CN101232365B - Mobile communication device and burst checking method used therebetween - Google Patents

Abstract

The invention discloses a mobile communication device and a method for burst test therein. The mobile communication device (10) comprises a carrier recovery module (118) for detecting burst according to sampled input data (I/Q); the carrier recovery module (118) comprises an angle calculator (140) for calculating a phase value of the input data (I/Q) and a burst detector (130) for testing burst with the phase value; the burst detector (130) comprises an single difference value module (501) comprising: a unit conversion module (801) for converting the phase value to a numerical value with the unit pi; a subtraction module (802) for subtracting the two numerical values and subtracting 0x2000 to obtain a difference value; a displacement module (803) for shifting the difference value to the right with one bit; an addition module (804) for calculating sum of the displaced difference value and 0x1000; and a phase recovery module (805) for recovering the sum to the phase value.

Description

Mobile communication equipment reaches the burst detection method that is used for wherein

Technical field

The present invention relates to mobile communication system, more particularly, relate to the PHS telephone plant and reach the burst detection method that is used for wherein.

Background technology

Wireless communication system allows the user transmitting and receive data between the user and/or between user and the base station.Generally speaking, wireless communication system is attempted under the situation of other users' that satisfy this system of sharing demand, makes each user's data transmission maximization.Time division multiple access (TDMA) is exactly a kind of example of utilizing maximized method that is used for making under the situation that makes the minimum interference between the user of wireless communication system to the bandwidth of distributing.Many dissimilar wireless communication systems have all adopted TDMA, for example personal handyphone system (PHS).

Fig. 1 shows the exemplary functional block diagram according to the PHS phone 10 of prior art.The PHS telephone system comprises the PHS phone 10 with antenna 12 and the base station 11 with antenna 13.Exemplary PHS phone 10 comprises signal processing module 16, memory 22, power supply 24 and I/O module 26.Signal processing module 16 comprises transmitter module 18 and receiver module 20.Transmitter module 18 converts user's input to the PHS compatible signal.Receiver module 20 will become the discernible form of user and output from the data transaction that antenna 12 receives.Signal processing module 16 utilizes memory 22 12 data that receive to be handled to the data of antenna 12 with from antenna sending.

In digital communication system, data generally are by the baseband signal of utilizing beared information carrier signal to be modulated to launch.Quadrature Phase Shift Keying modulation (QPSK) is a kind of phase place modulation of using in communication system usually.In QPSK, use four symbols to represent dibit value 00,01,10 and 11.QPSK is with this four sign map to four fixing phase angle.Another kind of example PI/4-DQPSK is utilized the differential coding scheme, and the mapping in this scheme between symbol and the phase angle changes.In addition, PI/4-DQPSK is mapped to a reality parallactic angle and an empty phase angle with in above-mentioned four symbols each, thereby produces the constellation of eight points.In the PHS phone, adopted simple transmitting/receiving technology, for example, PI/4-DQPSK modulation and incoherent differential ference spiral.

When utilizing non-coherent demodulation, it is very important that carrier wave recovers.A kind of carrier frequency recovery scheme is automatic frequency control (AFC).But in current PHS system, data are sent out with burst mode.Therefore, it is shorter relatively that AFC becomes stable response time, usually at several symbols to the dozens of symbol.Therefore, in PHS, adopted open-loop carrier frequency estimation, realized that by detecting burst carrier wave recovers.

In PHS, the targeting sequencing (PR) in the control time slot has suitable characteristic and can be used for detecting this burst (perhaps time slot).Referring to Fig. 2, Fig. 2 shows in the PHS system, control time slot (control channel, form CCH).In the PHS system, the PR symbol is the pattern that is formed for 16 times by " 1001 " repetition, utilizes this periodic characteristic of targeting sequencing PR, can fast detecting go out burst.

But, in the PHS phone, owing to for detection of the algorithm defective that happens suddenly, cause the module more complicated for the burst detection, and can not take full advantage of the characteristic of existing dsp chip.

