.

18. The method according to claim 10, further comprising:

receiving (S210) further radio signalling from a first node (12b) in said wireless ad-hoc network (10), wherein said further radio signalling comprises an iBF representation and an index value; and

checking (S212) if said iBF representation matches an identifier of said node (12a) or not, wherein said identifier is selected from a set of identifiers available to said node (12a), and wherein said identifier is selected based on said index value.

19. The method according to claim 18, wherein said iBF representation matches said identifier only if a bitwise logical AND operation between said iBF representation and said identifier is equal to said identifier.

20. The method according to claim 19, wherein in case said iBF

representation matches said identifier, the method further comprising:

increasing (S214) said index value by one; and transmitting (S216) further radio signalling, said further radio signalling comprising said iBF representation and said increased index value.

21. The method according to claim 20, further comprising:

detecting (S218) lack of reception of further radio signalling from a second node (i2d) in said wireless ad-hoc network (10); and in response thereto:

further (S220) increasing said index value by one; and

re-transmitting (S222) said transmitted further radio signalling, said retransmitted radio signalling comprising said iBF representation and said further increased index value.

22. The method according to claim 10, wherein said transmitted radio signalling is transmitted using IEEE 802.15.4 packets, wherein IEEE is short for Institute of Electrical and Electronics Engineers, and wherein said iBF representation is provided in at least one media access control, MAC, address field of said IEEE 802.15.4 packets.

23. A gateway (11) for enabling routing in a wireless ad-hoc network (10), the gateway comprising a processing unit (21) configured to:

broadcast (S102) radio signalling to nodes (12a, 12b, 12c, i2d, i2e) in said wireless ad-hoc network (10) for collecting path information from said gateway (11) to said nodes; and

receive (S104) radio signalling from at least one of said nodes (12a, 12b, 12c, i2d, i2e), wherein said received radio signalling comprises an in-packet Bloom Filter, iBF, representation identifying paths to at least two of said nodes (12a, 12b, 12c, i2d, i2e), said at least two nodes (12a, 12b, 12c, i2d, i2e) thereby becoming routable.

24. A node (12a) for enabling routing in a wireless ad-hoc network (10), the node comprising a processing unit (31) configured to:

receive radio signalling for collecting path information from a gateway (11) in said wireless ad-hoc network (10) to said node; and

transmit radio signalling comprising an in-packet Bloom Filter, iBF, representation identifying a path to said node (12a) towards said gateway (11), said node (12a) thereby becoming routable.

25. A computer program (42a) for enabling routing in a wireless ad-hoc network (10), the computer program comprising computer program code which, when run on a processing unit (21) of a gateway (11), causes the processing unit to:

receive (S104) radio signalling from at least one of said nodes (12a, 12b,

12c, i2d, i2e), wherein said received radio signalling comprises an in-packet Bloom Filter, iBF, representation identifying paths to at least two of said nodes (12a, 12b, 12c, i2d, i2e), said at least two nodes (12a, 12b, 12c, i2d, i2e) thereby becoming routable.

26. A computer program (42b) for enabling routing in a wireless ad-hoc network (10), the computer program comprising computer program code which, when run on a processing unit (31) of a node (12a), causes the processing unit to:

receive (S202) radio signalling for collecting path information from a gateway (11) in said wireless ad-hoc network (10) to said node; and

transmit (S204) radio signalling comprising an in-packet Bloom Filter, iBF, representation identifying a path to said node (12a) towards said gateway (11), said node (12a) thereby becoming routable.

27. A computer program product (41a, 41b) comprising a computer program (42a, 42b) according to at least one of claims 25 and 26, and a computer readable means (43) on which the computer program is stored.