Associated detecting method in a kind of time-division-synchronous CDMA access system
Technical field
The present invention relates to a kind of detection method, insert joint-detection (Joint Detection) method in (TimeDivision-Synchronous Code Division Multiple Access) system more specifically to a kind of Time Division-Synchronous Code Division Multiple Access, be used at time-division-synchronous CDMA access system, subscriber equipment (User Equipment) carries out joint-detection to its down link that receives (Downlink) signal, can significantly improve the detection performance of subscriber equipment, improve power system capacity.
Background technology
Insert in the 3-G (Generation Three mobile communication system) standard at Time Division-Synchronous Code Division Multiple Access, wireless signal transmits with the form of frame (Radio Frame) in physical layer (PhysicalLayer or Layer 1), and the frame of each described time-division-synchronous CDMA access system further is divided into the time slot (Time Slot) in subframe (Subframe) and each subframe again on time shaft.Time slot is as the most basic time quantum, and be used for distinguishing in time the data of the interior different user in same sub-district (Cell): the data of different user can be transmitted at different time slots in the same sub-district.When the data of different user in the same sub-district are transmitted in same time slot, then further it is distinguished by the difference in described time slot burst (Burst): in the same sub-district in the same time slot data of different user in different bursts, transmit.The duration of a burst is a time slot, comprising a training sequence part (Midamble Part), two data parts (Data Parts) and protection interval (GuardPeriod); The data of transmission user in the data division of burst, the data division that different user happens suddenly in the same time slot in the same sub-district use the scrambler (Scrambling Code) of different channel code (Channelisation Codes) and this sub-district specific (Cell Specific) that the data of wherein transmission are carried out spread spectrum (Spreading); The training sequence part of burst is not carried user data, is used to transmit training sequence, and the training sequence part that different user happens suddenly in the same time slot in the same sub-district uses different training sequence codes (Midamble Codes) as training sequence.A burst in the described time slot promptly is the physical channel (Physical Channel) in the time-division-synchronous CDMA access system, therefore in time-division-synchronous CDMA access system, the physical channel of different user can transmit in different time slots or in the burst of the difference of same time slot in the same sub-district.
In time-division-synchronous CDMA access system, when transmitting in the difference burst of physical channel at same time slot of different user in the same sub-district, the employed channel code collection of data division of all user's bursts is a Walsh code (Walsh Codes) collection, its mutually orthogonal between any two (Orthogonal).According to cross-correlation (Cross Correlation) characteristic of described Walsh code,, can the data division of different user burst be separated by despreading (De-spreading) operation at receiver end by analyzing in theory.Yet in the mobile communication system of reality, when wireless signal transmits in physical layer, the decline of wireless channel (Fading) characteristic can make the wireless signal of wherein transmission produce distortion, thereby at receiver end, no longer complete quadrature between the spread spectrum data of the different user burst of process decline, when receiver carries out de-spreading operation to the data division that happens suddenly through the different user that declines, receiver can not be separated the data division of user's burst from the data division of other user's bursts fully, promptly to can the phase mutual interference between the detection of the data division of different user burst, the error rate of the increase of the phase mutual interference meeting between different user receiver in the same time slot in the described same sub-district, the detection performance of reduction receiver.
For when the physical channel when different user in the same sub-district transmits in the difference of same time slot happens suddenly, improve the detection performance of receiver to the different user burst, improve the error performance of receiver, when receiving up (Uplink) link signal, Node B (Node B) end in the sub-district, associated detecting method is more and more adopted, because associated detecting method can be used to the phase mutual interference between the different user burst, than described de-spreading operation, can improve the detection performance of the receiver of Node B greatly, improve power system capacity for different user burst in the up link received signal.But when the receiving downlink signal, at the subscriber equipment end, remove the channel code that each user's burst is distributed separately, each subscriber equipment can not directly be learnt in the same sub-district existence of other user's burst and the channel code that happens suddenly and distributed for its user, therefore can not in its receiver, directly use the method for joint-detection, thereby influence the detection performance of subscriber equipment end receiver.
See also Time Division-Synchronous Code Division Multiple Access access 3-G (Generation Three mobile communication system) standard document 3GPP TS 25.221 and 25.223 (download of document is provided among the www.3gpp.org of 3GPP website) for the detailed description about frame, subframe, time slot, burst, physical channel, channel code, training sequence code, scrambler and spread spectrum and de-spreading operation in the time-division-synchronous CDMA access system.
Summary of the invention
The object of the present invention is to provide the associated detecting method in a kind of time-division-synchronous CDMA access system, be used at time-division-synchronous CDMA access system, make subscriber equipment carry out joint-detection to its down link signal that receives, can significantly improve the detection performance of subscriber station, improve power system capacity.
