The preparation of transferring intersystem connections
The present invention relates to a kind of method, be used for preparing connecting switching (switching (Handover)) wireless area with the subscriber terminal equipment of different wireless communication system compatibility from the wireless area of first wireless communication system of these wireless communication systems to second wireless communication system with one.Wireless communication system can belong to identical or different wireless communication standards (for example GSM, UTRA-TDD, UTRA-FDD ...), wherein at least the first wireless communication system is tdma system (time division multiple access (Time Division Multiple Access)), just transmit data in frame in succession, that be divided into time slot, the time slot within one of them frame is assigned to the unique user terminal equipment respectively.The present invention especially is used in the connection switching between second and the third generation digital mobile radio system that uses different transmission methods.
In wireless communication system, be that wave point between base station or the mobile radio station transmits the information such as voice, image information or other data by the radio station of electromagnetic wave by transmit leg and recipient, such as situation at mobile radio system.At this, utilize the carrier frequency be arranged at the frequency band of separately system's defined, realize irradiation of electromagnetic waves.In known GSM mobile radio system (global system for mobile communications (Global System for MobileCommunication System)), carrier frequency is arranged in the scope of 900MHz, 1800MHz and 1900MHz.For use the mobile radio system in the future of CDMA transmission method and TD/CDMA transmission method by wave point, such as the other system of the UMTS (Universal Mobile Telecommunications System (Universal Mobile Telecommunication)) or the third generation, carrier frequency is defined in the scope of about 2000MHz.
Between the different digital mobile radio system of the second generation and the third generation, should make connection switching without a doubt become possibility, because at first when the enlarging of third generation system begins, installing supply completely or cover.Have only population or industrial concentration zones should equip the system of the third generation when for example beginning, and the rural area continue only to use the system based on second generation mobile radio system to supply.Therefore exist subscriber terminal equipment in this incipient stage at least, these subscriber terminal equipments had both been supported for example transmission method of the second generation of GSM, supported one or more transmission methods of the third generation of TDD (time division duplex (Time Division Duplex)) pattern for example and/or FDD (Frequency Division Duplexing (FDD) (FrequencyDivision Duplex)) pattern again.
If so so-called multi-mode subscriber terminal equipment comes operational communications to connect by third generation mobile radio system, then must have the possibility of the transmission characteristic of measuring the parallel mobile radio system that exists, so that can carry out the connection switching of leading to this mobile radio system in case of necessity.
In the TDMA (time division multiple access) of for example GSM or UMTS (tdd mode) communication system, the time is divided framing, and these frames are divided into time slot at their this respects.Each subscriber terminal equipment is being given transmission and reception within its certain time slot by system assignment.Between two time slots in succession, the receiver of subscriber terminal equipment and transmitter may be utilized at other purpose, for example so that monitor adjacent wireless area or base station, and therefore created prerequisite at the possible connection switching of leading to another wireless area.At this, the receiver of subscriber terminal equipment must be tuned on the frequency of adjacent wireless area in short time, implements to measure on the wireless signal of these adjacent wireless areas, and adjusts back (zurueckstimmen) again then.
Existing with during the transmission of first system is connected, the subscriber terminal equipment of the wireless communication system compatibility different with two should be carried out measurement on the wireless area of second system, so that can be transferred to second system from first system connecting in case of necessity." different wireless communication systems " for example both had been understood that the system according to identical standard work of heterogeneous networks operator here, were understood that the system according to various criterion work again.
In order to be implemented into the switching in second system, subscriber terminal equipment must receive the synchronizing information of second system before real the measurement.This requires long relatively time of reception, makes that the time interval between two time slots distributing to subscriber terminal equipment of first system may be not enough to this.In addition, the part of fixing moment transmission such as this synchronizing information of frame number within a frame only.Under the situation of the disadvantageous time scale between the frame of two wireless communication systems, complete information might can not be received.
