Embodiment
In order to realize LTE-TDD signal and the transmitting of TD-SCDMA signal in same base station, in the embodiment of the present invention, determine that TD-SCDMA signal and LTE-TDD signal are converted to descending common switching time by up; In described common switching time, the TD-SCDMA signal produced for physical layer and LTE-TDD signal carry out interpolating operations respectively, are adjusted to identical by the intermediate frequency speed of two kinds of signals; TD-SCDMA signal identical for intermediate frequency speed and LTE-TDD signal are superposed, and sends the signal after superposition.
Below in conjunction with accompanying drawing, the preferred embodiment of the present invention is described in detail.
Consult shown in Fig. 3 A and 3B, in the embodiment of the present invention, communication system comprises some base stations, and base station comprises the first processing unit 10, second processing unit 11 and the 3rd processing unit 12, wherein,
First processing unit 10, for determining that TD-SCDMA signal and LTE-TDD signal are converted to descending common switching time by up;
Second processing unit 11, in described common switching time, the TD-SCDMA signal produced for physical layer and LTE-TDD signal carry out interpolating operations respectively, are adjusted to identical by the intermediate frequency speed of two kinds of signals;
3rd processing unit 12, for TD-SCDMA signal identical for intermediate frequency speed and LTE-TDD signal being superposed, and mails to receiving terminal by the signal after superposition by communication interface.
Based on above-mentioned principle, consult shown in Fig. 4, in the embodiment of the present invention, the detailed process that base station realizes TD-SCDMA signal and LTE-TDD signal mixing transmission is as follows:
Step 400: determine that TD-SCDMA signal and LTE-TDD signal are converted to descending common switching time by up.
In practical application, because TD-SCDMA signal and LTE-TDD signal are all 5ms subframes, and be all TDD mode, and DWPTS in the special subframe of LTE-TDD signal, UPPTS and GP can configure flexibly, namely can revise flexibly according to the requirement of switching time; Therefore, base station can in two kinds of signals common switching times, realize superposing of TD-SCDMA signal and LTE-TDD signal.
In the embodiment of the present invention, in order to realize the sub-frame configuration scheme that TD-SCDMA signal and LTE-TDD signal in switching time, point coexist, including but not limited to following three kinds:
TD-SCDMA’s5U2D to LTE-TDD’s DSUUU+3:9:2
TD-SCDMA’s3U4D to LTE-TDD’s DSUUD+11:1:2/10:2:2
TD-SCDMA’s2U5D to LTE-TDD’s DSUDD+3:9:2
Consult shown in Fig. 5, in practical application, preferably, the sart point in time alignment download of each signal can launched, and using the time started of the downlink of alignment as two kinds of signals common switching time, as:
The time started of the first sight: TD-SCDMATS6 alignd with the time started of LTE-TDD TS0;
The second sight: TD-SCDMATS4 starting point was alignd with the time started of LTE-TDD TS8;
The third sight: TD-SCDMATS3 starting point was alignd with the time started of LTE-TDD TS6.
After determining point common switching time, just corresponding interpolation multiple can be adopted, respectively interpolating operations is performed to TD-SCDMA signal and LTE-TDD signal, make these two kinds of signals through different interpolation process, intermediate frequency speed is reached an agreement, like this, the signal of two systems just can be launched from a radio-frequency channel by superposition.
Step 410: in described common switching time, the TD-SCDMA signal produced for physical layer and LTE-TDD signal carry out interpolating operations respectively, are adjusted to identical by the intermediate frequency speed of two kinds of signals.
In the present embodiment, the implementation method of step 410 is including but not limited to following two kinds:
1, adopt corresponding integral multiple interpolation multiple, the intermediate frequency speed of TD-SCDMA signal and LTE-TDD signal is all adjusted to first rate;
2, corresponding integral multiple interpolation multiple is adopted, the intermediate frequency speed of TD-SCDMA signal and LTE-TDD signal is all adjusted to first rate, and, adopt corresponding integral multiple or little several times interpolation multiple, the intermediate frequency speed of TD-SCDMA signal and LTE-TDD signal is promoted to the second speed further by first rate.
Step 420: TD-SCDMA signal identical for intermediate frequency speed and LTE-TDD signal are superposed, and send the signal after superposition.
Based on above-described embodiment, make detailed description by the specific implementation of step 410 below.
Consult shown in Fig. 6, as can be seen from the mixing Platform of base station, TD-SCDMA signal and LTE-TDD signal are after the interpolating operations of step 410, multiple common speed point can be reached, the screening conditions of these common rate points are: the sampling rate (Fs) meeting signal is greater than signal bandwidth (FBW), the common rate point meeting above-mentioned condition can carry out the superposition of TD-SCDMA signal and LTE-TDD signal, but only choose suitable best the suppressing mirror image of speed point ability, resource is optimum.