Above-mentioned goal of the invention realizes by following method of the present invention: the associated detecting method in a kind of time-division-synchronous CDMA access system, wherein in a sub-district of time-division-synchronous CDMA access system, when the burst of different user is transmitted in same descending time slot, use different channel code in the data division of described different user burst, use different training sequence codes in the training sequence part of described different user burst; In down link, employed training sequence code distributes according to the training sequence code method of salary distribution of system default in the training sequence part of described different user burst; It is characterized in that detecting in the process of its user's burst at the receiver of a subscriber equipment, for its down link received signal in a described time slot, the receiver of described subscriber equipment at first detects removes the happen suddenly existence of all the other training sequence codes outside the employed training sequence code of its user; Then, the receiver of described subscriber equipment according to the incidence relation of giving tacit consent between each training sequence code and each channel code, is inferred the existence of removing all the other channel code outside the channel code of being distributed for its user's burst according to detected training sequence code; At last, described subscriber equipment uses the channel code of being distributed for its user's burst, and all the other channel code of above-mentioned deduction gained, and its down link received signal in a described time slot is carried out joint-detection.
According to an aspect of the present invention, the receiver of described subscriber equipment detects described down link received signal successively and is removing happen suddenly channel impulse response on all the other training sequence codes outside the employed training sequence code of its user, and each channel impulse response peak power of gained compared with the threshold value of a setting, in thinking described down link received signal during greater than the threshold value set, the channel impulse response peak power has corresponding training sequence code.
According to another aspect of the present invention, the receiver of described subscriber equipment uses successively removes happen suddenly all the other training sequence codes outside the employed training sequence code of its user, slide relevant with described down link received signal, and with the correlation normalization of respectively sliding of gained, the slip correlation after each normalization of gained is the channel impulse response of described down link received signal on described each training sequence code.
According to a further aspect of the invention, the noise power measured by the receiver of described subscriber equipment of described threshold value is set; Described threshold value is the twice of described noise power-value.
According to a further aspect of the invention, described joint-detection is used any existing joint detection algorithm; Described joint detection algorithm is maximum likelihood joint detection algorithm or ZF joint detection algorithm.
Specific embodiment
Insert among the 3-G (Generation Three mobile communication system) UTRA TDD 1.28Mcps at Time Division-Synchronous Code Division Multiple Access, when transmitting in the difference burst of physical channel at same time slot of different user in the sub-district, the employed channel code of data division of different user burst is distributed by grid side (Network); The employed training sequence code of training sequence part of different user burst is produced through different cyclic shifts (CyclicShifts) by the specific basic training sequences sign indicating number in this sub-district (Basic Midamble Code), described basic training sequences sign indicating number is distributed in 4 possible basic training sequences sign indicating numbers by the grid side, described 4 basic training sequences sign indicating numbers are that one group of descending synchronous code (SYNC-DL Code) with the middle use of this cell downlink synchronizing channel (DwPCH) is corresponding one by one, and the user finishes the identification to the specific basic training sequences sign indicating number in this sub-district in Cell searching (Cell Search) process; By the training sequence code collection that different cyclic shift produced of the specific basic training sequences sign indicating number in described sub-district,, in the training sequence part of different user burst, distribute by following 3 kinds of modes:
1. the specific training sequence code of each user distributes (UE specific midamble allocation): in the uplink and downlink link, the employed training sequence code of training sequence part of different user burst is by high-rise each user of (Higher Layers) signaling.
2. the training sequence code of acquiescence distributes (Default midamble allocation): in the uplink and downlink link, the employed training sequence code of training sequence part of different user burst distributes according to the mode of system default, has the incidence relation of acquiescence between the channel code that the data portion branch of described each training sequence code and each user burst distributes.
3. public training sequence code distributes (Common midamble allocation): in down link, the employed training sequence code of training sequence part of different user burst distributes according to the channel code number that exists in the described time slot.
If in the uplink and downlink link, the employed training sequence code of training sequence part of different user burst is not notified by high-level signaling, and the public training sequence code method of salary distribution is not indicated by high-level signaling yet, then the employed training sequence code of training sequence part of different user burst will be according to the training sequence code method of salary distribution of acquiescence, and the incidence relation of giving tacit consent between the channel code of being distributed by itself and the data portion branch of described each user's burst is definite.
