HK1158429B - Distributed infrastructure for wireless data communications - Google Patents

Description

Distributed infrastructure for wireless data communication

The present application is a divisional application of the chinese patent application entitled "distributed infrastructure for wireless data communication" as filed on 8.2002, 17.17. 02808481.0.

Technical Field

The present invention relates to wireless communication systems, and more particularly to wireless packet data networks.

Background

FIG. 1 shows a schematic view of a

Fig. 1 illustrates a conventional single-router wireless packet data network 100. The packet router 102 receives data packets from the rest of the network 104 and routes them to one or more network access points 106 and 110. Network access point 106 transmits packets forward to user terminal 112 over forward wireless link 114 and 116. The user terminal 112 transmits the packet back to the network access point 106 over the reverse wireless link 118-120-110. The user terminal 112 may be a cellular telephone carried by a person, a portable computer, a mobile telephone in a car, or any other mobile device that must provide connectivity even when mobile.

Control point 122 is coupled to packet router 102. It manages the wireless link 114 as well as 120. Management includes a number of functions. For example, as the user terminal 112 moves around, the path loss and network access point 106 and 110 between them change. In the case shown in fig. 1, the control point 122 must cause the user terminal 112 to transmit with the minimum amount of power that needs to be received by the at least one network access point 106 and 110. The mobile station transmit power is minimal because it causes interference to transmissions from other mobile stations. As the user terminal moves from the area served by network access point 106 to the area served by network access point 108, there is a handoff of the user terminal 112 from network access point 106 to network access point 108. The control point 122 must manage the handoff. Other management functions are known to those skilled in the art.

FIG. 2

Fig. 2 illustrates a conventional multi-router wireless packet data network 200 that supports mobility protocols such as mobile ip (mobile ip) as described in internet engineering Task Force RFC 2002. The second packet router 202 is connected to the first packet router 102, to the rest of the network 104, or both (as shown). The second packet router 202 is connected to a network access point 204 and 206. In fig. 2, user terminal 112 is moving from the area served by network access point 110, which is served by forward link 208, to the area served by network access point 204, which is served by forward link 210. The control point 122 manages the wireless links during the handoff (including the management of the reverse link 212 and 214) in the same manner as in the handoff shown in fig. 1. Control may be transferred from the first control point 122 to the second control point 222 as needed. These control points are connected to the first and second packet routers 102 and 202, respectively.

Fig. 2 also shows home agents 224 and 230 and foreign agents 226 and 228. The home agent 224 is coupled to the first packet router 102 and the foreign agent 226 is coupled to the second packet router 202.

The user terminal 112 has a network address for which the packet router 102 advertises reachability. Accordingly, a packet directed to the user terminal 112 is sent to the first packet router 102. When user terminal 112 is within the coverage area of a network access point (106) associated with packet router 102, packet router 102 forwards the packet to control point 122, which sends the packet for transmission to the network access point that currently provides the forward wireless link for user terminal 112.

The user terminal 112 may leave the area served by the first packet router 102 and may enter the area served by the second packet router 202. The network 104 will send packets directed to the user terminal 112 to the packet router 102, which will then forward them to the home agent 224, and the home agent 224 keeps track of the current location of the user terminal 112 in the form of a "care-of" address. The home agent would then encapsulate these packets within packets directed to the care-of address of the user terminal (e.g., foreign agent 226) and send the packets through packet routers 102 and 202. Upon receiving these packets, foreign agent 226 will decapsulate the packets and forward the packets for transmission to user terminal 112 to control point 222. Control point 222 would then forward the packet for transmission to the network access point that is currently providing the forward wireless link for user terminal 112.

In this way, control of the network access point for the data connection has moved from control point 122 to control point 222. In another conventional approach, control does not move between the two access points, where the packet router 102 continues to forward packets for transmission to the user terminal 112 to the control point 122, which then sends the packets directly to whatever network access point provides the forward wireless link to the user terminal 112, regardless of the system in which the network access points are located. For example, control point 122 may forward the packet for transmission to both network access point 106 and 110 and to network access point 204 and 206.

