The interconnection system of a kind of LTE and WLAN and changing method
Technical field
The present invention relates to interconnecting and switching control problem of different wireless communication system, relate in particular to the interconnect system architecture of LTE (3GPP long evolving system) and WLAN (WLAN) and at the changing method of dual-mode terminal between two kinds of networks under this system architecture.
Background technology
Along with the diversified development trend of wireless communication technology, wireless networks such as GSM, UMTS, CDMA, Wi-Fi and LTE will coexist in one period, and multi-type network coexistence and fusion are mobile communication development in future trend.Existing heterogeneous network inserts and switches research and mainly concentrates on UMTS, CDMA and the WLAN, and internetwork fusion mode mainly contains loose coupling and close coupling dual mode.With WLAN and UMTS is example, and under the loose coupling framework, the Access Network of WLAN and UMTS is separate, and WLAN is connected with the UMTS core net through GGSN (GGSN).Under the close coupling pattern, WLAN is connected to the UMTS core net through GPRS serving GPRS support node (SGSN).Loose coupling has advantage on Project Realization, close coupling shows on performance of handoffs better.
At present for the connected mode of the most of loose coupling of adopting that is based on mobile IP technology of research of heterogeneous network.One Chinese patent application CN200810057535.7 (" a kind of heterogeneous wireless network of integration and communication means thereof "; Inst. of Computing Techn. Academia Sinica; On February 2nd, 2008) a kind of heterogeneous wireless network and communication means thereof of integration are provided, the Silkroad couple in router is positioned on the border of IPv4Internet and IPv6 network; Home agent equipment is the wireless wide area network service based on IPv4, is arranged in the network based on IPv6; Multi-module mobile terminal passes through the wireless wide area network based on IPv4 through the Silkroad tunneling mechanism, sets up the tunnel with the IPv6 network; Multi-module mobile terminal sends corresponding advertising of route according to parameters for tunnel to the tunnel interface of correspondence, and realization is communicated by letter with the IPv6 network.Through using this invention; Can in comprising the IPv4 wireless wide area network of network address translation apparatus or fire compartment wall, implement the MIPv6 agreement; For multi-module mobile terminal provides the seamless mobile environment of a unification and complete MIPv6 service function, significantly reduce the link load of wireless wide area network.One Chinese patent application CN200710161578.5 (" method of switching between a kind of heterogeneous wireless network, network entity and terminal "; Huawei Tech Co., Ltd; On September 29th, 2007) propose the method switched between a kind of heterogeneous wireless network, realized the quick switching problem of heterogeneous network.This method comprises pre-authentication information required when mobile node is confirmed pre-authentication, and mobile node is initiated the pre-authentication of objective network according to determined pre-authentication information, and after pre-authentication passed through, mobile node switched between heterogeneous network.Owing to carried out pre-authentication before between heterogeneous wireless network, switching, quickened the handoff procedure of mobile node at heterogeneous network.But these methods all be based on network layer and with on accomplish isomery and switch; These changing methods are less demanding for the coupling of heterogeneous system; Thereby the performance for switching also has considerable influence, particularly passing through between the heterogeneous network admit control realize aspect collaborative resource optimization management and the offered load optimum management ability a little less than.
Summary of the invention
The object of the present invention is to provide interconnection system and the changing method of a kind of LTE and WLAN, the present invention can reduce to switch the time delay of bringing between LTE and the WLAN, guarantees systematic function.
The interconnection system of a kind of LTE provided by the invention and WLAN, this system comprises Mobility Management Entity, gateway, and a plurality of LTE base station and a plurality of WLAN access point; Utilize interface to link to each other between each LTE base station, Mobility Management Entity is connected with gateway, and Mobility Management Entity all is connected with each LTE base station with gateway, and dual-mode terminal is through LTE wave point and LTE base station communication; It is characterized in that,
This system also comprises virtual base station; Virtual base station is connected with each WLAN access point with Mobility Management Entity, gateway and each LTE base station respectively;
In the LTE side, virtual base station is used for realizing and LTE base station identical functions that in the WLAN side, virtual base station is used to realize the function of route and tunnel transmission; Virtual base station is used for data are carried out route and are forwarded to corresponding WLAN access point as the interface that WLAN is linked into LTE; Data to sending to the LTE base station are transmitted; Mobility between the WLAN access point is managed; When LTE and WLAN switched, virtual base station encapsulated signaling and the data of LTE, makes signaling and data become the form that can on WLAN, transmit.
