Realize in a kind of heterogeneous network of technical field that the method that automaticallyes switch between TD-SCDMA Cellular Networks and the WLAN (wireless local area network) belongs to the cordless communication network technical field, specifically, relate to the design of frame format under two kinds of different network protocol of Cellular Networks, WLAN (wireless local area network) and Cellular Networks and WLAN (wireless local area network).
Background technology
In wireless communication field, Cellular Networks and WLAN (wireless local area network) are two kinds of wireless communication network of now main flow, along with development of wireless communication devices, the data volume that the user is produced in communication process increases sharply, the requirement of ability of data processing is also more and more higher, and in the cordless communication network of reality, facing such subject matter: the area coverage of Cellular Networks is wider, but its data throughput is lower; And its data throughput is very high in WLAN (wireless local area network), but its coverage is limited.Nowadays, though the development of Cellular Networks and wireless local area network technology is relative ripe,, makes and do not realize between them merging well because the development of these two kinds of wireless technologys is relatively independent.A large amount of uses of multimode, smart mobile phone at present, honeycomb inserts and WLAN (wireless local area network) has access to bigger facilitation to merging on the hand-held mobile terminal, but most of terminal also is based on the access that a kind of manual mode is switched two kinds of signals, does not have the handed over service of adaptive transparent mode.
In order to overcome this drawback in the cordless communication network, to realizing in the heterogeneous network that the research of merging between the heterogeneous networks seems particularly important, and relevant therewith technology also continues to bring out, and realizes that at present the method for switching between the Cellular Networks and WLAN (wireless local area network) in the heterogeneous network mainly contains following two kinds:
First method: its main thought is to realize communicating by letter between Cellular Networks and the WLAN by the configuration WLAN (wireless local area network), and, come authentication information to portable terminal announcement institute access network by the Extensible Authentication Protocol (EAP) among the definition RFC-2284.At first by wireless route in the WLAN (wireless local area network) is configured, but make portable terminal in extensible authentication procedure, can from wireless lan (wlan), receive general capacity information, these capacity informations mainly comprise the network information that WLAN had before received from Cellular Networks, secondly by portable terminal these capacity informations of decoding, then the sign and in its memory the storage these network informations so that portable terminal can select easily one of a plurality of different networks be used for communication.This method has mainly illustrated how to go cellular network service by WLAN (wireless local area network), only simply realized the fusion between two kinds of networks, and do not solve the problem of freely switching between two kinds of networks, therefore in the application of reality, also have significant limitation.
Second method: in order to realize the switching of Cellular Networks and WLAN (wireless local area network), at first between terminal and two kinds of networks, set up link separately respectively, realize two kinds of switchings between the network by certain converting system then, converting system mainly comprises: packet data serving node (PDSN), grouping control agent (PCF), couple in router (AR).Realize that the overall system structure of switching mutually between Cellular Networks and the WLAN (wireless local area network) is as follows: terminal is via the base station, base station controller (having the controlled function of agency) links to each other and forms the Cellular Networks link, terminal is via access point (AP), insert route, the grouping control agent links to each other and forms the WLAN (wireless local area network) link, Cellular Networks and WLAN (wireless local area network) link accessing group data service node in the lump then, and packet data serving node is connected with the switching system of internet and other sub-district again, can make collaborative work between Cellular Networks and the WLAN (wireless local area network) at last, when the terminal use needs Cellular Networks that communication session is provided, packet data serving node links to each other with base station controller, thereby connects the Cellular Networks link.When needing WLAN (wireless local area network) to provide when service packet data serving node will disconnect and being connected of base station controller, set up simultaneously and divide into groups being connected between the control agent, realize switching between Cellular Networks and the WLAN (wireless local area network) with this.Though this kind method has realized freely switching between two kinds of networks, but in network link, add corresponding apparatus, not only increased the expense of networking, also increased the complexity of networking, in a single day and in user's use, break down, need the personnel of specialty that network is investigated, the problem that makes can not in time be solved.
At the existing deficiency of above method, the present invention has proposed to realize the method that automaticallyes switch between the TD-SCDMA Cellular Networks and WLAN (wireless local area network) in the heterogeneous network specially.
Summary of the invention
Typical heterogeneous network distributed model as shown in Figure 1, when the mobile subscriber from the A district to the B district or from the B district during to the A district, the network coverage meeting of user position changes, simultaneously after A district or B district user reach some, because the phenomenon that the deficiency of Internet resources can occur blocking up.At above situation, in order to provide better network service, guarantee user's communications service quality to the user, just need carry out two kinds of switchings between the network this moment, inserts to select optimum network.Realize the automatic switching method between TD-SCDMA Cellular Networks and the WLAN (wireless local area network) in the present invention, its main thought: by suitable improvement to portable terminal, cellular basestation and WAP (wireless access point), newly-increased control frame and the negotiation flow process of obtaining resource request and response realizes the automatic switchover between Cellular Networks and the WLAN (wireless local area network).