There are several basic problems with this structure: the control points for each part of the network are independent failure points that must be highly reliable, thereby increasing their cost. Moreover, since they are unique for each network, as the number of network access points increases, the architecture does not scale, with a consequent increase in the total number of mobile terminals that can be served, and therefore the load given to the control points. Finally, the advent of high speed wireless protocols requires low latency control of control points, which is not possible due to transmission and queuing delays between control points and network access points.

Further, because the router is connected to one or more network access points, failure of the router results in failure of user service within the area served by the one or more network access points to which the router is connected.

Disclosure of the invention

The applicant has provided a solution to the above-mentioned drawbacks of the architecture by decentralizing the functionality of the control points and allowing the control points to be co-located with each network access point. The architecture proposed by the applicant is further optimized by co-locating foreign agents as well as network access points and control points.

Moreover, if a particular architecture employs multiple routers, each access point may be connected to more than one router.

Brief Description of Drawings

Fig. 1 illustrates a conventional single-router wireless packet data network.

Fig. 2 illustrates a conventional multi-router wireless packet data network.

Fig. 3 illustrates a single router wireless packet data network in accordance with the present invention.

Fig. 4 illustrates a multi-router wireless packet data network in accordance with an embodiment of the present invention.

Fig. 5 illustrates a multi-router wireless packet data network in accordance with another embodiment of the present invention.

Modes for carrying out the invention

FIG. 3

Fig. 3 illustrates a single-router wireless packet data network 300 in accordance with the present invention.

The user terminal 302 is used to transmit and receive wireless data packets. There are a plurality of network access points 304 and 308, each for transmitting and receiving wireless data packets to and from the user terminal 302. Router 310 is capable of sending packets to and receiving packets from network access point 304 and 308. Fig. 3 illustrates a situation where a user terminal is leaving an area served by a first network access point 304 and entering an area served by a second network access point 306.

There are multiple control points 312 and 316. As in the prior art, each control point is used to manage the radio link 318 324 between the user terminal 302 and the selected network access point 304 and 308. However, there are multiple control points 312-316 rather than a single control point 122. In the present invention, a user terminal is served by a control point co-located with a first network access point with which the user terminal has established communication for a particular data exchange. In the example of fig. 3, a user terminal 302 is currently connected to two network access points 304 and 306. If the first network access point to serve the user terminal is network access point 304, the control point would be control point 312. Otherwise, the control point would be control point 314. By using the invention, a plurality of user terminals accessing the network can be controlled by a plurality of control points, thereby sharing the load among the control points. Furthermore, a failure of a control point will only affect the user terminals served by it, not all user terminals.

Each control point 312 and 316 is used to select a network access point 304 and 308 for communication with the user terminal 302. In fig. 3, the first control point 312 has selected the first network access point 304 as the network access point for communication with the user terminal 302. However, when the user terminal 302 leaves the area served by the first network access point 304 and enters the area served by the second network access point 306, the first control point 312 selects the two network access points 304 and 306 to communicate with the user terminal 302. However, the first control point 312 selects only the second network access point 306 to communicate with the user terminal 302, thereby causing a soft handoff. The first control point 312 may retain control even after the process ends, or it may transfer control to the second control point 314. The third control point is not used in the process just described but is available when the user terminal 302 moves into the area served by the third network access point 308. The operator may create any convenient method for determining when to maintain control within the current control point and when to transfer control to another control point.

Soft handoff is not the only possible event that triggers a decision as to whether to maintain control within the current control point or transfer control to another control point. The operator may use load sharing, control point failures, and similar considerations to determine when to trigger a decision.

Packets directed to the user terminal 302 are routed from the router 310 to the control point that currently controls communication with the user terminal 302 using a mobility protocol such as Internet Engineering Task Force RFC 2002.

The actual network access point used for communication with the user terminal may be different from the control point associated with the network access point or may be the same.

Each control point may select multiple network access points to concurrently communicate with the user terminal as needed. In this case, all of the selected network access points may be different from the control point's associated network access point, or one of the selected network access points may be the same as the control point's associated network access point.

Each control point may cache data link protocol information for the user terminal as needed when the user terminal is not assigned to a traffic channel. If this is done, the cache control point may be associated with the network access point used first by the user terminal, with the network access point used last by the user terminal, or with any other point.

FIG. 4

Fig. 4 illustrates a multi-router wireless packet data network 400 according to an embodiment of the present invention.

