CN103596232B - Vertical handoff method and device - Google Patents

Abstract

The invention discloses a kind of vertical handoff method, obtain information and the mode of priority of user's selection of each access network that the mobile terminal on motion carrier currently can access；Under the mode of priority that described user selects, determine that described mobile terminal switches to the switching probability of each described access network, and when the switching probability of presently described access network is less than the switching probability of other described access networks, make described mobile terminal switch to the network in other described access networks.The invention also discloses a kind of Vertical Handover device.Use technical scheme, user's preference to network can not only be met, and can guarantee that quality of handoff, reduce unnecessary switching.

Description

Vertical handoff method and device

Technical field

The present invention relates to the Vertical Handoff Technology of car networking arenas, particularly relate to a kind of vertical handoff method and device.

Background technology

Car networking i.e. vehicle Internet of Things, is accompaniment networking technology and the focus of Applied D emonstration research thereof.Along with car is networked Development, in car networking, each network of relating to tends to merging.By the fusion between heterogeneous network, each network can be maximum Play the advantage of self, thus meet user's demand to network.

At present, the wireless access technology related in car networking mainly has: the 1) wireless access (Wireless under vehicle environment Access in the Vehicular Environment, WAVE), WAVE is mainly used in in-vehicle wireless communication, serves as special short Cheng Tongxin (Dedicated Short Range Communications, DSRC) or the basis towards vehicle mounted communication, can prop up Holding more advanced focus switching, mobile environment, safety and authentication, transmission range can reach 1000 meters；Due to WAVE Belonging to WLAN (Wireless Local Area Networks, WLAN) family, the present invention hereafter will use WLAN Network represents WAVE network；2) worldwide interoperability for microwave accesses (Worldwide Interoperability for Microwave Access, WiMAX), it is a kind of emerging wireless access wide band technology, its message transmission rate is high, coverage distance 50km, supports the translational speed of node 160km/h；3) 3G (Third Generation) Moblie Cellular Networks technology (3rd-Generation, 3G Cellular), it has wide coverage, it is possible to realize seamless switching, the advantage supporting the node of high-speed mobile, but transmission Speed is limited.When vehicle travels at urban environment, vehicle typically accesses wlan network, and wlan network is mainly used in vehicle and car Between between (Vehicle-to-Vehicle, V2V) and vehicle and roadside base station (Vehicle-to-Roadside, V2R) Communication, usually used as the radio communication of car self-organization network under urban environment (Vehicular Adhoc Network, VANET) Technology；When vehicle travels in suburb, vehicle typically accesses WiMAX or 3G Cellular network；And when vehicle travels remote During area, vehicle typically accesses 3G Cellular network.

Car networking has that it is unique, is mainly manifested in: one, car networking belongs to heterogeneous wireless network, and two, in car networking Vehicle termination self has the characteristic of movement.Vertical Handover refers to the switching between different type network, to adapt to varying environment The demand of lower different business.Under heterogeneous wireless network environment, the terminal use of high-speed mobile needs access network whenever and wherever possible, But, in vertical handover procedure, when after the preference difference selected network due to terminal use and switching, network connects Between and state be difficult to be protected, it is impossible to meet the switching demand of user.

Summary of the invention

In view of this, a kind of vertical handoff method of offer and device are provided, can not only meet User's preference to network, and can guarantee that quality of handoff, reduce unnecessary switching.

For reaching above-mentioned purpose, the technical scheme is that and be achieved in that:

The invention provides a kind of vertical handoff method, described method includes: obtains the mobile terminal on motion carrier and works as The mode of priority that the information of the front each access network that can access and user select；Under the mode of priority that described user selects, Determine that described mobile terminal switches to the switching probability of each described access network, and general in the switching of presently described access network When rate is less than the switching probability of other described access networks, described mobile terminal is made to switch to the net in other described access networks Network.

In such scheme, described mode of priority includes that network continues mode of priority, network bandwidth mode of priority, network charges Mode of priority and business adapt to mode of priority, and wherein, described business adapts to mode of priority and includes containing the preferential mould of session service Formula and do not contain session service mode of priority.

In such scheme, when the mode of priority that described user selects is network lasting mode of priority, with described motion carrier Movement tendency under switching probability P_h1Described access network is switched to as described mobile terminal under continuing mode of priority at network The switching probability P of network_th；Wherein, the switching probability P under the movement tendency of described motion carrier is determined in the following manner_h1: P_h1=P (ΔD_n<0)；Wherein,ΔD_nFor access network set in the time period away from From accumulated change and, K₁For transmit power, K₂For the path loss factor, u (x) is the calculating function of interference signal intensity, and u (x) is Obedience average is 0, variance is σ₂Gaussian random distribution function, wherein, x is stochastic variable；M is within the described setting time period Docking signal receives the number of times that intensity level carries out sampling, and RSS (i) is the received signal strength of current sampling point, and RSS (i-1) is front The received signal strength of one sampled point, i is current sampling number, i=1,2 ..., M；The mode of priority that described user selects is During network bandwidth mode of priority, with the switching probability P under peak transfer rate_h2As shifting described under network bandwidth mode of priority Dynamic terminal switches to the switching probability P of described access network_bh；Wherein, determine in the following manner under described peak transfer rate C Switching probability P_h2:Wherein,For the minimum transfer speed needed for mobile terminal current business can be supported Rate, described peak transfer rateWherein, W is bandwidth,For signal to noise ratio, I (d) is the interference signal intensity received during distance d between motion carrier and Network Access Point；It is excellent that described user selects When first pattern is network charges mode of priority, using the normalization numerical value α of network charges as institute under network charges mode of priority State mobile terminal and switch to the switching probability P of described access network_ch；The mode of priority that described user selects is containing conversation class industry During business mode of priority, using normalization numerical value β corresponding to the network priority containing session service as containing conversation class industry Under business mode of priority, described mobile terminal switches to the switching probability P of described access network_sh；The mode of priority that described user selects During for not containing session service mode of priority, the normalization numerical value γ corresponding not contain the network priority of session service The switching probability P of described access network is switched to as mobile terminal described under not containing session service mode of priority_eh。

In such scheme, when the mode of priority that described user selects is network lasting mode of priority, described mobile terminal is cut The switching probability shifting to each described access network is: described mobile terminal occurs event h simultaneously₃、h₄、h₅And h₁Probability P (h₃h₄h₅h₁)；When the mode of priority that described user selects is network bandwidth mode of priority, described mobile terminal switches to each institute The switching probability stating access network is: described mobile terminal occurs event h simultaneously₃、h₄、h₅And h₂Probability P (h₃h₄h₅h₂)；Institute Stating mode of priority that user selects when being network charges mode of priority, described mobile terminal switches to each described access network Switching probability is: described mobile terminal occurs event h simultaneously₃、h₄And h₅Probability P (h₃h₄h₅) and be multiplied by the normalizing of network charges Change numerical value α；When the mode of priority that described user selects is containing session service mode of priority, described mobile terminal switches to often The switching probability of access network described in is: described mobile terminal occurs event h simultaneously₃、h₄And h₅Probability P (h₃h₄h₅) and take advantage of Normalization numerical value β with the network priority containing session service；The mode of priority that described user selects is not for containing session During class business mode of priority, described mobile terminal switches to the switching probability of each described access network and is: described mobile terminal There is event h simultaneously₃、h₄And h₅Probability P (h₃h₄h₅) and be multiplied by the normalization of the network priority not containing session service Numerical value γ；Wherein, h₁For occurring access network setting time period T_nInterior distance accumulation change and the event less than 0, h₂For sending out Raw peak transfer rate is more than the event of the minimum transmission rate can supported needed for mobile terminal current business, h₃For receiving Signal intensity can access the event of the minimum received signal strength threshold value needed for corresponding network, h more than described mobile terminal₄For sending out The raw bit error rate is less than the event of the maximum bit error rate meeting mobile terminal service demand, h₅The event blocked is there is not for network.