Summary of the invention

In order to solve foregoing problems, one aspect of the present invention discloses a kind of mobile communication equipment 10.Equipment 10 comprises according to the carrier recovery block 118 that detects burst through the input data (I/Q) of sampling.Carrier recovery block 118 comprises for the angle computer 140 of the phase value that calculates input data (I/Q) and utilizes described phase value to detect the burst detector 130 of burst.130 difference blocks 501 of burst detector, secondary difference block 502, rolling average module 503 and detection output module 504.

Difference block 501 comprises unit transformation module 801, subtraction block 802, shift module 803, addition module 804 and bit recovery module 805 mutually.It is the numerical value of unit that unit transformation module 801 is used for phase value is changed over π; Subtraction block 802 calculates difference for two numerical value are subtracted each other and then deduct 0x2000; Shift module 803 is used for difference is moved to right one; Addition module 804 be used for calculating after the displacement difference with 0 * 1000 with; And phase bit recovery module 805 be used for will be described with revert to phase value.

Another aspect of the present invention discloses a kind of for the method that detects burst at mobile communication equipment.This method may further comprise the steps: the phase value that calculates described input data (I/Q) at each sampling; Calculate the difference of corresponding two adjacent phase values and calculate difference one time; Calculate corresponding adjacent two differences and calculate the secondary difference; Calculate the moving average of secondary difference at average window; And according to burst threshold and described moving average detection burst.

Calculating a difference carries out by following process: it is the numerical value of unit that described phase value is converted to π; The difference of corresponding two adjacent numerical value is deducted 0 * 2000 calculate difference; Described difference is moved to right one; Calculate after the displacement difference with 0 * 1000 with; And with described and be transformed into phase value.

Technical scheme disclosed in this invention can take full advantage of the characteristic of DSP, simplifies the design of Wireless Telecom Equipment, reduces cost, and raises the efficiency.

Description of drawings

Fig. 1 shows the schematic block diagram of PHS system;

Fig. 2 shows the form of controlling time slot (CCH) in the PHS system;

Fig. 3 shows the partial function block diagram in the PHS phone RX path;

Fig. 4 shows in detail the functional block diagram of the carrier recovery block 118 among Fig. 3;

Fig. 5 shows in detail the functional block diagram of the burst detector 130 among Fig. 4;

Fig. 6 A and 6B show the simulate signal waveform of difference and secondary difference respectively;

Fig. 7 shows the burst detection signal waveform of emulation;

Fig. 8 shows in detail the functional block diagram of a difference block among Fig. 5;

Fig. 9 shows the block diagram according to the method that detects for happening suddenly of the present invention;

Figure 10 is the more detailed diagram of the method for Fig. 9; And

Figure 11 illustrates in greater detail the step of the difference of calculating among Figure 10.

Embodiment

A lot of details have been set forth in the detailed description to the specific embodiment of the present invention below, so that fully understand the present invention.But, there are not these details can implement the present invention yet, be clearly for a person skilled in the art.With reference to the PHS phone the specific embodiment of the present invention is described below, but the present invention is not limited to the PHS phone.

With reference now to Fig. 3, present invention is described, the figure shows the block diagram of a part of the reception data path of PHS phone.AFE (analog front end) (AFE) part 110 comprises analog to digital converter 112, is used for importing data and becomes digital signal from analog signal conversion.Digital signal after the conversion is transferred to hardware accelerator 114.The signal after the carrier frequency shift compensation is handled and generated to 114 pairs of digital input datas of hardware accelerator.

Hardware accelerator 114 comprises decimation filter 116, and (N * fb) form through accelerating the input data, wherein N is the integer greater than 0 to decimation filter 116 with N times of character rate.Input data through accelerating are transferred to carrier recovery block 118 and circulator module 120 from decimation filter 116.The output of circulator module 120 is transferred to A/B buffer register 122.Carrier recovery block 118 detects burst, and estimates the carrier frequency shift between the signal of the signal that receives and emission, will be explained in more detail it below.

