Mobility management in wireless internet protocol networks

• US 20010044305A1
• Filed: 05/18/2001
• Published: 11/22/2001
• Est. Priority Date: 05/22/2000
• Status: Active Grant

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Reddy, Joseph Soma, Acampora, Anthony
• Granted Patent: US 6,907,017 B2
• Time in Patent Office: Days
• US Class Current: 455/436
• CPC Class Codes: H04L 61/5084 Providing for device mobility network addressing or numbering for mobility support in wireless networks H04W8/26; mobile IP H04W80/04
• CPC Class Codes: H04L 69/329 in the application layer [OSI layer 7]
• CPC Class Codes: H04W 36/0011 for data sessions of end-to-end connection
• CPC Class Codes: H04W 36/0019 adapted for mobile IP [MIP]
• CPC Class Codes: H04W 8/087 for preserving data network PoA address despite hand-offs
• CPC Class Codes: H04W 80/00 Wireless network protocols or protocol adaptations to wireless operation

Abstract

Handoff of (i) a mobile wirelessly communicating device—a mobile—between (ii) a plurality of stationary base stations within cells within a domain of (iii) a stationary gateway router all within (iv) a communications network based on the Internet Protocol (IP) is without interchange of control, and responsive to the mobile, only. The gateway router assigns to the mobile at a time before the handoff IP addresses suitable for the mobile to connect to the gateway router through all the plurality of base stations of the domain. Unilaterally deriving a handoff decision to switch base stations, the mobile directs its wireless communications link to a new base station where signal level registration is performed. Responsive to a link layer trigger at the new base station, the gateway router is informed of the handoff, and both the router and the mobile independently construct the mobile'"'"'s new IP address. Handoff latency is typically 40 ms.

Claims

1. A method of handing off of (i) a mobile wirelessly communicating device—

a mobile—

between (ii) a plurality of stationary base stations within cells within a domain of (iii) a stationary gateway router all within (iv) a communications network based on the Internet Protocol (IP), the method comprising;

assigning from the gateway router to the mobile at a time before the handoff a set of IP addresses suitable for the mobile to connect to the gateway router through all the plurality of base stations of the domain;

unilaterally deriving a handoff decision to switch base stations at the mobile;

directing a wireless communications link of the mobile to a new base station;

registering at a signal level at the new base station the wireless communications link of the mobile;

responsive to a link layer trigger at the new base station, informing the gateway router of the handoff; and

independently constructing at both the gateway router, and also at the mobile in consideration of the assigned set of IP addresses, the mobile'"'"'s new IP address;

wherein handoff transpires without interchange of control, and responsive to the mobile, only.

2. A method of an inter-cell handoff of (i) a mobile wirelessly communicating device between (ii) a plurality of stationary base stations within cells within a domain of (iii) a stationary gateway router all within (iv) a communications network based on the Internet Protocol (IP), the method comprising:

assigning, from the gateway router to the mobile at a time before the handoff, IP addresses suitable for the mobile to connect to the gateway router through all the plurality of base stations of the domain; and

, the mobile subsequently unilaterally deriving a handoff decision to switch base stations,

directing from the mobile its wireless communications link to a new base station;

registering at the signal level is performed with the new base station;

informing, responsively to a link layer trigger at the new base station, the gateway router of this handoff; and

independently constructing at both the mobile and the gateway router are the mobile'"'"'s new current address;

thereafter using at the gateway router the constructed new IP address of the mobile to tunnel packets to the mobile;

wherein the hand-off was summarily performed by the mobile alone, and without prior control communication with nor authorization of any of the plurality of base stations nor the gateway router.

3. A method of an inter-cell handoff of (i) a mobile wirelessly communicating device between (ii) stationary base stations within cells in a communications network based on the Internet Protocol (IP) CHARACTERIZED IN THAT

there is no, zero, over-the-air signaling to effectuate handoff.

4. The method according to

claim 3

FURTHER CHARACTERIZED IN THAT handoff latency is limited to delays

in a radio level of the handoff, and

in a wired network between the stationary base stations.