As shown in Figure 6, in the embodiment of the present invention, suppose that TD-SCDMA and the LTE-TDD mixing platform designed in base station receives the physical layer signal from TD-SCDMA carrier wave 1.28MHZ, the LTE-TDD signal of a 30.72MHZ, through multistage interpolation filtering, before carrying out Signal averaging, the common rate point that TD-SCDMA signal and LTE-TDD signal can reach can have two, be respectively: first common speed point is 30.72MHZ, second common speed point is 46.08MHZ; And after carrying out Signal averaging, again can also carry out interpolating operations to superposed signal, thus the 3rd the common speed point obtaining TD-SCDMA signal and LTE-TDD signal is 92.16MHZ.
As shown in Figure 6, in the embodiment of the present invention, the initial rate of the LTE-TDD signal that physical layer produces is 30.72MHZ, and therefore, base station only need adopt 1 times of interpolation multiple to carry out interpolating operations, namely LTE-TDD signal can be maintained 30.72MHZ; Meanwhile, in order to suppress signal noise, when performing interpolating operations, finite impulse response (FIR) able to programme (Programm Finite Impulse Response, PFIR) PFIR filter can be adopted to carry out filtering to LTE-TDD signal.
When LTE-TDD signal and TD-SCDMA signal are merged, be not leaked in the multicarrier of carrying TD-SCDMA signal to make the frequency spectrum in the passband of carrying LTE-TDD signal, PFIR filter is had higher requirement, under the prerequisite that programmable gate array (Field Programmable Gate ArrayFPGA) is resource-constrained at the scene, preferably, the PFIR filter that transition band is preferential can be selected, exchange the decay of transition band and precipitous for by some performances of sacrificing PFIR passband.Consult shown in Fig. 7 and Fig. 8, in the present embodiment, respectively to base station adopt the preferential filter of transition band and passband preferential the effect of filter made emulation, wherein, the preferential filter of what Fig. 7 showed the is preferential filter of transition band and passband carries out filtered signal transition band spectrogram to LTE-TDD signal respectively, and Fig. 8 shows is that the preferential filter of the preferential filter of transition band and passband carries out filtered signal passband spectrogram to LTE-TDD respectively.The performance parameter of two kinds of filters more as shown in table 3:
Table 3
For Fig. 8, as can be seen from Figure 8, although the preferential Filter ripple of transition band is much larger than the preferential filter of passband, but the passband ripple size of the preferential filter of transition band is also lower than 0.03dBc, such ripple is very little on the impact of signal quality, therefore, the filter that base station should preferentially adopt transition band preferential carries out filtering to LTE-TDD signal.
In like manner, the initial rate of TD-SCDMA signal is only 1.28MHZ, preferably, needs employing 24 times of interpolation multiples to carry out interpolating operations, just can by the speed-raising of TD-SCDMA signal to 30.72MHZ; Meanwhile, in order to suppress signal noise, when performing interpolating operations, preferably, the preferential PFIR filter of transition band also can be adopted to carry out filtering to TD-SCDMA signal, do not repeat them here.
Accordingly, in the embodiment of the present invention, the receiving terminal of base station also needs to adopt the preferential filter of transition band to carry out filtering to the LTE-TDD signal received from base station, because, if the filter that receiving terminal adopts passband preferential, then when receiving LTE-TDD signal, contiguous TD-SCDMA signal cannot be suppressed under transition band effectively, this is because the transition band of the PFIR filter of LTE-TDD signal is precipitous not, wherein contain TD-SCDMA signal, so the spurious reduction of LTE-TDD signal only has 30dBc, the requirement of radio frequency testing index cannot be met.
Consult shown in Fig. 9 and Figure 10, in the present embodiment, respectively to receiving terminal adopt the preferential filter of transition band and passband preferential the effect of filter made emulation, wherein, what Fig. 9 showed is adopt the preferential filter of passband to carry out filtered spectrogram to LTE-TDD signal, and Figure 10 displaying is adopt the preferential filter LTE-TDD signal of transition band to carry out filtered spectrogram.As can be seen from Fig. 9 and 10, the preferential filter of transition band is adopted to carry out filtering, can by the TD-SCDMA signal suppressing with LTE-TDD signal vicinity under transition band, inhibit close to 50dbc, effect is better.
Based on above-described embodiment, base station performs interpolating operations respectively for TD-SCDMA signal and LTE-TDD signal, by unified for the intermediate frequency speed of two kinds of signals for after 30.72MHZ, in this speed o'clock, two kinds of signals can be superposed, and carry out subsequent treatment, also again can perform interpolating operations based on the intermediate frequency speed of 30.72MHZ to two kinds of signals, make its intermediate frequency speed again improve; In the present embodiment, in order to make the mirror image of the signal after superposition obtain good filtering, preferably, the above-mentioned second way is adopted the intermediate frequency speed of two kinds of signals to be increased to again second common speed point, as 46.08MHZ.
