CA2313165A1 - Method and apparatus for data transmission in a wireless network - Google Patents
Method and apparatus for data transmission in a wireless network Download PDFInfo
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Abstract
A communication device for transporting data traffic exchanged between a first and a second end station, where the second end station is mobile in a data network. The communication device includes an address translator that provides to data packets traveling in the reverse direction of data flow, from the second end station to the first end station, translated location addresses when the first end station receiving the data packets is mobile within a data network. The address translator permits passage of data packets traveling in the reverse direction of data flow without providing the data packets with translated location addresses when the first end station receiving the data packets is fixed within the data network. The data packets received by the communication device in the forward direction of data flow, from the first end station to the second end station, have translated location addresses. The address translator is operative to replace the translated location addresses of the data packets traveling in the forward direction of data flow with an identity destination address that is recognizable by the second end station as being uniquely representative of the second end station.
Description
Ref. 11725ROUSOlU
Title: Method and Apparatus for Data Transmission in a Wireless Network Field of the Invention The present invention relates to the field of data transmission, such as data transmission that may occur in a wireless network. More particularly, it pertains to a method and apparatus for transmitting data to a mobile in a wireless network.
Background of the Invention Traditional IP routing protocols for wireline networks rave been developed with the assumption that the end terminals are stationary. Therefore, the IP addresses assigned to end terminals serve dual purpose - end station identifier and location identifier. An IP address used as an end station identifier (Layer 3 in OSI model) uniquely _dentifies an end station in a network and is used (along with additional parameters such as port numbers in the transport layer) to maintain active sessions between any two nodes communicating using IP protocols. IP based networks, together with their corresponding IP address space, are ::rganized in a hierarchical fashion. The hierarchical .. rga::izaLion allows ~caiabiiity ~~ =r routing a~:~; -educes memory, as well as processing requirements, on the routers to store and exchange routing information. As a result, an IP
Ref. 11725ROUSOlU
address of an end station in a wireline network is always associated with a network/sub-network. Therefore, from the routers' perspective, the IP address of an end station, in addition to being an end-station identifier, also serves as a location identifier and is used to forward the packet to the appropriate network/sub-network.
Unfortunately, IP routing, the most prevalent packet forwarding mechanism in wireline networks, was not designed to handle the mobile nature of end hosts in wireless l0 networks.
The first and second generation wireless networks, which carry voice as the primary traffic, have been designed to set up dedicated resources (end-to-end) between a mobile station and another mobile/fixed station. The allocation of dedicated resources from the beginning till the end of active voice calls eliminates the need for a location identifier to forward voice traffic, as this is taken care of by switching traffic over dedicated resources. As the mobile moves, the -~ocation updates for the mobile trigger the adjustment of appropriate portions of the dedicated resources (i.e. de-allocation of resources to previous location and re-allocation of resources to new location) in the wireless networks.
The main issue with using traditional (wireline based) ~P routing for data packet delivery to mobile nodes in a wireless network is that an IP address can no longer be used <~s a location identifier, because the mobiles change Locations while having active IP sessions. This is especially true ;~.f the wireless network is to have a wide -geographic coverage.
Title: Method and Apparatus for Data Transmission in a Wireless Network Field of the Invention The present invention relates to the field of data transmission, such as data transmission that may occur in a wireless network. More particularly, it pertains to a method and apparatus for transmitting data to a mobile in a wireless network.
Background of the Invention Traditional IP routing protocols for wireline networks rave been developed with the assumption that the end terminals are stationary. Therefore, the IP addresses assigned to end terminals serve dual purpose - end station identifier and location identifier. An IP address used as an end station identifier (Layer 3 in OSI model) uniquely _dentifies an end station in a network and is used (along with additional parameters such as port numbers in the transport layer) to maintain active sessions between any two nodes communicating using IP protocols. IP based networks, together with their corresponding IP address space, are ::rganized in a hierarchical fashion. The hierarchical .. rga::izaLion allows ~caiabiiity ~~ =r routing a~:~; -educes memory, as well as processing requirements, on the routers to store and exchange routing information. As a result, an IP
Ref. 11725ROUSOlU
address of an end station in a wireline network is always associated with a network/sub-network. Therefore, from the routers' perspective, the IP address of an end station, in addition to being an end-station identifier, also serves as a location identifier and is used to forward the packet to the appropriate network/sub-network.
Unfortunately, IP routing, the most prevalent packet forwarding mechanism in wireline networks, was not designed to handle the mobile nature of end hosts in wireless l0 networks.
The first and second generation wireless networks, which carry voice as the primary traffic, have been designed to set up dedicated resources (end-to-end) between a mobile station and another mobile/fixed station. The allocation of dedicated resources from the beginning till the end of active voice calls eliminates the need for a location identifier to forward voice traffic, as this is taken care of by switching traffic over dedicated resources. As the mobile moves, the -~ocation updates for the mobile trigger the adjustment of appropriate portions of the dedicated resources (i.e. de-allocation of resources to previous location and re-allocation of resources to new location) in the wireless networks.
The main issue with using traditional (wireline based) ~P routing for data packet delivery to mobile nodes in a wireless network is that an IP address can no longer be used <~s a location identifier, because the mobiles change Locations while having active IP sessions. This is especially true ;~.f the wireless network is to have a wide -geographic coverage.
2 Ref. 11725ROUSOlU
Existing solutions which address the mobility issue for IP hosts v~n wireless networks include the IP-based campus mobility scheme, Reverse-Address Translation (RAT), General Packet Radio Service (GPRS), Simple Mobile IP (SMIP) and the ~andoff Aware Wireless Access Internet Infrastructure (HAWAII). Unfcrtunateiy, each of these protocols is ~~haracterized by one or more disadvantages, such as:
~ use of the encapsulation technique to perform data transmission, which introduces overhead and thus requires l0 additional use of link bandwidth;
~ non-seamless mobility, i.e. the protocol does not maintain transport and higher-layer connections when the mobile node changes location;
~ additional transmission delay:
~ modifications (software or hardware) to the mobile host;
~ protocol-specific routers;
~ periodic refreshes of location information, thus introducing additional control traffic into the network and requiring additional use of link bandwidth.
The background information provided above clearly indicates that there exists a need in the industry to provide a method and apparatus for improved data transmission in a wireless network, more particularly for transmitting data to a mobile in a wireless network.
Existing solutions which address the mobility issue for IP hosts v~n wireless networks include the IP-based campus mobility scheme, Reverse-Address Translation (RAT), General Packet Radio Service (GPRS), Simple Mobile IP (SMIP) and the ~andoff Aware Wireless Access Internet Infrastructure (HAWAII). Unfcrtunateiy, each of these protocols is ~~haracterized by one or more disadvantages, such as:
~ use of the encapsulation technique to perform data transmission, which introduces overhead and thus requires l0 additional use of link bandwidth;
~ non-seamless mobility, i.e. the protocol does not maintain transport and higher-layer connections when the mobile node changes location;
~ additional transmission delay:
~ modifications (software or hardware) to the mobile host;
~ protocol-specific routers;
~ periodic refreshes of location information, thus introducing additional control traffic into the network and requiring additional use of link bandwidth.
The background information provided above clearly indicates that there exists a need in the industry to provide a method and apparatus for improved data transmission in a wireless network, more particularly for transmitting data to a mobile in a wireless network.
3 Ref. 11725ROUSOlU
Summary of the Invention Under a broad aspect, the present invention provides a communication device for transporting data traffic exchanged between two end stations, namely a first end station and a second end station. The first end station is mobile or fixed, while the second end station is mobile. The data traffic has a forward direction of data flow from the first end station to the second end station and a reverse direction of data flow from the second end station to the first end station. The data flow in each direction includes data packets . Each data packet entering the communication device .n either direction of data flow has a destination address.
~'he destination address contains information that makes the end station to which the data packet is destined recognizable, either on the basis of identity or location of the end station in the network.
In the forward direction of data flow, each data packet entering the communication device has a destination address -_~ the form of a translated location address. This :ranslated location address is the result of a location address translation performed on an identity destination address of the data packet, prior to its arrival at the communication device, for purposes of routing within the network. In particular, the location address translation is <3n operation that modifies the identity destination address of the data packet such that the translated destination address represents the current location of the second end :station within the network.
In the reverse direction of data flow, each data packet
Summary of the Invention Under a broad aspect, the present invention provides a communication device for transporting data traffic exchanged between two end stations, namely a first end station and a second end station. The first end station is mobile or fixed, while the second end station is mobile. The data traffic has a forward direction of data flow from the first end station to the second end station and a reverse direction of data flow from the second end station to the first end station. The data flow in each direction includes data packets . Each data packet entering the communication device .n either direction of data flow has a destination address.
~'he destination address contains information that makes the end station to which the data packet is destined recognizable, either on the basis of identity or location of the end station in the network.
In the forward direction of data flow, each data packet entering the communication device has a destination address -_~ the form of a translated location address. This :ranslated location address is the result of a location address translation performed on an identity destination address of the data packet, prior to its arrival at the communication device, for purposes of routing within the network. In particular, the location address translation is <3n operation that modifies the identity destination address of the data packet such that the translated destination address represents the current location of the second end :station within the network.
