CN1768547A - Method and apparatus for supporting P2P communication in TDD CDMA communication system - Google Patents
Method and apparatus for supporting P2P communication in TDD CDMA communication system Download PDFInfo
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Abstract
A method for supporting P2P communication between two user equipments in TDD CDMA systems, performed by user equipment, comprising: receiving signals transferred via the downlink control channel from network system; acquiring the timeslot allocation information and the spreading code allocation information of other active user equipments allocated in the specific downlink timeslot associated with the direct link used by said user equipments, according to the received signals; and synchronizing the P2P communication signals received by the user equipment and signals from network system, according to the acquired timeslot allocation information and spreading code allocation information, so as to reduce the interference caused by the downlink signals transmitted from network system to other user equipments during the P2P communication process.
Description
Technical field
The present invention relates to a kind of TDD of being used for CDMA (time-division duplex) communication system and support P2P (point-to-point) method for communicating and device, relate in particular to a kind of TDDCDMA of being used for communication system reduction user terminal and carrying out the method and apparatus that the P2P communication period is subjected to from the interference of traditional communication signal.
Technical background
In traditional cellular mobile communication system, a user terminal must could communicate with another user terminal by the relaying of base station, even these two user terminal close proximity still need the relaying of base station just can communicate with one another, in Fig. 1, shown this traditional communication pattern.Yet in some cases, as reside in two user terminals in the same sub-district each other during close proximity, do not need the base station in to allow two user terminals directly communicate then be more rational selection, so-called P2P communication that Here it is.
Fig. 2 has shown the P2P communication between two user terminals.As shown in Figure 2, suppose that two user terminals all reside in same sub-district and distance each other satisfies the condition of setting up the P2P link, then the dotted line among the figure is illustrated in the signaling link between P2P communication period UTRAN and the user terminal, and solid line is illustrated in the data link between the user terminal, and the arrow of dotted line and solid line is represented the direction of information flow.Obviously, as we can see from the figure, between UTRAN and user terminal, only there is signaling link, and between two user terminals, only has the data link.If ignore the extra that some is used to manage, adopt P2P communication can in the process of direct communication, save 50% Radio Resource so.In addition, owing to maintain control channel between UTRAN and user terminal, therefore, in the P2P communication period, the operator of wireless network still can be by the use of base stations control user terminal to wireless frequency.
Time division duplex (TDD) air interface is generally believed a kind of communication standard that can adapt to the requirement of uplink and downlink link different business more neatly in the communications field.In the third generation communication system that adopts the TDD communication pattern, the TD-SCDMA communication system, owing in the uplink and downlink link communication, use the simplification of the user terminal radio-frequency module that same carrier frequency brought, become and be more suitable for a kind of desirable communication system that P2P communication is combined with conventional communication mode.
In can adopting the TD-SCDMA communication system of P2P communication pattern, except two kinds of operator schemes that in traditional TD-SCDMA communication system, define: idle pulley and the connection mode, also introduced Direct Model and be described in two direct communications between the user terminal.Send signal or receive information flow direction to another user terminal according to a user terminal from another user terminal signal, be in communication linkage in the Direct Model can be defined as forward direction (FORWARD) link (for example: user terminal UE1 is to the link between the user terminal UE2) and after link (for example: user terminal UE2 is to the link between the user terminal UE1) to (BACKWARD).Because the P2P communication pattern is set up in conjunction with existing TD-SCDMA communication system, thereby during direct communication, UTRAN and with carry out other legacy user terminals that user terminal that P2P communicates by letter is distributed in same time slot and just can overhear the information of transmitting in this forward link or the backward chaining, that is: because P2P communication has changed the UP-UTRAN-DOWN communication pattern in traditional TD-SCDMA communication system, angle from UTRAN, even user terminal does not link with UTRAN, forward link is also relevant (according to different Resource Allocation Formulas with concrete certain uplink time slot or downlink time slots with backward chaining, forward link and backward chaining are corresponding to different uplink time slots or downlink time slots), so P2P communication meeting causes signal to disturb to traditional communication.Same reason, because in the P2P communication period, two user terminals that carry out P2P communication also can overhear the signal that transmits in uplink time slot relevant with its forward link or backward chaining or the downlink time slots, therefore, when legacy link and P2P link when sharing same time slot, line link or downlink communication will disturb the communication of P2P forward link or backward chaining traditionally, and this will seriously reduce the performance of the TDD cdma communication system that adopts the P2P communication pattern.
In order to improve the performance of the TD-SCDMA communication system that adopts the P2P communication pattern, need to eliminate effectively and introduce these signals that the P2P communication pattern brings for the TD-SCDMA communication system and disturb.
Hereinafter, the interference signal of at first introducing P2P communication pattern being brought being analyzed, then, to how eliminating interference signal being described again.In order hereinafter to analyze the convenience of discussing, now be called transmission time slot from a user terminal to the time slot that another user terminal transmits via above-mentioned forward link or reverse link, and this user terminal is called receiving slot via the time slot that forward link or reverse link receive from another user terminal signal, this transmission time slot and receiving slot are relevant with uplink time slot or downlink time slots in the subframe of traditional communication respectively.
1, the interference relevant between P2P link and legacy link with uplink time slot
Fig. 3 shown when P2P link is relevant with uplink time slot, the mutual interference mutually in the TD-SCDMA communication system that introducing P2P communicates by letter between P2P and the conventional link.As shown in Figure 3, suppose that user terminal UE1 and UE2 are operated in the P2P communication pattern, and user terminal UE3 is operated in conventional communication mode.Wherein, the transmission time slot of user terminal UE1 is relevant with the uplink time slot of user terminal UE3, that is: user terminal UE1 and user terminal UE3 are dispensed on same ascending time slot and send signal to user terminal UE2 and UTRAN respectively.S1 is the P2P link information that user terminal UE1 launches to user terminal UE2 via direct link (note is made forward link here), and S2 is the up-link information that user terminal UE3 launches to UTRAN via up link, and S1 has different spreading codes with S2.
