The content of invention
The objective of the invention is in order to satisfy PHS mobile communcations system higher the wanting that transmitting-receiving proposes to wireless signal, a kind of mobile communication base station system and beam switching method based on the wave beam switching type intelligent antenna is provided, can not in the PHS mobile communication, use to overcome existing smart antenna, with existing mobile communication base station equipment complexity, be difficult for realizing the deficiency of wave beam switching controls.
The object of the present invention is achieved like this:
Technical thought of the present invention is to take a time slot according to each mobile subscriber of TDMA/TDD of PHS system, and up link and down link use the characteristics of identical communication frequency, at different mobile subscribers, its corresponding communication time slot is carried out wave beam control; And estimate mobile subscriber's orientation, and use identical orientation to transmit in downlink phase by mobile subscriber's uplink signal.
Base station system of the present invention comprises: critical pieces such as multiple antenna array, digital phase shifter array, power splitter, receiving element, received signal field intensity indication (RSSI) sampling unit, modulating unit, transmitter unit, baseband processing unit, wave beam control transformation unit, reception emission change over switch K.Wherein:
Multiple antenna and digital phase shifter array are used for upward signal field intensity and signal quality according to the mobile subscriber, estimate mobile subscriber's orientation, and semi-mobile user is received and dispatched, and promptly the transmitting-receiving phase place of each road antenna is controlled.Be that each pre-set fixed beam can be controlled by baseband processing unit as required;
Power splitter is used in uplink phase, and the multipath reception signal is synthesized one road signal, will be assigned on the multichannel antenna through transmitting of transmitter unit in downlink phase;
Receiving element is used to finish the radiofrequency signal that aerial array is received and handles, promptly uplink phase to Frame receive, amplification, filtering;
Demodulating unit is used to finish high intermediate-freuqncy signal is carried out demodulation, and demodulated bitstream data is passed to the Base-Band Processing control unit;
The RSSI sampling unit is used to finish the data acquisition to each channel receiving signal intensity indication, and is sent to the Base-Band Processing control unit for subsequent treatment;
Modulating unit is used to finish in downlink phase, modulates receiving data to be demodulated from baseband processing unit, gives transmitter unit with modulating data then;
Transmitter unit is used for and will modulated intermediate-freuqncy signal be carried out up-conversion, makes it become radiofrequency signal and also launches through aerial array;
The Base-Band Processing control unit, be used for control, coordinate the whole system operation sequential, finish signal processing, switch transition and wave beam switching controls process are penetrated in the control transmitting-receiving, promptly gather the intensity indication of received signal according to RSSI, estimate signal quality level, compare with threshold value again, determine whether to carry out wave beam according to Different Results relatively and switch; To carry out that wave beam switches again by signal strength and signal quality are judged, finally find out a suitable mobile subscriber ground optimal beam direction, just determine a wave beam number, send into wave beam control transformation unit;
There is the various fixed narrow beam wave beam control transformation unit, is used for wave beam that baseband processing unit is sent here and number deciphers, and then the wave beam of this wave beam correspondence is loaded into the control end of digital phase shifter, realizes the control to required transmitting-receiving wave beam.
Above-mentioned Base-Band Processing control unit is a core cell of the present invention, is to be the center with the signal processor, and in conjunction with corresponding sequential, logic control unit etc. are realized.This base band controlled processing unit comprises protocol processing unit and smart antenna processing center unit, wave beam switching type intelligent antenna processing center unit, this protocol processing unit is made up of programmable logic device 1 and primary processor, mainly finishes the base station sequencing control, realizes complete protocol stack processing; This wave beam switching type intelligent antenna processing center unit is made up of coprocessor, programmable logic device 2 and wave beam switching controls output software, mainly finishes search, follows the tracks of and realize the wave beam switching controls.
Above-mentioned wave beam control transformation unit mainly is made of input interface, decoding unit, driver element, output interface, input interface receives from the wave beam of baseband processing unit number, decoder number is deciphered wave beam, produce the control signal bus, these control signal buses are converted to the control signal of digital phase shifter array after driving, be loaded into the switching that realizes on the digital phase shifter different beams.