The changing method of above-mentioned interconnection system comprises the switching of dual-mode terminal from LTE to WLAN, and the switching from WLAN to LTE, it is characterized in that,
Switching from LTE to WLAN comprises steps A 1 to steps A 8:
Steps A 1 when the current service network of dual-mode terminal is LTE, and detects the signal of WLAN access point, and dual-mode terminal sends measurement report according to the measurement rule of LTE base station indication to the LTE base station; Measure the content that rule comprises trigger condition, measuring period and the measurement report of measurement and report; The content of measurement report comprises cell ID and cell signal quality;
Steps A 2, handover decisions is analyzed and done in the LTE base station with the measurement report of reporting of user; When meet switch to the WLAN access point after, the LTE base station sends to virtual base station with handoff request, changes steps A 3 then over to, otherwise finishes handoff procedure;
Steps A 3, after virtual base station was received handoff request, virtual base station was set up through the WLAN access point of reporting with measurement report and is got in touch, and obtains the available resources and the load information of WLAN access point, and does and admit control;
Steps A 4, virtual base station is according to admitting the control result that handover request ack message is returned to the LTE base station, and the LTE base station sends to dual-mode terminal according to handover request ack message with switching command, and handover request ack message comprises allowing to switch or refusing to be switched;
Steps A 5, the switching command that obtains when dual-mode terminal when allowing to switch, the authentication of the standard that dual-mode terminal and WLAN access point carry out defining in the WLAN agreement and operation associated; LTE carries out the base station to switch and prepares and buffer memory data of giving dual-mode terminal to be sent, simultaneously it is forwarded to virtual base station;
Steps A 6 behind the access procedure of dual-mode terminal completion and WLAN access point, is sent switching to virtual base station and is confirmed to ask, and the while virtual base station is made and switched the affirmation response;
Steps A 7; When virtual base station receives the handoff completion message at terminal; Virtual base station reports handoff completion message to give Mobility Management Entity, and Mobility Management Entity reports gateway with handoff completion message and asks user plane to be upgraded, and it mainly is that downlink path is switched in requirement that user plane is upgraded; After gateway completion downlink path is switched, send the user plane renewal to Mobility Management Entity and feed back, Mobility Management Entity receives that user plane renewal feedback back is to virtual base station transmission switching completion response;
Steps A 8, virtual base station are sent resource to the LTE base station and are released order after receiving and switching the completion response, and the LTE base station discharges the resource relevant with dual-mode terminal; Last virtual base station is transferred to dual-mode terminal with data cached through the WLAN access point, realizes the harmless transmission of data;
Switching from WLAN to LTE comprises that step B1 is to step B8:
Step B1; Dual-mode terminal current service network is WLAN; And detecting the LTE signal of base station, dual-mode terminal sends measurement report according to the measurement rule of virtual base station indication to virtual base station, measures rule and comprises the trigger condition of measurement and report and the content of measurement report; The content of measurement report comprises little distinctive emblem, cell signal quality;
Step B2, handover decisions is analyzed and done to virtual base station with the measurement report of reporting of user; After meeting switching condition, virtual base station sends to the LTE base station with handoff request, changes step B3 then over to, otherwise finishes handoff procedure;
Step B3 after LTE receives handoff request in the base station, does according to the relevant informations such as available resources and load of self and to admit control;
Step B4, the LTE base station is according to admitting the control result that handover request ack message is returned to virtual base station, and virtual base station sends to dual-mode terminal according to handover request ack message with switching command;
Step B5, the switching command that obtains when dual-mode terminal is that synchronous access procedure is carried out in dual-mode terminal and LTE base station, otherwise stops this handoff procedure when allowing switching; Virtual base station is carried out to switch and is prepared and buffer memory data of giving dual-mode terminal to be sent, simultaneously it is forwarded to the LTE base station;
Step B6 behind the access procedure of dual-mode terminal completion and LTE base station, sends switch acknowledgment message to the LTE base station;
Step B7; When the LTE base station receives the handoff completion message at terminal; The LTE base station reports handoff completion message to give Mobility Management Entity, and Mobility Management Entity reports gateway with handoff completion message and asks user plane to be upgraded, and it mainly is that downlink path is switched in requirement that user plane is upgraded; After gateway completion downlink path is switched, send the user plane renewal to Mobility Management Entity and feed back, Mobility Management Entity receives that user plane renewal feedback back is to the transmission switching completion response of LTE base station;
Step B8, the LTE base station is sent resource to virtual base station and is released order after receiving and switching the completion response, and the LTE base station discharges the resource relevant with dual-mode terminal; Last LTE base station is with the data cached dual-mode terminal that is transferred to.