Circulator module 120 is used for carrier frequency is compensated to form rotation back signal.Signal is transferred to digital signal processor module (DSP) 124 after being stored in the rotation in the A/B buffer register 122.DSP 124 comprises equalizer module 126.Correlator block 128, limiter 130 and slow tracker 132.

Carrier recovery block 118 has two basic functions: one is to detect time division duplex (TDD) burst, another be estimating received signal and transmit between carrier frequency shift.This carrier frequency shift that estimates is used to drive the frequency that the skew of circulator module 120 in to received signal compensated or be used for driving the local carrier generator of AFC and proofreaies and correct.

With reference now to Fig. 4, describes carrier recovery block 118 in detail.Carrier recovery block 118 comprises angle computer 140, burst detector 130, carrier offset calculator (COC) 132, delay buffer 134 and average detector 214.

Burst detection sign (burstdetect) triggering from burst detector 130 is derived the carrier shift frequency from the signal of delay buffer 134 by COC 132.Resulting skew is transformed into the anglec of rotation, is delivered to the circulator module 120 among Fig. 1 then, makes the frequency shift (FS) that receives in the signal to be compensated.

Angle computer 140 calculates by the arctan angle based on homophase (I) and quadrature (Q) component of input data, will import data (I/Q) at each sampling and be transformed into pure phase position information.That is, for in-phase component I and the quadrature component Q of input data, phase angle θ=arctan (Q/I).Table 1 shows the example that size is 12 * 16 arctan table, and wherein π is represented as 0x10000.

Table 1 CORDIC Arctangent table

Arctan shows (Q.16)	The position scope	Value (no symbol)	Represented value
				[0]	[15∶0]	16384	Atan(1)＝1/4*π
[1]	[15∶0]	9672	Atan(1/2)
				[2]	[15∶0]	5110	Atan(1/4)
[3]	[15∶0]	2594	Atan(1/8)
				[4]	[15∶0]	502	Atan(1/16)
[5]	[15∶0]	652	Atan(1/32)
				[6]	[15∶0]	326	Atan(1/64)
[7]	[15∶0]	163	Atan(1/128)
				[8]	[15∶0]	81	Atan(1/256)
[9]	[15∶0]	41	Atan(1/512)
				[10]	[15∶0]	20	Atan(1/1024)
[11]	[15∶0]	10	Atan(1/2048)

The phase value that angle computer 140 calculates is output to burst detector 130.

Be the situation of different value for the N in the decimation filter 116, burst detector 130 can have the similar path configurations of N bar.But for simplicity, the burst detector 130 at the one embodiment of the invention of N=1 is described in detail below.In this case, each symbol is corresponding to a sampling, thereby adjacent two phase values are corresponding to the phase information of adjacent two symbols.

Burst detector 130 comprises difference block 501, secondary difference block 502, rolling average module 503 and detection output module 504 one time, as shown in Figure 5.

501 pairs of continuous two phase value calculated difference from angle computer 140 inputs of a difference block, that is, and θ (k)-θ (k-1).Then, the difference computing is carried out in 502 pairs of inputs from a difference block 501 of secondary difference block, and this is equivalent to carries out difference twice to all original phase values.The result of calculation of secondary difference block 502 is output to rolling average module 503 then.Moving average calculation on the average window that 503 pairs of secondary differences from secondary difference block 502 of rolling average module are M at width.That is, with two adjacent input additions and calculating and absolute value, then to nearest M absolute value summation.Detecting output module 504 will compare with the burst threshold ThB that is scheduled to from each moving average of rolling average module 503, if a moving average is littler than ThB, just generates the burst detection signal and it is outputed to COC 132 (Fig. 4).

In PHS equipment, burst detector 130 has utilized the targeting sequencing (PR) in the PHS control time slot to detect the TDD burst.Describe the theoretical foundation of this detection below in detail.