5. The method according to

claim 3

FURTHER CHARACTERIZED IN THAT

at a time before the handoff there is assigned to the mobile by a root node of the network not just one IP address from the network root node to the mobile through an initial one base station through which the mobile instantly first communicates, but instead an entire set of IP addresses from the root node to the mobile through each base station in the network;

and

the mobile stores this set of IP addresses.

6. The method according to

claim 5

FURTHER CHARACTERIZED IN THAT

self-registration of the mobile device with its new base station during the handoff is in consideration of the stored set of IP addresses.

7. A method of address registration of an Internet Protocol (IP) addressable mobile wirelessly communicating device, called a mobile, to successive stationary cellular base stations, one base station at a time, within an entire domain under a root node, called a gateway router, itself within a communications network based on the Internet Protocol (IP) CHARACTERIZED IN THAT

considering the network to have IP addresses that are fixed to each gateway router and stationary cellular base station, but variable to the mobile in consideration of where the mobile is within the domain and through which cellular base station it is presently communicating,

at a time of connection admission of a mobile to the network, assigning to the mobile not simply one IP address from the gateway router to the mobile through a single one base station through which the mobile instantly first communicates, but instead

assigning to the mobile an entire set of IP addresses suitable to address the mobile through each base station in the domain, if and when the mobile should ever wirelessly connect and communicate to each said base station.

8. The method address registration of an IP mobile according to

claim 7

extended to, at a later time then the assigning, handing off the mobile so registered between successive base stations of the network, the method FURTHER CHARACTERIZED IN THAT

when, due to movement, the mobile unilaterally determines that it wishes to communicate to and through another, new, cellular base station, then the mobile will, by reference to its assigned set of IP addresses, self-register with a new base station, by which self-registration the handoff is summarily completed.

9. In an Internet Protocol (IP) cellular communications network having

(i) a gateway router communicating to

(ii) intermediate cellular base stations within its domain, the domain of the gateway router, and further through these base stations to

(iii) wireless mobile devices called mobiles, these mobiles moving so as to communicate at different times to and through different ones of the base stations within the domain back to the gateway router;

an improvement wherein

a mobile is assigned a public IP address at a gateway router;

but

the mobile also has a current IP address at the base station with which it is communicating;

so that

packets addressed to the mobile first reach the gateway router; and

then

the gateway router funnels the packets to the mobile'"'"'s current base station address;

wherein the improvement is of the nature of micromobility scheme supporting hand-offs of the mobile between base stations.

10. In an Internet Protocol (IP) cellular communications network having

(i) a gateway router communicating to

(ii) intermediate cellular base stations within its domain, the domain of the gateway router, and further through these base stations to

(iii) wireless mobile devices called mobiles, these mobiles moving so as to communicate at different times to and through different ones of the base stations within the domain back to the gateway router;

an improvement wherein

a mobile measures pilot channels of a neighboring base station; and

, reason to switch base stations being derived,

the mobile makes a handoff decision and tunes its radio to the new base station;

whereupon

the mobile performs radio level registration with the new base station;

so that

a link layer trigger at the new base station informs the network layer of this handoff;

whereupon

the new base station informs the gateway router of the handoff;

so that

the mobile and the gateway router independently construct the mobile'"'"'s new current address;

whereafter

the gateway router uses the mobile'"'"'s new IP address to tunnel packets to the mobile;

wherein the improvement is of the nature of hand-off protocol supporting hand-offs of the mobile between base stations.

11. A method of an inter-cell handoff of (i) a mobile wirelessly communicating device between (ii) a plurality of stationary base stations within cells within a domain of (iii) a stationary gateway router all within (iv) a communications network based on the Internet Protocol (IP), the method comprising:

assigning from the gateway router to the mobile at a time before the handoff an IP address with (i) a public IP address pointing to the gateway router, but with (ii) another, second, current IP address that is variable dependent upon which of the plurality of base stations the mobile, in course of its physical movement within the domain, is communicating through, the mobile being supplied by the gateway router not only with this current IP address in respect of the initial one base station through which the mobile instantly first communicates, but also with this current IP address as besuits each and every base station within the domain through which the mobile might in the future communicate with the gateway router, the mobile thus having a complete set of IP addresses from the gateway router to the mobile through each base station in the network;

storing at the mobile this complete set of current IP addresses;

monitoring at the mobile pilot channels of one or more base station neighboring a base station through which it is presently communicating; and