In the reverse direction of data flow, each data packet
4 Ref. 11725ROUSOlU
entering the communication device has an identity destination address that is recognized by the first end station as being uniquely representative of itself within the network.
The communication device includes an address translator :hat processes data packets in the reverse direction of data flow. If the first end station is fixed, data packets are allowed to proceed without being subject to a location address translation.
The ccmmunication device advantageously accommodates end l0 station mobility within a network, without requiring vntroduction of significant overhead during forwarding of data packets within the network.
Under a specific non-limiting example of implementation of the invention, the communication device is implemented in an edge router located at the boundary of a wireless network, the edge router forming a point of interaction between segments of the same network that use different data transmission media, such as a wireless data transmission and a wireline data transmission. The edge router can be _mplemented in a Base Station Transceiver (BTSi for example, where the BTS services a set of mobile end stations.
Each BTS of the wireless network can be provided with an address translator. Data from the first end station, residing in an external network, arrives at a BTS via the segment of the network that uses wireline data transmission.
The data packets include a destination address in the form of 3 translated location address representative of the location ~f t::e second end station that is a mobile end sta~ior. in the ~.aireless network. The address translator in the BTS effects a reverse address translation that is an identity translation
entering the communication device has an identity destination address that is recognized by the first end station as being uniquely representative of itself within the network.
The communication device includes an address translator :hat processes data packets in the reverse direction of data flow. If the first end station is fixed, data packets are allowed to proceed without being subject to a location address translation.
The ccmmunication device advantageously accommodates end l0 station mobility within a network, without requiring vntroduction of significant overhead during forwarding of data packets within the network.
Under a specific non-limiting example of implementation of the invention, the communication device is implemented in an edge router located at the boundary of a wireless network, the edge router forming a point of interaction between segments of the same network that use different data transmission media, such as a wireless data transmission and a wireline data transmission. The edge router can be _mplemented in a Base Station Transceiver (BTSi for example, where the BTS services a set of mobile end stations.
Each BTS of the wireless network can be provided with an address translator. Data from the first end station, residing in an external network, arrives at a BTS via the segment of the network that uses wireline data transmission.
The data packets include a destination address in the form of 3 translated location address representative of the location ~f t::e second end station that is a mobile end sta~ior. in the ~.aireless network. The address translator in the BTS effects a reverse address translation that is an identity translation
5 Ref. 11725ROUSOlU
operation that replaces the translated location address with the original destination address in the form of an identity destination. address, specifically the IP address assigned to the mobile second end station. The data packets with their original identity destination addresses are then delivered by the BTS tc the second end station over the wireless link.
Data packets sent in the reverse direction, from the second end station to the first end station, arrive at the BTS from the second end station with a destination address that specifies the identity destination address assigned to the first end station.
If the first end station is mobile, the address translator in the BTS effects a location address translation on each data packet directed to the first end station.
If the first end station is fixed, the address translator in the BTS does not perform any address translation. Rather, the data packets with their original identity destination addresses are released from the BTS for forwarding to the first end station over the network.
Each address translator carries out the address translation operation by using an address translation table mapping end station location information and end station identity information. The address translation table in an address translator is updated by an address updating unit in t:he wireless network. When a mobile end station changes location within the network such than a new association between the location of the end station and its identity must be made, an updating unit that notices this new association broadcasts signaling information to all the address
operation that replaces the translated location address with the original destination address in the form of an identity destination. address, specifically the IP address assigned to the mobile second end station. The data packets with their original identity destination addresses are then delivered by the BTS tc the second end station over the wireless link.
Data packets sent in the reverse direction, from the second end station to the first end station, arrive at the BTS from the second end station with a destination address that specifies the identity destination address assigned to the first end station.
If the first end station is mobile, the address translator in the BTS effects a location address translation on each data packet directed to the first end station.
If the first end station is fixed, the address translator in the BTS does not perform any address translation. Rather, the data packets with their original identity destination addresses are released from the BTS for forwarding to the first end station over the network.
Each address translator carries out the address translation operation by using an address translation table mapping end station location information and end station identity information. The address translation table in an address translator is updated by an address updating unit in t:he wireless network. When a mobile end station changes location within the network such than a new association between the location of the end station and its identity must be made, an updating unit that notices this new association broadcasts signaling information to all the address
6 Ref. 11725ROUSOlU
translators of the wireless network such that the address translators can update their address translation tables.
Under another broad aspect the invention also provides an address updating unit for use in a wireless network including a plurality of fixed nodes and a plurality of mobile entities. The address updating unit is operative to receive information associating data indicative of a location of a certain mobile entity in the wireless network and data indicative of an identity of the certain mobile entity. The l0 data indicative of an identity of the certain mobile entity is recognizable by the certain mobile ,entity as being uniquely representative of itself. Based on this information, the address updating unit is operative to generate address translation signaling information and to direct the address translation signaling information to a plurality of fixed nodes of the wireless network.
Under yet another broad aspect, the present invention is directed to a system for transmitting data between a first end station and a second end station, where the second end station is mobile and the first end station is either fixed or mobile. The system includes two units and each unit includes an address translator.
Under a specific non-limiting example of implementation, data from the first end station, residing in an external network, arrives at the first unit. The external network can be a packet switched network or a circuit switched network.
The data packets arriving from the first end station include an identity destination address that specifies the IP address assigned to the second end station in the wireless network that is a mobile end station.
translators of the wireless network such that the address translators can update their address translation tables.
Under another broad aspect the invention also provides an address updating unit for use in a wireless network including a plurality of fixed nodes and a plurality of mobile entities. The address updating unit is operative to receive information associating data indicative of a location of a certain mobile entity in the wireless network and data indicative of an identity of the certain mobile entity. The l0 data indicative of an identity of the certain mobile entity is recognizable by the certain mobile ,entity as being uniquely representative of itself. Based on this information, the address updating unit is operative to generate address translation signaling information and to direct the address translation signaling information to a plurality of fixed nodes of the wireless network.
Under yet another broad aspect, the present invention is directed to a system for transmitting data between a first end station and a second end station, where the second end station is mobile and the first end station is either fixed or mobile. The system includes two units and each unit includes an address translator.
Under a specific non-limiting example of implementation, data from the first end station, residing in an external network, arrives at the first unit. The external network can be a packet switched network or a circuit switched network.
The data packets arriving from the first end station include an identity destination address that specifies the IP address assigned to the second end station in the wireless network that is a mobile end station.
7 Ref. 11725ROUSOlU
The address translator in the first unit performs a location address translation on the identity destination address of the data packets flowing in the forward direction, that is traveling from the first end station to the mobile second end station. The address translator in the second unit performs a reverse address translation on the destination addresses of the data packets traveling in the forward direction, where these destination addresses are translated location addresses. Thus, data packets traveling from the first end station, in an external network, to the mobile second end station, in the wireless network, undergo two back-to-back address translations, notably a first location address translation and a second reverse address translation.
The present invention is further directed to a method for transmitting data traffic between a first end station and a second end station, the second end station being mobile in a data network.
2o Brief Description of the Drawings These and other features of the present invention will become apparent from the following detailed description considered in connection with the accompanying drawings. It is to be understood, however, that the drawings are provided for purposes of illustration only and not as a definition of the boundaries of the invention, for which reference should be made to the appending claims.
Figure 1 is a block diagram of a wireless network;
The address translator in the first unit performs a location address translation on the identity destination address of the data packets flowing in the forward direction, that is traveling from the first end station to the mobile second end station. The address translator in the second unit performs a reverse address translation on the destination addresses of the data packets traveling in the forward direction, where these destination addresses are translated location addresses. Thus, data packets traveling from the first end station, in an external network, to the mobile second end station, in the wireless network, undergo two back-to-back address translations, notably a first location address translation and a second reverse address translation.
The present invention is further directed to a method for transmitting data traffic between a first end station and a second end station, the second end station being mobile in a data network.
2o Brief Description of the Drawings These and other features of the present invention will become apparent from the following detailed description considered in connection with the accompanying drawings. It is to be understood, however, that the drawings are provided for purposes of illustration only and not as a definition of the boundaries of the invention, for which reference should be made to the appending claims.
Figure 1 is a block diagram of a wireless network;
8 Ref. 11725ROUSOlU
Figure 2 is a functional block diagram of an address translator, in accordance with an embodiment of the present invention;
Figure 3 is a structural block diagram of an edge router used in the wireless network shown in Figure 1, implementing ~he address translator unit functionally illustrated in figure 2;
Figure 4 is a structural block diagram of an address updating unit, in accordance with an example of l0 .implementation of the present invention;
Figure 5 is a block diagram of the address space of the wireless network shown in Figure l;
Figure 6 is a flowchart illustrating the address Translation operation performed by the address translator illustrated at Figure 2;
Figure 7 is a block diagram of an example of a multi-network domain servicing mobiles.