Through introducing virtual base station, it is linked into the interface of LTE as WLAN.In the LTE side, virtual base station keeps transparent for the LTE side, has the function of general LTE base station.In the WLAN side, virtual base station can be controlled the WLAN access point.Switching between LTE and the WLAN realizes through virtual base station.Between virtual base station and WLAN access point, adopt Level 2 Tunnel Protocol L2TP or Ethernet tunnel protocol to realize data and the transmitting-receiving of signaling in the handoff procedure, with WLAN as the data of LTE system and the bottom transmission channel of signaling.The advantage of this method is for LTE, and handoff procedure and LTE handoff procedure are consistent, and is very little to the influence of existing LTE.WLAN is connected to LTE with a kind of tightly coupled mode, can satisfy user's quality of service requirements largely, reduces system and switches the time delay of bringing, and guarantees systematic function.
Description of drawings
Fig. 1 is the sketch map of a kind of LTE and WLAN heterogeneous network interconnect architecture;
Fig. 2 is the sketch map based on the user-plane protocol stack model of the LTE of L2TP agreement and WLAN interconnection;
Fig. 3 is the sketch map based on the control plane protocol stack model of the LTE of L2TP agreement and WLAN interconnection;
Fig. 4 is the sketch map based on the user-plane protocol stack model of the LTE in Ethernet tunnel and WLAN interconnection;
Fig. 5 is the sketch map based on the control plane protocol stack model of the LTE in Ethernet tunnel and WLAN interconnection;
Fig. 6 is the sketch map of the switching flow of dual-mode terminal from LTE to WLAN;
Fig. 7 is the sketch map of the switching flow of dual-mode terminal from WLAN to LTE.
Embodiment
The present invention has introduced the virtual base station entity, with the interface of virtual base station as WLAN and LTE intercommunication, the dual-mode terminal with LTE wireless access capability and WLAN wireless access capability can be switched between two kinds of networks.
Below through by embodiment and accompanying drawing the present invention being described in further detail, but following examples only are illustrative, and protection scope of the present invention does not receive the restriction of these embodiment.
As shown in Figure 1, LTE mainly is made up of Mobility Management Entity 1, gateway 2 and LTE base station 3.The functional definition of Mobility Management Entity 1, gateway 2 and LTE base station 3 meets the regulation of LTE consensus standard.N (n>0) individual LTE base station 3 can be arranged in the frame of broken lines among Fig. 1, utilize X2 interface to link to each other between the LTE base station 3.Link to each other through S1-MME interface between Mobility Management Entity 1 and each LTE base station 3.Gateway 2 utilizes S1-U interface to link to each other with each LTE base station 3.Mobility Management Entity 1 keeps being connected with each LTE base station in representing Mobility Management Entity 1 and gateway 2 and frame of broken lines being connected of gateway 2 and frame of broken lines among Fig. 1.Dual-mode terminal 6 is communicated by letter with LTE base station 3 through the LTE wave point.
WLAN is made up of virtual base station 4, WLAN access point 5.Virtual base station 4 links to each other with Mobility Management Entity 1 through S1-MME interface.Virtual base station 4 links to each other with gateway 2 through S1-U interface.Virtual base station 4 is connected to frame of broken lines through X2 interface and representes that virtual base station 4 is connected to each the LTE base station in the frame of broken lines through X2 interface.Virtual base station 4 can be managed the individual WLAN access point 5 of m (m>0).Virtual base station 4 communicates through Level 2 Tunnel Protocol (L2TP) or Ethernet tunnel protocol and WLAN access point 5.
Dual-mode terminal 6 is meant terminal equipments such as mobile phone with LTE access capability and WLAN access capability, computer.Data gateway 7 provides data, services for LTE and WLAN.The signal effective coverage range of each LTE base station 3 or each WLAN access point 5 is called a sub-district in the present invention.
Virtual base station 4 is linked into the interface of LTE as WLAN, and its major function is for to carry out route and to be forwarded to corresponding WLAN access point 5 data; Data to sending to LTE base station 3 are transmitted; Mobility between the WLAN access point 5 is managed; When LTE and WLAN switched, virtual base station 4 utilized Level 2 Tunnel Protocol L2TP or Ethernet tunnel protocol that signaling and the data encapsulation of LTE are become the form that can on WLAN, transmit.In the LTE side, virtual base station 4 has been realized and LTE base station 3 identical functions; In the WLAN side, virtual base station 4 has been realized the function of route and tunnel transmission.