In the TD-SCDMA communication system, what keep up link is a wherein most important feature synchronously, because only the signal from different user terminals arrives UTRAN simultaneously, just can guarantee the spreading code quadrature of the signal that the received main path via different user terminals of UTRAN sends.For legacy communications system, in connection mode, UTRAN is according to the specific signal burst structure, and the uplink transmit time of monitoring and control user terminal is to keep the uplink synchronisation of each user terminal; Yet, for the P2P communication pattern, set up process and do not participate in P2P communication process after the P2P link is set up because UTRAN only participates in P2P link, therefore, in the P2P communication period, two user terminals that participate in the P2P link all do not have dedicated channel to link to each other with UTRAN, in this case, even UTRAN can audit and estimate the synchronisation offset of the up link of two user terminals that are in the P2P link, this UTRAN does not have approach to utilize specific signal to happen suddenly to adjust two user terminals in the P2P communication to send the synchronous lead of signals yet, to keep the uplink synchronisation with UTRAN.
In Fig. 3, when sending signal in the ascending time slot in same distribution as user terminal UE1 and UE3, UTRAN can overhear the information S1 that sends to UE2 from user terminal UE1 (for UTRAN, S1 considered as interference signal I1), but as mentioned above, owing to do not have dedicated channel between UTRAN and the user terminal UE1, therefore, even if UTRAN overhears S1 information, and can estimate the synchronization shift information of UE1, can not utilize the business burst in the conventional communication mode to adjust the time that UE1 sends signal, this just means that also the user terminal UE1 that works in the P2P communication pattern may lose uplink synchronisation (the user terminal UE3 that works in conventional communication mode can keep uplink synchronisation by traditional mode and UTRAN) with UTRAN, that is to say that I1 and S2 can not arrive UTRAN synchronously, this will damage the synchronous of up link potentially, thereby cause the reduction of systematic function.
Same reason, when sending signal in the ascending time slot in same distribution as user terminal UE1 and UE3, user terminal UE2 also can overhear signal S2 that user terminal UE3 sends to UTRAN (for user terminal UE2, S2 can regard interference I2 as), it is also influential that this interference signal I2 receives S1 to user terminal UE2, and this may damage the quality of P2P communication potentially.
2, the relevant interference between P2P link and legacy link with downlink time slots
Fig. 4 shown when P2P link is relevant with downlink time slots, the mutual interference mutually in the TD-SCDMA communication system that introducing P2P communicates by letter between P2P and the conventional link.As shown in Figure 4, suppose that user terminal UE1 and UE2 are operated in the P2P communication pattern, and user terminal UE3 is operated in conventional communication mode.Wherein, the receiving slot of user terminal UE1 is relevant with the downlink time slots of user terminal UE3, that is: user terminal UE1 and user terminal UE3 are dispensed on same descending time slot and receive signal from user terminal UE2 and UTRAN respectively.S3 is the P2P link information from user terminal UE2 via direct link (note is done backward chaining here) transmission that user terminal UE1 receives, and S4 is the downlink information from UTRAN via the down link transmission of user terminal UE3 reception, and S3 has different spreading codes with S4.
In Fig. 4, the downlink information S4 that UTRAN sends to user terminal UE3, can to other with this user terminal UE3 in same time slot received signal but adopt the user terminal of different spreading codes to produce and disturb, this interference is also referred to as multiple access and inserts interference (MAI).
In Fig. 4, as user terminal UE1 and user terminal UE3 in the descending time slot in same distribution during received signal, user terminal UE1 can overhear UTRAN and send to the information S4 of user terminal UE3 (for user terminal UE1 via down link, S4 considered as interference signal I4), and generally the transmitting power from the signal of UTRAN is stronger, therefore, this interference signal I4 might seriously damage the quality of direct communication.
Same reason, when user terminal UE1 and user terminal UE3 in same distributed time slot during received signal, user terminal UE3 also can overhear information S3 that user terminal UE2 sends to user terminal UE1 (for user terminal UE3, S3 considered as interference signal I3, at this moment, the pseudo-UTRAN that user terminal UE2 can be used as in downlink time slots emission information), this interference signal I3 can damage near be positioned at the user terminal UE2 user terminal UE3 and with user terminal UE3 the same with the communication quality of this user terminal UE2 at other user terminals of same time slot received signal.
3, two P2P link between interference
Fig. 5 shown in the TD-SCDMA communication system that adopts the P2P communication pattern two P2P links between interference, wherein the user terminal of the user terminal of these two P2P link pair P2P link pair and another P2P link pair receives or sends signal in same distributed time slot.As shown in Figure 5, suppose that user terminal UE1 and UE2 are operated in a P2P link pair, and user terminal UE3 and UE4 are operated in another P2P link pair.
Because the symmetry of P2P link, in relevant time slot, signal S5 from user terminal UE1 to user terminal UE2 or S6 will become from interference signal I5 or the I6 of the user terminal UE4 of user terminal UE3 received signal.Obviously, interference signal I5 or I6 also may greatly damage the quality of direct communication.
In sum as can be known, in traditional TD-SCDMA communication system, introduce after the P2P link, have I1, I2, I3, I4, I5 and I6 totally 6 kinds of possible interference signals in the communication system.Whether can relate to UTRAN according to these interference signals, can be divided into two classes to above-mentioned 6 kinds of interference signals, the first kind is the interference between user terminal, such as I2, I3, I5 and I6; Second class relates to the interference of UTRAN, such as I1 and I4.
