Background technology
The control information of uplink special physical channel of WCDMA base station (DPCH) or Physical Random Access Channel (PRACH) is to be modulated on the different subchannels with data message, to general at present following method and the step of adopting of the demodulation of these control informations and data message, referring to Fig. 1:
1, the control subchannel of special-purpose physics control subchannel (DPCCH) or PRACH is separated sequence of operations such as spread spectrum (comprising descrambling code), channel estimating, rake (RAKE) merging, transformat combination indication (TFCI) decoding, obtains the channel fading in each footpath and the spreading factor (SF) of special physical data subchannel (DPDCH);
2, the subchannel data of special physical data subchannel (DPDCH) or PRACH is separated sequence of operations such as spread spectrum (comprising descrambling code), channel compensation, RAKE merging, obtains demodulation result.
Adopt above-mentioned demodulation method and step, can run into following two problems:
1, the characteristic of channel of DPDCH is that the channel fading factor generally uses the channel estimation results of DPCCH to obtain, and channel estimating has the delay of several time slots, different channel estimation methods has different delays, generally between 2~5 time slots, therefore, the result who separates behind the spread spectrum of DPDCH must store in first buffer (buffer memory 1), is used to wait for that the channel estimating of DPCCH finishes, obtain after the channel fading factor, carry out channel compensation and RAKE union operation;
2, the SF of PDCH is indefinite, and 8 kinds of selections such as 4,8,16,32,64,128,256 grades are arranged, and every time slot data volume is respectively 640,320,160,80,40,20,10 symbols.Only finish in the DPCCH of frame demodulation, after the TFCI decoding, the true SF that obtains this frame of ability.Therefore, general employing of demodulation to DPDCH separated spectrum spreading method twice, earlier carry out DPDCH and once separate operations such as spread spectrum, channel compensation and RAKE merging according to a minimum SF (being less than or equal to true SF certainly) that can obtain from the upper strata, store the RAKE amalgamation result of at least one frame into second buffer (buffer memory 2), finish and obtain after the true SF in order to wait for physics control subchannel TFCI decoding, carry out the DPDCH secondary and separate spread spectrum, thereby obtain demodulation result.
Because above-mentioned 2 points, the method for uplink baseband demodulating need be provided with buffer memory 1 and buffer memory 2 at present, therefore need take a large amount of memories, and the modern valency of historical facts or anecdotes is big.
Summary of the invention
Technical problem to be solved by this invention is: the invention provides a kind of method of new WCDMA base station uplink baseband demodulating, this method can reduce taking of memory in a large number.
The present invention solves the problems of the technologies described above the technical scheme that is adopted to be:
The uplink baseband demodulating method of a kind of WCDMA base station may further comprise the steps:
A, the baseband signal buffer is set on demodulating unit; Baseband signal is stored in the described baseband signal buffer, and described baseband signal buffer postpones time of an appointment with described baseband signal, forms to postpone baseband signal;
B, the described baseband signal of employing are handled the control subchannel, obtain the real spreading factor of the channel fading factor and subchannel data;
C, described subchannel data use described delay baseband signal, and utilize the described channel fading factor and the described real spreading factor that have obtained to carry out demodulation process, obtain demodulating data.
Described method, wherein: described step B comprises the steps:
B1, the described baseband signal of use are separated spread spectrum, channel estimating and rake to the control subchannel and are merged, and finish the demodulation of described control subchannel and obtain the described channel fading factor;
B2, the data after the demodulation of described control subchannel are carried out transformat combination decoding, obtain real spreading factor.
For concrete method 1, described step C comprises:
C1, the described delay baseband signal of employing are carried out subchannel data and are once separated spread spectrum;
C2, utilize acquired described fading factor described subchannel data to be separated once result data behind the spread spectrum carries out channel compensation and rake merges;
C3, with the subchannel data rake amalgamation result storage of at least one frame in second buffer, postpone certain hour, wait for after described step B2 operation is finished and obtain real spreading factor;
The described real spreading factor that C4, utilization are obtained carries out secondary to the delayed data subchannel rake amalgamation result data of described second buffer output and separates spread spectrum, obtains the demodulation result data.