In Fig. 2, provided based on the LTE of Level 2 Tunnel Protocol L2TP and the user-plane protocol stack model of WLAN interconnection.Data gateway 7 among the LTE all adopts the standard agreement stack model in the LTE agreement with gateway 2, adopts GPRS user-plane tunnel agreement GTP-U to realize the forwarding of packet.At virtual base station 4, will utilize PDCP PDCP to encapsulate again from the GTP-U packet of LTE side and become the PDCP bag.Between virtual base station 4 and WLAN access point 5, utilize Level 2 Tunnel Protocol L2TP to do encapsulation and carry out the transmission of data packet from the media access control layer MAC in the LTE protocol stack.
In Fig. 3, provided based on the LTE of L2TP agreement and the control plane protocol stack model of WLAN interconnection.Mobility Management Entity 1 all adopts the standard agreement stack model in the LTE agreement with virtual base station 4 at the protocol stack of LTE side.Virtual base station 4 is realized the S1-AP agreement identical with the LTE standard protocol stack and the conversion of PDCP, and the packet that just when transmitting with the signaling of WLAN access point 5, will come from media access control layer MAC utilizes Level 2 Tunnel Protocol L2TP to send to WLAN access point 5.
Also can between virtual base station 1 and WLAN access point 5, adopt privately owned Ethernet tunnel protocol to simplify protocol stack structure based on this thought, like Fig. 4 and shown in Figure 5.Through the forwarding of Ethernet tunnel realization packet, other part of protocol stack is identical with the protocol stack model based on Level 2 Tunnel Protocol between virtual base station 4 and the WLAN access point 5.The Ethernet tunnel is a kind of privately owned tunnel protocol.In ethernet ii type frame structure, there is type field to be used for representing the type of the data division in the frame.Represent that through the define styles field data division is the packet from the MAC layer in the frame, just can realize and L2TP Tunnel agreement identical functions.
In order to specify the present invention, the switching from LTE to WLAN is as shown in Figure 6, and its switching flow is:
The first step: dual-mode terminal 6 detects the signal of WLAN access point 5, sends measurement report according to LTE base station 3 indicated measurement configuration information to LTE base station 3.Particularly, measurement configuration information comprises measuring object, reports rule and quantizing rule.Measuring object mainly considers on which carrier frequency, which sub-district to be implemented to measure.Reporting rule is the mode of reporting, and reports after the Event triggered such as periodically reporting perhaps.Periodically send measurement report according to certain time interval when periodically reporting to LTE base station 3.Report the acknowledge(ment) signal power be meant in the sub-district after the Event triggered and send measurement reports to LTE base station 3 in greater than a certain threshold value, also the definable Else Rule is as reporting trigger condition.Quantizing rule is the quantizing rule that the received signal power of measuring is adopted, such as in some cycles, making even all or adopting filtering algorithm to carry out smoothly.Measurement report mainly comprises received signal power, cell ID and number of cells etc.Measurement report in this step comprises sign and signal power and other the little distinctive emblem and the signal power of WLAN access point 5.
Second step: the measurement report of LTE base station 3 analysis user also carries out handover decisions.When allowing to switch to WLAN access point 5, LTE base station 3 sends to virtual base station 4 with handoff request, otherwise any response is not done in LTE base station 3.If handover decisions is to switch to other LTE sub-district, then the switching law according to LTE carries out subsequent step.
Particularly, handover decisions is the deterministic process that whether can switch and switch to which sub-district to dual-mode terminal 6.Handover decisions can comprehensively be judged according to the signal power size of measurement report, the availability of respective cell and the resource operating position of this sub-district.With the sub-district availability is example, if though the sub-district signal quality in the measurement report reaches requirement, this sub-district does not allow to switch and gets into this sub-district, and then handover decisions is for forbidding switching to this sub-district.Handover decisions can require corresponding rule of design and algorithm according to systematic function.
The 3rd step: after virtual base station 4 was received the handoff request of sending LTE base station 3, virtual base station 4 was got in touch through setting up with the indicated WLAN access point 5 of handoff request, relevant informations such as the available resources of acquisition WLAN access point 5 and number of users, and do and admit control.Particularly, virtual base station 4 is according to the number of users, the available resources that obtain from WLAN access point 5 and whether satisfy that QoS of survice requires etc. the aspect judges whether to allow dual-mode terminal to be linked into WLAN access point 5, promptly admits control.Admit control to require corresponding rule of design and algorithm according to systematic function.With the number of users is example, but has reached the upper limit of service-user number when the number of users of WLAN access point 5, and then virtual base station 4 is just refused dual-mode terminal and is linked into WLAN access point 5.With available resources is example, when WLAN access point 5 does not have enough bandwidth, then refuses the access of dual-mode terminal.Whether to satisfy the QoS of survice requirement is example, when WLAN can't satisfy dual-mode terminal to the qos requirement of business, then refuses dual-mode terminal and inserts.Simultaneously, can consider simultaneously that also aspects such as number of users, available resources and QoS of survice requirement set up utility function, be used as admitting the foundation of control through the size of calculating utility function.