Communication quality for the TD-SCDMA communication system that guarantees to have the P2P communication pattern need work out effective method to eliminate above-mentioned 6 kinds of interference (being preferably under the situation that does not change present communication system physical layer).Wherein, in 6 kinds of interference signals of above-mentioned analysis, range for wireless communication and the intelligent Radio Resource control strategy of employing by limiting P 2 P support effectively can reduce or eliminate the first kind and disturb, be i.e. I2, I3, I5 and I6; And about the interference signal I1 in the interference of second class, the application people who submits on March 7th, 2003 is that CN030004, application number are in 03119894.5 the patent application of exercise question for " method and apparatus that the uplink synchronisation of point-to-point peer-to-peer communications keeps in the cordless communication network " for Koninklijke Philips Electronics N.V, applicant's file number, described the method and apparatus of eliminating interference signal I1 in detail, in this mode, add the content that this application discloses to insert; But the interference signal I4 in the interference of second class does not also propose effective solution at present.
From above-mentioned analysis to interference signal as can be known, interference signal I4 be when UTRAN via down link when user terminal UE3 transmits signal, to the interference signal of bringing at the user terminal UE1 of same descending time slot received signal with user terminal UE3.Because generally, UTRAN sends the transmitting power higher (being high enough to make all user terminals of sharing same downlink time slots in same cells to listen to) of signal, and this signal is a mixed signal that comprises the redundant information of many other user terminals, so I4 can not ignore usually, in user terminal UE1, must take the method for Multiuser Detection or joint-detection that this interference signal is eliminated, to guarantee the quality of direct communication.
Summary of the invention
The purpose of this invention is to provide a kind of being used for supports P2P method for communicating and device in TDD cdma communication system, with the interference from the down link signal that transmits at same descending time slot with this user terminal in the traditional communication that is reduced in effectively that user terminal is subjected in the direct communication process.
In order to realize purpose of the present invention, a kind ofly in TDD cdma communication system, support this user terminal and another user terminal to carry out P2P (point-to-point) method for communicating according to of the present invention, comprise step: receive by the signal of network system by the downlink control channel transmission by user terminal being used to of carrying out; According to the signal that is received, obtain time slot allocation information; According to the signal that is received, obtain the spreading code that is distributed in other the in running order user terminals in the specific downlink time slots and distribute information, wherein this specific downlink time slots is: employed downlink time slots when this user terminal carries out the signal reception via the direct link between it and this another user terminal; And distribute information according to this time slot allocation information that is obtained and this spreading code, the interference that when other user terminals transmit down link signals, brings from network system that reduces that this user terminal is subjected in the P2P communication process.
A kind ofly in TDD cdma communication system, be used to be supported between two user terminals and carry out the P2P method for communicating according to of the present invention by what network system was carried out, comprise step: via downlink control channel, to two user terminal sending time slots assignment information of carrying out P2P communication; The corresponding spreading code of each downlink time slots distributes information in generation and this time slot allocation information; And, send described spreading code respectively to these two user terminals and distribute information, so that the signal of the P2P that each user terminal in these two user terminals is received communication and signal Synchronization from this network system via downlink control channel.
The accompanying drawing summary
Fig. 1 is the schematic diagram that two user terminals communicate via the relaying of base station in conventional communication mode;
Fig. 2 is the schematic diagram that adopts the P2P communication pattern between two user terminals;
Fig. 3 is in the TD-SCDMA system that introduces the P2P communication pattern, the legacy link that adopts uplink time slot communication with directly link between the schematic diagram of interference signal generation;
Fig. 4 is in the TD-SCDMA system that introduces the P2P communication pattern, the legacy link that adopts downlink time slots communication with directly link between the schematic diagram of interference signal generation;
Fig. 5 is in the TD-SCDMA system that introduces the P2P communication pattern, two direct link between produce the schematic diagram of interference signal each other;
Fig. 6 is the schematic diagram of the time slot allocation information that adopts of the present invention;
Fig. 7 is that the spreading code that the present invention adopts distributes the schematic diagram of information;
Fig. 8 is when adopting downlink time slots communication, is time reference point with the UTRAN place, receives the time relationship schematic diagram from the down link signal of base station and UE2 respectively at user terminal UE2 and UE1 place;
Fig. 9 is the method flow diagram that makes the reception user terminal downlink synchronization in Direct Model that the present invention carries out.
Detailed Description Of The Invention
To the analysis of interference signal in the TD-SCDMA communication system of introducing the P2P communication pattern, the present invention is mainly around the problem from the interference signal of traditional base station down link that solves that the reception user terminal that carrying out P2P communication is subjected to according to above.
In fact, in the base station sub-system (UTRAN) of TD-SCDMA communication system, adopted a kind of advanced person's receiver, that is: eliminate multiple access with the method for Multiuser Detection or joint-detection and insert interference, this method is for example disclosing in ieee communication in October, the 1996 magazine 124-136 page or leaf, the author is S.Moshavi, name be called " be used for DS-CDMA communication Multiuser Detection " article and in May, 1996 IEEE can report in the 2nd 276-287 page or leaf of vehicle-mounted technology the 45th volume and disclose, the author is A.Klein, G.K.Kaleh and P.W.Baier, the article that name is called " ZF and the mmse equalizer that are used for Multiuser Detection in CDMA channel " has a detailed description, here the mode to insert is incorporated the technology contents that discloses in the above-mentioned article into.But, if the method that the elimination that Multiuser Detection or joint-detection is such is disturbed is applied in the receiver of user terminal, need satisfy following two conditions in advance:
1, acquisition and this user terminal are distributed in the spreading code information of all in running order user terminals of same time slot;
2, be in user terminal in the Direct Model when the signal that receives from direct link, keep and relevant downlink signal synchronization,, could effectively reduce the complexity of receiver realization because have only signal Synchronization from UTRAN.
