CN103095616A - Automatic frequency control method and device and mobile station of downlink wireless transmission - Google Patents
Automatic frequency control method and device and mobile station of downlink wireless transmission Download PDFInfo
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- CN103095616A CN103095616A CN2011103466438A CN201110346643A CN103095616A CN 103095616 A CN103095616 A CN 103095616A CN 2011103466438 A CN2011103466438 A CN 2011103466438A CN 201110346643 A CN201110346643 A CN 201110346643A CN 103095616 A CN103095616 A CN 103095616A
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Abstract
The invention provides an automatic frequency control method, a device and a mobile station of downlink wireless transmission. Feedback frequency is utilized to track reference frequency, and the feedback frequency is that local oscillation frequency of the current mobile station is added with compensation frequency. When a larger jump appears on the reference frequency, the compensation frequency can be utilized to compensate the jump, namely, difference between the feedback frequency and the reference frequency is reduced, time of locking output frequency to the reference frequency can be prolonged, the situation of losing lock due to jumping out of a hold-in range is avoided, and locking effect is improved.
Description
Technical field
The present invention relates to the mobile communication technology field, particularly a kind of auto frequency control method of descending wireless transmission, device and travelling carriage.
Background technology
At moving communicating field, often have larger frequency departure between the local oscillating frequency of travelling carriage (or terminal) and base station carrier frequency, this deviation is caused by two kinds of reasons usually: a kind of is inherent frequency error between the local oscillating frequency of base station and travelling carriage; Another kind is the Doppler frequency shift that travelling carriage moves introducing.
Doppler frequency shift is because Doppler effect produces, when Doppler effect refers to receive with the travelling carriage of certain speed motion the signal that sends from the remote signaling source, the actual frequency that receives can have deviation with tranmitting frequency, and its difference is exactly Doppler frequency shift, perhaps is Doppler frequency.Please refer to Fig. 1, it is the schematic diagram of Doppler frequency estimation.
As shown in Figure 1, suppose to receive when travelling carriage moves to end points Y with constant rate of speed v by end points X in time Δ t the wireless signal that sends from the base station.If the distance between base station and travelling carriage is enough far away, X and Y place can suppose to equate with the angle of the wireless signal of injecting, and are designated as θ.So, wireless signal is from the base station, is moved respectively at X point and Y point the path difference of walking when platform receives to be
Δs＝vΔtcosθ
The phase of received signal that is caused by path difference is poor is
Doppler frequency f
DCan calculate by the following method
Wherein, λ is carrier wave (being wireless signal) wavelength, and v is motion velocity of mobile station, f
cBe base station carrier frequency, c is the light velocity (c=2.998 * 10
8Meter per second), θ is the angle of carrier wave arrival direction and the travelling carriage direction of motion.When travelling carriage moves towards the base station, f
DFor on the occasion of; When travelling carriage during away from the base station, f
DBe negative value.
And automatic frequency is controlled (Automatic Frequency Control is hereinafter to be referred as AFC) device just for the device that overcomes the frequency departure between local oscillating frequency and base station carrier frequency.It adjusts local oscillating frequency according to the current base station carrier frequency that receives, and mainly comprises based on PHASE-LOCKED LOOP PLL TECHNIQUE with based on the maximal possibility estimation technology of base band signal process.Please refer to Fig. 2, it is the schematic diagram of existing automatic frequency control apparatus based on PHASE-LOCKED LOOP PLL TECHNIQUE.