In such scheme, described method also includes: determine that described mobile terminal occurs event h simultaneously in the following manner₃、h₄ And h₅Probability P (h₃h₄h₅), determine described mobile terminal generation event h₃Probability P_h3=P (h₃)；Determine described mobile terminal In event h of generation₃On the basis of occur event h₄Probability P (h₄|h₃)；Determine that described mobile terminal occurs event h at the same time₃With h₄On the basis of occur event h₅Probability P (h₅|h₃h₄)；Determine that described mobile terminal occurs event h simultaneously₃、h₄And h₅Probability P(h₃h₄h₅)=P (h₃)*P(h₄|h₃)*P(h₅|h₃h₄)。

Present invention also offers a kind of Vertical Handover device, described device includes: acquiring unit and switch unit, wherein, Described acquiring unit, for obtaining information and the user of each access network that the mobile terminal on motion carrier currently can access The mode of priority selected；Described switch unit, under the mode of priority that described user selects, determines that described mobile terminal is cut Shift to the switching probability of each described access network, and at the switching probability of presently described access network less than other described accesses During the switching probability of network, described mobile terminal is made to switch to the network in other described access networks.

In such scheme, described mode of priority includes that network continues mode of priority, network bandwidth mode of priority, network charges Mode of priority and business adapt to mode of priority, and wherein said business adapts to mode of priority and includes containing session service mode of priority With do not contain session service mode of priority.

In such scheme, when the mode of priority that described user selects is network lasting mode of priority, with described motion carrier Movement tendency under switching probability P_h1Described access network is switched to as described mobile terminal under continuing mode of priority at network The switching probability P of network_th；Wherein, the switching probability P under the movement tendency of described motion carrier is determined in the following manner_h1: P_h1=P (ΔD_n<0)；Wherein,ΔD_nSetting for access network In time period distance accumulation change and, K₁For transmit power, K₂For the path loss factor, u (x) is the meter of interference signal intensity Calculate function, u (x) for obey average be 0, variance be σ₂Gaussian random distribution function, wherein, x is stochastic variable；M is in institute Stating docking signal in setting the time period and receive the number of times that intensity level carries out sampling, RSS (i) is that the reception signal of current sampling point is strong Degree, RSS (i-1) is the received signal strength of previous sampled point, and i is current sampling number, i=1,2 ..., M；Described user When the mode of priority selected is network bandwidth mode of priority, with the switching probability P under peak transfer rate_h2As at the network bandwidth Under mode of priority, described mobile terminal switches to the switching probability P of described access network_bh；Wherein, described in determining in the following manner Switching probability P under peak transfer rate C_h2:Wherein,For mobile terminal current business can be supported Required minimum transmission rate, described peak transfer rateWherein, W is bandwidth,For signal to noise ratio, I (d) is the interference signal intensity received during distance d between motion carrier and Network Access Point； The mode of priority that described user selects is when being network charges mode of priority, using the normalization numerical value α of network charges as at network Under expense mode of priority, described mobile terminal switches to the switching probability P of described access network_ch；The preferential mould that described user selects When formula is containing session service mode of priority, make with the normalization numerical value β that the network priority containing session service is corresponding The switching probability P of described access network is switched to for mobile terminal described under containing session service mode of priority_sh；Described use When the mode of priority that family selects is not for containing session service mode of priority, not contain the network priority pair of session service The normalization numerical value γ answered switches to described access network as mobile terminal described under not containing session service mode of priority The switching probability P of network_eh。

In such scheme, when the mode of priority that described user selects is network lasting mode of priority, described mobile terminal is cut The switching probability shifting to each described access network is: described mobile terminal occurs event h simultaneously₃、h₄、h₅And h₁Probability P (h₃h₄h₅h₁)；When the mode of priority that described user selects is network bandwidth mode of priority, described mobile terminal switches to each institute The switching probability stating access network is: described mobile terminal occurs event h simultaneously₃、h₄、h₅And h₂Probability P (h₃h₄h₅h₂)；Institute Stating mode of priority that user selects when being network charges mode of priority, described mobile terminal switches to each described access network Switching probability is: described mobile terminal occurs event h simultaneously₃、h₄And h₅Probability P (h₃h₄h₅) and be multiplied by the normalizing of network charges Change numerical value α；When the mode of priority that described user selects is containing session service mode of priority, described mobile terminal switches to often The switching probability of access network described in is: described mobile terminal occurs event h simultaneously₃、h₄And h₅Probability P (h₃h₄h₅) and take advantage of Normalization numerical value β with the network priority containing session service；The mode of priority that described user selects is not for containing session During class business mode of priority, described mobile terminal switches to the switching probability of each described access network and is: described mobile terminal There is event h simultaneously₃、h₄And h₅Probability P (h₃h₄h₅) and be multiplied by the normalization of the network priority not containing session service Numerical value γ；Wherein, h₁For occurring network setting time period T_nInterior distance accumulation change and the event less than 0, h₂For occurring Big transfer rate is more than the event of the minimum transmission rate can supported needed for mobile terminal current business, h₃For occurring to receive signal Intensity can access the event of the minimum received signal strength threshold value needed for corresponding network, h more than described mobile terminal₄For occurring by mistake Code check is less than the event of the maximum bit error rate meeting mobile terminal service demand, h₅The event blocked is there is not for network.

In such scheme, described device determines that described mobile terminal occurs event h simultaneously in the following manner₃、h₄And h₅General Rate P (h₃h₄h₅): determine described mobile terminal generation event h₃Probability P_h3=P (h₃)；Determine that described mobile terminal is occurring thing Part h₃On the basis of occur event h₄Probability P (h₄|h₃)；Determine that described mobile terminal occurs event h at the same time₃And h₄Basis Upper generation event h₅Probability P (h₅|h₃h₄)；Determine that described mobile terminal occurs event h simultaneously₃、h₄And h₅Probability P (h₃h₄h₅)=P (h₃)*P(h₄|h₃)*P(h₅|h₃h₄)。

The vertical handoff method of present invention offer and device, first obtain what the mobile terminal on motion carrier currently can access The mode of priority that the information of each access network and user select；Then, under the mode of priority that described user selects, determine institute State mobile terminal and switch to the switching probability of each described access network, and be less than at the switching probability of presently described access network During the switching probability of other described access networks, described mobile terminal is made to switch to the network in other described access networks. So, the present invention is that the effective access network of motion carrier provides guarantee, can not only meet user's preference to network, and And ensure that quality of handoff, reduce unnecessary switching.

Further, the present invention sets up decision tree with network attribute and mode of priority, under the mode of priority that user selects Carrying out trade-off decision, so, the objective network switched is optimal network, embodies terminal use's real needs to network.

Accompanying drawing explanation

Fig. 1 be vertical handoff method of the present invention realize schematic flow sheet；

Fig. 2 is the structural representation from selection decision tree of vertical handoff method embodiment one of the present invention；

Fig. 3 is the motion model schematic diagram between motion carrier and the Network Access Point of vertical handoff method of the present invention；

Fig. 4 is the structural representation from selection decision tree of vertical handoff method embodiment two of the present invention；

Fig. 5 is the composition structural representation of Vertical Handover device of the present invention.

Detailed description of the invention

The main thought of the present invention is: first obtain each access network that the mobile terminal on motion carrier currently can access Information and user select mode of priority；Then, under the mode of priority that described user selects, determine that described mobile terminal is cut Shift to the switching probability of each described access network, and at the switching probability of presently described access network less than other described accesses During the switching probability of network, described mobile terminal is made to switch to the network in other described access networks；So, can not only Meet user's preference to network, and ensure that quality of handoff, reduce unnecessary switching.

Here, described motion carrier is primarily referred to as vehicle, and described access network includes wlan network, WiMAX network and 3G Honeycomb (Cellular) network.

Here, described mode of priority includes that network continues mode of priority, network bandwidth mode of priority, the preferential mould of network charges Formula and business adapt to mode of priority, and wherein, described business adapts to the type of service that mode of priority comprises according to described mobile terminal It is divided into containing session service mode of priority and does not contains session service mode of priority.