Detailed Description Figure 1 illustrates a wireless network 100 servicing a plurality of mobiles 112. The network 100 includes a plurality cf core routers 102 as well as edge routers 104 and x_06, the latter being located at edges of the wireless -_et~fecr k 1 00 . ~'dge Pouters 1 04 form points of interacts on between the wireless network 100 and an external network 110.
the external network 110 can be a packet switched network or
Figure 2 is a functional block diagram of an address translator, in accordance with an embodiment of the present invention;
Figure 3 is a structural block diagram of an edge router used in the wireless network shown in Figure 1, implementing ~he address translator unit functionally illustrated in figure 2;
Figure 4 is a structural block diagram of an address updating unit, in accordance with an example of l0 .implementation of the present invention;
Figure 5 is a block diagram of the address space of the wireless network shown in Figure l;
Figure 6 is a flowchart illustrating the address Translation operation performed by the address translator illustrated at Figure 2;
Figure 7 is a block diagram of an example of a multi-network domain servicing mobiles.
Detailed Description Figure 1 illustrates a wireless network 100 servicing a plurality of mobiles 112. The network 100 includes a plurality cf core routers 102 as well as edge routers 104 and x_06, the latter being located at edges of the wireless -_et~fecr k 1 00 . ~'dge Pouters 1 04 form points of interacts on between the wireless network 100 and an external network 110.
the external network 110 can be a packet switched network or
9 Ref. 11725ROUSOlU
a circuit switched network. In the latter case, the edge routers 104 also implement the function of gateways. Edge routers 106 are the last nodes in the forward direction of the mobile traffic that handle data packets before they are transmitted over wireless links tc mobiles 112. Each edge router 106 provides coverage to mobiles over a particular geographical region 108, where the geographical regions 108 for a plurality of edge routers 106 are potentially overlapping.
to In a specific non-limiting example of implementation, the wireless Network 100 is a cellular wireless telecommunications network that implements an IP based architecture. The edge routers 106 are implemented in Base Transceiver Stations (BTSs) that interface between the cellular mobiles lit and a landline portion of the wireless Network 100, where the latter is comprised of core routers 102, edge routers 104, 106 and any physical communication links interconnecting the routers 102, 104 and 106 to one another. Note that the core routers 102 are commercial off 'she shelf IP routers that require no mobile specific information and for shat reason their structure and cperation will not be described in detail in this specification.
The wireless network 100 includes a plurality of address Translators 200 shown in Figure 2. In the example of ~~mplementation of the invention illustrated in Figure l, an address translator 200 is provided in each edge router 104, ,~06.
The address translator 200 includes a first input 206 or receiving the data packets, a processing unit 202 and a data storage unit 204. The processing unit 202 is Ref. 11725ROUSOlU
responsible for translating the destination address of the data packets, thus generating a translated destination address. The data packets including the translated destination address are released from an output 210.
The address translator 200 further includes a second input 208 for receiving signaling information indicative of the location of a particular mobile 112. The processing unit 202 stores this information in the data storage unit 204. In particular, the data storage unit 204 maps, for each aarticular mobile 112 serviced by the wireless network 100, she identity of the particular mobile 112 to the location of the particular mobile 112, thus forming an address translation table. The location of a particular mobile 112 specifies the geographic position or area of the wireless network 100 where the particular mobile 112 is currently located, and may designate, for example, a subnetwork of the wireless network 100. The identity of a particular mobile 112 specifies an address that is recognizable by the particular mobile 112 as being uniquely representative of the particular mobile 112. For example, the identity of a particular mobile 112 can be specified by an IP address that is assigned to the particular mobile 112 from the global IP
address space of the wireless network 100. Such an IP address can be of permanent nature, in other words the same address is used to identify the mobile during its useful life.
Alternatively, the IP address could be of less persistent :nature, for instance a different IP address is assigned for each communication session, the address remaining the same during the communication session.
3o The signaling information is generated by an address updating unit 212 that is operative to receive location Ref. 11725ROUSOlU
updates regarding mobiles 112 as they move within the wireless network 100. The address updating unit 212 may be implemented anywhere within the wireless network 100, either as a stand-alone unit or integrated within another, system Level, functional unit of the network 100, and will be described in further detail below.
In the context of a cellular wireless network 100, each edge router 106 is implemented in a BTS. The structure of such a BTS will be described in further detail below;
l0 however, only the particulars of the BTS that are relevant to =his invention will be described and illustrated in the drawings. In particular, a BTS is at all times "aware" of :he identity of the mobiles 112 that are under its service umbrella. When a BTS becomes aware of a particular mobile 112 that has entered or left its coverage area, the BTS will 'ransmit to the address updating unit 212 a location update with respect to the particular mobile 112. This location update may take the form of a data packet having a destination address that is the address of the updating unit '?12 within the network 100, sent from the BTS to the address updating unit 212.
Two relevant elements of information are available at the BTS that implements the router 106, one is the list of identifiers of the mobiles 112 associated with the BTS and '.he other is the identifier of the BTS itself. In the context of an IP network, the identifiers of the mobiles 112 are the respective IP addresses of the mobiles that specify vheir identities, and in the case of the BTS, the identifier ..s Glso an IP address, -gin particular a subnet.
Ref. 11725ROUSOlU
The address updating unit 212 receives and processes a location update from a BTS with respect to a particular mobile 112, including the identifier of the particular mobile -X12 and the BTS identifier. On the basis of this location update, the address updating unit 212 associates to the particular mobile 112 a specific location within the network domain and generates signaling information for notifying all the address translators 200 of the location of the particular mobile 112 within the wireless network. For example, the l0 signaling information includes data representative of both the identity of the particular mobile 112 and the location of the particular mobile 112. The former is the global IP
address permanently assigned to the particular mobile 112 by the network 100, recognizable by the particular mobile 112 as being uniquely representative of the particular mobile 112.
The latter is the specific location address dynamically assigned to the particular mobile 112 by the address updating unit 212, where this specific location address is selected from a pool of addresses associated with the private address space of the BTS subnet. The specific location address has r_wo components, one being representative of the subnet, and one allowing to differentiate the particular mobile 112 from other mobiles 112 at that particular location.
The address updating unit 212 will then send this signaling information to the address translators 200 throughout the wireless network 100, for example via broadcasting, thus permitting the address translator 200 to dynamically update the mobile location information stored in she address translation table of the data storage unit 204 as '.he particular mobile 112 moves within the network domain.
Ref. 11725ROUSOlU
In one example of implementation, shown in Figure 4, the address updating unit 212 comprises an input 400 for receiving location updates from the BTS edge routers 106 with respect to the mobiles 112, a processor 402 for processing ;.he location updates and generating signaling information indicative of the location of the particular mobile 112 within the network domain, a memory 404 and an output 406 for Transmitting the signaling information to the address Translators 200. The address updating unit 212 stores in its memory 404 the hierarchical breakdown of the network private address space, in particular the private addresses that are ;~n use (assigned to a mobile 112) and those that are not in use (available to be assigned to a mobile 112).
In a non-limiting example of implementation, an address translator 200 is located at each edge router 104, 106 of the wireless network 100. Data packets travelling in the forward direction from a first end station in the external network 110 towards a second end station in the wireless network 100, the latter being a particular mobile 112, are intercepted by an address translator 200 as they arrive at an edge router 104. The same data packets are intercepted a second time by a second address translator 200, located at an edge muter 106, before they are passed into the radio link for transport to a particular mobile 112.
The data packets arriving at any one of the edge routers 104 bear a destination address representative of the identity of a particular mobile 112 to which the data packets are destined, that being the global IP address assigned to the mobile 112 by t::e network 100. ~t the first interception, the address translator 200 in the edge router 104 performs a location address translation, an operation that modifies the Ref. 11725ROUSOlU
original identity destination address of the data packets into a translated location address that represents the current location of the particular mobile 112 within the network domain. In addition to the location information in the translated location address, the location address translation also adds differentiation information allowing to distinguish the particular mobile 112 from other entities residing at the same subnet. At the second interception, the address translator 200 performs a reverse address translation shat is an identity translation operation that replaces the translated location address with the original identity destination address of the data packets. ' Figure 6 is a flowchart illustrating an example of the address translation operation in accordance with the present t5 invention. At step 600, data packets arriving from an external data packet network 110, and thus traveling in the forward direction, are intercepted at the edge of the wireless network 100, where the data packets include a destination address representative of the identity of a particular mobile 112. At step 602, a location address translation is performed, translating the destination address of the data packets from the identity to the location of the particular mobile 112 within the wireless network domain. At step 604, the data packets including the translated location address are routed through the wireless network 100 towards the particular mobile 112. At step 606, the data packets are intercepted again, prior to being passed into an RF
communication channel. At step 608, a reverse address translation is performed, translating the destination address cf the data packets from the location of the particular mobile 112 to the identity of the particular mobile 112. At step 610, the data packets including a destination address Ref. 11725ROUSOlU
representative of the identity of the particular mobile 112 are introduced in the RF communication link towards a particular mobile 112.