As shown in Figure 2, automatic frequency control apparatus 10 comprises: phase discriminator (PD) 100, the low pass filter (LPF) 110 that is connected with phase discriminator 100 and the voltage controlled oscillator (VCO) 120 that is connected with low pass filter 110, described voltage controlled oscillator 120 is connected with described phase discriminator 100, feeds back signal to described phase discriminator 100 to provide.Described phase discriminator 100, low pass filter 110 and voltage controlled oscillator 120 consist of a phase-locked loop circuit.The base station carrier frequency that receives is as the reference frequency f
r Offer phase discriminator 100, utilize the local oscillating frequency of current mobile station to follow the tracks of described reference frequency f
r, through automatic frequency control apparatus 10, obtain one with reference frequency f
rThe output frequency f that frequency is identical
o
For existing automatic frequency control apparatus 10, after travelling carriage carried out handover, due to the different base station of travelling carriage access, both were fully opposite in the relative position direction of switching between front and back, and Doppler frequency shift can produce larger saltus step, and namely conduct is with reference to frequency f
rThe base station carrier frequency that receives can produce larger saltus step, thereby the local oscillating frequency of current mobile station and reference frequency f
rHas larger difference.Thus, utilize the local oscillating frequency of current mobile station to follow the tracks of described reference frequency f
r, the time-delay that needs are long just can make output frequency f
oLock onto reference frequency f
r, namely lock onto the base station carrier frequency that receives, even may be owing to jumping out Timing Belt losing lock, namely locking effect is bad.
And based on the maximal possibility estimation technology of base band signal process, mainly for be frequently to float by the long-term or short-term of physical device the slow fading that causes, bad for paroxysmal frequency relatively large deviation locking effect.
Summary of the invention
The object of the present invention is to provide a kind of auto frequency control method, device and travelling carriage of descending wireless transmission, when being controlled at the larger saltus step of reference frequency appearance in order to the automatic frequency that solves existing descending wireless transmission, the problem that locking effect is poor.
For solving the problems of the technologies described above, the invention provides a kind of auto frequency control method of descending wireless transmission, comprising: a compensating frequency is provided, and the local oscillating frequency addition with described compensating frequency and current mobile station obtains a feedback frequency; One reference frequency is provided, and described reference frequency is the base station carrier frequency that receives; Utilize described feedback frequency to follow the tracks of described reference frequency, obtain an output frequency identical with described reference frequency frequency.
Optionally, in the auto frequency control method of described descending wireless transmission, described compensating frequency is Doppler frequency shift saltus step amount.
Optionally, in the auto frequency control method of described descending wireless transmission, described Doppler frequency shift saltus step amount is according to formula
Obtain, wherein, Δ f is Doppler frequency shift saltus step amount, and v is motion velocity of mobile station, and c is the light velocity, f
c1The base station carrier frequency before handover, f
c2It is the base station carrier frequency after handover.
Optionally, in the auto frequency control method of described descending wireless transmission, described motion velocity of mobile station is an instantaneous velocity.
Optionally, in the auto frequency control method of described descending wireless transmission, utilize global position system to obtain described instantaneous velocity.
Optionally, in the auto frequency control method of described descending wireless transmission, utilize phase-locked loop circuit to make described feedback frequency follow the tracks of described reference frequency, thereby obtain an output frequency identical with described reference frequency frequency.
The present invention also provides a kind of automatic frequency control apparatus of descending wireless transmission, comprising: phase discriminator; The low pass filter that is connected with described phase discriminator; The voltage controlled oscillator that is connected with described low pass filter; With the complex multiplier that described voltage controlled oscillator is connected, described complex multiplier also is connected with described phase discriminator.
Optionally, in the automatic frequency control apparatus of described descending wireless transmission, the input signal of described phase discriminator comprises: reference frequency and feedback frequency.
Optionally, in the automatic frequency control apparatus of described descending wireless transmission, the input signal of described complex multiplier comprises: the output frequency of compensating frequency and described voltage controlled oscillator.
The present invention also provides a kind of automatic frequency control apparatus of descending wireless transmission, comprising: phase discriminator; The low pass filter that is connected with described phase discriminator; The voltage controlled oscillator that is connected with described low pass filter; The complex multiplier that is connected with described voltage controlled oscillator; With the band pass filter that described complex multiplier is connected, described band pass filter also is connected with described phase discriminator.