The user terminal 402 is used to transmit and receive wireless data packets. There are a plurality of network access points 404 and 412, each for transmitting and receiving wireless data packets to and from the user terminal 402. There are one or more routers 414 and 416 capable of transmitting data packets to and receiving data packets from the network access point 404 and 412. Each network access point 404 and 412 is connected to only one router 414 and 416. There are one or more local agents 418 and 420. Each local agent 418-420 is associated with a router 414-416. The home agent encapsulates packets directed to the user terminal registered with them within packets directed to the user terminal's current care-of address. The address is the address of a foreign agent co-located with the control point that is controlling the communication with the user terminal. The foreign agent may be connected to the same router as the home agent or to a different router. The use of home agents and foreign agents is well known to those skilled in the art and is described in mobility protocols such as internet engineering Task Force RFC 2002.

There are multiple foreign agents 422 and 430. Each foreign agent 422, 430 is associated with a network access point 404, 412 and a control point 432, 440. Each foreign agent is operable to receive packets for user terminals currently served by a control point with which it is co-located. The foreign agent receives packets directed to it. If the packets contain packets directed to such a user terminal, it decapsulates the packets and forwards them to the control point.

There are multiple control points 432 and 440. As shown in fig. 3, each control point 432-440 is associated with a network access point 404-412. Each control point 432 & 440 is configured to select one or more network access points 404 & 412 for communication with the user terminal 402. Each control point 432-. Thus, the user terminal 402 maintains communication with the rest of the network even while moving.

The selected network access point may be different from or the same as the control point's associated network access point.

Each control point may be configured to select multiple network access points to concurrently communicate with the user terminal. If so, all of the selected network access points may be different from the control point's associated network access point, or one of them may be the same.

After handoff, control may either remain within the originating control point or may be transferred to a control point associated with a new network access point. As shown in the arrangement of fig. 3, the operator may create any convenient method for determining when to maintain control within the current control point and when to transfer control to another control point. Also in the arrangement of fig. 3, a soft handoff is not the only possible event that triggers a decision as to whether to maintain control within the current control point or transfer control to another control point. The operator may use load sharing, control point failures, and similar considerations to determine when to trigger a decision.

In any event, each control point may also be used to cache data link protocol information for the user terminal when the user terminal is not assigned to a traffic channel. This may be done in a control point related to the network access point used first by the user terminal, the network access point used last by the user terminal, or any other point.

FIG. 5

Fig. 5 illustrates a multi-router wireless packet data network 500 according to another embodiment of the present invention.

The wireless service area of the wireless packet data network 500 is covered by a plurality of network access points 502, five of which are shown for illustration purposes 502(1), 502(2), 502(3), 502(4), and 502 (5). The network access point 502 is configured to transmit signals to a plurality of user terminals 516 over a forward wireless link 518 and to receive signals from the plurality of user terminals 516 over a reverse wireless link 520. Each network access point 502 is connected to a plurality of packet routers 506. Each connection between any packet router 506 and any network access point 502 is used to provide bi-directional switching of data packets. The packet router 506 is connected to the rest of the network 508. Also, the packet routers 506 may be connected two by two.

Packets directed to a user 516 via a network 508 are provided to one of the routers 506, such as router 502 (1). The decision of which router 506 to use is made in accordance with routing protocols such as Open Shortest Path First (OSPF), Border Gateway Protocol (BGP), and other routing protocols known to those skilled in the art. Packet router 502(1) forwards the packet to home agent 510(1) associated with router 506 (1). The home agent 510(1) is used to keep track of the current location of the user terminal 516 in the form of a care-of address. The care-of address is the address of the foreign agent 512 co-located with the access point serving the user terminal 516. The use of home agents and foreign agents is well known to those skilled in the art and is described in mobility protocols such as Internet Engineering Task Force RFC 2002. The home agent 510(1) then encapsulates the packet into a packet directed to the care-of address of the user terminal 516 (e.g., foreign agent 512(3)), and sends the encapsulated packet over the connection between the packet router 506(1) and the network access point 502 (3).