In the reverse direction, data packets arriving at any one of the BTS edge routers 106 from a mobile 112 bear a destination address that specifies the identity of the end station to which the packets are being sent, that being the global IP address of the end station. If the first end station is mobile, the address translator 200 in the BTS edge router 106 effects a location address translation on each data packet directed to the end station, replacing the c;riginal destination address with a translated location address. The location address translation modifies the destination address such that it now designates the current location of the end station in the network. The data packets with the translated location address are then released from the BTS 106 for forwarding to the end station over the network 100. If the first end station is fixed, the address translator 200 in the BTS 106 does not perform any address translation. Rather, the data packets with their original destination address are released from the BTS '~06 for forwarding to the end station over the network 100.
The address translator 200 is capable to determine whether the first end station is mobile or fixed on the basis of the information in the address translation table. In a non-limiting example of implementation, upon receipt of data packets from the second end station, the processing unit 202 of the address Translator 200 is operative to scan the a.~dress translation table of the data storage unit X04 on a 3o basis of the destination address included with the data packets. If a match is found, the first end station is Ref. 11725ROUSOlU
qualified as mobile and the address translator 200 performs a location address translation on each data packet directed to this first end station, replacing the original destination address with a translated location address. If a match is not found, the first end station is qualified as fixed and the data packets with their original destination address are released from the address translator 200 without undergoing any address translation.
Figure 3 illustrates an example of the structure of the BTS edge router 106, in accordance with the example of implementation of the present inventiow. The BTS 106 includes a controller/processor 300 and a memory 302, together responsible for implementing the standard functionality of the BTS 106. As mentioned earlier, this standard functionality will not be described because it is well known by those skilled in the art. The BTS 106 includes a first input 308 for receiving the data packets destined for a particular mobile 112 located within the geographical region 108 covered by the BTS 106, as well as a first output 312 for releasing the data packets in the radio link for transport to the particular mobile 112. In the reverse direction, the BTS 106 includes a second input 314 for receiving data packets from a particular mobile 112, where these data packets are destined to an end station that may be either mobile or fixed, either located in the network 100 or in an external network. The BTS 106 also includes a second output 316 for releasing data packets for forwarding over the network 100.
Specific to the present invention, the BTS 1~6 includes ~xn address translator unit 304 and a third input 310 for receiving signaling information from the address updating Ref. 11725ROUSOlU
unit 212. In the forward direction, the address translator unit 304 performs a reverse address translation on the translated location addresses of data packets received at first input 308, replacing the translated location addresses with the original identity destination addresses that are included with the data packets that are sent as radio frames from first output 312. In the reverse direction, if the data packets received at second input 314 are being sent to a mobile end station, the address translator unit 304 performs a location address translation on the destination addresses of the data packets, generating translated location addresses that are included with the data packets that are released to the network 100 from second output 316. If the data packets received at second input 314 are being sent to a fixed end station, they are passed to second output 316 without performing any address translation operation. A data storage unit 306 is operative to store the location and identity information for the plurality of mobiles 112, susceptible to move within the network domain, in an address translation table. The address translator unit 304 updates the contents of the address translation table on a basis of the signaling information received at third input 310 from the address updating unit 212. Further, the address translator unit 304 consults the address translation table for performing the address translation operation on data packets received at inputs 308 and 314, on a basis of the destination address of these data packets.
The structure of an edge router 104 is similar to that shown in Figure 3, and as such will not be described in aetail. In particular, specific to the present invention, the edge router 104 includes an address translator unit, with Ref. 11725ROUS01U
data storage unit, as well as an input for receiving signaling information from the address updating unit 212.
Dote that in an alternative example of implementation, the address translator 200 is implemented as a plurality of stand-alone address translator units, distinct from the edge routers 104, 106, located at the edges of the network 100.
Such stand-alone address translator units will simply intercept data packets prior to their arrival at the edge routers 104, 106, perform the appropriate address translation operation and pass the data packets on to the corresponding edge router 104 or 106. The stand-alone address translator units will include an input for receiving the signaling information from the address updating unit 212, a processor and a data storage unit for storing the location information for the plurality of mobiles 112 serviced by the network 100.
The processor will perform the appropriate address translation operation on data packets received at the stand-alone address translator unit prior to their release to the corresponding edge router 104 or 106.
Assume that in a specific example of implementation a wireless cellular telecommunications network 100 implements an IP based architecture, as shown in Figure 5, where the network 100 is associated with a globally unique address space 47Ø0.0/8. Each mobile 112 is assigned a globally unique IP address from the network's globally unique address space (47Ø0.0/8), corresponding to the identity of the mobile 112. For example, in Figure 5 mobile 112 is assigned identity 47.1.1.23. In order to provide for the dynamic Nature of the location of the mobiles 112 within the network domain, a private address space is associated with every node within the wireless network 100, including the edge routers Ref. 11725ROUSOlU
104 and 106. When a mobile 112 enters the geographical region 108 covered by a particular BTS 106, the latter being associated with a particular private address space, the particular BTS 106, aware of the mobile 112 that is now located within its coverage area, will send a location update to the address updating unit 212. On a basis of this location update, the address updating unit 212 will assign to the mobile 112 a private address, selected from the pool of addresses belonging to the private address space of the l0 particular BTS 106, corresponding to the location of the mobile 112. For example, in Figure 5 the mobile 112 is assigned location 10.1.1.87, an address selected from the private address space 10.1.1.0/24 of the BTS 106. The address updating unit 212 will then generate and send signaling information indicative of the identity 47.1.1.23 and the location 10.1.1.87 of the mobile 112 to the address translator 200 which will update the contents of its data storage unit 204.
Data packets arriving from external data packet network 110 will include a destination address representative of the identity :.:f mobile 112, specifically 47.1.1.23. Assuming that the address translator 200 is implemented as functional units within the edge routers 104 and 106, when the data packets are first intercepted at edge router 104 (10Ø0.0/8) of the wireless network 100, the address translator unit will translate the destination address from the identity to the location of the mobile 112, specifically from 47.1.1.23 to
a circuit switched network. In the latter case, the edge routers 104 also implement the function of gateways. Edge routers 106 are the last nodes in the forward direction of the mobile traffic that handle data packets before they are transmitted over wireless links tc mobiles 112. Each edge router 106 provides coverage to mobiles over a particular geographical region 108, where the geographical regions 108 for a plurality of edge routers 106 are potentially overlapping.
to In a specific non-limiting example of implementation, the wireless Network 100 is a cellular wireless telecommunications network that implements an IP based architecture. The edge routers 106 are implemented in Base Transceiver Stations (BTSs) that interface between the cellular mobiles lit and a landline portion of the wireless Network 100, where the latter is comprised of core routers 102, edge routers 104, 106 and any physical communication links interconnecting the routers 102, 104 and 106 to one another. Note that the core routers 102 are commercial off 'she shelf IP routers that require no mobile specific information and for shat reason their structure and cperation will not be described in detail in this specification.
The wireless network 100 includes a plurality of address Translators 200 shown in Figure 2. In the example of ~~mplementation of the invention illustrated in Figure l, an address translator 200 is provided in each edge router 104, ,~06.
The address translator 200 includes a first input 206 or receiving the data packets, a processing unit 202 and a data storage unit 204. The processing unit 202 is Ref. 11725ROUSOlU
responsible for translating the destination address of the data packets, thus generating a translated destination address. The data packets including the translated destination address are released from an output 210.
The address translator 200 further includes a second input 208 for receiving signaling information indicative of the location of a particular mobile 112. The processing unit 202 stores this information in the data storage unit 204. In particular, the data storage unit 204 maps, for each aarticular mobile 112 serviced by the wireless network 100, she identity of the particular mobile 112 to the location of the particular mobile 112, thus forming an address translation table. The location of a particular mobile 112 specifies the geographic position or area of the wireless network 100 where the particular mobile 112 is currently located, and may designate, for example, a subnetwork of the wireless network 100. The identity of a particular mobile 112 specifies an address that is recognizable by the particular mobile 112 as being uniquely representative of the particular mobile 112. For example, the identity of a particular mobile 112 can be specified by an IP address that is assigned to the particular mobile 112 from the global IP
address space of the wireless network 100. Such an IP address can be of permanent nature, in other words the same address is used to identify the mobile during its useful life.
Alternatively, the IP address could be of less persistent :nature, for instance a different IP address is assigned for each communication session, the address remaining the same during the communication session.
3o The signaling information is generated by an address updating unit 212 that is operative to receive location Ref. 11725ROUSOlU
updates regarding mobiles 112 as they move within the wireless network 100. The address updating unit 212 may be implemented anywhere within the wireless network 100, either as a stand-alone unit or integrated within another, system Level, functional unit of the network 100, and will be described in further detail below.