Accordingly, when the mode of priority that described user selects is network lasting mode of priority, with the fortune of described motion carrier Switching probability P under dynamic trend_h1Described access network is switched to as described mobile terminal under continuing mode of priority at network Switching probability P_th；

When the mode of priority that described user selects is network bandwidth mode of priority, with peak transfer rate (Data Transfer Rate, DTR) under switching probability P_h2Institute is switched to as mobile terminal described under network bandwidth mode of priority State the switching probability P of access network_bh；

When the mode of priority that described user selects is network charges mode of priority, make with the normalization numerical value α of network charges The switching probability P of described access network is switched to for mobile terminal described under network charges mode of priority_ch；

When the mode of priority that described user selects is containing session service mode of priority, with the net containing session service Normalization numerical value β corresponding to network priority switches to described as mobile terminal described under containing session service mode of priority The switching probability P of access network_sh；

When the mode of priority that described user selects is not for containing session service mode of priority, not contain session service Normalization numerical value γ corresponding to network priority cut as mobile terminal described under not containing session service mode of priority Shift to the switching probability P of described access network_eh。

The technical solution of the present invention is further elaborated with specific embodiment below in conjunction with the accompanying drawings.

Fig. 1 be vertical handoff method of the present invention realize schematic flow sheet, as it is shown in figure 1, vertical handoff method of the present invention Comprise the following steps:

Step 101, obtains information and the user of each access network that the mobile terminal on motion carrier currently can access The mode of priority selected；

Here, described access network includes wlan network N₁, WiMAX network N₂With 3G Cellular network N₃。

At present, third generation partner program (The 3rd Generation Partnership Project, 3GPP) Define four class Business Stream grades altogether, be conversation class (Conversational Service), Streaming Media class respectively (Streaming Service), interactive class (Interactive Service) and background class (Background Service). Wherein, session service is the real time business of a quasi-representative, it is desirable to end-to-end delay and shake are little, and this type of business has voice meeting Words, multimedia conferencing and IP phone etc.；The data transmission of Streaming Media class business has unipolarity, is also real time business, to delay Requiring more relaxed, this type of business has video request program, internet video live broadcasting etc.；Interaction service uses request response modes, To postponing almost without requiring, this type of business main representative is web browsing；Transmission delay is not generally limited by background class traffic System, typical services such as E-mail or backstage FTP download etc..This four classes business has different wanting according to self feature to network Asking: what session service stressed is quality of the conversation, when its real-time characteristic needs network to switch, the impact on session is the least, 3G Cellular technology can ensure the quality of session, during so mobile terminal service comprises session service, WLAN well Network N₁, WiMAX network N₂With 3G Cellular network N₃Priority be N₃>N₂>N₁；Streaming Media class business datum amount compares Greatly, network is needed to have enough Bandwidth guaranteeds and cheap data costs, wlan network N₁, WiMAX network N₂And 3G Cellular network N₃Network priority be N₁>N₂>N₃；Interaction service is similar to the requirement of network with background class traffic, right Postponing less demanding, data volume is also little, so corresponding priority is N₁>N₂>N₃.In the ordinary course of things, on mobile terminal Business may comprise one or more business, this needs the preference combining user to consider decision-making.

The individual preference selected for network according to mobile terminal, the present invention first determines that following a few class is at user option excellent First pattern, described mode of priority includes that network continues mode of priority, network bandwidth mode of priority, network charges mode of priority and industry Business adapts to mode of priority.Wherein,

Described network continues mode of priority, is that user terminal wishes that certain network of access of long period is avoided occurring Many switchings, it is ensured that the network duration of access is the biggest.Continued the definition of mode of priority by described network, therefore exist Network continues under mode of priority, with the switching probability P under the movement tendency of described motion carrier_h1As at network persistently preferential mould Under formula, described mobile terminal switches to the switching probability P of a certain described access network_th。

Described network bandwidth mode of priority, is that user terminal wishes that accessed network has higher transfer rate.By The definition of described network bandwidth mode of priority, therefore under network bandwidth mode of priority, general with the switching under peak transfer rate Rate P_h2The switching probability P of a certain described access network is switched to as mobile terminal described under network bandwidth mode of priority_bh。

Described network charges mode of priority, be due to each network needed for communication cost differ, mobile terminal wishes to connect The network service entered spends than less expensive network；

Described business adapts to mode of priority, is that mobile terminal is under current business, it is desirable to the network of access is the most satisfied The requirement of terminal traffic；Described business adapts to mode of priority and includes again containing session service mode of priority and do not contain conversation class Business mode of priority.

The switching probability distribution under mode of priority without correspondence is adapted at described network charges mode of priority and business, this In, by the method for normalization numerical value, network charges and service priority can be normalized, normalization numeric representation User's preference to network, normalized value shows that the most greatly user is the highest for this network preference degree.

Step 102, under the mode of priority that described user selects, determines that described mobile terminal switches to each described access The switching probability of network, and at the switching probability of presently described access network less than the switching probability of other described access networks Time, make described mobile terminal switch to the network in other described access networks.

Below in conjunction with embodiment one and embodiment two, to abovementioned steps 102 be embodied as be further elaborated.

Embodiment one:

When the mode of priority that described user selects is network lasting mode of priority, under the movement tendency with described motion carrier Switching probability P_h1The switching probability of described access network is switched to as described mobile terminal under continuing mode of priority at network P_th；

Concrete, the movement tendency of described motion carrier refer to mobile terminal on motion carrier away from or connect close to network The state of access point.The movement tendency of described motion carrier is the important parameter triggering Vertical Handover, this is because it can have influence on Time and the switching times etc. of network are maintained after network insertion.The movement tendency of motion carrier has a front tropism, and it is believed that Within a short period of time, the movement locus of motion carrier is close to straight line.Fig. 3 is the motion carrier of vertical handoff method of the present invention And the motion model schematic diagram between Network Access Point, as it is shown on figure 3, when motion carrier moves to be in position A, motion carries Distance d between the access point C of body and network 3G Cellular₁Less than the distance between itself and the access point D of network WiMAX d₂.After motion carrier moves to position B, along with the access point C of the continuation of motion, motion carrier and network 3G Cellular Between distance d₁Increasingly greater than distance d between itself and the access point D of network WiMAX₂, according to changing method based on distance Then need again to carry out network switching, thus create ping-pong.And the method that the present invention changes sum by distance accumulation is come Determine the movement tendency of motion carrier, then determine that under described movement tendency mobile terminal switches to currently to access each The switching probability of network.

In general, the movement tendency of motion carrier can be according to the change of distance d between motion carrier and Network Access Point Change and determine, determine the distance between current kinetic carrier and Network Access Point and previous moment motion carrier and this network insertion The difference of the distance between point, if difference is just, represents that motion carrier is away from Network Access Point；If difference is negative, represent Motion carrier is close to Network Access Point.

Here, the method for the distance accumulation change sum that present invention introduces is to set time period T_nIn, get M sampling Motion carrier and Network Access Point between distance d (i) (i=1,2 ..., M) value, then can get T_nThe accumulated change of interior distance With, as shown in formula (1):

${\mathrm{\&Delta;D}}_n=\underset{i=1}{\overset{M}{\&Sigma;}}\&lsqb;d\left(i\right)-d(i-1)\&rsqb;,---\left(1\right);$

As Δ D_n> 0 time, it is judged that motion carrier is away from Network Access Point；As Δ D_n< when 0, it is judged that motion carrier is Close to Network Access Point.After motion carrier accesses the most close Network Access Point, network can be increased to a certain extent and maintain Time, thus reduce switching times.

Wherein, distance d (i) between described current kinetic carrier and Network Access Point, receive according to motion carrier Received signal strength RSS (i) determines, is setting time period T_nIn, get RSS (i) value of M sampling, wherein, (i= 1,2 ..., M), determine distance d (i) between sampling instant motion carrier and Network Access Point according to formula (2):

$d\left(i\right)={10}^{\frac{K_1+u\left(x\right)-RSS\left(i\right)}{K_2}}---\left(2\right);$

Here, the switching probability P under the movement tendency of described motion carrier_h1Probability distribution can pass through formula (3) and come really Fixed:

P_h1=P (Δ D_n<0) (3)；

In formula (3), Δ D_nTime period T is being set for network_nIn distance accumulation change and.