When the intermediate frequency speed of TD-SCDMA signal and LTE-TDD signal is increased to 46.08MHZ again by 30.72MHZ, the interpolation multiple of integral multiple can be adopted, also can adopt the interpolation multiple of little several times, in the present embodiment, describe in detail for the interpolation multiple of little several times.
Suppose the interpolation multiple of employing 3/2 times, then the implementation of interpolating operations is as follows:
Generally, 3 times of interpolations are first carried out in the process of 3/2 times of interpolation filtering, then carrying out 2 times of extractions, complete little several times interpolating operations by two steps.In the present embodiment, adopt polyphase circuit to complete the operation of interpolation and extraction, because interpolating operations makes the speed of signal improve, so interpolation multiple simultaneously
p > Q, wherein, P is the output number of phases (also claiming the sub-number of phases) of circuit, and Q reads step-length when son outputs signal mutually, and the essence of interpolating operations is exactly export one at P heterogeneous middle contiguous Q.
Such as, P=3, Q=1, namely represent in 3 circuitry phases, and each circuit exports mutually; Consult shown in Figure 11, suppose that primary signal is a, b, c, d4 data, be after the interpolating operations of 3 by interpolation multiple, all signals produced mutually all export, and namely outputing signal is a1, a2, a3, b1, b2, b3, c1, c2, c3 successively ....Such input 4 number, exports 12 numbers.
Again such as, P=3, Q=2, then selectively export based on step size Q=2, consult shown in Figure 12, suppose that primary signal is a, b, c, d4 data, be after the interpolating operations of 3/2 by interpolation multiple, all signals produced mutually export at interval of one again, input 4 number a like this, b, c, d, export 6 number a1, a3, b2, c1, c3, d2.So just in time complete the interpolation task of interpolation multiple 4*3/2=6.
Consult shown in Figure 13, in the embodiment of the present invention, P=3, the structure of the polyphase interpolating filter of 9 filter coefficients as shown in the figure, in this kind of structure, each sub-phase filter all uses respective multiplier to complete filter function, executed in parallel between each sub-phase filter, be applicable to application signal speed low, the process that multiplier is many.
Polyphase interpolating filter completes interpolation functions by use high speed selector, often inputs a signal, just has P road signal to export, and each phase all completes filtering when low speed.Reversing switch is selection band filter being exported to data.For 3 times of interpolations, heterogeneous output order is 1 phase, 2 phases, 3 phases, 1 phase, 2 phases, 3 phases, 1 phase, 2 phases.。。For 3/2 times of interpolation, then isolate Q phase and export a phase, above-mentioned output just becomes 1 phase, 3 phases, 2 phases, 1 phase, 3 phases ... completed just completing little several times interpolation functions by high speed reversing switch.
After aforesaid operations, the intermediate frequency speed of TD-SCDMA signal and LTE-SCDMA signal just all reaches 46.08MHZ, meets the requirement of overlap-add operation completely, can superpose at this speed point to above-mentioned two kinds of signals.
Correspondingly, when receiving terminal process intermediate frequency speed is the intermediate-freuqncy signal of 46.08MHZ, need filtering extraction to transform to 30.72MHZ, extract
If integral multiple extracts, as P=1, Q=3, the data then inputted enter filter successively, and output is the superposition of each sub-phase, and consulting Figure 14 can find out, input 6 signal a, b, c, d, e, f, and export 2 data (a+b+c), (d+e+f) output data quantity, is made to be 1/3 of input data.
If little several times extract, as P=2, Q=3, then superpose based on P=2, the signal be skipped fills null value.Then consult shown in Figure 15, input 6 signal a, c, e, g, i, k, and export 4 signals (a+c), e, (g+i), k, output data quantity so just can be made to be 2/3 of input data, thus complete superposition based on less calculating.
Consult shown in Figure 16, to extract factor M=3, the multiphase filter of 9 filter coefficients is example.
High-speed data sends to each height phase in the mode of time-division the signal of input, and each height completes filter function when low rate, and the mutually filtered signal of each height completes the superposition of data.Multiphase filtering extracts by using a high speed selector to complete extract function, often inputs a signal, and reversing switch switches and just switches a second son phase.
Such as, for the extraction operation of 1/3 times, heterogeneous input sequence is 1 phase, 2 phases, 3 phases, 1 phase, 2 phases, 3 phases, 1 phase, 2 phases ...