Known a kind of being used for from EP 1 005 246 A2 in the method for delivering wireless connections based on the cordless communications system of TDMA, wherein, mobile radio station with the wireless connections of first base station during, on a time slot, attempt, on another time slot at least, set up wireless connections with second base station.
Known a kind of method that is used for the connection switching between two wireless communication systems from WO 96/05707 A1, wherein, subscriber terminal equipment communicates by two systems during at certain time intervals simultaneously.
Known a kind of method from DE 100 08 058 C1 at last, wherein, distribute so-called fault time slot to subscriber terminal equipment, in these fault time slots, can receive the signal of other wireless communication system, be used for handoff preparation, wherein, the wireless communication system of current supply does not transmit data to subscriber terminal equipment during this fault time slot.
In the so-called 1.28Mcps pattern of above-mentioned 3GPP TDD standard, be also referred to as the low spreading rate (LCR of TDD, Low Chiprate) in the standardized scope of pattern or TDSCDMA, studied the tissue of the described measurement that is used to prepare a kind of transferring intersystem connections at present.At this, it should make subscriber terminal equipment (UE-subscriber equipment (User Equipment)) but energy measurement and in case of necessity analyzing and processing have certain signal of the adjacent wireless area of identical or different transmission standard.Under the situation of adjacent gsm wireless sub-district, such signal can for example be FCCH and SCH (synchronizing channel (Synchronisation Channel)); And under the situation of adjacent FDD wireless area or HCR TDD wireless area (the high spreading rate pattern of HCR-3.84Mcps TDD (High Chiprate Modus)), such signal can for example be main SCH and from SCH.
In certain configuration of the time slot that distributes up direction (UL-up link (Uplink)) and down direction (DL-down link (Downlink)) to the connection of subscriber terminal equipment, for this subscriber terminal equipment signal of the adjacent wireless area of energy measurement not, because, and/or transit time, just to the conversion of another frequency oversize too short for the Measuring Time of using.Cheap subscriber terminal equipment, the transit time of so-called low-cost UE typically are positioned at 0.8ms.The Measuring Time of such weak point causes unfriendly, or can not receive the coherent signal of adjacent wireless area, or this subscriber terminal equipment requires long time at interval, may occur in case of necessity connecting within this time interval interrupting.
By Fig. 2 this problem is described exemplarily.Show one and have the sequence that length is respectively two so-called subframes (Sub-Frame) of 5ms.This frame structure is corresponding to the structure of described TDD LCR pattern.In each subframe, in time slot (ts0...ts6-Timeslot), not only travel to and fro between subscriber terminal equipment transmission signal along up direction but also along down direction.Between the transmission direction within the subframe, stipulated fixed-site and transit point (SP-transit point (Switching Point)) that can flexible positioning.In the example of Fig. 2, observe a subscriber terminal equipment, not only distributed the Radio Resource that is used to transmit data or other signaling information for this subscriber terminal equipment along up direction but also along down direction.This characterizes by the arrow that upwards refers at up direction in time slot ts1, or characterizes by the arrow at the downward finger of down direction in time slot ts4.In other time slot of subframe, give the subscriber terminal equipment distributing radio resource, but these Radio Resources are used to travel to and fro between the transfer of data of other subscriber terminal equipment in case of necessity.Among time interval MTA, the MTB between distributed time slot ts0 of institute and ts4 (Measuring Time (Measurement Time)), therefore can receive the signal of adjacent wireless area by subscriber terminal equipment, so that start one the connection switching of leading in these adjacent wireless areas in case of necessity.
Starting point is in the example of Fig. 2, subscriber terminal equipment during this time interval, receive to support the adjacent base station of fdd mode signal (MTA, MTB).Exemplarily under described subframe, show the frame structure of the adjacent wireless area of FDD.By the normally nonsynchronous fact of adjacent wireless system, generally between the zero hour separately of frame certain time warping appears, as also exemplarily illustrating.The base station of the adjacent wireless area of FDD sends the signal of the synchronous channel SCH that is received by observed subscriber terminal equipment with the interval of the rule within this frame.As can be seen from Figure 2, and the time interval separately (MTA, MTB) too little, be used to discern wireless area so that receive the signal in succession of the synchronizing channel of sufficient amount.From having received at least three synchronizing sequences, so-called in succession, just guaranteed identification from SCH code (SSC, Secondary SCH Code) beginning.