Be 16 for example at spreading gain (Spreading Factor), in the same sub-district in the same time slot maximum user's burst number be 16 o'clock, under the training sequence code method of salary distribution of above-mentioned acquiescence, the incidence relation of giving tacit consent between each training sequence code and each channel code is as shown in the table:
?M(1) | ?C
16(1)
|
?M(2) | ?C
16(2)
|
?M(3) | ?C
16(3)
|
?M(4) | ?C
16(4)
|
?M(5) | ?C
16(5)
|
?M(6) | ?C
16(6)
|
?M(7) | ?C
16(7)
|
?M(8) | ?C
16(8)
|
?M(9) | ?C
16(9)
|
?M(10) | ?C
16(10)
|
?M(11) | ?C
16(11)
|
?M(12) | ?C
16(12)
|
?M(13) | ?C
16(13)
|
?M(14) | ?C
16(14)
|
?M(15) | ?C
16(15)
|
?M(16) | ?C
16(16)
|
C wherein
16(i) expression channel code, footmark 16 expression spreading gains are 16, i=1,2 ..., the sequence number of 16 expression channel code; M (i) represents training sequence code, i=1, and 2 ..., the sequence number of 16 expression training sequence codes, each training sequence code is produced through 16 different cyclic shifts (Cyclic Shifts) by the specific basic training sequences sign indicating number in each sub-district.
Being set in spreading gain is 16, in the same sub-district in the same time slot maximum user's burst number be 16 o'clock, in the down link of a sub-district, transmitted 16 different users' bursts, wherein C in the same time slot altogether
16(1) distributing to the user happens suddenly and 1 uses C
16(2) distributing to the user happens suddenly and 2 uses C
16(3) distributing to the user happens suddenly and 3 uses C
16(4) distributing to the user happens suddenly and 4 uses C
16(5) distributing to the user happens suddenly and 5 uses C
16(6) distributing to the user happens suddenly and 6 uses C
16(7) distributing to the user happens suddenly and 7 uses C
16(8) distributing to the user happens suddenly and 8 uses C
16(9) distributing to the user happens suddenly and 9 uses C
16(10) distributing to the user happens suddenly and 10 uses C
16(11) distributing to the user happens suddenly and 11 uses C
16(12) distributing to the user happens suddenly and 12 uses C
16(13) distributing to the user happens suddenly and 13 uses C
16(14) distributing to the user happens suddenly and 14 uses C
16(15) distributing to the user happens suddenly and 15 uses C
16(16) distributing to the user happens suddenly and 16 uses; Described 16 different users happen suddenly employed training sequence code according to the acquiescence the training sequence code method of salary distribution distribute, the channel code of being distributed according to each user burst, according to the incidence relation of giving tacit consent between each training sequence code in the last table and each channel code, can determine each user employed training sequence code that happens suddenly, wherein M (1) is happened suddenly by the user and 1 uses, M (2) is happened suddenly by the user and 2 uses ..., the rest may be inferred M (16) is happened suddenly by the user and 16 uses.
The method according to this invention, detecting its user at the receiver of subscriber equipment 1 happens suddenly in 1 the process, for its down link received signal in a described time slot, the receiver of subscriber equipment 1 at first detects removes happen suddenly all the other training sequence code M (2) outside the 1 employed training sequence code M (1) of its user, M (3), the existence of M (16): the receiver of subscriber equipment 1 detects described down link received signal successively in training sequence code M (2), M (3), channel impulse response on the M (16) (Channel Impulse Response), for example the receiver of subscriber equipment 1 uses training sequence code M (2) successively, M (3), M (16) slides relevant (Slide Correlation) with described down link received signal and with the correlation normalization (Normalize) of respectively sliding of gained, slip correlation after each normalization of gained is described down link received signal in training sequence code M (2), M (3), channel impulse response on the M (16), each channel impulse response peak power is compared with the threshold value (Threshold) of a setting, the noise power that described threshold value is measured by the receiver of subscriber equipment 1 is set, for example described threshold value is the twice of described noise power-value, has corresponding training sequence code in the channel impulse response peak power is thought described down link received signal during greater than the threshold value set; Then, the receiver of subscriber equipment 1 is according to detected training sequence code, according to the incidence relation of giving tacit consent between each above-mentioned training sequence code and each channel code, infers and removes the 1 channel code C that is distributed that happens suddenly for its user
16The existence of all the other channel code (1); At last, subscriber equipment 1 uses the 1 channel code C that is distributed that happens suddenly for its user
16(1), and all the other channel code of above-mentioned deduction gained, its down link received signal in a described time slot is carried out joint-detection: described joint-detection can be used any existing joint detection algorithm, for example maximum likelihood (Maximum Likelihood) joint detection algorithm or ZF (Zero Forcing) joint detection algorithm.By 3 above-mentioned steps, the receiver of subscriber equipment 1 can be isolated happen suddenly data division in 1 of its user from the testing result of joint-detection, finishes happen suddenly 1 the testing process to its user.
In the method for the invention, by detecting the existence of described each training sequence code, subscriber equipment can be learnt the existence of other user's burst in the same time slot in the same sub-district and the channel code that happens suddenly and distributed for its user indirectly, therefore can in its receiver, use the method for joint-detection, thereby can significantly improve the detection performance of subscriber equipment, improve power system capacity.