Optionally, in the automatic frequency control apparatus of described descending wireless transmission, the input signal of described phase discriminator comprises: reference frequency and feedback frequency.
Optionally, in the automatic frequency control apparatus of described descending wireless transmission, the input signal of described complex multiplier comprises: the output frequency of compensating frequency and described voltage controlled oscillator.
The present invention also provides a kind of travelling carriage, comprises global position system; The algorithm device that is connected with described global position system; The automatic frequency control apparatus that is connected with described algorithm device.
Optionally, in described travelling carriage, described global position system is in order to the instantaneous velocity that obtains described travelling carriage and described instantaneous velocity is transferred to described algorithm device.
Optionally, in described travelling carriage, utilize described algorithm device to obtain Doppler frequency shift saltus step amount, and described Doppler frequency shift saltus step amount is transferred to described automatic frequency control apparatus.
In auto frequency control method, device and the travelling carriage of descending wireless transmission provided by the invention, utilize feedback frequency track reference frequency, described feedback frequency is that the local oscillating frequency of current mobile station adds a compensating frequency, when larger saltus step appears in reference frequency, can utilize described compensating frequency to compensate this saltus step, namely reduce the difference of feedback frequency and reference frequency, thereby can improve the time that output frequency locks onto reference frequency, can not occur jumping out Timing Belt and the situation of losing lock has improved locking effect yet.
Description of drawings
Fig. 1 is the schematic diagram of Doppler frequency estimation;
Fig. 2 is the schematic diagram of existing automatic frequency control apparatus based on PHASE-LOCKED LOOP PLL TECHNIQUE;
Fig. 3 is the flow chart of auto frequency control method of the descending wireless transmission of the embodiment of the present invention;
Fig. 4 is the schematic diagram of automatic frequency control apparatus of the descending wireless transmission of the embodiment of the present invention.
Embodiment
Be described in further detail below in conjunction with auto frequency control method, device and the travelling carriage of the drawings and specific embodiments to the descending wireless transmission of the present invention's proposition.According to the following describes and claims, advantages and features of the invention will be clearer.It should be noted that, accompanying drawing all adopts very the form of simplifying and all uses non-ratio accurately, only in order to convenient, the purpose of the aid illustration embodiment of the present invention lucidly.
Core concept of the present invention is, a kind of auto frequency control method, device and travelling carriage of descending wireless transmission are provided, utilize feedback frequency track reference frequency, described feedback frequency is that the local oscillating frequency of current mobile station adds a compensating frequency, when larger saltus step appears in reference frequency, can utilize described compensating frequency to compensate this saltus step, namely reduce the difference of feedback frequency and reference frequency, thereby can improve the time that output frequency locks onto reference frequency, can not occur jumping out Timing Belt and the situation of losing lock has improved locking effect yet.
Please refer to Fig. 3, it is the flow chart of auto frequency control method of the descending wireless transmission of the embodiment of the present invention.As shown in Figure 3, the auto frequency control method of the descending wireless transmission of the embodiment of the present invention comprises the steps:
Step S10: a compensating frequency is provided, and the local oscillating frequency addition with described compensating frequency and current mobile station obtains a feedback frequency;
Step S11: a reference frequency is provided, and described reference frequency is the base station carrier frequency that receives;
Step S12: utilize described feedback frequency to follow the tracks of described reference frequency, obtain an output frequency identical with described reference frequency frequency.
Please refer to Fig. 4, it is the schematic diagram of automatic frequency control apparatus of the descending wireless transmission of the embodiment of the present invention.As shown in Figure 4, automatic frequency control apparatus 20 comprises: phase discriminator 200; The low pass filter 210 that is connected with described phase discriminator 200; The voltage controlled oscillator 220 that is connected with described low pass filter 210; The complex multiplier 230 that is connected with described voltage controlled oscillator 220; With the band pass filter 240 that described complex multiplier 230 is connected, described band pass filter 240 also is connected with described phase discriminator 200.