In the context of a cellular wireless network 100, each edge router 106 is implemented in a BTS. The structure of such a BTS will be described in further detail below;
l0 however, only the particulars of the BTS that are relevant to =his invention will be described and illustrated in the drawings. In particular, a BTS is at all times "aware" of :he identity of the mobiles 112 that are under its service umbrella. When a BTS becomes aware of a particular mobile 112 that has entered or left its coverage area, the BTS will 'ransmit to the address updating unit 212 a location update with respect to the particular mobile 112. This location update may take the form of a data packet having a destination address that is the address of the updating unit '?12 within the network 100, sent from the BTS to the address updating unit 212.
Two relevant elements of information are available at the BTS that implements the router 106, one is the list of identifiers of the mobiles 112 associated with the BTS and '.he other is the identifier of the BTS itself. In the context of an IP network, the identifiers of the mobiles 112 are the respective IP addresses of the mobiles that specify vheir identities, and in the case of the BTS, the identifier ..s Glso an IP address, -gin particular a subnet.
Ref. 11725ROUSOlU
The address updating unit 212 receives and processes a location update from a BTS with respect to a particular mobile 112, including the identifier of the particular mobile -X12 and the BTS identifier. On the basis of this location update, the address updating unit 212 associates to the particular mobile 112 a specific location within the network domain and generates signaling information for notifying all the address translators 200 of the location of the particular mobile 112 within the wireless network. For example, the l0 signaling information includes data representative of both the identity of the particular mobile 112 and the location of the particular mobile 112. The former is the global IP
address permanently assigned to the particular mobile 112 by the network 100, recognizable by the particular mobile 112 as being uniquely representative of the particular mobile 112.
The latter is the specific location address dynamically assigned to the particular mobile 112 by the address updating unit 212, where this specific location address is selected from a pool of addresses associated with the private address space of the BTS subnet. The specific location address has r_wo components, one being representative of the subnet, and one allowing to differentiate the particular mobile 112 from other mobiles 112 at that particular location.
The address updating unit 212 will then send this signaling information to the address translators 200 throughout the wireless network 100, for example via broadcasting, thus permitting the address translator 200 to dynamically update the mobile location information stored in she address translation table of the data storage unit 204 as '.he particular mobile 112 moves within the network domain.
Ref. 11725ROUSOlU
In one example of implementation, shown in Figure 4, the address updating unit 212 comprises an input 400 for receiving location updates from the BTS edge routers 106 with respect to the mobiles 112, a processor 402 for processing ;.he location updates and generating signaling information indicative of the location of the particular mobile 112 within the network domain, a memory 404 and an output 406 for Transmitting the signaling information to the address Translators 200. The address updating unit 212 stores in its memory 404 the hierarchical breakdown of the network private address space, in particular the private addresses that are ;~n use (assigned to a mobile 112) and those that are not in use (available to be assigned to a mobile 112).
In a non-limiting example of implementation, an address translator 200 is located at each edge router 104, 106 of the wireless network 100. Data packets travelling in the forward direction from a first end station in the external network 110 towards a second end station in the wireless network 100, the latter being a particular mobile 112, are intercepted by an address translator 200 as they arrive at an edge router 104. The same data packets are intercepted a second time by a second address translator 200, located at an edge muter 106, before they are passed into the radio link for transport to a particular mobile 112.
The data packets arriving at any one of the edge routers 104 bear a destination address representative of the identity of a particular mobile 112 to which the data packets are destined, that being the global IP address assigned to the mobile 112 by t::e network 100. ~t the first interception, the address translator 200 in the edge router 104 performs a location address translation, an operation that modifies the Ref. 11725ROUSOlU
original identity destination address of the data packets into a translated location address that represents the current location of the particular mobile 112 within the network domain. In addition to the location information in the translated location address, the location address translation also adds differentiation information allowing to distinguish the particular mobile 112 from other entities residing at the same subnet. At the second interception, the address translator 200 performs a reverse address translation shat is an identity translation operation that replaces the translated location address with the original identity destination address of the data packets. ' Figure 6 is a flowchart illustrating an example of the address translation operation in accordance with the present t5 invention. At step 600, data packets arriving from an external data packet network 110, and thus traveling in the forward direction, are intercepted at the edge of the wireless network 100, where the data packets include a destination address representative of the identity of a particular mobile 112. At step 602, a location address translation is performed, translating the destination address of the data packets from the identity to the location of the particular mobile 112 within the wireless network domain. At step 604, the data packets including the translated location address are routed through the wireless network 100 towards the particular mobile 112. At step 606, the data packets are intercepted again, prior to being passed into an RF
communication channel. At step 608, a reverse address translation is performed, translating the destination address cf the data packets from the location of the particular mobile 112 to the identity of the particular mobile 112. At step 610, the data packets including a destination address Ref. 11725ROUSOlU
representative of the identity of the particular mobile 112 are introduced in the RF communication link towards a particular mobile 112.
In the reverse direction, data packets arriving at any one of the BTS edge routers 106 from a mobile 112 bear a destination address that specifies the identity of the end station to which the packets are being sent, that being the global IP address of the end station. If the first end station is mobile, the address translator 200 in the BTS edge router 106 effects a location address translation on each data packet directed to the end station, replacing the c;riginal destination address with a translated location address. The location address translation modifies the destination address such that it now designates the current location of the end station in the network. The data packets with the translated location address are then released from the BTS 106 for forwarding to the end station over the network 100. If the first end station is fixed, the address translator 200 in the BTS 106 does not perform any address translation. Rather, the data packets with their original destination address are released from the BTS '~06 for forwarding to the end station over the network 100.
The address translator 200 is capable to determine whether the first end station is mobile or fixed on the basis of the information in the address translation table. In a non-limiting example of implementation, upon receipt of data packets from the second end station, the processing unit 202 of the address Translator 200 is operative to scan the a.~dress translation table of the data storage unit X04 on a 3o basis of the destination address included with the data packets. If a match is found, the first end station is Ref. 11725ROUSOlU
qualified as mobile and the address translator 200 performs a location address translation on each data packet directed to this first end station, replacing the original destination address with a translated location address. If a match is not found, the first end station is qualified as fixed and the data packets with their original destination address are released from the address translator 200 without undergoing any address translation.
Figure 3 illustrates an example of the structure of the BTS edge router 106, in accordance with the example of implementation of the present inventiow. The BTS 106 includes a controller/processor 300 and a memory 302, together responsible for implementing the standard functionality of the BTS 106. As mentioned earlier, this standard functionality will not be described because it is well known by those skilled in the art. The BTS 106 includes a first input 308 for receiving the data packets destined for a particular mobile 112 located within the geographical region 108 covered by the BTS 106, as well as a first output 312 for releasing the data packets in the radio link for transport to the particular mobile 112. In the reverse direction, the BTS 106 includes a second input 314 for receiving data packets from a particular mobile 112, where these data packets are destined to an end station that may be either mobile or fixed, either located in the network 100 or in an external network. The BTS 106 also includes a second output 316 for releasing data packets for forwarding over the network 100.
Specific to the present invention, the BTS 1~6 includes ~xn address translator unit 304 and a third input 310 for receiving signaling information from the address updating Ref. 11725ROUSOlU
unit 212. In the forward direction, the address translator unit 304 performs a reverse address translation on the translated location addresses of data packets received at first input 308, replacing the translated location addresses with the original identity destination addresses that are included with the data packets that are sent as radio frames from first output 312. In the reverse direction, if the data packets received at second input 314 are being sent to a mobile end station, the address translator unit 304 performs a location address translation on the destination addresses of the data packets, generating translated location addresses that are included with the data packets that are released to the network 100 from second output 316. If the data packets received at second input 314 are being sent to a fixed end station, they are passed to second output 316 without performing any address translation operation. A data storage unit 306 is operative to store the location and identity information for the plurality of mobiles 112, susceptible to move within the network domain, in an address translation table. The address translator unit 304 updates the contents of the address translation table on a basis of the signaling information received at third input 310 from the address updating unit 212. Further, the address translator unit 304 consults the address translation table for performing the address translation operation on data packets received at inputs 308 and 314, on a basis of the destination address of these data packets.
The structure of an edge router 104 is similar to that shown in Figure 3, and as such will not be described in aetail. In particular, specific to the present invention, the edge router 104 includes an address translator unit, with Ref. 11725ROUS01U
data storage unit, as well as an input for receiving signaling information from the address updating unit 212.
Dote that in an alternative example of implementation, the address translator 200 is implemented as a plurality of stand-alone address translator units, distinct from the edge routers 104, 106, located at the edges of the network 100.
Such stand-alone address translator units will simply intercept data packets prior to their arrival at the edge routers 104, 106, perform the appropriate address translation operation and pass the data packets on to the corresponding edge router 104 or 106. The stand-alone address translator units will include an input for receiving the signaling information from the address updating unit 212, a processor and a data storage unit for storing the location information for the plurality of mobiles 112 serviced by the network 100.
The processor will perform the appropriate address translation operation on data packets received at the stand-alone address translator unit prior to their release to the corresponding edge router 104 or 106.
