GB2442041A

GB2442041A - A method of selecting a network access point for handover

Info

Publication number: GB2442041A
Application number: GB0618105A
Authority: GB
Inventors: Angelo Centonza
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2006-09-15
Filing date: 2006-09-15
Publication date: 2008-03-26
Anticipated expiration: 2026-09-15
Also published as: GB2442041B; GB0618105D0

Abstract

A mobile communication device (1) sends an indication to a serving radio access point (2) of all radio access points (2, 3, 4) it can detect and a communication application type. The indication is formulated from the serving radio access point (2) to a serving network access point (6) and it is determined whether any detected radio access points are controlled by the serving network access point. If detected radio access points are not controlled by the serving network access point (6), the indication is forwarded to an anchor point (5) which determines which new network access point (7, 8) of the detected radio access points (3, 4) best serves the required application type and location of the mobile device and then a handover decision is provided to the serving network access point and to the new network access point.

Description

A METHOD OF SELECTING A NETWORK ACCESS POINT FOR HANI)OVER

OF A MOBILE DEVICE

This invention relates to a method of selecting a network access point for handover of a mobile device, in particular where diffrent types of network access point are within range.

In hybrid systems where there is no access between different radio access network gateways. there needs to he a method of target network access point section.

A particular example of this is in bng term evolution (LTE)/system architecture evolution (SAE) scenario for universal mobile telecommunications system (UMTS) networks where it is desirable for different access networks to he able to be interconnected, although the invention is not limited to this type of network. In this type of scenario, a node, or system anchor point, managing a number of base stations, known as nxbilily management entity plus user plane entity (MME/UPE) in the UMTS network and as wireless local area network (WLAN) access points in a WLAN network, is also allowed to have connections to neighbour base stations "outside" its domain of control. These outside base stations may be part of a network which is owned or managed by a different operator. The ability of the MME/UPE to connect to "external" NodeBs is by virtue of an interface which allows more than one MMEIUPE to he connected to one NodeB, so as to reduce delays during cross domain hardovers.

In UMTS, this interface is known as the SI-flex interface.

In accordance with a first aspect of the present invention a method of selecting a network access point for handover of a mobile device comprises sending an indication from the mobile device to a serving radio access point of all radio access points detected and a communication application type; forwarding the indication from the serving radio access point to a serving network access point: determining whether any detected radio access points are controlled by the serving network access point; if any are not controlled by the serving network access point, forwarding the indication to an anchor point; determining at the anchor point which new network access point of the detected radio access points best serves the required application type and location of the mobile device; and providing a handover decision to the serving network access point and to the new network access point.

Preferably, the chosen new network access point automatically signals to the serving network access point to release resources and allow a handover, in response to the handover decision from the anchor point.

Preferably, a table of network access points and related radio access points is stored al the anchor point.

Preferably. a handover request is made by pinging the network access points.

Preferably, the pinging handover request detci-mines load factor, quality of service and cost at each new network access point.

Preferably, the new network access point is determined from a combination of availability, communication application type, resources and round trip delay in response to the handover request from the anchor point.

Preferably, the network access points comprise any of wireless local area networks, WIMAX. or UMTS networks.

Preferably. the application type comprises one of voice, data, or streaming.

An example of a method of selecting a network access point for handover of a mobile device in accordance with the present invention will now he described with reference to the accompanying drawings in which: Figure 1 is a block diagram illustrating a network scenario for integrated Figure 2 illustrates a message exchange sequence for load sharing technique in hybrid networks for inter/intra handover.

The SI-flex interface links MME/IJPE with Node Bs and can cover node B's which are outside the operator domain in a border domain belonging to another operator, so that UE's do not stiffer discontinuity from hard handover, which is particularly important e.g. in voice, video conferencing, or mobile tv. The present invention addresses the problem of target MME/UPE selection in cases when the UR moves outside the SI-flex domain of a serving MME/UPE. Load sharing in hybrid networks like the LTE/SAE network is essential for efficient operation of the telecommunication platform. However, to date, no specific techniques or criteria for load sharing have been determined.

In the example of Fig. I, a liE I is nioving out of range of its serving radio access point, or node B 2 and sensing a stronger signal from other access points, so the UE requires a handover to a new access point. The UE is within range of another Node B 3 in the same SI-flex domain as its serving node B 2 and is also within range of a WLAN access point 4. In its current set up. the UE 1 receives traffic along a route from a gateway, in this case a system anchor point 5. via a serving network access point 6, MME/UPE and the serving node B 2.