Below, will discuss with regard to above-mentioned two conditions respectively:
1, obtains spreading code and distribute information
Be in the communication system of example with TD-SCDMA, the spreading code that is in all user terminals uses of mode of operation is all controlled by base station sub-system UTRAN.In communication process, radiofrequency signal is to transmit information with the form of frame, and each radio frequency frame is divided into 2 subframes, and each subframe is made of 7 time slots, each user terminal that is distributed in same time slot utilizes the different spreading code of base station sub-system distribution, sends or receive signal separately.
Because downlink control channel, as BCCH (Broadcast Control Channel), position in each radio frequency frame or subframe is fixed, and no matter be operated in conventional communication mode or be operated in the P2P linking scheme, user terminal can both receive the information from downlink control channel, therefore, user terminal can be according to the control information from UTRAN that transmits via downlink control channel, and the spreading code that obtains all user terminals of shared same time slot with it distributes information.
Wherein, spreading code distributes packets of information to draw together two parts: (i) in each frame or subframe, (ii) relevant with each downlink time slots that the is distributed spreading code of time slot allocation information that each time slot is used for up link or is used for down link distributes information.
In embodiment of the present invention, above-mentioned time slot allocation information and spreading code distribute information, have adopted the mode of mapping respectively, with relevant information stores in corresponding time slot allocation figure and frequency spreading code division figure, particularly:
(1) about time slot allocation information
Be in the communication system of example with TD-SCDMA, each subframe comprises 7 time slots, and note is made TS0-TS6 respectively, therefore, in time slot allocation figure, only utilize the byte of one eight bit long just can realize with a subframe in the mapping of 7 time slots.
Wherein, time slot is corresponding with a bit in the byte, and as shown in Figure 6, time slot TS0-TS6 is corresponding with the Bit6-Bit0 in the byte respectively, and byte Bit7 keeps.For each bit among the byte Bit6-Bit0, suppose: when its value was 1, expression was used as downlink time slots with this bit time slot corresponding; When its value was 0, expression was used as uplink time slot with this bit time slot corresponding.Because in the TD-SCDMA system, TS0 always distributes as down link, TS1 always distributes as up link, and therefore, the value perseverance of Bit6 is 1 in the byte, and the value perseverance of Bit5 is 0.
(2) distribute information about the spreading code relevant with each downlink time slots that is distributed
After the time slot allocation in a radio frequency frame or the subframe is finished, base station sub-system (UTRAN) can be according to the downlink time slots that comprises in this subframe, the spreading code that corresponding generation is relevant with each downlink time slots that is distributed distributes information, is example with the TD-SCDMA system still below.
In this communication system, downlink time slots can have nearly the different code channels uses of 16 spreading codes for different user terminals or same terminal, so in order to express the operating position of each spreading code in the downlink time slots, need 16 bits, that is: the byte of 2 eight bit long represents that spreading code distributes information.By as can be known aforementioned, in 7 time slots that each subframe comprises, TS1 is always as up link, so each subframe has 6 time slots at most as down link, for the spreading code of representing these 6 time slots uses information, needs the byte of 12 eight bit long altogether.
Below by concrete example, illustrate that the spreading code that comprises distributes information in a downlink time slots.Suppose in above-mentioned time slot allocation figure shown in Figure 6, byte Bit4 and Bit1 equal 1, that is: TS2 and TS5 are as downlink time slots, the byte that then in the frequency spreading code division figure of correspondence shown in Figure 7, should comprise 4 eight bit long, wherein: two bytes of first group are corresponding to the assignment information of each spreading code of TS2 time slot, and two bytes of second group are corresponding to the assignment information of each spreading code of TS5 time slot.The part that background color is more shallow among Fig. 7 is two bytes of first group, and it respectively can be for the spread spectrum codes C ode15 of maximum 16 user terminals or the code channel use information to Code0 in the corresponding TS2 time slot from Bit15 to Bit0; And the darker part of background color is two bytes of second group, and it respectively can be for the spread spectrum codes C ode15 of maximum 16 user terminals or the code channel use information to Code0 in the corresponding TS5 time slot from Bit15 to Bit0.For above-mentioned two groups of values of the pairing bit of each spreading code in totally four bytes, be defined as follows: when the bit value corresponding with this spreading code is 1, represent that this spreading code is used by user terminal in corresponding time slot; And when the bit value corresponding with this spreading code is 0, represent that this spreading code also do not distribute to user terminal in corresponding time slot, for example: when the Bit8 in two bytes of the 1st group and Bit0 are 1 and other bits when being 0, among expression and the 1st group of time slot corresponding TS2, have only the spreading code corresponding with Bit8 and Bit0 to be used by user terminal, other spreading code then also is not assigned to user terminal and uses.
As mentioned above, assignment information by each spreading code that each downlink time slots in each time slot allocation information of subframe and the subframe is comprised is mapped to respectively in time slot allocation figure and the frequency spreading code division figure, base station sub-system UTRAN can be via down control channel, the information that comprises in this time slot allocation figure and the frequency spreading code division figure is sent to each user terminal, thereby make user terminal obtain that spreading code distributes information in time slot allocation information and the relevant downlink time slots.
Certainly, if desired, user terminal also can use with above-mentioned similar methods and obtain time slot allocation information relevant with uplink time slot and spreading code distribution information.