In conjunction with Fig. 3 and Fig. 4, the auto frequency control method of descending wireless transmission provided by the invention and the specific implementation of device are as follows:
At first, provide a compensating frequency, thereby by with the local oscillating frequency addition of described compensating frequency and current mobile station, acquisition one feedback frequency approaches described feedback frequency and even equals reference frequency, i.e. the base station carrier frequency that receives of travelling carriage.In the present embodiment, described compensating frequency draws based on following considerations:
Travelling carriage receives the base station carrier frequency after handover after carrying out handover, according to Doppler effect as can be known, the base station carrier frequency after the handover that travelling carriage receives is different from the carrier frequency of base station emission, namely has a Doppler frequency shift; Simultaneously, before handover, travelling carriage is away from the front base station of handover, thereby the Doppler frequency shift that the base station of travelling carriage before with respect to handover has is negative value, and after handover, travelling carriage near handover after the base station, thereby the Doppler frequency shift that the base station of travelling carriage after with respect to handover has on the occasion of.
That is, the base station carrier frequency that the base station carrier frequency that receives after handover receives before with respect to handover has a Doppler frequency shift saltus step amount, and the base station carrier frequency of establishing before handover is f
c1, the base station carrier frequency after handover is f
c2Simultaneously, the distance of supposing the base station before and after travelling carriage and handover is enough far away, can consider the height of base station, thereby the angle between the arrival direction of the direction of motion of travelling carriage and base station carrier is respectively 180 degree and 0 degree, thus, and according to the formula that provides in background technology (1), can obtain Doppler frequency shift saltus step amount, namely in the present embodiment, compensating frequency used is
Wherein, v is motion velocity of mobile station, and c is the light velocity.
Certainly, in other embodiments of the invention, also can adopt other compensating frequencies, for example, consider in real world, the distance between travelling carriage and base station can not be enough far away, thereby need to consider the height of base station, be that angle between the arrival direction of the direction of motion of travelling carriage and base station carrier is not 180 degree and 0 degree, and need specifically be selected certain angle according to actual conditions.The present invention is not restricted this, and for for simplicity, it is that 180 degree and 0 are spent that the present embodiment is chosen angle.
In addition, in the compensating frequency that the present embodiment provides, only considered factor of Doppler effect, thereby described compensating frequency is Doppler frequency shift saltus step amount.In other embodiments of the invention, in the frequency that affords redress, also can consider to cause other factors of frequency departure between the local oscillating frequency of travelling carriage and base station carrier frequency, even equal reference frequency by this compensating frequency, feedback frequency is approached.
In the present embodiment, described motion velocity of mobile station can obtain by the global position system in travelling carriage, and the base station carrier frequency before described handover is that travelling carriage is known, and to be travelling carriage scan and obtain preparing switch step the base station carrier frequency after handover.For reliable compensating frequency is provided, described motion velocity of mobile station is an instantaneous velocity.
In the present embodiment, after the base station carrier frequency before obtaining motion velocity of mobile station, handover, the base station carrier frequency after handover, can be by the algorithm device in a travelling carriage, according to formula
Obtain compensating frequency.Described algorithm device can be any one device that can realize aforementioned calculation function, for example, can simply comprise an adder and a multiplier.Certainly, for arithmetic speed and accuracy, described algorithm device can be comprised of more complicated device, and the present invention is not restricted this.
Described algorithm device can be connected with described global position system, and the motion velocity of mobile station that global position system is obtained transfers to described algorithm device, as the input signal of described algorithm device.
After having obtained described compensating frequency, with the local oscillating frequency addition of described compensating frequency and current mobile station.The local oscillating frequency of current mobile station herein is that the frequency of oscillation that the signal transmission is used is carried out in the base station that travelling carriage is last and switching is front, is also the base station carrier frequency that receives before handover.