,

deriving at the mobile a handoff decision to switch base stations;

directing at the mobile it'"'"'s wireless communications link to the new base station;

whereupon

registering at the signal level is performed with the new base station;

then, responsive to a link layer trigger at the new base station,

informing a network layer including the gateway router of this handoff;

so that, responsive to this informing,

independently constructing at both the mobile and the gateway router are the mobile'"'"'s new current IP address;

thereafter

using at the gateway router the constructed new current IP address of the mobile to tunnel packets to the mobile;

wherein the improvement is of the nature of hand-off protocol supporting hand-offs of the mobile between base stations.

12. A method of managing an Internet Protocol (IP) address of a wireless mobile unit (WMU) within an IP network having in a hierarchy a plurality of gateway routers each connected within its associated domain to a plurality of intermediate routers each connected to one or more base stations where any of the gateway routers, the intermediate routers, the base stations and the WMUs are within the IP network and have IP addresses, the method comprising:

whenever a WMU enters the domain of a gateway router,

assigning from the gateway router to the WMU (i) a globally-unique IP address, and

attributing to the WMU at the gateway router (ii) a plurality of new IP addresses,

wherein (1) the gateway router, (2) all base stations within the domain associated the gateway router, and (3) all WMUs that have been both (i) assigned globally-unique IP addresses and (ii) attributed a plurality of IP addresses, by the gateway router, collectively constitute, in combination with intermediate routers if any be present, a local domain called a “

cellular domain”

;

keeping track, at the gateway router in respect of the assigned globally-unique IP address of each WMU, as to which base station each WMU is currently communicating with within the cellular domain;

encapsulating at the gateway router for each network communications packet that is both (i) received from a corresponding host and (ii) addressed to some WMU within the cellular domain at the WMU'"'"'s globally unique IP address, a new IP packet having as a destination address some one of the plurality of attributed IP addresses of the WMU that is selected in consideration of which base station the WMU is currently communicating with and through; and

communicating the encapsulated packet in accordance with its new destination address to the destination WMU via said base station that is currently communicating with the WMU;

wherein addressing of the WMUs within the cellular domain is dynamic in consideration of the plurality of IP addresses (i) first attributed to a WMU by the gateway router of that cellular domain, and (ii) then used by the gateway router to encapsulate an IP packet destined for the WMU; and

wherein (i) the attribution of the set of IP addresses to each WMU by the gateway router, and (ii) the subsequent use by the gateway router of any of these attributed addresses to communicate an IP packet to a destination WMU, is transparent to the corresponding host, and also to the WMU above the IP layer of the WMU.

13. The method according to

claim 12

wherein the set of IP addresses attributed to each WMU within the cellular domain by the gateway router is a set of private IP addresses, meaning IP addresses that are unique only within the cellular domain and which private IP addresses are permissibly reused by other IP hosts, including by other gateway routers as are associated with other cellular domains.

14. The method according to

claim 12

wherein the set of IP addresses attributed to each WMU within the cellular domain by the gateway router is a set of IP addresses universally unique to each base station;

wherein when a IP host communicates with a WMU through the gateway router that is associated with that WMU then a packet is encapsulated with the IP address of the base station.

15. The method according to

claim 12

wherein the WMU communicates with other hosts upon the IP network in accordance with the global IP address that it has been loaned.

16. The method according to

claim 12

wherein the communicating is also via intermediate routers.

17. The method according to

claim 16

wherein the communicating is via intermediate routers having one routing table entry per base station.

18. A method of managing an Internet Protocol (IP) address of a wireless mobile unit (WMU) within an IP network, by which IP address the WMU is attached to the IP network, the IP network being divided into domains each of which domains is associated with a gateway router communicating to a plurality base stations wireless communicating to WMUs, the method comprising:

loaning with the gateway router of each domain to each WMU that is admitted into the domain a unique global IP address;

while also

attributing with the gateway router to each WMU that is admitted into the domain a set of new IP addresses;

wherein each WMU has (i) a unique global IP address, and also (ii) a set of new IP addresses from the gateway router of the domain to which it is admitted;