In order to ensure the sufficiently long time interval of the signal that is used to receive adjacent wireless area, suggestion now, by dynamic channel allocation (DCA, Dynamic Channel Allocation) is used in the different time slot of signal transmission once in a while to the subscriber terminal equipment branch, so that generate the long as far as possible time interval that is used to observe adjacent wireless area.This for example shown in the image pattern 3 like that, by the time slot ts4 limited time along the signal transmission of down direction from the initial allocation of Fig. 2 be re-assigned to time slot ts3 and realize.Time interval MTB redistributes by this and has prolonged a time slot, and has therefore realized receiving three synchronizing sequence SCH in succession.
In addition, at levels of standards 3GPP 3G TR 25.888, V0.2.0 (2002-8), suggestion in " Improvement of inter-frequency and inter-system Measurementfor 1.28Mcps TDD (between the frequency of 1.28Mcps TDD and the improvement of the measurement between system) " (version 6), carry out and not only to go up redistributing of coordinating along up direction but also along the time of down direction transmission, as this in Fig. 4, exemplarily illustrate.
The aforesaid method of redistributing all causes the big signaling workload based on the required signaling of new Resources allocation unfriendly, cause high mathematical logic workload at the DCA algorithm that is used for providing idling-resource, and cause in case of necessity at the control up direction transmitting power, adaptivity antenna and synchronously in problem.
The present invention based on task be, a kind of method and wireless communication system of avoiding the described shortcoming of known method is described.This task solves by method and the wireless communication system according to the described feature of independent claims.By knowing expansion scheme of the present invention in the dependent claims.
The present invention has advantageously utilized the following fact, promptly transmits the signal of identical connection in two subframes in succession respectively.This not only is applicable to up direction but also be applicable to down direction.Advantageously made full use of in addition, realized having certain redundant data transmission, just in recipient's base station or subscriber terminal equipment, also can rebuild the data that do not receive fully based on so-called error protection.
By diagram in detail method of the present invention is described in detail.At this
Fig. 1 illustrates the frame circuit diagram of two wireless communication systems, especially mobile radio systems,
Fig. 2 illustrates according to first of the subframe of the prior art exemplary configuration,
Fig. 3 illustrates according to second of the subframe of the prior art exemplary configuration,
Fig. 4 illustrates according to the 3rd of the subframe of prior art the exemplary configuration,
Fig. 5 illustrates according to the 3rd of subframe of the present invention the exemplary configuration, and
Fig. 6 a and 6b illustrate according to the exemplary configuration within prior art and the nested frame according to the present invention.
Form by a plurality of network elements, especially a plurality of moving exchanging center MSC (MobileSwitching Center), wireless network controller (RNC) (Radio Network Controller) and base station NB (node (Node) B) respectively as the mobile radio system shown in the example of known wireless communication system among Fig. 1, wherein, only show a base station NB-TDD or NB-FDD respectively.First system for example supports the TDD-LCR pattern, and second system supports the fdd mode of UMTS system.
Each system comprises a plurality of mobile switching centres respectively, the networking each other within a system respectively of this mobile switching centre, and set up the passage that leads to fixed network PSTN (public switch telephone network, Public Switched Telephone Network).In addition, these mobile switching centres are connected with the wireless network controller of the resource that is used to distribute wireless technology.The feasible once more possibility that is connected to become of leading to the base station of in these wireless network controllers each.Base station NB can set up with triggering by wave point and lead to being connected of subscriber terminal equipment UE, subscriber terminal equipment that for example move or fixing.For simplicity, Fig. 1 illustrates a unique subscriber terminal equipment UE, this subscriber terminal equipment UE can be optionally both with first system TDD, communicate with second FDD of system again.The transmission that exists activation between the base station NB-TDD of the subscriber terminal equipment UE and first system connects, for example conversation connects.