Inband signaling for reception:

s _r(t)＝A(t)cos(Δ _ωct+θ′(t)+φ)+n(t)，

Wherein, $A\left(t\right)=\underset{k}{\mathrm{\Σ}}g(t-\mathrm{kT}),$ G (t) is the cosine impulse that rises, Δ ω _cBe carrier shift, θ ' is the receiver phase modulation (t), and φ is the fixed phase offsets between the transmitter and receiver, and n (t) is Gaussian noise.If ignore poor between transmitter phase modulation and the receiver phase modulation, then S _r(t) phase signal only is phz (t)=2 π Δ ft+ θ (t)+φ.

After a difference, phase difference variable is:

phzDiff1(t)＝phz(t)-phz(t-T)＝2πΔfT+θ(t)-θ(t-T)。Very clear, the signal after this difference is the one-period signal, and its center is 1/4 π+2 π Δ fT, and the cycle is 2T, and phase value exists

In, as shown in Figure 6A.

After twice difference, phase difference variable is:

phzDiff2(t)＝phzDiff1(t)-phzDiff1(t-T)＝θ(t)+θ(t-2T)-2θ(t-T)。

Signal after this twice difference is centered by 0, and the cycle is the periodic signal of 2T.The value of this signal is in [π, π], shown in Fig. 6 B.

The burst detection algorithm is the rolling average of the average window calculating secondary difference of M at a width.That is, with adjacent two secondary differences addition and calculate absolute value, on this average window, a nearest M absolute value is added up then.Then, this algorithm each moving average that will calculate and a default burst threshold ThB compare to have judged whether that burst is detected.Order

$\mathrm{sumPhase}=\underset{m=0}{\overset{M-1}{\mathrm{\Σ}}}\mathrm{abs}(\mathrm{phzDiff}2(t-\mathrm{mT})+\mathrm{phzDiff}2(t-\mathrm{mT}-T)),$

Wherein the M length of window is selected M=16 in situation of the present invention.Above-mentioned equation can be reduced to

$\mathrm{sumPhase}=\underset{m=0}{\overset{M-1}{\mathrm{\Σ}}}\mathrm{abs}(\mathrm{\θ}(t-\mathrm{mT})-\mathrm{\θ}(t-\mathrm{mT}-T)-\mathrm{\θ}(t-\mathrm{mT}-2T)+\mathrm{\θ}(t-\mathrm{mT}-3T))$

$=\underset{m=0}{\overset{M-1}{\mathrm{\Σ}}}\mathrm{abs}(\mathrm{phzDiff}1(t-\mathrm{mT})-\mathrm{phzDiff}1(t-\mathrm{mT}-2T))$

In Fig. 7, show the sumPhase signal.This figure is to be 3f at sampling rate _bExample shown in, f _bIs-symbol speed.Very clear, during PR, sumPhase is much smaller than other signal periods, so this is the good indicator that burst detects.

If aumPhase is less than burst detection threshold ThB, then burst is detected.The value of ThB in situation of the present invention, is selected ThB=3* π from repeatedly deriving the simulation.

In an above-mentioned difference is calculated, because the arctan angle is in [π, π] scope, so if directly carry out difference, then the scope of θ (k)-θ (k-1) is inevitable in [2 π, 2 π] scope.This will cause angle to be obscured, and for example 7 π/4 may be actually-π/4.Cause the basic reason of this problem to be the restriction that arctan calculates.Because this calculating must be arranged in the fixed range of 2 π, for example [π, π] or [0,2 π], but the true phase place of importing data is continually varying.Suppose that positive receiving phase is the symbol of 3 π/4, and current phase place is pi/2, then the new phase place behind symbol time is actually 5 π/4.Yet the arctan in [π, π] calculates according to scope, and the result is-3 π/4.So if directly carry out difference, then can not distinguish phase change is pi/2 or-3 pi/2s.

Obscure in order to solve this phase place, must export difference, that is, the scope of θ (k)-θ (k-1) is adjusted.In the PHS system, targeting sequencing repeats 16 times by " 1001 " and constitutes.Because the PHS system adopts the PI/4-DQPSK modulation scheme, so " 10 " mean-π/4 phase changes, and " 01 " means 3 π/4 phase changes.Therefore, ideally, difference θ (k)-θ (k-1) should be at [π/4,3 π/4].Consider the influence of noise, frequency shift (FS) and timing jitter, add certain surplus in the both sides of this scope, then this scope will be [3 π/4,5 π/4], and its width just is 2 π, can not cause phase place to be obscured.