Due to P_th=P_h1, therefore can determine that described mobile terminal switches to each described under network continues mode of priority The switching probability P of access network_th:

$P_{th}=P(\underset{i=1}{\overset{M}{\&Sigma;}}\&lsqb;{10}^{\frac{K_1+u\left(x\right)-RSS\left(i\right)}{K_2}}-{10}^{\frac{K_1+u\left(x\right)-RSS(i-1)}{K_2}}\&rsqb;<0)---\left(4\right);$

When the mode of priority that described user selects is network bandwidth mode of priority, with the switching probability under peak transfer rate P_h2The switching probability P of described access network is switched to as mobile terminal described under network bandwidth mode of priority_bh；

Concrete, described peak transfer rate C is the important indicator that network selects, and directly influences business on mobile terminal Quality.Peak transfer rate C can determine according to Shannon's theorems formula (5):

$C={\mathrm{Wlog}}_2(1+\frac{RSS\left(d\right)}{I\left(d\right)})---\left(5\right);$

In formula (5), W is bandwidth,For signal to noise ratio, I (d) is between motion carrier and Network Access Point Distance d time the interference signal intensity that receives.

Switching probability P under described peak transfer rate_h2Probability distribution can pass through formula (6) and determine:

In formula (6),For the minimum transmission rate needed for mobile terminal current business can be supported.

Due to P_bh=P_h2, therefore can determine that described mobile terminal switches to a certain described under network bandwidth mode of priority The switching probability P of access network_bh:

Adapt under mode of priority at network charges mode of priority or business, by the method for normalization numerical value to network charges It is normalized with service priority, and using normalization numerical value α corresponding to network charges as at the preferential mould of network charges Under formula, described mobile terminal switches to the switching probability P of a certain described access network_ch, it may be assumed that P_ch=α；Also with network priority pair The normalization numerical value answered switches to cutting of a certain described access network as described mobile terminal under adapting to mode of priority in business Change probability.Wherein, the normalization numeric representation user preference to network, normalized value shows that the most greatly user is for this network Preference is the highest.

Concrete, it is considered that network charges does not changes, and therefore, network charges is carried out normalizing Normalization numerical value after change processes has certain stability.Here, suppose that the normalizing of the network charges that α is a certain access network Change numerical value, α_iFor the normalization numerical value of the network charges of i-th network (i=1,2,3), α_iConcrete value condition need combine The expense standard of real network.Concrete, for wlan network N₁, WiMAX network N₂With 3G Cellular network N₃For, Wlan network N₁Network charges normalization numerical value be α₁, WiMAX network N₂Network charges normalization numerical value be α₂, 3G Cellular network N₃Network charges normalization numerical value be α₃.If the network charges of a certain access network is the highest, then this access network The normalization numerical value that the network charges of network is corresponding is the lowest, it may be assumed that network charges its corresponding normalization numerical value is inverse ratio.Citing comes Say, 3G Cellular network N₃Network charges higher than WiMAX network N₂Network charges, thus have α₃<α₂。

The analysis of the four class Business Stream grades by 3GPP is defined, the impact that network is selected by the business on mobile terminal Mainly session service, therefore, the type of service on mobile terminal is not divided into two big classes by the present invention: containing session service and not Containing session service.Corresponding, need excellent to the network corresponding with not containing session service containing session service respectively First level is normalized numerical value and processes.For wlan network N₁, WiMAX network N₂With 3G Cellular network N₃For, containing When having session service, the priority of network is N₃>N₂>N₁, when not containing session service, the priority of network is N₁>N₂> N₃。

Assume that β is that a certain described access network is at the normalization number containing session service mode of priority lower network priority Value, β_iFor i-th network (i=1,2,3) at the normalization numerical value containing session service mode of priority lower network priority, β_i The concrete value condition performance that needs the support combining real network to contain session service determine.Concrete, β₁、β₂And β₃ It is respectively wlan network N₁, WiMAX network N₂With 3G Cellular network N₃Excellent containing session service mode of priority lower network The normalization numerical value of first level.If the performance that a certain access network support contains session service is the best, then this access network is containing There is the normalization numerical value under session service mode of priority the highest, it may be assumed that for a certain access network, support containing session The performance its corresponding normalization numerical value of class business is proportional.Due to wlan network N₁, WiMAX network N₂With 3G Cellular Network N₃The performance of network own, when containing session service, the priority of network is N₃>N₂>N₁, therefore, three networks contain The corresponding normalization numerical value of session service is β₃>β₂>β₁.From above-mentioned analysis, it may be determined that containing session service mode of priority Under described mobile terminal switch to the switching probability P of a certain described access network_sh=β.

Assume that γ is that a certain access network is at the normalization number not containing session service mode of priority lower network priority Value, γ_iFor i-th network (i=1,2,3) at the normalization number not containing session service mode of priority lower network priority Value, γ_iThe concrete value condition performance that needs the support combining real network not contain session service determine.Specifically , γ₁、γ₂And γ₃It is respectively wlan network N₁, WiMAX network N₂With 3G Cellular network N₃Do not containing conversation class industry The normalization numerical value of business mode of priority lower network priority.If a certain access network support does not contains the performance of session service more Good, then this network normalization numerical value under not containing session service mode of priority is the highest, it may be assumed that support not contain conversation class The performance its corresponding normalization numerical value of business is proportional.Due to wlan network N₁, WiMAX network N₂With 3G Cellular net Network N₃The performance of network own, when not containing session service, the priority of network is N₁>N₂>N₃, therefore, three access networks The corresponding normalization numerical value not containing session service is γ₁>γ₂>γ₃.From above-mentioned analysis, it may be determined that do not containing session Under class business mode of priority, described mobile terminal switches to the switching probability P of a certain described access network_eh=γ.

Embodiment two:

When the mode of priority that described user selects is network lasting mode of priority, described mobile terminal switches to each described The switching probability P of access network_thFor: there is event h in described mobile terminal simultaneously₃、h₄、h₅And h₁Probability P (h₃h₄h₅h₁)；

When the mode of priority that described user selects is network bandwidth mode of priority, described mobile terminal switches to each described The switching probability P of access network_bhFor: there is event h in described mobile terminal simultaneously₃、h₄、h₅And h₂Probability P (h₃h₄h₅h₂)；

When the mode of priority that described user selects is network charges mode of priority, described mobile terminal switches to each described The switching probability P of access network_chFor: there is event h in described mobile terminal simultaneously₃、h₄And h₅Probability P (h₃h₄h₅) and be multiplied by net The normalization numerical value α of network expense；

When the mode of priority that described user selects is containing session service mode of priority, described mobile terminal switches to often The switching probability P of access network described in_shFor: there is event h in described mobile terminal simultaneously₃、h₄And h₅Probability P (h₃h₄h₅) and It is multiplied by the normalization numerical value β of the network priority containing session service；

When the mode of priority that described user selects is not for containing session service mode of priority, described mobile terminal switches to The switching probability P of each described access network_ehFor: there is event h in described mobile terminal simultaneously₃、h₄And h₅Probability P (h₃h₄h₅) And it is multiplied by the normalization numerical value γ of the network priority not containing session service；

Here, h₁For occurring access network setting time period T_nInterior distance accumulation change and the event less than 0, h₂For Peak transfer rate is occurred to be more than the event that can support the minimum transmission rate needed for mobile terminal current business, h₃For connecing Receive signal intensity and can access the event of the minimum received signal strength threshold value needed for corresponding network, h more than described mobile terminal₄For The bit error rate is occurred to be less than the event of the maximum bit error rate meeting mobile terminal service demand, h₅The thing of blocking rate is there is not for network Part, therefore has P_h1=P (h₁), P_h2=P (h₂), P_h3=P (h₃), P_h4=P (h₄), P_h5=P (h₅)。