2, be in user terminal in the Direct Model when the signal that receives from direct link, keep and relevant downlink signal synchronization from UTRAN
In traditional TD-SCDMA system, if ignored the multidiameter effect, then the down link mixed signal that is sent by UTRAN should be to arrive each user terminal synchronously; Yet because in the TD-SCDMA system that introduces P2P communication, from the useful signal S3 of P2P communications user terminal with from the transmission path of the interference signal I4 of UTRAN very big difference is arranged, (referring to accompanying drawing 4), therefore signal S3 will be different with the time of I4 arrival user terminal UE1, that is: be in user terminal UE1 in the Direct Model when the signal S3 that receives from direct link, can not guarantee with synchronous from the down link signal I4 of UTRAN.In this case, even can obtaining by the time slot allocation information of UTRAN emission and spreading code, user terminal UE1 distributes information from downlink control channel, because signal S3 and I4 arrive user terminal UE1 simultaneously, though still can adopt this moment traditional associated detecting method to come in user terminal UE1, to eliminate interference signal I4, owing to asynchronous reason of time will cause increasing greatly such as the complexity of channel estimating, joint-detection realization etc.
In order to simplify the operation of receiver among the user terminal UE1 dramatically, eliminate simultaneously dl interference signal I4 effectively, receiving the necessary link that becomes assurance P2P communication quality synchronously that user terminal UE1 place realizes direct link signal S3 and interference signal I4.
As can see from Figure 4, can not arrive under the situation of user terminal UE1 synchronously at useful signal S3 and interference signal I4, can have two kinds of methods to make them arrive user terminal UE1 synchronously: the one, the Timing Advance of adjustment UTRAN transmit (I4), make its signal S3 of the I4 that transmits and user terminal UE2 emission to arrive user terminal UE1 two synchronously are Timing Advances of adjusting user terminal UE2 transmit (S3), make the signal S3 of this user terminal UE2 emission and the signal I4 that UTRAN launches arrive user terminal UE1 synchronously.Wherein, first method---emission time initial lead of UTRAN adjusted so that I4 and S3 arrive user terminal UE1 synchronously is impossible realization; this be because; in communication process; usually can exist the P2P link of the identical descending time slot of a plurality of uses right; and make dl interference signal I4 and all these carry out the signal that user terminal received (as S3) that P2P communicates by letter synchronously by a public signal time lead (TA) by the UTRAN emission; be impossible guarantee; therefore; must adjust the Timing Advance of its emission useful signal S3 at user terminal UE2 place; could ensure each user terminal of being in the Direct Model when the signal that receives from each different direct link, keep and relevant downlink signal synchronization from UTRAN.
In conjunction with the accompanying drawings 8 above-mentioned synchronizing process is described before, have 2 needs to illustrate earlier:
(i) in the traditional communication mode, foundation and maintenance and UTRAN's is synchronous
In the Cell searching stage, each user terminal at first all in the mode of traditional communication, is set up downlink synchronization with UTRAN, then, by follow the tracks of in the subframe pilot channel and will this detected pilot channel as the time reference in its subframe, keep downlink synchronization with UTRAN.
(ii) in the P2P communication pattern, keep synchronous with relevant downlink time slots
When user terminal UE2 and UE1 are in the Direct Model that P2P communicates by letter, between UE2 and UE1, there is special-purpose channel, and the business burst structure of the dedicated channel in the business burst structure of this dedicated channel and the traditional TD-SCDMA communication system is identical, this means that power control information and synchronization shift information are also contained in the business burst of the forward direction of dedicated channel of this P2P link and backward chaining.In traditional TD-SCDMA communication system, be included in the uplink synchronization that synchronization shift information in the business burst can be used for remaining on the UTRAN place, in like manner, in P2P communication, the synchronization shift information that is included in the business burst of direct link also can be used for remaining on when receiving the direct link signal synchronous with relevant conventional downlink by the P2P user terminal.
From 2 top explanations as can be known, owing to set up beginning (Cell searching stage) in communication, each user terminal set up in a conventional manner respectively with the down link of UTRAN synchronously, thereby when setting up P2P communication, two user terminals can have common time reference further to determine the synchronous of direct link signal and down link signal; Simultaneously, owing in the business burst of the dedicated channel of P2P, include the synchronization shift information identical with traditional approach, thereby P2P set up with the process of communicating by letter in, user terminal can utilize this synchronization shift information to set and adjust the Timing Advance that it transmits, to guarantee the synchronous of direct link signal and down link signal.
Below with reference to accompanying drawing 8 and accompanying drawing 4, be described in and receive the synchronizing process that the user terminal place guarantees direct link signal and down link signal,, suppose that this useful signal S3 and interference signal I4 share same downlink time slots here for user terminal UE1.
At first, as public reference point, the time relationship between the time of reception of each user's received signal and UTRAN place reference point common time as shown in Figure 8 with UTRAN.In Fig. 8, T0 is in relevant downlink time slots, downlink time reference at the UTRAN place, T1 and T2 are respectively the time of reception point when user terminal UE1 and UE2 place receive signal, aforesaid, user terminal UE1 and UE2 can discern T1 and T2 from the mode of the pilot channel of UTRAN by discovery and tracking.Period T
URTAN-UE2(its value equals T2-T0) and period T
URTAN-UE1(its value equals T1-T0) is respectively signal is sent to UE2 and UE1 from UTRAN delivery time.T
UE2-UE1(its value equals T21-T2) to be supposition user terminal UE2 send a test signal and this test signal arrives the time period between the time point T1 of UE1 and traditional base station signal arrival UE1 constantly at T21 to UE1 constantly at T2, here, in order to guarantee that useful signal S3 and interference signal I4 arrive UE1 at synchronization, should make that T21 overlaps with moment T1 constantly.
Then, user terminal UE1 calculates Timing Advance by estimation by the channel impulse response of each training sequence of UE2 emission, and this Timing Advance that calculates is included in from user terminal UE1 to the business burst that user terminal UE2 sends as synchronization shift information.Owing in business burst, include the training sequence that the measuring and calculating Timing Advance uses, thereby even if two user terminals all are in the mobile status, user terminal UE1 and UE2 also can momentarily estimate and adjust the Timing Advance that transmits.