The present invention determines how to select the best network access point (MMR/UPE, WLAN access network gateway, etc.) in a platform formed by different radio access networks, such as WLAN and UMTS. The hybrid system has the characteristic of having one anchor point 5 from which traffic is distributed to the appropriate radio access network (RAN). This anchor point is provided with relevant information on the type of application the new traffic load belongs to, so that the anchor point can decide which RAN this traffic needs to be handed over to. The steps for this technique are described in more detail with reference to Fig. 2.

The liE I carries out radio access point detection 9 by performing measurements on all available access points and once a set of access points 3. 4 has been detected, typically on the basis of signal strength, then the UE I sends a request to the serving MME/UPE 6 for handover, listing the radio access points 3, 4 discovered and the type of application used, i.e. voice, lile transfer, etc. The serving MME/UPE 6 receives the request 10 and carries out a radio access point check up 11 which determines that neither of' the radio access points 3. 4 detected by the liE 1 are under the domain of the serving MME/UPE One radio access point 3 is under the control of another MME/VPE 7 and the other radio access point 4 is under the control of a WLAN access network 8.

The serving MME/UPE 6 sends a message 12 to the anchor point 5 with the radio access points 3,4 discovered by the liE, along with an application class of each radio access point and a mobility entity handover request. The anchor point carries out mobility entity discover 13 by looking up in predefined tables to discover the mobility entities 7. 8 connected to the radio access points 3, 4 detected. The anchor point sends a ping-like handover request 14 to all the detected mobility entities 7, 8 and each mobility entity replies 15 immediately to the pinging and sends its load factor to the anchor point. The replies may also include the quality of service (QoS) supported and the cost of the radio bearer set up for that particular QoS and application.

The anchor point 5 calculates a round trip delay from the anchor point to each RAN gateway, or mobility entity, since the closest gateway for the same type of network niight he much further away than a gateway for a different type of network, or a gateway giving a weaker signal might have better functionality. The anchor point then makes a handovcr decision 16 based on the calculated round trip delay and other parameters required for that tJE. For example, if the UE application class is marked as "delay-sensitive" the anchor point will make a handover decision based Ofl the mobility entity with enough resources to sustain the application and with the lowest delay. If the application class is marked as "hit rate-sensitive" the anchor point will chose the mobility entity with lowest load factor. The anchor point then communicates 17 the handover decision to the serving MME/UPE 6 and to the selected mobility entity 8, requesting that the serving MME/UPF. release its resources and allow the transfer. The selected mobility entity 8 prepares I 8 bearer resources and radio resources for UE channel setup.

The technique of the present invention has the advantage of reducing handover delays for delay sensitive applications when a user moves outside the RAN domain on which the user is camped. Also, this technique allows selecting the best RAN for traffic deployment based on the application type. i.e. delay-sensitive or bit rate-sensitive. The use of such a technique brings the advantage of having fast decision on load shearing even when the UE moves outside the SI -Flex domain. i.e. when it moves outside the scope of an MME/UPF. or equivalent access network gateway.

Claims

1. A niethod of selecting a network access point for handover of a mobile device, the method comprising sending an indication from the mobile device to a serving radio access point of all radio access points detected and a communication application type; forwarding the indication from the serving radio access point to a serving network access point: determining whether any detected radio access Oj ills are controlled by the serving network access point; if any are not controlled by the serving network access point, forwarding the indication to an anchor point: determining at tile anchor point which new network access point of the detected radio access points best serves tile required application type ard location of tile mobile device; and providing a handover decision to the serving network access point and to tile new network access point.

2. A method according to claim I, wherein the chosen new network access point automatically signals to the serving network access point to release resources and allow a handover, in response to the handover decision from the anchor point.

3. A method according to claim I or claim 2, wherein a table of network access points and related radio access points is stored at the anchor point.

4. A method according to any preceding claim, wherein a handover request is made by pinging the network access points.

5. A method according to claim 4, wherein the pinging handover request determines load factor, ciuality of service and cost at each new network access point.

6.. A method according to claim 4, or claim 5, wherein the new network access point is determined from a combination of availability, communication application type, resources and round trip delay in response to the handover request from the anchor point.

7. A method according to any preceding claim, wherein the network access points comprise any of wireless local area networks, WI MAX, or UMTS networks.

8. A method according to any preceding claim. wherein the application type comprises one of voice, data, or streaming.