Described method 1, wherein: the fixed time that described baseband signal postpones, play channel estimating and rake and finish the total delay that is produced and decide from receiving described baseband signal by described control subchannel.
For concrete method 2, described step C comprises:
C1, the described delay baseband signal of employing and the described real spreading factor that has obtained are separated spread spectrum to described subchannel data;
C2, utilize acquired described fading factor described subchannel data to be separated result data behind the spread spectrum carries out channel compensation and rake merges, obtain the demodulation result data.
Described method 2, wherein: the fixed time that described baseband signal postpones, play transformat combination decoding and finish the total delay that is produced and decide from receiving described baseband signal by described control subchannel.
The uplink baseband demodulating method of a kind of WCDMA base station, described WCDMA base station comprises several same demodulating unit; Said method comprising the steps of:
A, at described several demodulating unit outer setting one baseband signal buffers; Baseband signal is stored in the described baseband signal buffer, and described baseband signal buffer postpones time of an appointment with described baseband signal, forms to postpone baseband signal;
B, the described baseband signal of employing are handled the control subchannel of each demodulating unit, obtain the channel fading factor of each demodulating unit and the real spreading factor of subchannel data;
The subchannel data of C, described each demodulating unit uses described delay baseband signal, and utilizes the described channel fading factor and the described real spreading factor that have obtained to carry out demodulation process, obtains the demodulating data of each demodulating unit.
Beneficial effect of the present invention is: method of the present invention is because employing baseband signal buffer (buffer memory 0) postpones baseband signal, so reduced total occupancy of memory; Particularly the channel of being supported is many more, and when the number of channel was big more, less than the memory space of existing method, the advantage of storage base band data was just big more further for total occupancy of the inventive method memory.Because the quantity of demodulation module DPCH to be processed and Physical Random Access Channel is the important content of specification, generally at 64 more than the channel, the previous sub-district of order is all more than more than 100 channels, therefore total occupancy of method of the present invention (comprising method 1 and method 2) memory is far smaller than the memory space of existing method, so reduced the realization cost significantly.Simultaneously, because in subchannel data demodulation process process, buffer memory 1 or buffer memory 1 and buffer memory 2 have been cancelled, there has not been data write, two adjacent modules (separating spread spectrum module and channel compensation RAKE merging module as DPDCH) can be integrated into one, reduced the complexity that subchannel data demodulation control realizes, data flow is more unobstructed than existing method.
Embodiment
With embodiment the present invention is described in further detail with reference to the accompanying drawings below:
Referring to Fig. 2,3,4.The main feature of uplink baseband demodulating method of the present invention is: a baseband signal buffer (buffer memory 0 among Fig. 3, Fig. 4) is set in demodulating unit, to import baseband signal and store buffer memory 0 into, postpone the fixed time, the respective handling of DPCCH is used the baseband signal of input, it is the Real-time Baseband signal, the respective handling of DPDCH is used the baseband signal after postponing, and promptly postpones baseband signal; Its basic procedure may further comprise the steps as shown in Figure 2:
A, a baseband signal buffer (buffer memory 0) is set in demodulating unit, baseband signal is stored in the described buffer memory 0, buffer memory 0 postpones time of appointment with described baseband signal, forms to postpone baseband signal;
B, the described baseband signal of employing are handled control subchannel (the control subchannel of DPCCH or PRACH), obtain the real spreading factor SF of the channel fading factor and subchannel data;
C, described subchannel data (subchannel data of DPDCH or PRACH) use described delay baseband signal, and utilize the described channel fading factor and the described real spreading factor that have obtained to carry out demodulation process, obtain demodulating data.