Here, determine that described mobile terminal occurs event h simultaneously₃、h₄And h₅Probability P (h₃h₄h₅), including:

Determine described mobile terminal generation event h₃Probability P (h₃)=P_h3；

Determine that described mobile terminal is in event h of generation₃On the basis of occur event h₄Probability P (h₄|h₃)；

Determine that described mobile terminal occurs event h at the same time₃And h₄On the basis of occur event h₅Probability P (h₅|h₃h₄)；

Determine that described mobile terminal occurs event h simultaneously₃、h₄And h₅Probability,

P(h₃h₄h₅)=P (h₃)*P(h₄|h₃)*P(h₅|h₃h₄)。

Concrete, described received signal strength RSS is the most basic condition triggering Vertical Handover, that reflects current letter The quality in road.Received signal strength RSS is the function about distance d, with RSS (d) represent motion carrier and Network Access Point it Between distance d time received signal strength, RSS (d) can pass through formula (8) and determine:

RSS (d)=K₁-K₂lg(d)+u(x) (8)；

In formula (8), K₁For transmit power, K₂For the path loss factor, d is between motion carrier and Network Access Point Distance；U (x) is interference signal intensity, u (x) for obey average be 0, variance be σ₂Gaussian random distribution function, wherein, x is Stochastic variable.

Switching probability P under described received signal strength_h3Probability distribution can pass through formula (9) and determine:

P_h3=P (RSS (d) > η) (9)；

In formula (7), η is the minimum signal strength threshold value that mobile terminal accesses needed for corresponding network.

Concrete, described error rate BER is the function about signal to noise ratio (Signal-to-Noise Ratio, SNR).When When the bit error rate of network is higher than certain threshold value, show that network can not meet the demand of some business on mobile terminal.BER (d) is Bit error rate during distance d between motion carrier and Network Access Point, can pass through formula (10) and determine:

$BER\left(d\right)=Q\left(\sqrt{\frac{RSS\left(d\right)}{I\left(d\right)}}\right),---\left(10\right);$

In formula (10), the expression formula of Q () isWherein, y, t be with Machine variable.

Switching probability P under the described bit error rate_h4Probability distribution can pass through formula (11) and determine:

P_h4=P (BER (d) < τ) (11)；

In formula (11), BER (d) is the bit error rate, and τ is the maximum bit error rate meeting mobile terminal service demand.

Concrete, described blocking rate BR is when the channel of a certain Local Area Network is the most occupied, thus causes new terminal Service call will be refused by system.The number of channel of various wireless access technologys depends on the performance parameter of each communication system, will After wireless network coverage area is normalized, determine the blocking rate P of kth channel_kFor:

$P_k=\frac{\frac{{(-{\mathrm{\&lambda;AX}}^{-1}e)}^k}{k!}}{\underset{n=0}{\overset{m}{\&Sigma;}}\frac{{(-{\mathrm{\&lambda;AX}}^{-1}e)}^n}{n!}}---\left(12\right);$

In formula (12), m is the total quantity of available channel in overlay area, and λ is that mobile terminal arrives and accesses in the unit time The average arrival rate of network, λ >=0, n=0,1 ..., m, k=0,1 ..., m；A is the probability matrix that mobile terminal arrives network, A =(a₁,a₂,…,a_n), e is rank, n × 1 unit vectors, and X is service condition distribution matrix: Wherein ,-u₁、-u₂、…、-u_nDeparture rate for mobile terminal service；h_pqFor variable, description is state transition probability, p=1, 2 ..., n, q=1,2 ..., n.

Due to the switching probability P under described blocking rate_h5=1-P_k, so the switching probability P under blocking rate_h5Probability distribution Formula (13) can be passed through determine:

$P_{h5}=1-\frac{\frac{{(-{\mathrm{\&lambda;AX}}^{-1}e)}^m}{m!}}{\underset{n=0}{\overset{m}{\&Sigma;}}\frac{{(-{\mathrm{\&lambda;AX}}^{-1}e)}^n}{n!}}---\left(13\right).$

For ensureing that the present invention has higher practicality, each parameter of network attribute and the movement tendency of motion carrier Determining and can obtain according to the statistics in setting the time period under practical situation, each parameter of described network attribute includes receiving signal Intensity, peak transfer rate, the bit error rate and blocking rate.And about each parameter of network attribute and the movement tendency of motion carrier Statistic processes can determine according to various prior aries, repeat no more here.

P in the present embodiment_th、P_bh、P_ch、P_shAnd P_ehCan be determined to (18) according to formula (14) respectively.Each Under described mode of priority, it is consistent that described mobile terminal switches to the determination method of the switching probability of each network, therefore, and this In only provide the formula determined, can determine according to prior art as detailed determination process, repeat no more here.

P_th=P (h₁h₃h₄h₅)=P (h₃)P(h₄|h₃)P(h₅|h₃h₄)P(h₁|h₃h₄h₅) (14)；

P_bh=P (h₂h₃h₄h₅)=P (h₃)P(h₄|h₃)P(h₅|h₃h₄)P(h₂|h₃h₄h₅) (15)；

P_ch=P (h₃h₄h₅) α=P (h₃)P(h₄|h₃)P(h₅|h₃h₄)α (16)；

P_sh=P (h₃h₄h₅) β=P (h₃)P(h₄|h₃)P(h₅|h₃h₄)β (17)；

P_eh=P (h₃h₄h₅) γ=P (h₃)P(h₄|h₃)P(h₅|h₃h₄)γ (18)；

Wherein, P (h₃)P(h₄|h₃)P(h₅|h₃h₄)=P (h₃h₄h₅)。

Wherein, P (h₃)=P_h3For there is event h₃Probability, P (h₄|h₃) it is in event h of generation₃On the basis of occur thing Part h₄Probability distribution, P (h₄|h₃) P (h can be passed through₃)、P(h₄) determine.P(h₅|h₃h₄) it is event h that occurs at the same time₃And h₄ On the basis of occur event h₅Probability distribution；P(h₁|h₃h₄h₅) it is event h that occurs at the same time₃、h₄And h₅On the basis of occur thing Part h₁Probability distribution；P(h₂|h₃h₄h₅) it is event h that occurs at the same time₃、h₄And h₅On the basis of occur event h₂Probability divide Cloth；P(h₃h₄h₅) it is event h that simultaneously occurs₃、h₄And h₅Probability distribution.

When the described switching probability in presently described access network is less than the switching probability of other described access networks, make institute State mobile terminal and switch to the network in other described access networks, particularly as follows:

Network is selected to continue under mode of priority at mobile terminal, if P_thi>P_th0, then mobile terminal is made to switch to i-th net Network；Otherwise, make described mobile terminal keep accessing described current network；Wherein, P_th0For described under continuing mode of priority at network Mobile terminal switches to the switching probability of current network, P_bhi=max (P_bh1,P_bh2,P_bh3), P_bhiFor i-th network at network Continue described mobile terminal under mode of priority and switch to the switching probability of this access network, wherein, i=1,2,3.

Under mobile terminal selects network bandwidth mode of priority, if P_bhi>P_bh0, then mobile terminal is made to switch to i-th net Network；Otherwise, make described mobile terminal keep accessing described current network；Wherein, P_bh0For described under network bandwidth mode of priority Mobile terminal switches to the switching probability of current network, P_bhi=max (P_bh1,P_bh2,P_bh3), P_bhiFor i-th network at network Under band preference pattern, described mobile terminal switches to the switching probability of this access network, wherein, i=1, and 2,3.

Under mobile terminal selects network charges mode of priority, if P_chi>P_ch0, then mobile terminal is made to switch to i-th net Network；Otherwise, make described mobile terminal keep accessing described current network；Wherein, P_ch0For described under network charges mode of priority Mobile terminal switches to the switching probability of current network, P_chi=max (P_ch1,P_ch2,P_ch3), P_chiFor i-th network at network Under expense mode of priority, described mobile terminal switches to the switching probability of this access network, wherein, i=1, and 2,3.