Link such as Fig. 2 of being set up between terminal equipment and two networks, the description of image the connection procedure between terminal and TD-SCDMA Cellular Networks and the WLAN (wireless local area network).In order to guarantee the steady switching of terminal between network, terminal equipment has been proposed certain requirement, the structured flowchart of its terminal such as Fig. 3, mainly be under the control of processor (CPU), subsystem by Cellular Networks subsystem and WLAN (wireless local area network) is handled the signal of each automatic network, and finish conversion between the different system instruction by handover module, to realize the communication between CPU and two subsystems.Simultaneously management frames and the broadcast frame structure in the Cellular Networks of obtaining resource in the WLAN (wireless local area network) defined respectively as Fig. 5-1, Fig. 6-1, the form of frame mainly is made up of MAC head and frame entity, wherein the MAC head has mainly comprised some control informations, and the frame entity is only the band resource information of the required transmission of user.
Concrete operation fluid layer such as Fig. 4, at first detect the network signal intensity of position by the terminal equipment signal detection module, thereby the signal that definite position has covered which kind of network and which network is more stable, provides preliminary judgement so that select suitable network to insert for terminal; Next is the operating position by the band resource of control centre's monitoring network of network, and obtain the band resource surplus of network by the monitoring modular of terminal equipment, judge that with this can network be that portable terminal provides available channel, thereby determine which network allows terminal to insert.Wherein the obtain manner of WLAN (wireless local area network) band resource surplus is to be sent to wlan network administrative center by the monitoring resource part of local area network (LAN) subsystem in the terminal equipment to obtain network resource request, after network management center is to the Internet resources monitoring, send response to terminal, after decoding to response, terminal obtains the band resource surplus of network, and be directly to broadcast this monitoring information to after the band resource monitoring in the Cellular Networks system, and the band resource surplus of broadcast frame being decoded and obtaining network by the monitoring resource module of Cellular Networks subsystem in the terminal equipment to community user by the network control center.If the band resource abundance of network is then sent the request of access by terminal to network, if net frequency band network inadequate resource, terminal can be to the user report access failure.
This programme can be realized the automatic switchover between TD-SCDMA Cellular Networks and the WLAN (wireless local area network), three big characteristics are arranged, the one, WLAN terminal obtains the definition of management frames of resource and the negotiations process of terminal and WAP (wireless access point), the 2nd, the frame of base station broadcast Radio Resource design in the Cellular Networks, the 3rd, the mapping method of band resource surplus.The present invention has not only realized terminal the inserting according to qualifications of two net areas of coverage, and under the situation that terminal is moved and the network coverage of terminal region changes, also can realize two kinds of quick automatic switching between the network.
Embodiment
For can clearer statement implementation detail of the present invention, at first to introduce the relevant parameter that relates to this programme, and be described in detail as follows:
A
w, A
tRepresent the intensity that network transmitted among WLAN and the TD-SCDMA respectively, that is to say the amplitude of signal.
α, β represent the minimum threshold of signal in WLAN and the TD-SCDMA network respectively, it promptly is the minimum signal strength that can guarantee the required emission of terminal use's proper communication network, in case can cause the signal to noise ratio of network low excessively less than this numerical value, thereby influence the user's communications quality.
C
w, C
tRepresent band resource amount total in WLAN and the TD-SCDMA network respectively.
M
w, M
tRepresent respectively in WLAN and the TD-SCDMA network by the shared band resource amount of terminal use.
R
w, R
tRepresent the required band resource amount in practical communication of each user in WLAN and the TD-SCDMA network respectively.
f
w, f
tThe minimum threshold of representing WLAN and TD-SCDMA network intermediate frequency band resources respectively, promptly be the necessary bandwidth degree that can satisfy terminal use's proper communication, have only when the frequency bandwidth in the network during greater than minimum threshold network just have enough bandwidth resources to come to distribute corresponding channel for portable terminal.