Please refer to Fig. 4, the local oscillating frequency of described compensating frequency and current mobile station can pass through complex multiplier 230 additions.In the present embodiment, the local oscillating frequency of described compensating frequency and current mobile station is by after complex multiplier 230 additions, then by a band pass filter 240, the signal of output is feedback frequency thus.But by described some interfering frequencies of band pass filter 240 filterings, improve the quality of feedback frequency.In other embodiments of the invention, also can be without band-pass filter, be that automatic frequency control apparatus 20 does not comprise band pass filter 240, thereby described complex multiplier 230 also is connected with phase discriminator 200, and the signal that obtains by complex multiplier is directly as feedback frequency; The signal that perhaps obtains by complex multiplier passes through other some processing again, to improve the quality of the feedback frequency that obtains thus.
Please continue with reference to figure 4, reference frequency and feedback frequency are inputted phase discriminator simultaneously, namely by this feedback frequency track reference frequency, finally obtain an output frequency identical with described reference frequency frequency.Reference frequency herein is the base station carrier frequency that receives, and more specifically, described base station is the base station after handover.At this, described feedback frequency is followed the tracks of described reference frequency and is based on PHASE-LOCKED LOOP PLL TECHNIQUE and realizes, concrete, described reference frequency and feedback frequency are input to phase discriminator, be input to low pass filter through after described phase discriminator, be input to voltage controlled oscillator through after described low pass filter filtering, phase-locked loop does not repeat them here as a kind of known technology of frequency-tracking.
In auto frequency control method and device by descending wireless transmission provided by the invention, utilize feedback frequency track reference frequency, described feedback frequency is that the local oscillating frequency of current mobile station adds a compensating frequency, when larger saltus step appears in reference frequency, can utilize described compensating frequency to compensate this saltus step, thereby reduce the difference of feedback frequency and reference frequency, can improve output frequency and lock onto time of reference frequency, can not occur jumping out Timing Belt and the situation of losing lock has improved locking effect yet.
In addition, in the present embodiment, travelling carriage need comprise global position system in order to realize above-mentioned locking effect; The algorithm device that is connected with described global position system; The automatic frequency control apparatus that is connected with described algorithm device.The concrete type of action preamble of each parts discloses, do not repeat them here, need to prove, obtained a compensating frequency by described algorithm device, therefore described algorithm device is connected with described automatic frequency control apparatus, more particularly, described algorithm device is connected with complex multiplier in described automatic frequency control apparatus, for described complex multiplier provides input signal, described input signal is compensating frequency.So the travelling carriage of configuration, natch, improved locking effect.
Foregoing description is only the description to preferred embodiment of the present invention, is not any restriction to the scope of the invention, and any change, modification that the those of ordinary skill in field of the present invention is done according to above-mentioned disclosure all belong to the protection range of claims.
Claims (15)
1. the auto frequency control method of a descending wireless transmission, is characterized in that, comprising:
One compensating frequency is provided, and the local oscillating frequency addition with described compensating frequency and current mobile station obtains a feedback frequency;
One reference frequency is provided, and described reference frequency is the base station carrier frequency that receives;
Utilize described feedback frequency to follow the tracks of described reference frequency, obtain an output frequency identical with described reference frequency frequency.
2. the auto frequency control method of descending wireless transmission as claimed in claim 1, is characterized in that, described compensating frequency is Doppler frequency shift saltus step amount.
3. the auto frequency control method of descending wireless transmission as claimed in claim 2, is characterized in that, described Doppler frequency shift saltus step amount is according to formula
Obtain, wherein, Δ f is Doppler frequency shift saltus step amount, and v is motion velocity of mobile station, and c is the light velocity, f
c1The base station carrier frequency before handover, f
c2It is the base station carrier frequency after handover.
4. the auto frequency control method of descending wireless transmission as claimed in claim 3, is characterized in that, described motion velocity of mobile station is an instantaneous velocity.
5. the auto frequency control method of descending wireless transmission as claimed in claim 4, is characterized in that, utilizes global position system to obtain described instantaneous velocity.