Select business to adapt under mode of priority at mobile terminal, and current service of user terminal contain session service, If P_shi>P_sh0, then mobile terminal is made to switch to i-th network；Otherwise, make described mobile terminal keep accessing described current net Network；Wherein, P_sh0The switching probability of current network is switched to for mobile terminal described under containing session service mode of priority, P_shi=max (P_sh1,P_sh2,P_sh3), P_shiCut for i-th network described mobile terminal under containing session service mode of priority Shift to the switching probability of this access network, wherein, i=1,2,3.

Select business to adapt under mode of priority at mobile terminal, and current service of user terminal does not contains conversation class industry Business, if P_ehi>P_eh0, then mobile terminal is made to switch to i-th network；Otherwise, make described mobile terminal keep access described currently Network；Wherein, P_eh0The switching switching to current network for mobile terminal described under not containing session service mode of priority is general Rate, P_ehi=max (P_eh1,P_eh2,P_eh3), P_ehiMove eventually for i-th network is described under not containing session service mode of priority End-grain cutting shifts to the switching probability of this access network, wherein, i=1, and 2,3.

Vertical handoff method of the present invention before step 101, also includes the step generating decision tree, corresponding to embodiment one Generate decision tree step particularly as follows: be the first root node with at user option mode of priority, respectively with network continue the most excellent First pattern, network bandwidth mode of priority and the event node that network charges mode of priority is described first root node, fit with business The decision node answering mode of priority to be described first root node, respectively to have session service mode of priority and not contain conversation class Business mode of priority is the event node of described decision node.Wherein, described event node represents this node, and event occurs, institute State decision node represent in decision making process this point need to carry out Tactic selection.

Fig. 2 is the structural representation from selection decision tree of vertical handoff method embodiment one of the present invention, as in figure 2 it is shown, From selecting in decision tree, square is decision node (Decision Node), and the decision node in decision tree represents in decision-making During this point need to carry out Tactic selection；Circle is event node (Event Node), the event node in decision tree Represent in this occurrence of random events；Line is the branch of decision tree.Decision node a represents at user option preferential mould Formula；Decision node b represents whether current business is contained session service and carry out judging to select by mobile terminal.Event node 1 table Show and whether occur access network setting time period T_n, wherein, there is access network in interior distance accumulation change and the event less than 0 Network is setting time period T_nInterior distance accumulation change and the event less than 0 are designated as event h₁；Event node 2 indicates whether to occur Peak transfer rate is more than the event of the minimum transmission rate can supported needed for mobile terminal current business, wherein, maximum occurs Transfer rate is designated as event h more than the event of the minimum transmission rate needed for supporting mobile terminal current business₂；Event node 3 represent under selection network charges mode of priority, determine that mobile terminal switches to a certain access based on network charges normalization numerical value The event that network switches；Event node 4 and 5 represent respectively selection business adapt under mode of priority containing session service and When not containing session service, determine that mobile terminal switches to a certain described access network based on network priority normalization numerical value There is the event of network switching.Described decision tree is with decision node a as root node, respectively with event 1,2 and 3 for described root node Under event node, with decision node b for decision node a under decision node, respectively with event 4 and 5 for decision node b under Event node.

Corresponding to the step generating decision tree of embodiment two particularly as follows: to be received signal strong whether to dock the collection of letters number Degree detection is chosen as the second root node, is described the with the random event that whether switches under the received signal strength of detection First event node of two root nodes, whether meeting, with the bit error rate, the random event switched is described first event node Whether second event node, meet the 3rd event joint that random event is described second event node switched with blocking rate Point, is the decision node under described 3rd event node with at user option mode of priority, respectively with network persistently preferential mould Formula, network bandwidth mode of priority and the four, the 5th and the 6th event node that network charges mode of priority is described decision node, Adapting to mode of priority with business is the sub-decision node of described first decision node, respectively with have session service mode of priority and Do not contain the 7th and the 8th event node that session service mode of priority is described sub-decision node.

Fig. 4 is the structural representation from selection decision tree of vertical handoff method embodiment two of the present invention, as shown in Figure 4, From selecting in decision tree, square is decision node, and the decision node in decision tree represents in decision making process at this point Need to carry out Tactic selection；Circle is event node, and the event node in decision tree represents in this occurrence of random events； Line is the branch of decision tree.Decision node a represents at user option mode of priority；Decision node b represents that mobile terminal is to working as Whether front business contains session service carries out judging to select；Decision node c represents whether dock the collection of letters number and is received letter Number intensity detection selects；Event node 1 indicates whether to occur access network setting time period T_nIn distance accumulation change and Event less than 0, wherein, occurs access network setting time period T_nInterior distance accumulation change and the event less than 0 are designated as Event h₁；Event node 2 indicates whether minimum peak transfer rate occurring more than supporting needed for mobile terminal current business , wherein, there is peak transfer rate more than the minimum transfer can supported needed for mobile terminal current business in the event of transfer rate The event of speed is designated as event h₂；Event node 3 represents under selection network charges mode of priority, based on network charges normalization number Value determines that mobile terminal switches to the event that a certain access network switches；Event node 4 and 5 represents that selection business is fitted respectively Answer under mode of priority containing session service with when not containing session service, determine shifting based on network priority normalization numerical value Dynamic terminal switches to the event of a certain described access network generation network switching.Event node 6 indicates whether to occur to receive signal Intensity (Receive Signal Strength, RSS) can access the minimum reception needed for corresponding network more than described mobile terminal The event of signal strength threshold, wherein, needed for occurring received signal strength can access corresponding network more than described mobile terminal The event of minimum received signal strength threshold value is designated as event h₃；Event node 7 whether occur the bit error rate (Bit Error Ratio, BER) less than the event of the maximum bit error rate meeting mobile terminal service demand, wherein, there is the bit error rate (Bit Error Ratio, BER) it is designated as event h less than the event of the maximum bit error rate meeting mobile terminal service demand₄；Event node 8 represents The event whether switched under blocking rate (Blocking Rate, BR), wherein, network does not occur the event blocked to be designated as Event h₅。

Above-mentioned vertical handoff method is for three kinds of wireless networks WLAN, WiMAX and the 3G related in the networking of existing car Cellular, can determine the access network of optimum by the vertical handoff method of the present invention according to the mode of priority that user selects As objective network.In actual applications, if in car networking the wireless network that relates to be four kinds and above time, the technology of this area Personnel just can make corresponding extension according to the mode of priority that user selects according to the general knowledge of this area, thus mobile terminal is cut Shift to the network of optimum, repeat no more here.

Fig. 5 is the composition structural representation of Vertical Handover device of the present invention, as it is shown in figure 5, described Vertical Handover device bag Include acquiring unit and switch unit, wherein,

Described acquiring unit 51, for obtaining the current each access network that can access of the mobile terminal on motion carrier The mode of priority that information and user select；

Here, described mode of priority includes that network continues mode of priority, network bandwidth mode of priority, the preferential mould of network charges Formula and business adapt to mode of priority, and wherein said business adapts to mode of priority and includes containing session service mode of priority and do not contain There is session service mode of priority.

Described switch unit 52, under the mode of priority that described user selects, determines that described mobile terminal switches to The switching probability of each described access network, and at the switching probability of presently described access network less than other described access networks Switching probability time, make described mobile terminal switch to the network in other described access networks.