Band resource surplus in WLAN and TD-SCDMA network can be expressed as respectively: C
w-M
w, C
t-M
t
For the ease of communicating by letter between terminal and the network, we should represent the band resource surplus with binary form, therefore also need the band resource surplus is quantized and encodes:
1. quantize: suppose that it is d that WLAN and GSM network adopt spacing respectively
w, d
tUniform quantization, d wherein
w, d
tThe minimum quantization unit of expression band resource, the shared band resource of each user all is its integral multiple.Can get thus, quantized interval number (quantized level) is respectively: m=(C
w-M
w)/d
w, n=(C
t-M
t)/d
tWherein m, n=0,1,2......
2. encode: adopt natural binary code that m, n are encoded
The required bit of encoding:
With IEEE 802.11g wireless local area network (WLAN) system is example: the total available band resource of assumed wireless LAN system is 54Mbps, the band resource that the user has taken in this WLAN (wireless local area network) is 40Mbps, and to get quantization step be 0.5Mbps, at this moment, typical IEEE 802.11g WLAN (wireless local area network) band resource mapping relations such as table 1:
Table 1
The present invention mainly is the research of terminal being switched between honeycomb and WLAN (wireless local area network) on the basis of heterogeneous network, at first set up heterogeneous network model such as Fig. 1, wherein the A district represents single net (Cellular Networks) area of coverage, two net (Cellular Networks and the WLAN (wireless local area network)) areas of coverage of B district expression.Next sets up the link between terminal and Cellular Networks and the WLAN (wireless local area network), as Fig. 2, wherein 201 the expression Cellular Networks base station and base station control center, the WAP (wireless access point) of 202 expression WLAN, 201,202 mainly use and receive and launch wireless signal, realize the transfer of data between portable terminal and two networks, simultaneously the information of each automatic network is controlled and managed, the mobile terminal device of 203 expression intelligence.
The structure of terminal equipment 203 such as Fig. 3 now are described in detail as follows: terminal equipment mainly comprises 5 modules in moving: Cellular Networks subsystem, wireless local net system, switching device (307), processor (308), memory (309).Wherein Cellular Networks subsystem and wireless local net system can be divided into again: antenna part (301,302), signal detection module (303,304), Internet resources monitoring modular (305,306).The major function of each several part: 301,302 transmission and the receptions of responsible portable terminal signal in Cellular Networks and WLAN (wireless local area network) respectively; 303,304 be respectively applied for the signal strength signal intensity that detects Cellular Networks and WLAN (wireless local area network); 305, the 306 band resource surpluses of being responsible for obtaining Cellular Networks and WLAN respectively, the shared band resource amount of real-time monitoring terminal user self simultaneously; The 307 main IP that are responsible for solve the incompatibility problem of two kinds of procotols simultaneously, thereby guarantee the steady switching of portable terminal between TD-SCDMA and WLAN to the mapping between the IMSI (international member identification code).And processor called and produced in memory 309 main responsible storage terminals and the networking communication process data and instruction.
The frame structure of WLAN (wireless local area network) and TD-SCDMA Cellular Networks such as Fig. 5-1, Fig. 6-1 now specifically describe as follows:
The frame structure of WLAN (wireless local area network) mainly comprises the MAC head of regular length and the mac frame entity of variable-length, wherein, the MAC head comprises frame control domain and address field again, frame control domain (1 byte) comprises protocol version subdomain (2 bit), frame type subdomain (2 bit) and frame subtype subdomain (4 bit), and address field (8 byte) comprises source address (4 byte) and destination address (4 byte).The mac frame entity is made of unit identity code (1 byte), message length subdomain (1 byte) and information subdomain (variable-length), and the length of information subdomain is by the quantification progression decision of radio band resource mapping.Specific definition such as Fig. 5-2 of two kinds of frames of involved in the present invention wireless office net.
The broadcast frame structure of TD-SCDMA Cellular Networks mainly comprises the MAC head and the variable-length Medium Access Control (MAC) Service Data Unit of regular length.The MAC head comprises protocol type (2 bit) and channel type (1 byte).Medium Access Control (MAC) Service Data Unit has mainly reflected the operating position of the band resource of cellular network, Medium Access Control (MAC) Service Data Unit comprises that information type identifier (2 bit), message length (1 byte) and information unit (variable-length) constitute, and the length of information unit also quantizes progression by frequency band and determines.The specific definition of the Cellular Networks broadcast frame that relates in the present invention such as Fig. 6-2.
The concrete implementation step of this programme such as Fig. 4 now are described in detail as follows in conjunction with Fig. 3:
Step 401: preferentially receive wireless lan signal, and signal is sent into terminal 304, through the signal strength signal intensity A that obtains WLAN (wireless local area network) is adjudicated in the sampling of signal by 302 of terminal
w, and signal strength signal intensity is sent to processor 308 handles, turn to step 403 then.