Baseband processing unit of the present invention realizes that the step of wave beam switching is as follows:
Step 1, on the control time slot because the carrying public information uses the omni-beam in the coverage to cover, when the mobile subscriber, begins to enable wave beam and switches during the stage at the voice of business time-slot;
Step 2, at a mobile subscriber, through the received signal data after the demodulation, the N frame is a statistic unit period on each work period receive path, received signal is FRAME
1, FRAME
2... FRAME
N
Step 3, at a mobile subscriber, each work period indicates the received signal intensity on the receive path and samples, and the N frame is a statistic unit period.The indication of received signal intensity is respectively RSSI
1, RSS
2... RSSI
N
Step 4 is at a mobile subscriber, at a statistic unit in the period, to the RSSI that collects
1, RSS
2... RSSI
NCarry out statistical average and obtain RSSI;
Step 5 at a mobile subscriber, is adjudicated each frame reception quality of data of statistic unit period, and the statistics frame error rate;
Step 6: with the RSSI value and the frame error rate that obtain and preset thresholding and compare, estimate that the mobile subscriber is whether on wave beam orientation, place at present;
Step 7: if the mobile subscriber in present aspect, then next statistic unit still uses the wave beam orientation identical with this statistic unit period to receive and dispatch in the period, and repeating step 2~step 6.
Step 8: if the mobile subscriber not on current wave beam orientation, then next statistic unit is in the period, the wave beam orientation automatically switches on the another one wave beam orientation, and repeating step 2~step 6.
The judgement to quality of signals in the above-mentioned steps comprises two aspects: the one, and whether " unique identifier word " be correct among the received signal Frame FRAME; The 2nd, whether the check results of this received signal Frame FRAME is correct.
In the above-mentioned steps " at a mobile subscriber ", be exactly at a time slot, " each work period " is exactly every frame.
What above-mentioned wave beam orientation was estimated comprises that poll is estimated and accurately estimates two kinds of methods.
The present invention has following advantage:
In the system of the present invention owing to adopt fixedly narrow beam to receive and dispatch, with omnidirectional antenna relatively, this narrow beam can effectively increase the coverage distance of system, minimizing is from the interference of non-moving user location; Also improve simultaneously the utilance of frequency, can effectively improve up receiving sensitivity, effectively increased wireless communication distance, can also reduce the switching times of mobile subscriber when conversing.
The present invention because except the RSSI of intensity indication to received signal carried out statistical decision, also the quality of itself was adjudicated to received signal, has increased the statistical decision that whether signal that is received is missed frame when judgement optimum beam orientation.Thereby got rid of owing to disturb, cause received signal intensity on certain wave beam to be higher than the received signal intensity of other wave beam, make system make of the mistaken verdict of this wave beam for the wave beam at mobile subscriber place.This method than uses signal receiving strength (RSSI) more credible, more reliable as the method for criterion merely.
The present invention is owing to adopt the wave beam switching type intelligent antenna, thereby base station system can be searched for automatically, follows the tracks of the mobile subscriber, evades the interference of non-moving user location, improved frequency efficiency.
The present invention can reduce the hardware cost of system greatly owing to only need can finish once cover reception system the detection of communication and azimuth of mobile user.Simultaneously because device of the present invention does not need to carry out online or from first calibration, system is simple, be easy to realize.
Embodiment
With reference to Fig. 1, system of the present invention mainly is made up of parts such as multiple antenna, digital phase shifter array, power splitter wave beam suitching type aerial array, receiving element, wave beam control transformation unit, demodulating unit, received signal field intensity indication RSSI sampling unit, transmitter unit, modulating unit, Base-Band Processing control unit, reception emission change over switch K.Wherein: multiple antenna, digital phase shifter array, power splitter, wave beam ripple control transformation unit four parts are formed wave beam suitching type aerial array.
Power splitter synthesizes one road signal in uplink phase with the multipath reception signal, will be assigned on the multichannel antenna through transmitting of transmitter unit in downlink phase:
Receiving element is handled the radiofrequency signal that aerial array receives, and mainly comprises the low noise processing and amplifying, radiofrequency signal is down-converted to the high intermediate-freuqncy signal of 243.95MHz.In addition, receiving element also carries out envelope detected to high intermediate-freuqncy signal, obtains the field intensity signal of received signal, and gives RSSI sampling unit.