Further, when the mode of priority that described user selects is network lasting mode of priority, with described motion carrier Switching probability P under movement tendency_h1Described access network is switched to as described mobile terminal under continuing mode of priority at network Switching probability P_th；

When the mode of priority that described user selects is network bandwidth mode of priority, with the switching probability under peak transfer rate P_h2The switching probability P of described access network is switched to as mobile terminal described under network bandwidth mode of priority_bh；

When the mode of priority that described user selects is network charges mode of priority, make with the normalization numerical value α of network charges The switching probability P of described access network is switched to for mobile terminal described under network charges mode of priority_ch；

When the mode of priority that described user selects is containing session service mode of priority, with the net containing session service Normalization numerical value corresponding to network priority is made β and is switched to for described mobile terminal under containing session service mode of priority described The switching probability P of access network_sh；

When the mode of priority that described user selects is not for containing session service mode of priority, not contain session service Normalization numerical value γ corresponding to network priority cut as mobile terminal described under not containing session service mode of priority Shift to the switching probability P of described access network_eh。

Further, described device determines switching probability under the movement tendency of described motion carrier in the following manner P_h1:

P_h1=P (Δ D_n<0)；

Wherein,ΔD_nSetting for access network In time period distance accumulation change and, K₁For transmit power, K₂For the path loss factor, u (x) is the meter of interference signal intensity Calculate function, u (x) for obey average be 0, variance be σ₂Gaussian random distribution function, wherein, x is stochastic variable；M is in institute Stating docking signal in setting the time period and receive the number of times that intensity level carries out sampling, RSS (i) is that the reception signal of current sampling point is strong Degree, RSS (i-1) is the received signal strength of previous sampled point, and i is current sampling number, i=1,2 ..., M.

Further, described device determines switching probability P under described peak transfer rate C in the following manner_h2:

Wherein,For the minimum transmission rate needed for mobile terminal current business can be supported, described peak transfer rateWherein, W is bandwidth,For signal to noise ratio, I (d) is motion carrier and net The interference signal intensity received during distance d between network access point.

Further, when the mode of priority that described user selects is network lasting mode of priority, described mobile terminal switches Switching probability to each described access network is: described mobile terminal occurs event h simultaneously₃、h₄、h₅And h₁Probability P (h₃h₄h₅h₁)；

When the mode of priority that described user selects is network bandwidth mode of priority, described mobile terminal switches to each described The switching probability of access network is: described mobile terminal occurs event h simultaneously₃、h₄、h₅And h₂Probability P (h₃h₄h₅h₂)；

When the mode of priority that described user selects is network charges mode of priority, described mobile terminal switches to each described The switching probability of access network is: described mobile terminal occurs event h simultaneously₃、h₄And h₅Probability P (h₃h₄h₅) and be multiplied by network The normalization numerical value α of expense；

When the mode of priority that described user selects is containing session service mode of priority, described mobile terminal switches to often The switching probability of access network described in is: described mobile terminal occurs event h simultaneously₃、h₄And h₅Probability P (h₃h₄h₅) and take advantage of Normalization numerical value β with the network priority containing session service；

When the mode of priority that described user selects is not for containing session service mode of priority, described mobile terminal switches to The switching probability of each described access network is: described mobile terminal occurs event h simultaneously₃、h₄And h₅Probability P (h₃h₄h₅) and It is multiplied by the normalization numerical value γ of the network priority not containing session service；

Wherein, h₁For occurring network setting time period T_nInterior distance accumulation change and the event less than 0, h₂For occurring Peak transfer rate is more than the event of the minimum transmission rate can supported needed for mobile terminal current business, h₃For occurring to receive letter Number intensity can access the event of the minimum received signal strength threshold value needed for corresponding network, h more than described mobile terminal₄For occurring The bit error rate is less than the event of the maximum bit error rate meeting mobile terminal service demand, h₅The event blocked is there is not for network.

Further, described device determining, described mobile terminal occurs event h in the following manner simultaneously₃、h₄And h₅General Rate P (h₃h₄h₅):

Determine described mobile terminal generation event h₃Probability P_h3=P (h₃)；

Determine that described mobile terminal is in event h of generation₃On the basis of occur event h₄Probability P (h₄|h₃)；

Determine that described mobile terminal occurs event h at the same time₃And h₄On the basis of occur event h₅Probability P (h₅|h₃h₄)；

Determine that described mobile terminal occurs event h simultaneously₃、h₄And h₅Probability P (h₃h₄h₅)=P (h₃)*P(h₄|h₃)*P (h₅|h₃h₄)。

It will be understood by those of skill in the art that each processing unit in the Vertical Handover device shown in Fig. 5 and son thereof The function that realizes of unit can refer to the associated description of forenamed vertical changing method and understands.It will be appreciated by those skilled in the art that In Vertical Handover device shown in Fig. 5, the function of each processing unit can be realized by the program that runs on processor, it is possible to Realized by concrete logic circuit.

Obviously, those skilled in the art should be understood that each processing unit of the above-mentioned present invention or each step can be used General calculating device realizes, and it can concentrate on single calculating device, or is distributed in multiple calculating device institutes group On the network become, alternatively, it can realize with calculating the executable program code of device, it is thus possible to they stored Performed by calculating device in the storage device, or they are fabricated to respectively each integrated circuit modules, or by them In multiple modules or step be fabricated to single integrated circuit module and realize.So, the present invention be not restricted to any specifically Hardware and software combines.

The above, only presently preferred embodiments of the present invention, it is not intended to limit protection scope of the present invention.

Claims (6)

1. a vertical handoff method, it is characterised in that described method includes:

Obtain information and the preferential mould of user's selection of each access network that the mobile terminal on motion carrier currently can access Formula；

Under the mode of priority that described user selects, determine that described mobile terminal switches to the switching of each described access network general Rate, and when the switching probability of presently described access network is less than the switching probability of other described access networks, make described movement Terminal switches to the network in other described access networks；

Described mode of priority includes that network continues mode of priority, network bandwidth mode of priority, network charges mode of priority and business Adapting to mode of priority, wherein, described business adapts to mode of priority and includes containing session service mode of priority and do not contain session Class business mode of priority；

When the mode of priority that described user selects is network lasting mode of priority, with cutting under the movement tendency of described motion carrier Change probability P_h1The switching probability P of described access network is switched to as described mobile terminal under continuing mode of priority at network_th； Wherein, the switching probability P under the movement tendency of described motion carrier is determined in the following manner_h1:

P_h1=P (Δ D_n<0)；

Wherein,ΔD_nFor access network in the time of setting In Duan distance accumulation change and, K₁For transmit power, K₂For the path loss factor, u (x) is the calculating letter of interference signal intensity Number, u (x) for obey average be 0, variance be σ₂Gaussian random distribution function, wherein, x is stochastic variable；M is for set described In the section of fixing time, docking signal receives the number of times that intensity level carries out sampling, and RSS (i) is the received signal strength of current sampling point, RSS (i-1) being the received signal strength of previous sampled point, i is current sampling number, i=1,2, and, M；Described switching probability P_h1For Described mobile terminal generation event h₁Probability；

When the mode of priority that described user selects is network bandwidth mode of priority, with the switching probability P under peak transfer rate_h2Make The switching probability P of described access network is switched to for mobile terminal described under network bandwidth mode of priority_bh；Wherein, with following Mode determines the switching probability P under described peak transfer rate C_h2:

Wherein,For the minimum transmission rate needed for mobile terminal current business can be supported, described peak transfer rateWherein, W is bandwidth,For signal to noise ratio, I (d) is motion carrier and net The interference signal intensity received during distance d between network access point, RSS (d) represents between motion carrier and Network Access Point Distance d time received signal strength；Described switching probability P_h2For described mobile terminal generation event h₂Probability；

The mode of priority that described user selects is when being network charges mode of priority, using the normalization numerical value α of network charges as Under network charges mode of priority, described mobile terminal switches to the switching probability P of described access network_ch；

When the mode of priority that described user selects is containing session service mode of priority, excellent with the network containing session service Normalization numerical value β corresponding to first level switches to described access as mobile terminal described under containing session service mode of priority The switching probability P of network_sh；

When the mode of priority that described user selects is not for containing session service mode of priority, not contain the net of session service Normalization numerical value γ corresponding to network priority switches to as mobile terminal described under not containing session service mode of priority The switching probability P of described access network_eh。