Above-mentionedly carry out the synchronous process of conventional downlink, mainly comprise following step at direct link:
(1) UE1 and UE2 set up respectively and the downlink synchronization of maintenance and UTRAN
User terminal UE1 and UE2 set up downlink synchronization in the Cell searching stage, and by following the tracks of the synchronous (step 1) of pilot channel maintenance down link.
(2) UE2 determines the time that it transmits
In the process that directly link is set up, user terminal UE2 is in relevant downlink time slots, constantly as the moment that transmits to user terminal UE1, and the T2 in this downlink time slots is constantly to a user terminal UE1 emission signal (step 2) with T2.
(3) time difference of UE1 measuring and calculating direct link signal and down link signal
In the process that directly link is set up, when user terminal UE1 receives by UE2 in the business burst that T2 sends constantly, according to the training sequence information that comprises in this business burst, measuring and calculating T
UTRAN-UE2+ T
UE2-UE1-T
UTRAN-UE1(T21-T1) time difference, and this measurement result sent to user terminal UE2 (step 3) as feedback information.
(4) UE2 is provided with the Timing Advance that sends signal
User terminal UE2 is provided with the Timing Advance that it transmits, and adjusts the time that this user terminal UE2 transmits with this Timing Advance according to the feedback information from user terminal UE1.(step 4)
(5) UE1 estimates and sends synchronization shift information to UE2
User terminal UE1 calculates synchronization shift information by estimation by the channel impulse response of each training sequence of UE2 emission, and the synchronization shift information that this calculates is arranged on from user terminal UE1 to the business burst that user terminal UE2 sends, wherein calculate synchronization shift information based on channel impulse response, can be according to 3GPP TS 25.928, disclosed standard is calculated in " 1.28McpsUTRA TDD physical Layer " agreement, here the mode to insert is incorporated disclosed technology contents in this standard into.(step 5)
(6) UE2 adjusts the Timing Advance that sends signal
User terminal UE2 adjusts the Timing Advance (step 6) that it sends signal according to the synchronization shift information that comprises in the business burst from user terminal UE1.
(7) repeated execution of steps 5 and step 6
Judge whether P2P communication finishes (step 7), if direct communication does not finish as yet, then as long as directly link is also relevant with this downlink time slots, that is: this directly links with this downlink time slots and shares same time slot, just constantly repeat above-mentioned steps 5 and 6, keep synchronously to guarantee the direct link signal S3 down link signal I4 relevant with this.
Pass through above-mentioned steps, can arrive simultaneously from the useful signal S3 of user terminal UE2 and interference signal I4 and to receive user terminal UE1 from UTRAN, thereby on the basis that has guaranteed downlink synchronization, distribute information according to the spreading code that obtains, user terminal UE1 can utilize methods such as Multiuser Detection or joint-detection, elimination is from the dl interference signal (I4) of UTRAN, to guarantee the communication quality of the TDD cdma system that introducing P2P communicates by letter.
Certainly, at two user terminals that are in the direct communication pattern under the very near situation, that is: receive from the moment T1 of the signal of UTRAN and T2 almost equal the time as UE1 and UE2, direct link signal S3 and down link signal I4 arrive the time difference of user terminal UE1 and almost can ignore, at this moment, above-mentioned synchronizing process can be omitted, and only needs spreading code to distribute information, and user terminal UE1 can eliminate the adverse effect that interference signal I4 brings by joint-detection.
In addition, what need indicate is, the Timing Advance of the transmission signal that user terminal UE2 sets and adjusts by above-mentioned steps, can only guarantee that useful signal S3 and interference signal I4 arrive user terminal UE1 simultaneously, and can not guarantee that useful signal S4 and interference signal I3 arrive user terminal UE3 simultaneously in the accompanying drawing 4, therefore, in user terminal UE3, its receiver can not distribute information according to the spreading code that obtains, and eliminates the influence (perhaps utilizing asynchronous associated detecting method to eliminate the influence of I3 on the basis that increases complexity) that interference signal I3 produces in this user terminal UE3 effectively.Fortunately, in practical communication, since when user terminal UE3 when adopting conventional synchronization joint-detection (JD) method from S4, to extract the information of expecting, it is to derive from the mixed signal S4 that is received that its overwhelming majority that is subjected to is disturbed, at this moment, interference signal I3 can ignore to the influence of useful signal S4.
The support descending time slot P2P method for communicating in the TD-SCDMA system of the invention described above can adopt computer software to realize, also can adopt computer hardware to realize, or adopt the mode of computer software to realize.
Beneficial effect
In sum, support P2P method for communicating and device in a kind of being used for provided by the present invention in the TD-SCDMA system, because the user terminal that is in the direct communication pattern can obtain spreading code distribution information via down link, therefore, this user terminal can utilize and be distributed in the spreading code that is just being used by other user terminals in the same downlink time slots with it and distribute information, adopt methods such as Multiuser Detection or joint-detection, the interference of eliminating effectively that user terminal is subjected in the direct communication process from the down link signal that transmits at same time slot with this user terminal in the traditional communication.
In addition, owing to support in P2P method for communicating and the device in the TD-SCDMA system in a kind of being used for provided by the invention, adopted and made the direct link signal that is in related time-slot and the step of downlink signal synchronization, greatly simplified at user terminal and eliminated the calculating process that down link signal disturbs, simplified the hardware configuration of user terminal receiver according to spreading code distribution information.