Demodulating unit carries out demodulation to the high intermediate-freuqncy signal of 243.95MHz, and demodulated bitstream data is passed to the Base-Band Processing control unit.
RSSI sampling unit field intensity is to received signal sampled, and is sent to the Base-Band Processing control unit for subsequent treatment
Modulating unit is the inverse process of demodulating unit, and the downlink data bit stream that it sends the Base-Band Processing control unit here is modulated into the analog if signal of 10.8MHz.
Transmitter unit carries out up-conversion to modulated 10.8MHz intermediate-freuqncy signal, makes it become radiofrequency signal; At last, the radio frequency radiofrequency signal is carried out power amplification, and launch through aerial array.
Wave beam control transformation unit mainly is made of input interface, decoding unit, driver element, several parts of output interface, as shown in Figure 4.Store a plurality of fixedly narrow beams in this wave beam ripple control transformation unit, shown in Fig. 3 a and 3b.The fixed beam of Fig. 3 a mainly comprises: wave beam 300a, 301a, 302a, 303a, 304a.The beamwidth of this wave beam 300a is 120 degree, and the omni-beam in the coverage is used for Common Control Channel and Traffic Channel; This wave beam 301a, 302a, 303a, 304a all are used for Traffic Channel, and its width is 30 degree, and beam direction is respectively 47 degree, 17 degree ,-17 degree ,-47 degree.The mobile subscriber uses the 300a wave beam to receive and dispatch in the link setup stage, and when the mobile subscriber entered talking state, system start-up wave beam switched system was started working, and under the situation that does not influence conversation, begins the mobile subscriber is carried out bearing search and tracking.When being the work of wave beam switched system, input interface receives all wave beam 300a, 301a, 302a, 303a, the 304a from the Base-Band Processing control unit, decoder number is deciphered these wave beams, produce control signal bus 5031,5032,5033......503M, these control signal buses through driving after the line 5051,5052 of overdriving, 5053......505M be loaded on digital phase shifter 1, digital phase shifter 2, digital phase shifter 3, the digital phase shifter 4...... digital phase shifter M, thereby realized the switching of different beams.The fixed beam of Fig. 3 b comprises: 300b, 310b, 3202b, 330b, 311b, 312b, 313b, 321b, 322b, 323b, 331b, 332b, 333b.The width of this wave beam 300b is 180 degree, and the omni-beam in the coverage is used for Common Control Channel and Traffic Channel; This wave beam 310b, its beamwidth of 320b, 330b are 60 degree, and beam direction is respectively 60 degree, 0 degree ,-60 degree, and these wave beams all are used for Traffic Channel; The beamwidth of this wave beam 311b, 313b, 321b, 322b, 323b, 331b, 332b, 333b is 20 degree, beam direction is respectively 80 degree, 60 degree, 40 degree, 20 degree, 0 degree ,-20 degree ,-40 degree ,-60 degree ,-80 degree, and these wave beams all are used for Traffic Channel.The mobile subscriber uses the 300b wave beam to receive and dispatch in the link setup stage; When the mobile subscriber entered talking state, system start-up wave beam switched system was started working, and under the situation that does not influence conversation, began the mobile subscriber is carried out bearing search and tracking.When being the work of wave beam switched system, input interface receives all the wave beam 300b from the Base-Band Processing control unit, 310b, 3202b, 330b, 311b, 312b, 313b, 321b, 322b, 323b, 331b, 332b, 333b, decoder number is deciphered these wave beams, produce control signal bus 5031,5032,5033......503M, these control signal buses are through driving after the line 5051 of overdriving, 5052,5053......505M be loaded into digital phase shifter 1, digital phase shifter 2, digital phase shifter 3, on the digital phase shifter 4...... digital phase shifter M, thereby realized the switching of different beams.
The Base-Band Processing control unit is the core of whole device, mainly is made of protocol processes part, the big line processing center two parts function of wave beam control type intelligence, as shown in Figure 2.Wherein, the protocol processes part mainly is made of primary processor and programmable logic device, is used to finish the base station sequencing control, realizes complete protocol stack processing.Wave beam switching type intelligent antenna processing center mainly is made of coprocessor, programmable logic device, the output of wave beam switching controls, is used to realize to search for, the algorithm of tracking, smart antenna etc.