Assume that in a specific example of implementation a wireless cellular telecommunications network 100 implements an IP based architecture, as shown in Figure 5, where the network 100 is associated with a globally unique address space 47Ø0.0/8. Each mobile 112 is assigned a globally unique IP address from the network's globally unique address space (47Ø0.0/8), corresponding to the identity of the mobile 112. For example, in Figure 5 mobile 112 is assigned identity 47.1.1.23. In order to provide for the dynamic Nature of the location of the mobiles 112 within the network domain, a private address space is associated with every node within the wireless network 100, including the edge routers Ref. 11725ROUSOlU
104 and 106. When a mobile 112 enters the geographical region 108 covered by a particular BTS 106, the latter being associated with a particular private address space, the particular BTS 106, aware of the mobile 112 that is now located within its coverage area, will send a location update to the address updating unit 212. On a basis of this location update, the address updating unit 212 will assign to the mobile 112 a private address, selected from the pool of addresses belonging to the private address space of the l0 particular BTS 106, corresponding to the location of the mobile 112. For example, in Figure 5 the mobile 112 is assigned location 10.1.1.87, an address selected from the private address space 10.1.1.0/24 of the BTS 106. The address updating unit 212 will then generate and send signaling information indicative of the identity 47.1.1.23 and the location 10.1.1.87 of the mobile 112 to the address translator 200 which will update the contents of its data storage unit 204.
Data packets arriving from external data packet network 110 will include a destination address representative of the identity :.:f mobile 112, specifically 47.1.1.23. Assuming that the address translator 200 is implemented as functional units within the edge routers 104 and 106, when the data packets are first intercepted at edge router 104 (10Ø0.0/8) of the wireless network 100, the address translator unit will translate the destination address from the identity to the location of the mobile 112, specifically from 47.1.1.23 to
10.1.1.87. The data packets including the translated dest~~nation address representative of the location of the mobile 112 (10.1.1.87) are next forwarded by the commercial off the shelf IP routers 102 within the core of the wireless ne~work 100 based cn the translated destination address Ref. 11725ROUSOlU
(10.1.1.87). When the data packets arrive at the appropriate BTS 106 (10.1.1.0/24), the address translator unit will translate the destination address from the location to the identity of the mobile 112, specifically from 10.1.1.87 to 47.1.1.23. The BTS 106 will then send the data packets over t':ze RF link, including a destination address representative of the identity of the mobile 112, notably 47.1.1.23.
As shown in Figure S, when mobile 112 leaves the geographical region 108 served by a first BTS 106 ;=0.1.1.0/24) and enters the geographical region served by a second BTS 106 (10.2.2.0/24), the second BTS 106 will send a location update to the address updating unit 212. The address updating unit 212 will then assign a new private address to the mobile 112, specifically location 10.2.2.62, selected from the private address space (subnet) 10.2.2.0/24 of the corresponding BTS 106. The previously allocated private address, location 10.1.1.87, will now be available for new mobiles lit entering the geographical region 108 served by the first BTS 106 (10.1.1.0/24). The address updating unit 212 will next generate and send signaling information indicative of the updated location for mobile 112 tc the address translator 200.
In an alternative example of implementation, the address translation operation described above is not limited to mobiles susceptible to move within a single network domain, but may also be applied for mobiles susceptible to move within two or more network domains. In the example shown in Figure 7, a particular mobile 700 has left its home network 704 and ;~s ~risit-ing the external network 706, and a correspondent node 702 in external network 708 is sending data packets to the mobile 700. Although the correspondent Ref. 11725ROUSOlU
node 702 could send the data packets to the home network 704, where they could be intercepted and forwarded to the mobile 700 in the visited external network 706, this is an inefficient method of routing the data packets to the mobile 700.
Specific to this alternative example of implementation, the external networks 706 and 708 both include an address translator 200, which receives signaling information from the address updating unit 212 located within the home network 704. When a mobile enters the external network 706, it acquires a temporary address from the addwess space of the visited network 706, which is sent to the address updating unit 212. The address updating unit 212 then generates and sends signaling information indicative of the location (address in the visited network 706) of the mobile to the address translators 200 in the external network 706 and 708, which update the contents of their data storage units 204 accordingly. Data packets released from the correspondent node 702 that are destined for mobile 700 include a destination address that is representative of the identity of the mobile 700. These data packets are first intercepted at the address translator 200 located within the external network 708, where their destination address is translated from the identity to the location of the mobile 700. The data packets including the translated destination address are then sent directly to the external network 706 which is being visited by the mobile 700. Upon arrival at the external network 706, the data packets are intercepted a second time by an address translator 200. The address translator 200 in the visited network 706 re-translates the destination address included with the data packets from the location to the identity of the ~robile 700. Subsectuent to this second Ref. 11725ROUSOlU
address translation operation, the data packets are transmitted to the mobile 700.
In yet another alternative example of implementation, the address translation operation described above is performed on the source address included with data packets, as opposed to the destination address. Traditionally, the source address included with data packets emanating from a particular network is checked to ensure consistency with the address space advertised by the particular network. Where l0 r_he address in the source address field does not correspond t_o the address space advertised by the particular network, fihe data packets may be dropped for security reasons. In the example shown in Figure 7, data packets sent out by the mobile 700 while visiting external network 706 would include as a source address the identity of the mobile 700, specifically the global address from the address space of the home network 704. Since this does not correspond to the address space advertised by the network 706, there is a risk that data packets transmitted by the mobile 700 would be dropped en route to their destination, for example the correspondent node 702.
Specific to this second alternative example of implementation, the external networks 706 and 708 both include an address translator 200 which performs the address translation operation on the source address included with data packets received at input 206, as opposed to the destination address. Each such address translator 200 receives signaling information from the address updating unit 2 locG~ed within the home Network ?04. When a mobile enters the external network 706, it acquires a temporary address from the address space of the visited network 706, Ref. 11725ROUSOlU
which is sent to the address updating unit 212. The address updating unit 212 then generates and sends signaling information indicative of the location (address in the visited network 706) of the mobile to the address translators 200 in the external network 706 and 708, which update the contents of their data storage units 204 accordingly. Data packets released from the mobile 700 while visiting external network 706 that are destined for correspondent node 702 include a source address that is representative of the identity of the mobile 700. These data packets are first intercepted at the address translator 200 located within the external network 706, where their source address is translated from the identity to the location of the mobile 700, such that the source address corresponds to the address ~>pace advertised by network 706. The data packets including the translated source address are then sent directly to the external network 708, where the data packets are intercepted a second time by an address translator 200. The address translator 200 in the external network 708 re-translates the 2o source address included with the data packets from the location to the identity of the mobile 700. Subsequent to This second address translation operation, the data packets are transmitted to the correspondent node 702.
The above detailed description of the present invention should not be read in a limitative manner as refinements and variations are possible without departing from the spirit of the invention. The scope of the invention is defined in the appended claims and their equivalents.
(10.1.1.87). When the data packets arrive at the appropriate BTS 106 (10.1.1.0/24), the address translator unit will translate the destination address from the location to the identity of the mobile 112, specifically from 10.1.1.87 to 47.1.1.23. The BTS 106 will then send the data packets over t':ze RF link, including a destination address representative of the identity of the mobile 112, notably 47.1.1.23.
As shown in Figure S, when mobile 112 leaves the geographical region 108 served by a first BTS 106 ;=0.1.1.0/24) and enters the geographical region served by a second BTS 106 (10.2.2.0/24), the second BTS 106 will send a location update to the address updating unit 212. The address updating unit 212 will then assign a new private address to the mobile 112, specifically location 10.2.2.62, selected from the private address space (subnet) 10.2.2.0/24 of the corresponding BTS 106. The previously allocated private address, location 10.1.1.87, will now be available for new mobiles lit entering the geographical region 108 served by the first BTS 106 (10.1.1.0/24). The address updating unit 212 will next generate and send signaling information indicative of the updated location for mobile 112 tc the address translator 200.
In an alternative example of implementation, the address translation operation described above is not limited to mobiles susceptible to move within a single network domain, but may also be applied for mobiles susceptible to move within two or more network domains. In the example shown in Figure 7, a particular mobile 700 has left its home network 704 and ;~s ~risit-ing the external network 706, and a correspondent node 702 in external network 708 is sending data packets to the mobile 700. Although the correspondent Ref. 11725ROUSOlU
node 702 could send the data packets to the home network 704, where they could be intercepted and forwarded to the mobile 700 in the visited external network 706, this is an inefficient method of routing the data packets to the mobile 700.
Specific to this alternative example of implementation, the external networks 706 and 708 both include an address translator 200, which receives signaling information from the address updating unit 212 located within the home network 704. When a mobile enters the external network 706, it acquires a temporary address from the addwess space of the visited network 706, which is sent to the address updating unit 212. The address updating unit 212 then generates and sends signaling information indicative of the location (address in the visited network 706) of the mobile to the address translators 200 in the external network 706 and 708, which update the contents of their data storage units 204 accordingly. Data packets released from the correspondent node 702 that are destined for mobile 700 include a destination address that is representative of the identity of the mobile 700. These data packets are first intercepted at the address translator 200 located within the external network 708, where their destination address is translated from the identity to the location of the mobile 700. The data packets including the translated destination address are then sent directly to the external network 706 which is being visited by the mobile 700. Upon arrival at the external network 706, the data packets are intercepted a second time by an address translator 200. The address translator 200 in the visited network 706 re-translates the destination address included with the data packets from the location to the identity of the ~robile 700. Subsectuent to this second Ref. 11725ROUSOlU
address translation operation, the data packets are transmitted to the mobile 700.