At least one wireless area Z-TDD or Z-FDD have been formed by each base station NB-TDD, NB-FDD.When subregion or in the hierarchical organization of wireless area, each base station also is supplied a plurality of wireless areas.The wireless area of different system can intersect arbitrarily geographically.
OMC operation and maintenance centre separately (OMC-Operation and Maintenance) (not shown) has been realized the control and the maintenance function of mobile radio system or part mobile radio system.This structure functional can be used other wireless communication system, especially have on the user access networks of wireless terminal block.
Below exemplaryly set forth method of the present invention by Fig. 5.The fact below this has advantageously utilized is promptly always distributed the transmission channel of a physics symmetrically in two subframe #i and #i+1, just resource unit allocation is applicable to two subframes.According to the example among Fig. 2, in time slot ts1, give subscriber terminal equipment Resources allocation unit at transfer of data along up direction, wherein, this distribution both had been applicable to first subframe, was applicable to second subframe again.Same being applicable to by the base station is used in along the Resource Unit of the transfer of data of down direction.
Advantageously utilized the following fact in addition, promptly, be equipped with error protection to data by before the transmission of wave point.This generally is also referred to as FEC (forward error correction (Forward ErrorCorrection)).Typically encode such as the data of the business of voice data transmission with 1/2 code rate, just the initial data with message double, and therefore become two bits that are encoded from a bit.Bit with the coding that generated similarly is divided on two subframes subsequently, makes each subframe contain complete message.Additional information is pure redundancy, and these information have realized rebuilding owing to the message that has mistake ground to receive is disturbed in transmission the recipient.In order further to improve fail safe, also on four subframes (being equivalent to 20ms), realized the nested of message, just four subframes in succession contain the part of a data-signal that is encoded.This elaborates Fig. 6 following.
As exemplarily illustrating among Fig. 5, interrupt travelling to and fro between the signal transmission of subscriber terminal equipment in the subframe (#i+1) according to the present invention in two subframes.Obviously prolonged the time interval MTB of the SCH that is used to observe and discern adjacent FDD wireless area thus.Although still guarantee to receive reliably the part that is transmitted of message for the redundancy section that does not receive message that occurs thus, not only along up direction, but also in the other subframe (#i) that continues on for transmitting, transmit with the transmitting power that improves along down direction.Can advantageously compensate by the less FEC that interrupts causing (in fact no longer existing redundant) by the transmitting power that improves.Also can carry out this interruption so longways a plurality of subframe centerings in succession, when subscriber terminal equipment successfully is through with the identification of adjacent wireless area till.In addition, also can follow before interrupted subframe and/or subframe afterwards realizes the raising of transmitting power by a plurality of.For example this can depend on described nested coefficient and controls.
At the method that is used to regulate transmitting power of TDD LCR mode standardization, subscriber terminal equipment can not be carried out the autonomous raising of transmitting power, but indicates in signaling by the base station aspect this according at present.Do not allow subscriber terminal equipment in addition, when the ratio that has satisfied echo signal and interference (target SIR), by so-called TPC order (through-put power control (Transmit Power Control)) in the higher transmitting power of place, base station request.
First expansion scheme according to the inventive method, with above-mentioned standardized means on the contrary, the subscriber terminal equipment request improves the transmitting power of base station, and same autonomous improve some, follow before one or more interrupted subframes and/or the transmitting power of subframe afterwards.After successfully measuring and discern adjacent wireless area, can advantageously reduce the transmitting power of base station once again by the subscriber terminal equipment request, and/or the reduction of the transmitting power that independently draws oneself up.At this, for example realize changing the signaling of base station transmitting power by the known signaling that is used to control transmitting power.