The course of work of the present invention is as follows:
In up link working hour, the base station is in accepting state.Base-Band Processing control unit control transmit-receive switch K throws to receiving position.Reception data on the aerial array enter receiving element by digital phase shifter array, merit branch/synthesizer.The signal that the receiving element butt joint takes in is put, big filtering, delivers to the demodulating unit of back then; Demodulating unit is further handled receiving data, then the data after the demodulation is delivered to the Base-Band Processing control unit.Simultaneously, demodulating unit also calculates in this time slot the received signal intensity indication RSSI calculating of sampling, and delivers to the Base-Band Processing control unit.The Base-Band Processing control unit reads, stores the sampled data of RSSI in this cycle, and through demodulating unit 405 demodulated received Frame FRAME, for subsequent treatment.
In down link working hour, Base-Band Processing control unit control transmit-receive switch K throws to transmitting site; In addition, the signal frame that the Base-Band Processing control unit will be launched is given modulating unit and is modulated, modulating unit will be given transmitter unit through the signal after the modulation, and transmitter unit amplifies transmitting, and deliver on the aerial array through merit branch/synthesizer, digital phase shifter paroxysm.
No matter be up, down link working hour, the Base-Band Processing control unit all can number send to wave beam wave beam control transformation unit.Wave beam control transformation unit number is deciphered in real time to wave beam, produces real control bit, and these control bits are sent on the digital phase shifter battle array, from having realized needed wave beam orientation.
Fig. 5 illustrates typical time division multiple access TDMA involved in the present invention, TDD working timing figure.
A complete work period is made up of adjacent a up link and a descending line link.The down link period, base station, the mobile subscriber receives; Uplink period, the base station receives, mobile subscriber's emission.505,506,507,508 4 slot s lot are up link among the figure, and 509,510,511,512 4 slot s lot are down link.
In addition, 505 and 509 be respectively up link, the down link of a communication channel among Fig. 5.Same 506 and 510 is respectively up link, the down link of a communication channel; 507,511 is respectively up link, the down link of a communication channel; 508,512 is respectively up link, the down link of a communication channel.Up link on communication channel and down link use identical reception, tranmitting frequency.
With reference to Fig. 6, be provided with a frame statistical counter J in this flow process, the N frame is a statistic unit period.This flow process is the method according to RSSI and frame error rate judgement wave beam number, and it is finished by the Base-Band Processing control unit among Fig. 2.
For the core content of this method is described, work period of only having drawn among the figure, at the workflow of a time slot, detailed process that its control wave beam switches is as follows:
1. whether judge this time slot in talking state,,, begin statistical work from the following cycle and carry out again then with the zero clearing of frame statistical counter if not in talking state; If in talking state, then whether the judgment frame counters count time is statistic unit period, i.e. a J=N; If discontented statistic unit period, then finish the work of this cycle;
2. the thresholding THR_erfram that sets frame error rate respectively is 50%, received signal intensity indication RSSI thresholding THR_rssi is 35dB μ V, in the statistic unit period of regulation, i.e. whether J=N then surpasses according to as shown in Figure 8 following steps comparison frame error rate and presets thresholding:
At first, statistics frame counter O reset, the zero clearing of mistake frame counter;
Secondly, judge that if be the mistake frame, then frame counter adds one by mistake by each work period quality to received signal;
Then, after the statistic unit period finishes, obtain the total mistake frame number ErrFrame in the statistical time range, again with the frame number N of total mistake frame number divided by the statistic unit period, obtain frame error rate, do not preset thresholding THR_erfram if frame error rate surpasses, do not illustrate that signal quality is good, the wave beam in next cycle number can be constant; Preset thresholding THR_erfram if frame error rate surpasses, illustrate that signal quality is bad, whether the signal receiving strength that at this moment reconvicts indication RSSI is lower than presets thresholding THR_rssi;
3. whether the mean value of statistics RSSI is less than presetting thresholding THR_rssi, surpass the situation that presets thresholding THR_erfram for frame error rate, then by the Base-Band Processing control unit by following steps shown in Figure 7, each cycle to the RSSI of each time slot access of sampling:
At first, statistics frame counter O reset, received signal intensity indication accumulator RSS_IACC zero clearing;
Secondly, be that J=N is in the period, to the sampled value RSSI of each frame to a statistic unit period
1RSSI
2... RSSI
NSummation;
Then, the RSSI=RSSI_ACC/N that averages;
4. calculate the control wave beam number of next work period, preset thresholding, then judge the mobile subscriber not on the wave beam number, need to reappear the control wave beam number of estimating the next work period, otherwise wave beam is number constant if signal receiving strength indication RSSI is lower than;
5. the wave beam control number of estimating is sent to wave beam control transformation unit, the work period finishes.