In yet another alternative example of implementation, the address translation operation described above is performed on the source address included with data packets, as opposed to the destination address. Traditionally, the source address included with data packets emanating from a particular network is checked to ensure consistency with the address space advertised by the particular network. Where l0 r_he address in the source address field does not correspond t_o the address space advertised by the particular network, fihe data packets may be dropped for security reasons. In the example shown in Figure 7, data packets sent out by the mobile 700 while visiting external network 706 would include as a source address the identity of the mobile 700, specifically the global address from the address space of the home network 704. Since this does not correspond to the address space advertised by the network 706, there is a risk that data packets transmitted by the mobile 700 would be dropped en route to their destination, for example the correspondent node 702.
Specific to this second alternative example of implementation, the external networks 706 and 708 both include an address translator 200 which performs the address translation operation on the source address included with data packets received at input 206, as opposed to the destination address. Each such address translator 200 receives signaling information from the address updating unit 2 locG~ed within the home Network ?04. When a mobile enters the external network 706, it acquires a temporary address from the address space of the visited network 706, Ref. 11725ROUSOlU
which is sent to the address updating unit 212. The address updating unit 212 then generates and sends signaling information indicative of the location (address in the visited network 706) of the mobile to the address translators 200 in the external network 706 and 708, which update the contents of their data storage units 204 accordingly. Data packets released from the mobile 700 while visiting external network 706 that are destined for correspondent node 702 include a source address that is representative of the identity of the mobile 700. These data packets are first intercepted at the address translator 200 located within the external network 706, where their source address is translated from the identity to the location of the mobile 700, such that the source address corresponds to the address ~>pace advertised by network 706. The data packets including the translated source address are then sent directly to the external network 708, where the data packets are intercepted a second time by an address translator 200. The address translator 200 in the external network 708 re-translates the 2o source address included with the data packets from the location to the identity of the mobile 700. Subsequent to This second address translation operation, the data packets are transmitted to the correspondent node 702.
The above detailed description of the present invention should not be read in a limitative manner as refinements and variations are possible without departing from the spirit of the invention. The scope of the invention is defined in the appended claims and their equivalents.
Claims (36)
1. A communication device for transporting data traffic exchanged between two end stations, namely a first end station and a second end station, the second end station being mobile, the data traffic being characterized by:
a) a forward direction of data flow from the first end station to the second end station;
b) a reverse direction of data flow from the second end station to the first end station;
c) the data flow in each direction of data flow includes data packets, said communication device comprising:
i) a first input for receiving data packets in the forward direction of data flow, the data packets at said first input having translated location addresses;
ii) a second input for receiving data packets in the reverse direction of data flow;
iii) a first output for releasing from said communication device data packets in the forward direction of data flow;
iv) a second output for releasing from said communication device data packets in the reverse direction of data flow;
v) an address translator coupled to said second input, said address translator being operative to:
- provide data packets at said second input with translated location addresses when the first end station receiving the data packets is mobile within a data network;
- permit passage of data packets at said second input to said second output without providing the data packets with translated location addresses when the first end station receiving the data packets is fixed within the data network.
a) a forward direction of data flow from the first end station to the second end station;
b) a reverse direction of data flow from the second end station to the first end station;
c) the data flow in each direction of data flow includes data packets, said communication device comprising:
i) a first input for receiving data packets in the forward direction of data flow, the data packets at said first input having translated location addresses;
ii) a second input for receiving data packets in the reverse direction of data flow;
iii) a first output for releasing from said communication device data packets in the forward direction of data flow;
iv) a second output for releasing from said communication device data packets in the reverse direction of data flow;
v) an address translator coupled to said second input, said address translator being operative to:
- provide data packets at said second input with translated location addresses when the first end station receiving the data packets is mobile within a data network;
- permit passage of data packets at said second input to said second output without providing the data packets with translated location addresses when the first end station receiving the data packets is fixed within the data network.
2. A communication device as defined in claim 1, wherein the translated location address of a data packet received at said first input is representative of the current location of the second end station within a data network.
3. A communication device as defined in claim 2, wherein a data packet received at said second input includes an identity destination address that is recognizable by the first end station as being uniquely representative of the first end station.
4. A communication device as defined in claim 3, wherein, when said first end station is mobile, the translated location address provided to a data packet received at said second input is representative of the current location of the first end station within a data network.
5. A communication device as defined in claim 4, wherein said address translator is operative to replace the translated location address of a data packet received at said first input with an identity destination address that is recognizable by the second end station as being uniquely representative of the second end station.
6. A communication device as defined in claim 5, said communication device further comprising a third input coupled to said address translator for receiving signaling information indicative of a location of a third end station within a data network, said address translator operative to associate the location of the third end station to an identity destination address that is recognizable by the third end station as being uniquely representative of the third end station.
7. A communication device as defined in claim 6, wherein said address translator includes a data storage unit for holding an address translation table mapping the location of the third end station to the identity destination address that is recognizable by the third end station as being uniquely representative of the third end station.
8. A communication device as defined in claim 7, wherein said address translator is operative to process the signaling information received at said third input to modify the address translation table.
9. A communication device as defined in claim 8, wherein said address translator is operative to search said address translation table on a basis of the identity destination address of a particular data packet received at said second input in order to determine whether the first end station is mobile or fixed.
10. A communication device as defined in claim 9, wherein, when the first end station is mobile, said address translator is operative to search said address translation table for the identity destination address of the particular data packet received at said second input in order to derive the translated location address to be provided to the particular data packet.
11. A communication device as defined in claim 10, wherein said address translator is operative to search said address translation table for the translated location address of a particular data packet received at said first input to derive the identity destination address that is recognizable by the second end station as being uniquely representative of the second end station.
12. A communication device as defined in claim 11, wherein the second end station is a first mobile in a wireless network, said communication device being implemented in a Base Transceiver Station (BTS) of the wireless network, the BTS servicing a first subnet within the wireless network.
13. A communication device as defined in claim 12, wherein the translated location address of a data packet received at said first input includes:
a) data representative of the first subnet;
b) differentiation information for distinguishing the first mobile from other mobiles located within the first subnet.
a) data representative of the first subnet;
b) differentiation information for distinguishing the first mobile from other mobiles located within the first subnet.
14. A communication device as defined in claim 13, wherein the identity destination address that is recognizable by the first mobile as being uniquely representative of the first mobile is a global IP address assigned to the first mobile within the wireless network.
15. A communication device as defined in claim 14, wherein the first end station is a second mobile in the wireless network.
16. A communication device as defined in claim 15, wherein the identity destination address that is recognizable by the second mobile as being uniquely representative of the second mobile is a global IP address assigned to the second mobile within the wireless network.
17. A communication device as defined in claim 16, wherein the translated location address provided by the address translator to a data packet received at said second input is representative of the current location of the second mobile within the wireless network.
18. A communication device as defined in claim 17, wherein the translated location address provided by the address translator to a data packet received at said second input includes:
a) data representative of a second subnet within the wireless network;
b) differentiation information for distinguishing the second mobile from other mobiles located within the second subnet.
a) data representative of a second subnet within the wireless network;
b) differentiation information for distinguishing the second mobile from other mobiles located within the second subnet.
19. An address updating unit for use in a wireless network including a plurality of fixed nodes and a plurality of mobile entities, said address updating unit operative to receive information associating data indicative of a location of a certain mobile entity in the wireless network and data indicative of an identity of the certain mobile entity and, on a basis of this information, generate address translation signaling information and distribute the address translation signaling information to a plurality of fixed nodes of the wireless network.
20. An address updating unit as defined in claim 19, wherein the data indicative of an identity of the certain mobile entity is recognizable by the certain, mobile entity as being uniquely representative of the certain mobile entity.
21. An address updating unit as defined in claim 20, wherein the address translation signaling information includes data representative of the current location of the certain mobile entity within the wireless network.
22. A system for transmitting data traffic between a first end station and a second end station, the second end station being mobile, the data traffic being characterized by:
a) a forward direction of data flow from the first end station to the second end station;
b) a reverse direction of data flow from the second end station to the first end station;
c) the data flow in each direction of data flow includes data packets, said system comprising:
a) a first unit for intercepting data packets in the forward direction of data flow, said first unit including:
- a first address translator operative to provide data packets traveling in the forward direction of data flow with translated location addresses;
ii) a second unit for intercepting data packets having translated location addresses traveling in the forward direction of data flow, said second unit including:
- a second address translator operative to replace the translated location addresses of data packets traveling in the forward direction of data flow with an identity destination address that is recognizable by the second end station as being uniquely representative of the second end station.
a) a forward direction of data flow from the first end station to the second end station;
b) a reverse direction of data flow from the second end station to the first end station;
c) the data flow in each direction of data flow includes data packets, said system comprising:
a) a first unit for intercepting data packets in the forward direction of data flow, said first unit including:
- a first address translator operative to provide data packets traveling in the forward direction of data flow with translated location addresses;
ii) a second unit for intercepting data packets having translated location addresses traveling in the forward direction of data flow, said second unit including:
- a second address translator operative to replace the translated location addresses of data packets traveling in the forward direction of data flow with an identity destination address that is recognizable by the second end station as being uniquely representative of the second end station.