Though the present invention is example with TD-SCDMA, described and be used for supporting P2P method for communicating and device in the TD-SCDMA system, but those skilled in the art should be appreciated that, it should be not limited to be applied in the TD-SCDMA system, and this communication means and device also are applicable in other the TDD cdma system.
It will be appreciated by those skilled in the art that disclosed in this invention being used for support P2P method for communicating and device at the TDD cdma system, can also on the basis that does not break away from content of the present invention, make various improvement.Therefore, protection scope of the present invention should be determined by the content of appending claims.
Claims (22)
1, a kind ofly in TDD cdma communication system, support this user terminal and another user terminal to carry out P2P (point-to-point) method for communicating, comprise step by user terminal being used to of carrying out:
The signal that reception is transmitted by downlink control channel by network system;
According to the signal that is received, obtain time slot allocation information;
According to the signal that is received, obtain the spreading code that is distributed in other the in running order user terminals in the specific downlink time slots and distribute information, wherein this specific downlink time slots is: employed downlink time slots when this user terminal carries out the signal reception via the direct link between it and this another user terminal; And
Distribute information according to this time slot allocation information that is obtained and this spreading code, the interference that when other user terminals transmit down link signals, brings from network system that reduces that this user terminal is subjected in the P2P communication process.
2, communication means as claimed in claim 1, wherein said spreading code distribute information to comprise the spreading code information of being used by other user terminals in the described downlink time slots at least.
3, communication means as claimed in claim 1 or 2, the step that wherein reduces interference signal are at least a methods of carrying out in Multiuser Detection (MUD) and the joint-detection (JD).
4, communication means as claimed in claim 3, at least a method in wherein said Multiuser Detection (MUD) and the joint-detection (JD) are to disturb by utilizing the spreading code information of being used by other user terminals in the described downlink time slots to reduce signal.
5, communication means as claimed in claim 4 also comprises step:
Carry out stage of Cell searching at this user terminal, set up the downlink synchronization with network system, and keep downlink synchronization with network system by following the tracks of pilot channel;
In described downlink time slots, when this user terminal transmitted via described direct link, the step of its execution comprised:
(i) in the process that described direct link is set up, according to receive from the time that network system transmitted, set this user terminal sends signal to this another user terminal in described downlink time slots time;
(ii) this time in described downlink time slots, send test massage to this another user terminal;
(iii) receive feedback signal from this another user terminal, this feedback signal be this another user terminal after receiving described test signal, will receive that time of this test signal and this another user terminal receive that the time that transmits from network system compares and the difference that obtains;
(iv), set this user terminal sends Timing Advance from signal to this another user terminal according to this feedback signal; And
(v) according to this Timing Advance, adjust this user terminal to the time that this another user terminal transmits, thereby make this another user terminal receive from the signal of the down link of network system and signal Synchronization from the described direct link of this user terminal.
6, communication means as claimed in claim 5 further comprises:
(, send the P2P signal of communication to this another user terminal vi) in described adjusted launch time;
(vii) receive synchronization shift information from this another user terminal, this synchronization shift information be this another user terminal after receiving described P2P signal of communication, according to this P2P signal of communication, the synchronisation offset that obtains of estimation; And
(, adjust this user terminal sends Timing Advance from signal to this another user terminal viii) according to this synchronization shift information.
7, as claim 5 or 6 described communication meanss, also comprise step: in the P2P communication period, according to synchronization shift information from this another user terminal, this user terminal is adjusted it to the time that this another user terminal transmits, thereby makes the P2P signal of communication of this user terminal emission and the downlink signal synchronization of network system emission arrive this another user terminal.
8, as claim 5,6 or 7 described communication meanss, wherein: in described downlink time slots, when this user terminal during via described direct link received signal, the step of execution comprises:
(a) in the process that described direct link is set up, when this user terminal is received described another user terminal to the detection signal of its transmission, poor from time that network system transmitted that this user terminal calculates that its time of receiving this detection signal receives with it, and the difference that calculates sent to this another user terminal as feedback signal.
9, communication means as claimed in claim 8, wherein: in described downlink time slots, when this user terminal during via described direct link received signal, the step of execution also comprises:
(b) in the process that described direct link is set up, when this user terminal is received the P2P signal of communication of this another user terminal emission, according to this P2P signal of communication, estimate the synchronization shift information of this another user terminal, and this synchronization shift information is sent to this another user terminal.
10, communication means as claimed in claim 8 or 9 also comprises step:
In the P2P communication period, according to P2P signal of communication, calculate the synchronization shift information of this another user terminal, and this synchronization shift information is sent to this another user terminal from described another user terminal.
11, a kind ofly in TDD cdma communication system, be used to be supported between two user terminals and carry out the P2P method for communicating, comprise step by what network system was carried out:
Via downlink control channel, to two user terminal sending time slots assignment information of carrying out P2P communication;
The corresponding spreading code of each downlink time slots distributes information in generation and this time slot allocation information; And
Via downlink control channel, send described spreading code respectively to these two user terminals and distribute information, so that the signal of the P2P that each user terminal in these two user terminals is received communication and signal Synchronization from this network system.
12, communication means as claimed in claim 11, wherein said spreading code distribute information to be included in the spreading code information of being used by other user terminals in the described downlink time slots at least.
13, a kind of user terminal that can carry out P2P (point-to-point) communication in TDD cdma communication system comprises:
A signal receiving/transmission device is used for receiving and sending wireless signal;
A time slot allocation information deriving means is used for obtaining time slot allocation information according to the information via the downlink control channel transmission;
A spreading code distributes information acquisition device, be used for according to information via the downlink control channel transmission, obtain the spreading code that is distributed in other the in running order user terminals in the specific downlink time slots and distribute information, wherein this specific downlink time slots is: employed downlink time slots when this user terminal carries out the signal reception via the direct link between it and another user terminal; And
A device that reduces interference signal, be used for distributing information the interference that when other user terminals transmit down link signals, brings from network system that reduces that this user terminal is subjected in the P2P communication process according to this time slot allocation information that is obtained and this spreading code.