Consider the above-mentioned specific of a difference computing, and in order to take full advantage of the characteristic of DSP, one time difference block 501 has adopted a kind of structure that is more conducive to calculate a difference.Difference block 501 comprises unit transformation module 801, subtraction block 802, shift module 803, addition module 804 and bit recovery module 805 (with reference to figure 8) mutually.

It is the value of unit that unit transformation module 801 will change over π from the θ (k) of angle computer 140 inputs, and is expressed as Q15 fixing point form (in the situation that adopts 16 word DSP).Then, subtraction block 802 is carried out computing diff θ (k)=θ (k)-θ (k-1)-0x2000 (in the Q15 form, 0x2000 represents 1/4).Next, 803 couples of diff θ (k) from subtraction block 802 of shift module carry out computing diff θ (k)=diff θ (k)＞＞1 and (note, here this fixing point form can be considered to Q14), and diff θ (k) as a result sent to addition module 804.Addition module 804 is carried out computing diff θ (k)=diff θ (k)+0 * 1000 (in the Q14 form, 0 * 1000 expression 1/4) then and diff θ (k) is as a result sent to phase bit recovery module 805.At last, phase bit recovery module 805 will revert to phase value from the diff θ (k) of addition module 804.

Described above and realized exemplary means of the present invention.Another aspect of the present invention relates to the method that burst detects that is used for shown in Figure 9.This method mainly comprises five steps: the phse conversion step S901 that all input data (I/Q) is transformed into pure phase position information; Adjacent two outputs of step S901 are carried out a difference step S902 of difference; Adjacent two outputs of step S902 are carried out the secondary difference step S903 of difference; Be on the average window of M to the rolling average step S904 of the continuous output moving average calculation of step S903 at preset width; And the output of step S904 during less than predetermined threshold value ThB the output indication detect the detection output step S905 of the signal burstdetect of burst.

Figure 10 illustrates in greater detail method shown in Figure 9.This method starts from step S1001, and the k that is used for to counting through the input data (I/Q) of sampling is put 0.In step S1002, whenever receive a sampling then, k is added 1, and import data i (k) for what receive through sampling, utilize its in-phase component I (k) and quadrature component Q (k) to calculate its phase angle θ (k)=arctan (Q (k)/I (k)).Whether in determining step S1003, judge k then greater than 1, if otherwise return step S1002, carry out a difference d θ (k)=θ (k)-θ (k-1) otherwise advance to step S1004, this method advances to step S1005 then.In step S1005, whether judge k greater than 2, if otherwise turn back to step S1002, otherwise continue to step S1006.In step S1006, the difference result of step S1004 is carried out difference d again ²θ (k)=d θ (k)-d θ (k-1).Then, in step S1007, for predetermined average window length M, judge k-M-2 〉=0, that is, whether exist abundant secondary difference result to be used for suing for peace in average length of window.If the judged result of step S1007 is that then process does not turn back to step S1002, else process advances to step S1008.In step S1008, the result that will calculate in step S1006 carries out rolling average in average window length M, that is: $\mathrm{sum}\left(k\right)=\underset{m=0}{\overset{M-1}{\mathrm{\&Sigma;}}}\mathrm{abs}({\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="RE-S200710154164XE00021.png,RE-S200710154164XE00091.png"\; state="\{\{state\}\}">d</figure-callout>}}^2\mathrm{\&theta;}(k-m)+{\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="RE-S200710154164XE00021.png,RE-S200710154164XE00091.png"\; state="\{\{state\}\}">d</figure-callout>}}^2\mathrm{\&theta;}(k-m-1)).$ Then, in step S1009, judge sum (k)＜ThB, wherein ThB is preset threshold value.If the judged result of step S1009 is that then process does not turn back to step S1002, otherwise advances to step S1010.In step S1010, the output indication detects the signal of burst, and process turns back to step S1002 then.