Method the most according to claim 1, it is characterised in that

When the mode of priority that described user selects is network lasting mode of priority, described mobile terminal switches to each described access The switching probability of network is: described mobile terminal occurs event h simultaneously₃、h₄、h₅And h₁Probability P (h₃h₄h₅h₁)；

When the mode of priority that described user selects is network bandwidth mode of priority, described mobile terminal switches to each described access The switching probability of network is: described mobile terminal occurs event h simultaneously₃、h₄、h₅And h₂Probability P (h₃h₄h₅h₂)；

When the mode of priority that described user selects is network charges mode of priority, described mobile terminal switches to each described access The switching probability of network is: described mobile terminal occurs event h simultaneously₃、h₄And h₅Probability P (h₃h₄h₅) and be multiplied by network charges Normalization numerical value α；

When the mode of priority that described user selects is containing session service mode of priority, described mobile terminal switches to each institute The switching probability stating access network is: described mobile terminal occurs event h simultaneously₃、h₄And h₅Probability P (h₃h₄h₅) and be multiplied by and contain There is the normalization numerical value β of the network priority of session service；

When the mode of priority that described user selects is not for containing session service mode of priority, described mobile terminal switches to each The switching probability of described access network is: described mobile terminal occurs event h simultaneously₃、h₄And h₅Probability P (h₃h₄h₅) and be multiplied by Do not contain the normalization numerical value γ of the network priority of session service；

Wherein, h₁For occurring access network setting time period T_nInterior distance accumulation change and the event less than 0, h₂For occurring Peak transfer rate is more than the event of the minimum transmission rate can supported needed for mobile terminal current business, h₃For occurring to receive letter Number intensity can access the event of the minimum received signal strength threshold value needed for corresponding network, h more than described mobile terminal₄For occurring The bit error rate is less than the event of the maximum bit error rate meeting mobile terminal service demand, h₅The event blocked is there is not for network.

Method the most according to claim 2, it is characterised in that described method also includes:

Determine that described mobile terminal occurs event h simultaneously in the following manner₃、h₄And h₅Probability P (h₃h₄h₅),

Determine described mobile terminal generation event h₃Probability P_h3=P (h₃)；

Determine that described mobile terminal is in event h of generation₃On the basis of occur event h₄Probability P (h₄|h₃)；

Determine that described mobile terminal occurs event h at the same time₃And h₄On the basis of occur event h₅Probability P (h₅|h₃h₄)；

Determine that described mobile terminal occurs event h simultaneously₃、h₄And h₅Probability

P(h₃h₄h₅)=P (h₃)*P(h₄|h₃)*P(h₅|h₃h₄)。

4. a Vertical Handover device, it is characterised in that described device includes: acquiring unit and switch unit, wherein,

Described acquiring unit, for obtain the information of each access network that mobile terminal on motion carrier currently can access with The mode of priority that user selects；

Described switch unit, under the mode of priority that described user selects, determines that described mobile terminal switches to each institute State the switching probability of access network, and at the switching probability of presently described access network less than the switching of other described access networks During probability, described mobile terminal is made to switch to the network in other described access networks；

Described mode of priority includes that network continues mode of priority, network bandwidth mode of priority, network charges mode of priority and business Adapting to mode of priority, wherein said business adapts to mode of priority and includes containing session service mode of priority and do not contain conversation class Business mode of priority；

When the mode of priority that described user selects is network lasting mode of priority, with cutting under the movement tendency of described motion carrier Change probability P_h1The switching probability P of described access network is switched to as described mobile terminal under continuing mode of priority at network_th； Wherein, the switching probability P under the movement tendency of described motion carrier is determined in the following manner_h1:

P_h1=P (Δ D_n<0)；

Wherein,ΔD_nFor access network in the time of setting In Duan distance accumulation change and, K₁For transmit power, K₂For the path loss factor, u (x) is the calculating letter of interference signal intensity Number, u (x) for obey average be 0, variance be σ₂Gaussian random distribution function, wherein, x is stochastic variable；M is for set described In the section of fixing time, docking signal receives the number of times that intensity level carries out sampling, and RSS (i) is the received signal strength of current sampling point, RSS (i-1) being the received signal strength of previous sampled point, i is current sampling number, i=1,2 ..., M；Described switching probability P_h1 For described mobile terminal generation event h₁Probability；

When the mode of priority that described user selects is network bandwidth mode of priority, with the switching probability P under peak transfer rate_h2Make The switching probability P of described access network is switched to for mobile terminal described under network bandwidth mode of priority_bh；Wherein, with following Mode determines the switching probability P under described peak transfer rate C_h2:

Wherein,For the minimum transmission rate needed for mobile terminal current business can be supported, described peak transfer rateWherein, W is bandwidth,For signal to noise ratio, I (d) is motion carrier and net The interference signal intensity received during distance d between network access point, RSS (d) represents between motion carrier and Network Access Point Distance d time received signal strength；Described switching probability P_h2For described mobile terminal generation event h₂Probability；

The mode of priority that described user selects is when being network charges mode of priority, using the normalization numerical value α of network charges as Under network charges mode of priority, described mobile terminal switches to the switching probability P of described access network_ch；

When the mode of priority that described user selects is containing session service mode of priority, excellent with the network containing session service Normalization numerical value β corresponding to first level switches to described access as mobile terminal described under containing session service mode of priority The switching probability P of network_sh；

When the mode of priority that described user selects is not for containing session service mode of priority, not contain the net of session service Normalization numerical value γ corresponding to network priority switches to as mobile terminal described under not containing session service mode of priority The switching probability P of described access network_eh。

Device the most according to claim 4, it is characterised in that

When the mode of priority that described user selects is network lasting mode of priority, described mobile terminal switches to each described access The switching probability of network is: described mobile terminal occurs event h simultaneously₃、h₄、h₅And h₁Probability P (h₃h₄h₅h₁)；

When the mode of priority that described user selects is network bandwidth mode of priority, described mobile terminal switches to each described access The switching probability of network is: described mobile terminal occurs event h simultaneously₃、h₄、h₅And h₂Probability P (h₃h₄h₅h₂)；

When the mode of priority that described user selects is network charges mode of priority, described mobile terminal switches to each described access The switching probability of network is: described mobile terminal occurs event h simultaneously₃、h₄And h₅Probability P (h₃h₄h₅) and be multiplied by network charges Normalization numerical value α；

When the mode of priority that described user selects is containing session service mode of priority, described mobile terminal switches to each institute The switching probability stating access network is: described mobile terminal occurs event h simultaneously₃、h₄And h₅Probability P (h₃h₄h₅) and be multiplied by and contain There is the normalization numerical value β of the network priority of session service；

When the mode of priority that described user selects is not for containing session service mode of priority, described mobile terminal switches to each The switching probability of described access network is: described mobile terminal occurs event h simultaneously₃、h₄And h₅Probability P (h₃h₄h₅) and be multiplied by Do not contain the normalization numerical value γ of the network priority of session service；

Wherein, h₁For occurring network setting time period T_nInterior distance accumulation change and the event less than 0, h₂For there is maximum Transfer rate is more than the event of the minimum transmission rate can supported needed for mobile terminal current business, h₃For occurring reception signal strong Degree can access the event of the minimum received signal strength threshold value needed for corresponding network, h more than described mobile terminal₄For there is error code Rate is less than the event of the maximum bit error rate meeting mobile terminal service demand, h₅The event blocked is there is not for network.

Device the most according to claim 5, it is characterised in that described device determines that described mobile terminal is same in the following manner Shi Fasheng event h₃、h₄And h₅Probability P (h₃h₄h₅):

Determine described mobile terminal generation event h₃Probability P_h3=P (h₃)；

Determine that described mobile terminal is in event h of generation₃On the basis of occur event h₄Probability P (h₄|h₃)；

Determine that described mobile terminal occurs event h at the same time₃And h₄On the basis of occur event h₅Probability P (h₅|h₃h₄)；

Determine that described mobile terminal occurs event h simultaneously₃、h₄And h₅Probability P (h₃h₄h₅)=P (h₃)*P(h₄|h₃)*P(h₅| h₃h₄)。