14, user terminal as claimed in claim 13, wherein said spreading code distribute information to comprise the spreading code information of being used by other user terminals in the described downlink time slots at least.
15, as claim 13 or 14 described user terminals, at least a method that the device of wherein said reduction interference signal is carried out in Multiuser Detection (MUD) and the joint-detection (JD) reduces interference signal.
16, user terminal as claimed in claim 15, at least a method in wherein said Multiuser Detection (MUD) and the joint-detection (JD) are to disturb by utilizing the spreading code information of being used by other user terminals in the described downlink time slots to reduce signal.
17, user terminal as claimed in claim 16 also comprises:
A synchronizer is used for carrying out at this user terminal stage of Cell searching, sets up the downlink synchronization of this user terminal and network system, and keeps downlink synchronization with network system by following the tracks of pilot channel;
The time-setting mechanism that transmits, be used for process in described direct link foundation, according to receive from the time that network system transmitted, set this user terminal sends signal to this another user terminal in described downlink time slots time;
A test signal dispensing device is used for this time at described downlink time slots, sends test massage to this another user terminal;
A feedback signal receiving system, be used to receive feedback signal from this another user terminal, this feedback signal be this another user terminal after receiving described test signal, will receive that time of this test signal and this another user terminal receive that the time that transmits from network system compares and the difference that obtains;
A Timing Advance setting device is used for according to this feedback signal, sets this user terminal sends Timing Advance from signal to this another user terminal; And
The time adjusting device that transmits based on above-mentioned feedback signal, be used for according to this Timing Advance, adjust this user terminal to the time that this another user terminal transmits, thereby make this another user terminal receive from the signal of the down link of network system and signal Synchronization from the described direct link of this user terminal.
18, user terminal as claimed in claim 17 also comprises:
A synchronization shift information receiving system, be used to receive synchronization shift information from this another user terminal, this synchronization shift information be this another user terminal after receiving described P2P signal of communication, according to this P2P signal of communication, the synchronisation offset that obtains of estimation; With
The time adjusting device that transmits based on synchronization shift information is used for according to this synchronization shift information, adjusts this user terminal sends Timing Advance from signal to this another user terminal.
19, as claim 17 or 18 described user terminals, also comprise:
A feedback signal generating means, be used for process in described direct link foundation, when this user terminal is received described another user terminal to the detection signal of its transmission, poor from time that network system transmitted that this user terminal calculates that its time of receiving this detection signal receives with it, and the difference that calculates sent to this another user terminal as feedback signal.
20, user terminal as claimed in claim 19 also comprises:
A synchronization shift information generating apparatus, be used for when this user terminal is received the P2P signal of communication of this another user terminal emission, according to this P2P signal of communication, estimate the synchronization shift information of this another user terminal, and this synchronization shift information is sent to this another user terminal.
21, a kind ofly in TDD cdma communication system, can support two user terminals to carry out the network system of P2P communication, comprise:
A time slot allocation information dispensing device is used for via downlink control channel, to two user terminal sending time slots assignment information of carrying out P2P communication;
A spreading code distributes information generation device, is used for generating with the corresponding spreading code of each downlink time slots of this time slot allocation information distributing information; And
A spreading code distributes information transmitting apparatus, be used for via downlink control channel, send described spreading code respectively to these two user terminals and distribute information, so that the signal of the P2P that each user terminal in these two user terminals is received communication and signal Synchronization from this network system.
22, network system as claimed in claim 21, wherein said spreading code distribute information to comprise the spreading code information of being used by other user terminals in the described downlink time slots at least.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA031104150A CN1536925A (en) | 2003-04-11 | 2003-04-11 | Method and device for supporting P2P Communication in TDD CDMA communicaton system |
| CN03110415.0 | 2003-04-11 | ||
| PCT/IB2004/050354 WO2004091238A1 (en) | 2003-04-11 | 2004-03-29 | A method and apparatus for supporting p2p communication in tdd cdma communication systems |
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| CN1768547A true CN1768547A (en) | 2006-05-03 |
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| CN200480008979.1A Pending CN1768547A (en) | 2003-04-11 | 2004-03-29 | Method and apparatus for supporting P2P communication in TDD CDMA communication system |
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| CN101843155A (en) * | 2007-10-29 | 2010-09-22 | 松下电器产业株式会社 | Wireless communication base station apparatus, and wireless communication mobile station apparatus and control channel allocation method |
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| CN104380644A (en) * | 2014-05-23 | 2015-02-25 | 华为技术有限公司 | A method for information transmission, a base station and a user device |
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| CN102017500A (en) * | 2008-05-02 | 2011-04-13 | 高通股份有限公司 | Method and apparatus for uplink ACK/NACK resource allocation |
| US9288021B2 (en) | 2008-05-02 | 2016-03-15 | Qualcomm Incorporated | Method and apparatus for uplink ACK/NACK resource allocation |
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| CN105846966A (en) * | 2008-05-02 | 2016-08-10 | 高通股份有限公司 | Method and apparatus for uplink ack/nack resource allocation |
| CN105846967B (en) * | 2008-05-02 | 2020-11-03 | 高通股份有限公司 | Method and apparatus for uplink ACK/NACK resource allocation |
| CN105409313A (en) * | 2013-07-15 | 2016-03-16 | 三星电子株式会社 | Method and apparatus for canceling interference in wireless communication system |
| US10840955B2 (en) | 2013-07-15 | 2020-11-17 | Samsung Electronics Co., Ltd. | Method and apparatus for cancelling interference signal in wireless communication system |
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