According to above-mentioned basic thought, the present invention has two kinds of concrete implementation methods.Method 1 is referring to Fig. 3, and its concrete steps are:
A, a buffer memory 0 is set in demodulating unit, baseband signal is stored in the buffer memory 0, buffer memory 0 postpones time of an appointment with described baseband signal, forms to postpone baseband signal;
B1, the described baseband signal of use are separated spread spectrum, channel estimating and RAKE to the control subchannel and are merged, and finish the demodulation of described control subchannel and obtain the described channel fading factor;
B2, the data after the demodulation of described control subchannel are carried out TFCI decoding, obtain real spreading factor SF;
C1, the described delay baseband signal of employing are carried out subchannel data and are once separated spread spectrum;
C2, utilize acquired described fading factor described subchannel data to be separated once result data behind the spread spectrum carries out channel compensation and RAKE merges;
C3, with the subchannel data RAKE amalgamation result storage of at least one frame in buffer memory 2, postpone certain hour, (obtaining) obtained SF after waiting step B2 operation was finished;
The SF that C4, utilization are obtained carries out secondary to the delayed data subchannel RAKE amalgamation result data of buffer memory 2 outputs and separates spread spectrum, obtains the demodulation result data.
In the method 1, compare the total delay time of Real-time Baseband signal, play channel estimating and RAKE and finish the total delay that is produced and decide from receiving the Real-time Baseband signal by DPCCH through the delay baseband signal of buffer memory 0.For example the maximum delay of certain algorithm is 3 time slots, then if postpone baseband signal than Real-time Baseband signal delay greater than 3 time slots, just can guarantee to postpone baseband signal finish DPDCH once separate spread spectrum the time, the channel estimating of corresponding D PCCH is finished, the channel fading factor obtains, and the channel compensation operation and the RAKE that can carry out DPDCH immediately merge.Like this, the buffer memory 1 in the existing method is deleted, and buffer memory 2 is constant, has increased buffer memory 0.
Method 2 as shown in Figure 4, its steps A, B1, B2 are identical with method 1, concrete steps are thereafter:
C1, the described delay baseband signal of employing and the SF that has obtained separate spread spectrum to described subchannel data;
C2, utilize acquired described fading factor described subchannel data to be separated result data behind the spread spectrum carries out channel compensation and RAKE merges, obtain the demodulation result data.
In the method 2, compare the total delay time of Real-time Baseband signal, play TFCI decoding and finish the total delay that sequence of operations produces and decide from receiving described baseband signal by described control subchannel through the delay baseband signal of buffer memory 0.For example the maximum delay of certain algorithm is 18 time slots, then if postpone baseband signal than Real-time Baseband signal delay greater than 18 time slots, in the time of just can guaranteeing to postpone the baseband signal input, the sequence of operations of DPCCH is finished, and the channel fading factor and true SF obtain, at this moment, can directly use true SF to separate spread spectrum, and no longer need to separate spread spectrum twice, also no longer need to dispose minimum SF, carry out channel compensation and RAKE afterwards again and merge, obtain demodulation result.Like this, buffer memory 1 and buffer memory 2 in the existing method are all deleted, have increased buffer memory 0.
Below, we carry out quantitative analysis to the occupancy volume of existing method and the inventive method 1 and method 2 memories:
The size of buffer memory 0=buffer memory timeslot number * 2560chip/ time slot * 2 (I/Q) * antenna number * sample rate * data bit width=480K (method 1)/2.16M (method 2)
Wherein: the buffer memory timeslot number is got 4 (methods 1) or 18 (methods 2), and antenna number gets 2, and sample rate gets 2, and data bit width gets 6.
Size=the number of channel of buffer memory 1 * every channel footpath number * buffer memory timeslot number * every time slot symbolic number * 2 (real imaginary part) * every channel of data bit width=80K
Wherein: the buffer memory timeslot number gets 4, and every channel footpath number gets 8, and every time slot symbolic number is got 80 (are example with SF=32), and data bit width gets 16.
Size=the number of channel of the buffer memory 2 * buffer memory timeslot number * every time slot symbolic number * data bit width=every channel of 22.5K
Wherein: the buffer memory timeslot number gets 18, and every time slot symbolic number is got 80 (are example with SF=32), and data bit width gets 16.