A difference below with reference to the step S1004 of Figure 11 is explained in more detail.As previously mentioned, obscure for fear of angle, and take full advantage of the characteristic of DSP, step S1004 has adopted a kind of process of novelty.

At first, in step S1101, will carry out that the angle θ (k) of adjacent two phase values of difference and θ (k-1) convert to π is the numerical value of unit, and in the situation that for example adopts 16 word DSP, it is expressed as Q15 fixing point form.In step S1102, θ (k) and the θ (k-1) that represents with Q15 fixing point form carried out computing diff θ (k)=θ (k)-θ (k-1)-0x2000 then.In step S1103, the result who obtains among the step S1102 is carried out computing diff θ (k)=diff θ (k)＞＞1.Process advances to step S1104 then, in this step the result among the step S1103 is carried out computing diff θ (k)=diff θ (k)+0x1000.At last, in step S1105, S1101 is opposite with step, and the result among the step S1104 is remapped into phase value.

The preferred embodiments of the present invention have more than been described.Although described the present invention in a particular embodiment, the present invention also can realize with the form of hardware, software, firmware or its combination, and can be applied in system, subsystem and parts thereof or the subassembly.When realizing with software, element of the present invention is that code segment is to finish necessary task basically.

Claims (4)

1. a mobile communication equipment (10), comprise the carrier recovery block (118) that happens suddenly according to the input Data Detection through sampling, described carrier recovery block (118) comprises for the angle computer (140) of the phase value that calculates the input data and utilizes described phase value to detect the burst detector (130) of burst

Described burst detector (130) comprise calculating from the difference block (501) of a difference of continuous two phase values of described angle computer (140), the difference of calculating continuous two differences calculate the secondary difference secondary difference block (502), on average window to the rolling average module (503) of secondary difference moving average calculation and if described moving average less than burst threshold then detect the detection output module (504) of burst

Wherein, described rolling average module (503) with adjacent two secondary differences addition and calculate and absolute value, then a nearest M absolute value is sued for peace to calculate the moving average of secondary difference, wherein M is the length of average window,

Wherein, a described difference block (501) comprises unit transformation module (801), subtraction block (802), shift module (803), addition module (804) and bit recovery module (805) mutually,

Unit transformation module (801), being used for described phase value is changed over π is the numerical value of unit, and is expressed as Q15 fixing point form;

Subtraction block (802) calculates difference for two adjacent described numerical value are subtracted each other and then deduct 0x2000;

Shift module (803) is used for and will be moved to right one by the difference that described subtraction block (802) calculate;

Addition module (804), be used for to calculate difference and 0x1000 after the displacement with; And

Phase bit recovery module (805) be used for will be described with revert to phase value,

A wherein said difference block (501) utilizes 16 word DSP to realize.

2. mobile communication equipment as claimed in claim 1 (10) is personal hand-held phone PHS phone.

3. one kind is used for detecting the method that happens suddenly at mobile communication equipment, may further comprise the steps:

Calculate the phase value of input data at each sampling;

Calculate the difference of corresponding two adjacent phase values and calculate difference one time;

Calculate the difference of corresponding adjacent two differences and calculate the secondary difference;

By with adjacent two secondary differences addition and calculate and absolute value, then nearest M absolute value summation come moving average in average window calculating secondary difference, wherein, M is the length of average window; And

If described moving average is less than burst threshold then detect burst, wherein

Calculating a difference carries out by following process:

It is the numerical value of unit that described phase value is converted to π, and is expressed as Q15 fixing point form;

The difference of corresponding two adjacent numerical value is deducted 0x2000 calculate difference;

Described difference is moved to right one;

Calculate difference and 0x1000 after the displacement with; And

With described and be transformed into phase value,

Difference of wherein said calculating is carried out in 16 word DSP.

4. method as claimed in claim 3 is constantly carried out at described input data.

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