Step 403: 304 detected signal strength signal intensities are directly sent into processor 308 judge signal strength signal intensity A
wWith the size of threshold alpha, work as A
wDirectly turn to step 402 during<α; Work as A
wTurn to step 405 during>α.
Step 405: the resource residual amount of consulting to obtain WLAN by the frame between terminal and the WLAN (wireless local area network), detailed process such as Fig. 7: at first obtain network bands resource request frame by 306 control centres (wireless router) transmission of terminal to WLAN (wireless local area network), come the band resource of monitoring wireless local area network (LAN) simultaneously by wireless router, come the type of judgment frame then according to the control domain of claim frame by wireless router, and, send band resource to terminal 306 afterwards and obtain response frame according to the address that address field obtains terminal equipment.306 according to the information unit in the response frame, obtains the surplus C of the band resource of WLAN (wireless local area network) by decoding
w-M
w, and this direct information processor 308 handled, turn to step 407 subsequently.
Step 407: the return value according to 306, judge band resource surplus C by processor 308
w-M
wWith f
wSize, work as C
w-M
w>f
wThe time, from memory 309, transfer and send to insert request instruction by terminal handler 308 to WLAN (wireless local area network), after the authentication of wireless router, authentication, send and reply permission response to portable terminal, this moment, terminal was set up related with WLAN (wireless local area network), terminal successfully inserts WLAN (wireless local area network), and in the process of portable terminal and wireless LAN communication, simultaneously by the 306 actual band resource amount R that take that detect and send to WLAN (wireless local area network) the user
w, judge C by WLAN (wireless local area network) control centre
w-M
wWith R
wSize, work as C
w-M
w>R
wThe time, keep connecting, person's wireless router does not send the related notice of cancellation to terminal, and terminal inserts the WLAN (wireless local area network) failure, turns to step 402; Work as C
w-M
w<f
wThe time, directly turn to step 402.
Step 402: receive the signal of Cellular Networks by 301 of terminal, through obtaining the Cellular Networks signal strength signal intensity A of sub-district, place after 303 pairs of Cellular Networks signal samplings judgements
t, and this numerical value is transferred to processor 308 handles, turn to step 404 simultaneously.
Step 404: the signal strength signal intensity A that judges Cellular Networks by processor 308
tWith the size of minimum threshold β, work as A
tDuring<β, the cellular network signals deficiency is described, access failure (showing that sub-district, portable terminal place does not have suitable network to use for the user this moment); Work as A
tDuring>β, turn to step 406.
Step 406: cellular network is broadcasted the network information (band resource that refers in particular to this subzone network utilizes situation) of this sub-district by the mobile phone users of base station in the sub-district, obtains the band resource surplus C of cellular network after 305 pairs of broadcast message decodings by terminal after antenna 301 receives the Cellular Networks signal
t-M
t, and with these information sending processor 308 processing, and turn to step 408.Wherein the detection of the band resource of Cellular Networks is finished by base station and base station controller, at first base station controller is configured to follow the tracks of the statistic that all are mapped to radio bearer BO (buffer area takies) value on a certain transmission channel MAC by RRC (Radio Resource control), wherein the BO value can be used for reflecting the situation that takies of wireless transmission channel, that is to say cellular network band resource utilize situation; Secondly in each TTI (Transmission Time Interval), the MAC layer of base station controller all can utilize MAC-Data-REQ primitive to receive a BO value from each RLC (Radio Link control) entity; Utilize primitive CMAC-Measure-REQ to obtain the measurement report of MAC by RRC (Radio Resource control) more at last, and this report is broadcast to community user, finish monitoring the Cellular Networks band resource with this by the base station to the MAC entity requests.
Step 408: compare C by processor 308
t-M
tWith f
tSize, work as C
t-M
t<f
tThe time, access failure; Work as C
t-M
t>f
tThe time, from 309, transfer and send the access request instruction by processor 308 to base station controller, reply the approval response instruction to the terminal transmission after base station controller authentication, authentication, this moment, mobile terminal device and Cellular Networks connected, and promptly terminal equipment is in holding state; After this by 305 real-time monitoring terminal users of terminal actual band resource occupancy R in communication process
t, and these data are informed base station controller, judge C by base station controller
t-M
tWith R
tSize, work as C
t-M
t>R
tThe time, keep being connected between terminal and the Cellular Networks; Work as C
t-M
t<R
tThe time, the resource of cellular network can't satisfy user's demand, and Cellular Networks control centre cancellation this moment is connected with terminal, and this moment, terminal inserted the Cellular Networks failure.