Upon receiving the encapsulated packet, foreign agent 512(3) decapsulates the encapsulated packet and forwards the packet for transmission to user terminal 516 to control point 514(3) associated with network access point 502 (3). Control point 514(3) manages wireless links 518(3) and 520 (3). Management includes power control, handoff, and other management functions known to those of ordinary skill in the art. The control point 514(3) forwards packets for transmission to the network access point 502, the network access point 502 now providing a radio link for the user terminal 516.

As described above, the user terminal 516 is served by the control point 514(3), which is co-located with the network access point 502(3), the user terminal 516 having established communication with the network access point 502 (3). However, as shown in fig. 5, the user terminal 516 is moving from an area served by the network access point 502(3) to an area served by the network access point 502 (4). Control point 514(3) now manages the wireless links 518 and 520 of the two network access points 502(3) and 502 (4). In one embodiment, once the user terminal 516 leaves the area served by the network access point 502(3) and goes to the area served by the network access point 502(4), the control point 514(3) continues to manage the second network access point 502 (4). In another embodiment, control point 514(3) transfers management to control point 514(4) once user terminal 516 leaves the area served by network access point 502(3) and travels to the area served by network access point 502 (4). Also, although two access point 502 handoffs have been described, each control point 514 may be used to manage multiple network access points 502 to concurrently communicate with the user terminal 516.

Although two specific embodiments have been described, due to the distributed nature and full interconnectivity of the network, a network operator may create any convenient method for determining when to maintain control within a current control point 514 and to transfer control to another control point 514. Thus, the actual network access point 502 communicating with the user terminal 516 may be different from, or may be the same as, the control point 514 associated with the network access point 502.

A soft handoff is not the only possible event that triggers a decision as to whether to maintain control within the current control point 514 or transfer control to another control point 514. The operator may use load sharing, control point 514 failures, and similar criteria to determine when to trigger a decision.

Each control point 514 may cache the data link protocol information for the user terminal 516 as needed when the user terminal 516 is not assigned to a traffic channel. If this is done, the cache control point 514 may be associated with the network access point 502 first used by the user terminal 516, the network access point 516 last used by the user terminal, or any other network access point 502.

Industrial applicability of the invention

The present invention is capable of use in industry and of being manufactured and used regardless of whether a distributed packet data network is expected to provide mobility.

Several examples and modes of practicing the invention are described herein. The true spirit and scope of the invention should not be limited thereto, however, and it is intended that the appended claims and their equivalents be limited only.

Claims (8)

1. A wireless data communication system apparatus, comprising:

a plurality of network access points; and

a plurality of control points, each control point of the plurality of control points associated with one of the plurality of network access points,

each network access point of the plurality of network access points is configured to:

communicating with at least two routers of a plurality of routers through the at least two routers being directly connected to the plurality of routers; and

communicating with at least one remote user under control of an associated control point, the associated control point managing a handoff of the at least one remote user.

2. The wireless data communication system apparatus of claim 1, wherein each control point of the plurality of control points is configured to control communication between at least one network access point of the plurality of network access points and the at least one remote user.

3. The wireless data communication system apparatus of claim 1, wherein each control point of the plurality of control points is configured to transfer control over at least one network access point of the plurality of network access points to a different control point.

4. The wireless data communication system apparatus of claim 1, further comprising:

a plurality of routers; and

a plurality of home agents, each of the plurality of home agents associated with a router of the plurality of routers.

5. The wireless data communication system apparatus of claim 1, further comprising:

a plurality of foreign agents, each foreign agent of the plurality of foreign agents being co-located with a network access point of the plurality of network access points.

6. A method of data flow control in a distributed data communication system, comprising:

receiving, at a network access point, data for transmission to a remote user; and

transmitting the received data from the network access point to the remote user over a wireless link under control of a first control point that manages handoff of the remote user and is co-located with the network access point, wherein the network access point is configured to communicate with at least two of a plurality of routers through the at least two routers being directly connected to the plurality of routers.

7. The method of claim 6, wherein said transmitting received data from said network access point to said remote user over said wireless link under control of said first control point, said first control point managing handoff of said remote user and co-located with said network access point comprises:

transmitting the received data from the network access point to a remote user under control of the first control point, the first control point being co-located with a network access point different from the transmitting network access point.

8. The method of claim 6, further comprising transferring control from the first control point to the second control point.