23. A system as defined in claim 22, wherein each data packet traveling in the forward direction of data flow that is intercepted by said first unit includes an identity destination address that is recognizable by the second end station as being uniquely representative of the second end station.
24. A system as defined in claim 23, wherein the translated location address provided by said first unit to a data packet traveling in the forward direction of data flow is representative of the current location of the second end station within a data network.
25. A system as defined in claim 24, wherein said first and second units are further operative to intercept data packets traveling in the reverse direction of data flow, said second address translator being operative to:
a) provide data packets traveling in the reverse direction of data flow with translated location addresses when the first end station receiving the data packets is mobile within a data network;
b) permit passage of data packets traveling in the reverse direction of data flow without providing the data packets with translated location addresses when the first end station receiving the data packets is fixed within the data network.
a) provide data packets traveling in the reverse direction of data flow with translated location addresses when the first end station receiving the data packets is mobile within a data network;
b) permit passage of data packets traveling in the reverse direction of data flow without providing the data packets with translated location addresses when the first end station receiving the data packets is fixed within the data network.
26. A system as defined in claim 25, wherein, when the first end station is mobile within a data network, said first address translator is operative to replace the translated location address of a data packet traveling in the reverse direction of data flow with an identity destination address that is recognizable by the first end station as being uniquely representative of the first end station.
27. A system as defined in claim 20, wherein said first and second units include an input for receiving signaling information indicative of the location of a third end station within a data network, each of said first and second address translator units operative to associate the location of the third end station to an identity destination address that is recognizable by the third end station as being uniquely representative of the third end station.
28. A system as defined in claim 27, wherein each of said first and second address translators includes a data storage unit holding an address translation table mapping the location of the third end station to the identity destination address that is recognizable by the third end station as being uniquely representative of the third end station.
29. A system as defined in claim 28, wherein each of said first and second address translators is operative to process the signaling information received at said input to modify the address translation table.
30. A method for transmitting data traffic between a first end station and a second end station, the second end station being mobile in a data network, the data traffic being characterized by:
a) a forward direction of data flow from the first end station to the second end station;
b) a reverse direction of data flow from the second end station to the first end station;
c) the data flow in each direction of data flow includes data packets, said method comprising:
i) performing a first interception of the data packets traveling in the forward direction of data flow;
ii) providing the data rackets traveling in the forward direction of data flow with translated location addresses;
iii) performing a second interception of the data packets having translated location addresses traveling in the forward direction of data flow;
iv) replacing the translated location addresses of data packets traveling in the forward direction of data flow with an identity destination address that is recognizable by the second end station as being uniquely representative of the second end station.
a) a forward direction of data flow from the first end station to the second end station;
b) a reverse direction of data flow from the second end station to the first end station;
c) the data flow in each direction of data flow includes data packets, said method comprising:
i) performing a first interception of the data packets traveling in the forward direction of data flow;
ii) providing the data rackets traveling in the forward direction of data flow with translated location addresses;
iii) performing a second interception of the data packets having translated location addresses traveling in the forward direction of data flow;
iv) replacing the translated location addresses of data packets traveling in the forward direction of data flow with an identity destination address that is recognizable by the second end station as being uniquely representative of the second end station.
31. A method as defined in claim 30, wherein, at said first interception, each data packet traveling in the forward direction of data flow includes an identity destination address that is recognizable by the second end station as being uniquely representative of the second end station.
32. A method as defined in claim 31, wherein, at said first interception, the translated location address provided to a data packet traveling in the forward direction of data flow is representative of the current location of the second end station within a data network.
33. A method as defined in claim 32, said method further comprising:
a) performing a first interception of the data packets traveling in the reverse direction of data flow;
b) if the first end station is mobile within a data network i) providing the data packets traveling in the reverse direction of data flow with translated location addresses;
ii) performing a second interception of the data packets having translated location addresses traveling in the reverse direction of data flow;
iii) replacing the translated location addresses of data packets traveling in the reverse direction of data flow with an identity destination address that is recognizable by the first end station as being uniquely representative of the first end station;
c) if the first end station is fixed within the data network, permitting passage of data packets to the first end station without providing the data packets with translated location addresses.
a) performing a first interception of the data packets traveling in the reverse direction of data flow;
b) if the first end station is mobile within a data network i) providing the data packets traveling in the reverse direction of data flow with translated location addresses;
ii) performing a second interception of the data packets having translated location addresses traveling in the reverse direction of data flow;
iii) replacing the translated location addresses of data packets traveling in the reverse direction of data flow with an identity destination address that is recognizable by the first end station as being uniquely representative of the first end station;
c) if the first end station is fixed within the data network, permitting passage of data packets to the first end station without providing the data packets with translated location addresses.
34. A communication device for transporting data traffic exchanged between two end stations, namely a first end station and a second end station, the second end station being mobile, the data traffic being characterized by:
a) a forward direction of data flow from the first end station to the second end station;
b) a reverse direction of data flow from the second end station to the first end station;
c) the data flow in each direction of data flow includes data packets, said communication device comprising:
i) first input means for receiving data packets in the forward direction of data flow, the data packets at said first input means having translated location addresses;
ii) second input means for receiving data packets in the reverse direction of data flow;
iii) first output means for releasing from said communication device data packets in the forward direction of data flow;
iv) second output means for releasing from said communication device data packets in the reverse direction of data flow;
v) address translator means coupled to said second input means, said address translator means being operative to:
- provide data packets at said second input means with translated location addresses when the first end station receiving the data packets is mobile within a data network;
- permit passage of data packets at said second input means to said second output means without providing the data packets with translated location addresses when the first end station receiving the data packets is fixed within the data network.
a) a forward direction of data flow from the first end station to the second end station;
b) a reverse direction of data flow from the second end station to the first end station;
c) the data flow in each direction of data flow includes data packets, said communication device comprising:
i) first input means for receiving data packets in the forward direction of data flow, the data packets at said first input means having translated location addresses;
ii) second input means for receiving data packets in the reverse direction of data flow;
iii) first output means for releasing from said communication device data packets in the forward direction of data flow;
iv) second output means for releasing from said communication device data packets in the reverse direction of data flow;
v) address translator means coupled to said second input means, said address translator means being operative to:
- provide data packets at said second input means with translated location addresses when the first end station receiving the data packets is mobile within a data network;
- permit passage of data packets at said second input means to said second output means without providing the data packets with translated location addresses when the first end station receiving the data packets is fixed within the data network.
35. An address translator for data packets for use in a first data network comprising:
a) an input for receiving data packets including a source address representative of an identity of a mobile from which the data packets originated, the source address being an address selected from an address space of a second data network that is different from the first data network, the mobile susceptible to move within a network domain;
b) a processing unit coupled to said input for providing the data packets with a translated source address, where the translated source address is an address within the global address space of the first network;
c) an output for releasing the data packets including the translated source address.
a) an input for receiving data packets including a source address representative of an identity of a mobile from which the data packets originated, the source address being an address selected from an address space of a second data network that is different from the first data network, the mobile susceptible to move within a network domain;
b) a processing unit coupled to said input for providing the data packets with a translated source address, where the translated source address is an address within the global address space of the first network;
c) an output for releasing the data packets including the translated source address.
36. An address translator for data packets for use in a first data network comprising:
a) an input for receiving data packets including a translated source address, where the translated source address is an address within the global address space of a second data network that is different from the first data network;
b) a processing unit coupled to said input for replacing the translated source address with an identity source address representative of an identity of a mobile from which the data packets originated, the mobile susceptible to move within a network domain;
c) an output for releasing the data packets including the identity source address.
a) an input for receiving data packets including a translated source address, where the translated source address is an address within the global address space of a second data network that is different from the first data network;
b) a processing unit coupled to said input for replacing the translated source address with an identity source address representative of an identity of a mobile from which the data packets originated, the mobile susceptible to move within a network domain;
c) an output for releasing the data packets including the identity source address.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US60227000A | 2000-06-23 | 2000-06-23 | |
| US09/602,270 | 2000-06-23 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2313165A1 true CA2313165A1 (en) | 2001-12-23 |
Family
ID=24410686
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002313165A Abandoned CA2313165A1 (en) | 2000-06-23 | 2000-06-29 | Method and apparatus for data transmission in a wireless network |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2313165A1 (en) |
-
2000
- 2000-06-29 CA CA002313165A patent/CA2313165A1/en not_active Abandoned
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