By above quantitative analysis as seen, the size of buffer memory 0 and the number of channel are irrelevant, are certain, the size of buffer memory 1 and buffer memory 2 all with number of channel positive correlation; And buffer memory 0 occupancy volume of method 2 is a fixed number 2.16M, and the buffer memory occupancy volume of existing method and method 1 is relevant with the number of channel, the comparison of the relation of the three and the number of channel and buffer memory occupancy volume size is referring to Fig. 5, by curve among the figure as seen, when the number of channel greater than 6 the time, the memory space that method 1 is occupied just begins less than existing method; When the number of channel greater than 21 the time, the memory space that method 2 is occupied is also less than existing method; Just when the number of channel greater than 21 the time, the memory space that method 1 of the present invention and method 2 are occupied is all less than existing method, and along with the increase (big more) of the number of channel, total memory space that method 1 and method 2 are occupied will be significantly smaller than existing method.And the quantity of demodulation module DPCH to be processed and Physical Random Access Channel is the important content of specification, generally at 64 more than the channel, at this moment, the memory space that method 1 is occupied is 1.92M, and method 2 is 2.16M, and existing method is 6.56M, this shows, method 1 of the present invention and method 2 have reduced taking of memory with respect to existing method, in a large number so reduced the realization cost significantly under the prerequisite that does not change any algorithm.And because in subchannel data demodulation process process, buffer memory 1 (method 1) or buffer memory 1 and buffer memory 2 (method 2) have been cancelled, there has not been data write, two adjacent modules (separating spread spectrum module and channel compensation RAKE merging module as DPDCH) can be integrated into one, so reduced the complexity that subchannel data demodulation control realizes, data flow is more unobstructed than existing method.
Said method 1 and method 2, in the demodulation total delay, method 1 is the same with existing methods demodulation total delay, greatly about the here back of a frame real time data 2~5 time slots (relying on concrete demodulating algorithm); And the demodulation total delay of method 2 wants ratio method 1 to increase by 1 frame, because what method 2 adopted is directly to separate spread spectrum, the SF of a certain frame (spreading factor) must receive whole frame DPCCH data and finish DPCCH and separate to be in harmonious proportion and just can obtain after the TFCI decoding, so base band data that need a certain frame is many storage, after obtaining the SF of this frame, separate spread spectrum and demodulation again, memory time is greater than a frame, so the total delay ratio method 1 of method 2 will increase by 1 frame.Above-mentioned two kinds of methods are suitable for the different system of qos requirement and adopt, and the advantage of method 1 is to postpone lessly, be suitable for the occasion that postpones to have relatively high expectations, but under supporting that channel is greater than 74 situation, memory space is greater than method 2; And the advantage of method 2 is under supporting that channel is greater than 74 situation, and memory space is less, and implementation structure is also simpler; But method 1 delay is bigger relatively, is more suitable in postponing to require lower occasion.
Method of the present invention can be extended to baseband signal buffer (buffer memory 0) is moved on to the demodulating unit outside, and several demodulating units are shared a buffer memory; Because algorithm is identical, be identical the time of delay of each demodulating unit, so several demodulating units can share a buffer memory, thereby further reduce the memory usage of demodulating unit.Referring to Fig. 6 a and Fig. 6 b, described method comprises several same demodulating unit, as 100,200, and 300 3 demodulating units; At three demodulating unit outer setting, one baseband signal buffer 31, and shared this baseband signal buffer 31 of these three demodulating units; The steps include:
A, at three demodulating unit outer setting, one baseband signal buffer 31; Baseband signal is stored in the described baseband signal buffer 31, and described baseband signal buffer 31 postpones time of an appointment with baseband signal, forms to postpone baseband signal;
B, the described baseband signal of employing are handled the control subchannel of each demodulating unit, obtain the channel fading factor of each demodulating unit and the real spreading factor of subchannel data;
The subchannel data of C, described each demodulating unit uses described delay baseband signal, and utilizes the described channel fading factor and the described real spreading factor that have obtained to carry out demodulation process, obtains the demodulating data of each demodulating unit.
Said method can adopt concrete method 1 and the method 2 shown in Fig. 6 a and Fig. 6 b to realize that the process of its realization is identical with the method step of aforementioned single demodulating unit with concrete steps equally, so do not repeat them here.Because several demodulating units are shared baseband signal buffer 31 in this method, therefore further reduced the memory usage of demodulating unit, realize that cost more reduces.
Be understandable that, for those of ordinary skills, can be equal to replacement or change according to technical scheme of the present invention and inventive concept thereof, and all these changes or replacement all should belong to the protection range of the appended claim of the present invention.