Be alternative in or be complemented at first expansion scheme of the inventive method, subscriber terminal equipment signals to the base station and represents, do not send data along up direction in next one subframe subsequently, or it adopts a subframe that is used to observe adjacent wireless area.For example realize this signaling by one or more bits that are not used according to present standard of synchronizing sequence, these synchronizing sequences send to along up direction from subscriber terminal equipment the so-called UpPTS (uplink pilot time slot (Uplink Pilot Timeslot)).Two bits can send signal indication at this by for example adopting, and in four supporting, nested subframes which subscriber terminal equipment should use observe adjacent wireless area.The cognitive untapped subframe of this signaling is passed through in the base station, and knows that correspondingly it can not or needn't receive the data of subscriber terminal equipment in this subframe.The base station can stop the transmission to subscriber terminal equipment of oneself in the same way in this subframe, so that for example advantageously reduce the interference effect of parallel transmission in this subframe.
Be alternative in first expansion scheme of the inventive method, as this cognitive conclusion of the upcoming subframe that is used to observe adjacent wireless area, the transmitting power of oneself can independently be improved in the base station, and does not require the additional signaling of subscriber terminal equipment.Be alternative in this place in addition, its transmitting power can independently be improved in the base station, and orders indicating user terminal equipment to improve transmitting power equally by TPC, and wherein, especially all other the subframe for nested frame advantageously realizes this point.
According to one of the inventive method other alternative expansion scheme, the needs that subscriber terminal equipment will be used to observe the time interval of adjacent wireless area signal to the base station.So suitable subframe is determined in the base station, and this subframe is signaled to subscriber terminal equipment by suitable known signaling mechanism.According to above-mentioned method, in the subframe former and/or subsequently, or in other subframe of nested frame, improve transmitting power separately.This again can be aspect subscriber terminal equipment independently or the indication by the base station realize.In this case, can be advantageously the base station that exists in case of necessity be used to define the best suitable time interval that is used to observe about the cognition of the relative time structure of adjacent wireless area or wireless system.
Below exemplarily set forth first the inventive method by Fig. 6 a and 6b.In Fig. 6 a and 6b, illustrated in the configuration for example shown in Figure 1, the transfer of data between subscriber terminal equipment and base station.For the transmission along up direction of leading to the base station, in time slot ts1, distributed one or more Resource Units, for example CDMA code for subscriber terminal equipment.Distribute one or more Resource Units for transmission in the same way along down direction.With message, be that certain data volume waiting for transmission nestedly is transferred to so-called nested frame or TTI (Transmission Time Interval, Transmission Time Interval) by four subframes.Along among the time interval MTA and MTB between the sending separately of up direction and down direction, subscriber terminal equipment can be carried out the observation of adjacent wireless area.As shown in Fig. 6 a, these time intervals but fall short of, so that guarantee to receive reliably at least three synchronizing sequences in succession of adjacent FDD base station.
Based on this problem, subscriber terminal equipment interrupts to the current base station transmit signals that is supplied and receives this signal of base station at a subframe, as shown in Fig. 6 b.At the long time that forms therefrom at interval among the MTB, subscriber terminal equipment can receive the synchronizing sequence of sufficient amount of the synchronizing channel of adjacent FDD base station, and can discern this synchronizing channel.Although in order to interrupt travelling to and fro between the transmission of the current base station that is supplied and receive the reliable reception of still guaranteeing data-signal, subscriber terminal equipment orders the transmitting power that requires the base station to improve for example 2dB by the corresponding TPC of expression that signals to the base station, or the value of echo signal and noise ratio (target SIR) improved 2dB, and this echo signal and noise ratio are signaled to the base station.During the subframe of other in nested frame, subscriber terminal equipment comes to send data-signal along up direction with the transmitting power that has improved 2dB equally, so that make the cognition that the base station does not interrupt transmitting also realize enough detections and error correction, because remaining data-signal has higher detection fail safe thus.