The 4th step: virtual base station 4 is according to admitting the control result that handover request ack message is returned to LTE base station 3, and LTE base station 3 sends to dual-mode terminal 6 according to handover request ack message with switching command.Handover request ack message is included in and allows that virtual base station 4 mainly comprises the address information of virtual base station etc. for the indicated system information of dual-mode terminal access under the switching condition.Particularly, because this instance is to switch to WLAN from LTE, WLAN access point 5 periodic its pilot frequency information of broadcasting and address informations, so dual-mode terminal just can obtain the address information and the pilot frequency information of WLAN access point when detecting the WLAN signal.
The 5th step: the switching command that obtains when dual-mode terminal 6 when allowing to switch, the authentication of the standard that dual-mode terminal 6 and WLAN access point 5 carry out defining in the WLAN agreement and operation associated.LTE base station 3 is carried out to switch and is prepared and buffer memory data of giving dual-mode terminal to be sent, simultaneously it is forwarded to virtual base station 4.The switching command that obtains when dual-mode terminal 6 then stops this handoff procedure when not allowing to switch, and data forwarding is not carried out in the LTE base station.Particularly, the authentication between dual-mode terminal 6 and the WLAN access point 5 and operation associated can be with reference to the WLAN consensus standard, dual-mode terminal 6 and WLAN 5 accomplish the access procedure of just having realized after operation associated with WLAN access point 5.
The 6th step: behind the access procedure of dual-mode terminal 6 completion and WLAN access point 5, send switching to virtual base station 4 and confirm.
The 7th step: when virtual base station 4 receives the handoff completion message of dual-mode terminal 6; Virtual base station 4 reports handoff completion message to give Mobility Management Entity 1; Mobility Management Entity 1 reports gateway 2 with handoff completion message and asks user plane to be upgraded, and it mainly is that downlink path is switched in requirement that user plane is upgraded.After gateway 2 completion downlink path are switched, send user plane renewal feedback to Mobility Management Entity 1, Mobility Management Entity 1 receives that user plane renewal feedback back is to virtual base station 4 transmissions switching completion response.
The 8th step: after virtual base station 4 receives and switch to accomplish response, send resources to LTE base station 3 and release order, LTE base station 3 discharges the resource relevant with dual-mode terminal 6.Last virtual base station 4 is transferred to dual-mode terminal 6 with data cached through WLAN access point 5, realizes the harmless transmission of data.
Switching flow from WLAN to LTE is as shown in Figure 7, and its switching flow and LTE are similar to the switching flow of WLAN, and the main difference point is: the first step, dual-mode terminal 6 are the signals that detect LTE base station 3, and send measurement report to virtual base station 4.In second step, virtual base station 4 analysis to measure reports is also carried out handover decisions, sends handoff request to LTE base station 3 after meeting switching condition.In the 3rd step, after LTE base station 3 receives handoff request, admit control according to the relevant informations such as available resources and number of users of oneself.In the 4th step, LTE base station 3 returns to virtual base station 4 with handover request ack message, and virtual base station 4 sends to dual-mode terminal 6 with switching command.In the 5th step, when allowing to switch, dual-mode terminal 6 carries out being linked into LTE base station 3 synchronously with LTE base station 3.Virtual base station 4 buffer memorys send to the data of dual-mode terminal 6 and send to LTE base station 3.In the 6th step, dual-mode terminal 6 sends to switch to LTE base station 3 to be confirmed.In the 7th step, handoff completion message is sent to Mobility Management Entity 1 in LTE base station 3, and Mobility Management Entity 1 reports gateway 2 with handoff completion message and asks user plane to be upgraded.In the 8th step, LTE base station 3 is sent resources to virtual base station 4 and is released order after receiving and switching the completion response
The above is preferred embodiment of the present invention, but the present invention should not be confined to the disclosed content of this embodiment and accompanying drawing.So everyly do not break away from the equivalence of accomplishing under the disclosed spirit of the present invention or revise, all fall into the scope of the present invention's protection.