And for above-mentioned 2/3 times of extraction operation, then switch according to step size Q=2, above-mentioned input just becomes 1 phase, 3 phases, 2 phases, 1 phase, 3 phases ..., obviously, just completed by the switching of reversing switch and just complete little several times extraction operation.
Further, in order to obtain the effect of better filtering superposed signal mirror image, in the embodiment of the present invention, after by TD-SCDMA signal and LTE-SCDMA Signal averaging, before sending to receiving terminal, again can carry out interpolating operations to the signal after superposition, its intermediate frequency speed is increased to next common rate point again, as, 92.16MHZ.
In the present embodiment, base station is when performing the signal after by superposition and raising speed again, and when platform can be adopted to adopt half-band filter (Halfband, HB) filter to realize interpolating operations, this is divided into again two kinds of situations:
Based on Fs/Fbw consider, Fs is the intermediate frequency speed after superposed signal speed-raising, i.e. 92.16MHZ, and Fbw is the bandwidth that intermediate-freuqncy signal takies, HB filter is divided into again broadband HB filter (filter that namely transition band is mild) and arrowband HB filter (filter that transition band is precipitous).In order to realize the effect better suppressing mirror image, in the embodiment of the present invention, within relative hour, adopt arrowband HB filter at Fs/Fbw, adopt broadband HB filter when Fs/Fbw is relatively large, thus the requirement of system image suppression can be met, also take into account the requirement that resource is saved simultaneously.So-called Fs/Fbw is relatively little also can be described by mirror image inhibition greatly relatively with Fs/Fbw, as, after first carrying out filtering with broadband HB filter, if mirror image suppress reach arrange threshold value (as, 70dbc), then adopt broadband HB filter to carry out filtering, if mirror image suppress not reach arrange threshold value (as, 70dbc), then use arrowband HB filter instead and carry out filtering.On the contrary, arrowband HB filter also first can be adopted to carry out filtering, time undesirable, then be changed to broadband filter, do not repeat them here.
Consult shown in Figure 17, Figure 18 and Figure 19, after adopting broadband HB filter and arrowband HB filter to carry out filtering to intermediate-freuqncy signal respectively, as can be seen from the state of intermediate frequency signal transition band and pass band damping, when Fs/Fbw is relatively large, if adopt broadband HB filter to carry out filtering, side mirror picture suppresses to only have 33dBc, and this will have a strong impact on the radio-frequency (RF) index of communication system.Wherein, Figure 17 is the transition band frequency spectrum analogous diagram (decay of observation transition band) after broadband HB filter and arrowband HB filter filtering, Figure 18 is the frequency spectrum analogous diagram (observation transition band decay) that broadband HB filter suppresses mirror image, and Figure 19 is the passband frequency spectrum analogous diagram (observation passband ripple) after broadband HB filter and arrowband HB filter filtering.Consult shown in Figure 19, the passband ripple of amplified broad band HB filter and arrowband HB filter can be found out, although the passband ripple of arrowband HB filter is greater than the passband ripple of broadband HB filter, but ripple is less than 0.005dBc, can ignore the impact of communication system, therefore, now use arrowband HB filter, mirror image can be made well to be suppressed, concrete effect is consulted shown in Figure 20, and Figure 20 is the frequency spectrum analogous diagram (decay of observation transition band) that arrowband HB filter suppresses mirror image.
In practical application, broadband HB filter order 8 rank fewer than the coefficient of arrowband HB filter coefficient, meanwhile, the ripple of broadband HB filter is little, so broadband HB filter ripple is applicable to being applied in the higher system of signal rate, and arrowband HB filter is applicable to being applied in the lower system of signal speed.Such as, when signal bandwidth is 184.32MHZ to 92.16MHZ, adopts broadband HB filter, consult shown in Figure 21, along with
increasing is twice, and now HB filter in broadband is to the suppression of mirror image more than 90dBc, meets the user demand of system completely.
In the embodiment of the present invention, a kind of mixing platform is newly devised in base station, by the common switching time at TD-SCDMA signal and LTE-TDD signal, respectively interpolating operations is carried out to these two kinds of signals, the intermediate frequency speed of these two kinds of signals is increased to unified assigned rate, again the identical TD-SCDMA signal of intermediate frequency speed and LTE-TDD signal are superposed and sent, like this, just the mixing achieving TD-SCDMA signal and LTE-TDD signal in same base station sends, simultaneously, also can when carrying out filtering to the rear signal of superposition, by the flexible selection of broadband HB filter and arrowband HB filter, the signalling mirror picture of order is suppressed in ideal range.
Obviously, those skilled in the art can carry out various change and modification to the present invention and not depart from the spirit and scope of the present invention.Like this, if these amendments of the present invention and modification belong within the scope of the claims in the present invention and equivalent technologies thereof, then the present invention is also intended to comprise these change and modification.