6. as the auto frequency control method of the described descending wireless transmission of any one in claim 1 to 5, it is characterized in that, utilize phase-locked loop circuit to make described feedback frequency follow the tracks of described reference frequency, thereby obtain an output frequency identical with described reference frequency frequency.
7. the automatic frequency control apparatus of a descending wireless transmission, is characterized in that, comprising:
Phase discriminator;
The low pass filter that is connected with described phase discriminator;
The voltage controlled oscillator that is connected with described low pass filter;
With the complex multiplier that described voltage controlled oscillator is connected, described complex multiplier also is connected with described phase discriminator.
8. the automatic frequency control apparatus of descending wireless transmission as claimed in claim 7, is characterized in that, the input signal of described phase discriminator comprises: reference frequency and feedback frequency.
9. the automatic frequency control apparatus of descending wireless transmission as claimed in claim 7 or 8, is characterized in that, the input signal of described complex multiplier comprises: the output frequency of compensating frequency and described voltage controlled oscillator.
10. the automatic frequency control apparatus of a descending wireless transmission, is characterized in that, comprising:
Phase discriminator;
The low pass filter that is connected with described phase discriminator;
The voltage controlled oscillator that is connected with described low pass filter;
The complex multiplier that is connected with described voltage controlled oscillator;
With the band pass filter that described complex multiplier is connected, described band pass filter also is connected with described phase discriminator.
11. the automatic frequency control apparatus of descending wireless transmission as claimed in claim 10 is characterized in that, the input signal of described phase discriminator comprises: reference frequency and feedback frequency.
12. the automatic frequency control apparatus as claim 10 or 11 described descending wireless transmission is characterized in that, the input signal of described complex multiplier comprises: the output frequency of compensating frequency and described voltage controlled oscillator.
13. a travelling carriage is characterized in that, comprising:
Global position system;
The algorithm device that is connected with described global position system;
The automatic frequency control apparatus that is connected with described algorithm device.
14. travelling carriage as claimed in claim 13 is characterized in that, described global position system is in order to the instantaneous velocity that obtains described travelling carriage and described instantaneous velocity is transferred to described algorithm device.
15. travelling carriage as described in claim 13 or 14 is characterized in that, utilizes described algorithm device to obtain Doppler frequency shift saltus step amount, and described Doppler frequency shift saltus step amount is transferred to described automatic frequency control apparatus.
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Cited By (4)
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| CN104991441A (en) * | 2015-07-22 | 2015-10-21 | 广州供电局有限公司 | GPS synchronous time giving circuit |
| CN105207766A (en) * | 2014-06-27 | 2015-12-30 | 展讯通信（上海）有限公司 | Frequency shift compensation method, device and mobile terminal |
| CN106464641A (en) * | 2014-06-12 | 2017-02-22 | Lg电子株式会社 | Method and apparatus for configuring synchronization reference in wireless communication system |
| CN115225135A (en) * | 2021-04-20 | 2022-10-21 | 大唐移动通信设备有限公司 | Signal transmission method and device and readable storage medium |
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106464641A (en) * | 2014-06-12 | 2017-02-22 | Lg电子株式会社 | Method and apparatus for configuring synchronization reference in wireless communication system |
| US10292156B2 (en) | 2014-06-12 | 2019-05-14 | Lg Electronics Inc. | Method and apparatus for indicating on/off-state of past subframes in wireless communication system |
| CN106464641B (en) * | 2014-06-12 | 2019-11-05 | Lg电子株式会社 | The method and apparatus of synchronous reference is configured in wireless communication system |
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| CN115225135A (en) * | 2021-04-20 | 2022-10-21 | 大唐移动通信设备有限公司 | Signal transmission method and device and readable storage medium |
| CN115225135B (en) * | 2021-04-20 | 2023-12-29 | 大唐移动通信设备有限公司 | Signal transmission method and device and readable storage medium |
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