encapsulating each packet that is (i) received at the gateway router across the IP network and (ii) addressed to the WMU at its global address by action of wrapping the packet in another IP packet having an IP address from the set attributed to the WMU, which WMU IP address corresponds to one of the plurality of base stations currently serving the WMU; and

then

sending the encapsulated packet first to the one of the plurality of base stations that is currently communicating with the WMU, and then over the air to the WMU;

wherein a hand-off between base stations caused by movement of the WMU is by control message to the gateway router, which gateway router will thereafter encapsulate each packet destined to the moved WMU care of its new base station, and in accordance with the new WMU IP address that is associated with the new base station;

wherein IP packets destined for the WMU are always routed to the correct base station that is currently wirelessly connected to the WMU by action of an address-substitution-and-update interface between (i) the base station and the gateway router, or (ii) the WMU and the gateway router, or (iii) both the base station and the WMU and the gateway router;

wherein this address-substitution-and update interface is opaque to both (i) hosts upon the IP network addressing the WMU by its global IP address, and (ii) transport and application layers within the WMU itself.

19. The method according to

claim 18

wherein the set of new IP addresses attributed with the gateway router to each WMU is a set of private IP addresses each of which IP addresses of the set is associated with some particular one out of the plurality of base stations to which, and through which, particular one base station the WMU is presently communicating.

20. The method according to

claim 18

wherein the set of new IP addresses attributed with the gateway router to each WMU is a set of IP addresses each of which IP addresses of the set is universally unique to some particular one out of the plurality of base stations, some one of which, and through which, base stations the WMU is presently communicating.

21. The method according to

claim 18

wherein routing of at least some packets received at the gateway router to an addressed WMU is via an intermediate router.

22. A method of managing an Internet Protocol (IP) address of a wireless mobile unit (WMU) within a IP network having in a hierarchy (i) a plurality of gateway routers each connected to (ii) a plurality of intermediate routers each connected to (iii) s plurality of base stations each connectable to (iv) one or more WMUs, where each of the gateway routers, intermediate routers, base stations and WMUs has an IP address, the method comprising:

establishing for a domain associated with each gateway router (i) a public pool of unique, global IP addresses and (ii) a pool of private IP addresses associated with the base stations ultimately connected to the gateway router;

loaning with and from the gateway router of each domain to each WMU admitted to that domain one of the unique global IP addresses from the pool established for the domain;

wherein the loaned unique, global IP address is usable by the WMU to communicate upon the IP network for so long as the WMU is connected to any base station that is within the domain of the gateway router loaning the WMU the unique, global IP address;

receiving at a gateway router a packet addressed to some WMU within the domain of the gateway router, and encapsulating this packet within another IP packet having as its address one of the private IP addresses from the pool, which private IP address corresponds to a base station currently serving the WMU; and

then

sending the encapsulated packet to the base station currently serving the addressed WMU, and then over-the-air from this base station to the WMU;

whereupon when a WMU performs a hand-off between base stations, then a control message is sent by one or both of the base station and/or the WMU to the gateway router, this control message informing the gateway router of the change in identity of the base station currently serving the WMU;

whereupon the gateway router will accordingly change the private IP address used for wrapping those packets destined, via the base station currently serving the WMU, to the WMU;

wherein packets upon the network which are addressed to a particular WMU are always routed to and through a base station that is currently communicating with the WMU regardless that the WMU moves from one base station to another;

wherein communication of packets between (i) various base stations as may from time to time wirelessly communicate with the WMU as a consequence of movement of the WMU, and (ii) the gateway router, is transparent to the WMU, which WMU communicates with all other hosts on the network in accordance with the global IP address that it has been loaned.

23. The method according to

claim 22

wherein

each gateway server maintains a table of (i) each global IP address which has been loaned to a WMU within its domain, and (ii) the IP address of the base station currently serving each WMU;

wherein a table entry for each WMU is created when the WMU enters the domain; and

wherein the base station currently serving each WMU within the domain is updated whenever the WMU is handed off.

24. The method according to

claim 22

wherein

each base station maintains a table of (i) each global IP address which has been loaned to a WMU with which it is communicating, and (ii) a link layer address of the WMU;

wherein a table entry for each WMU is created when the WMU connects with the base station.