Fig. 9 has described example of estimation control wave beam related among Fig. 6 number.Because pre-design number of beams is few, have only 5 in this example, then control wave beam and adopted simple polling mode.Scan with these 5 wave beams respectively during work, and signal strength and signal quality are judged, finally find a suitable mobile subscriber's optimum beam orientation.Specifically: when the user shifts out current beam coverage, need estimate new control wave beam number again, its method is as follows:
At first, judge earlier whether current control wave beam BFC_num equals maximum control wave beam wave beam BFC_max, when 5 wave beams of employing, maximum wave beam number is 4;
If current control wave beam BFC_num is not equal to maximum control wave beam wave beam BFC_max, then new control wave beam number equals current control wave beam and number adds 1, that is: BFC_num+1;
If current control wave beam BFC_num equals maximum control wave beam wave beam BFC_max, then new control wave beam number is changed to minimum value BFC_min, be generally 0;
So, system can carry out poll scanning in all beam areas.
Figure 10 has described another example of related control wave beam number estimation among Fig. 6 in more detail, and this system uses the accurate estimation technique that the mobile subscriber is accurately estimated, is applicable to the orientation is required more accurate system.It accurately estimates to be estimated to form by the poll in two stages, and process is as follows:
(1) controls the pre-estimation of wave beam number, this step has been used among Fig. 3 b 4 wave beams shown in 300b, 310b, 320b, the 330b number, azimuth of mobile user is carried out pre-estimation, it estimates that flow process is identical with the flow process that Fig. 9 describes, still adopt the method for poll, the different different beams number of only being to use.
(2) on the basis of pre-estimation, begin to control the accurate estimation 1002b of wave beam,, then select for use three wave beams of 311b, 312b, 313b shown in Fig. 3 b to carry out the orientation and accurately estimate if the control wave beam position of pre-estimation is 310b; If the control wave beam position 320b of pre-estimation then selects for use three wave beams of 321b, 322b, 323b shown in Fig. 3 b to carry out the orientation and accurately estimates; The rest may be inferred, if the control wave beam position 330b of pre-estimation then selects for use three wave beams of 331b, 332b, 333b shown in Fig. 3 b to carry out the orientation and accurately estimates;
(3) use different wave beams number accurately to estimate to control the wave beam orientation, promptly still adopt the method for poll to find a suitable mobile subscriber's optimum beam orientation by Figure 10 flow process.
The system that base station of the present invention and mobile subscriber communicate, as shown in figure 11.This system is made of base station, aerial array two parts.Receive and dispatch with different wave beams the mobile subscriber of different azimuth this base station, for example to different mobile subscriber 1105,1106, can provide the wave beam 1103,1104 with different transmit-receive positions respectively.Not only improved base station and mobile phone communication distance, offset the interference on the non-beam direction, and improved communication quality.When location of mobile users was moved, beam direction can be adjusted in the base station, to realize the automatic scan and follow to the mobile subscriber.When base station apparatus of the present invention carries out the wave beam estimation, not only intensity indication is to received signal carried out outside the statistical decision, also quality is carried out statistical decision to received signal, thereby the wave beam estimated value is more accurately credible, simultaneously, the present invention uses poll and wave beam accurately to estimate the method that combines, and makes that the wave beam estimation is more accurate, speed is faster.
Figure l3 base station of the present invention when two mobile subscriber roads words, a real-time snapshot schematic diagram of the control signal waveform that grasps with oscilloscope.Put through a pair of mobile phone, they have taken time slot Slot2 and time slot Slot4 respectively, move two mobile phones then respectively.When the mobile phone that occupies the Slot2 time slot moves on to the wave beam orientation No. 1, promptly corresponding, and the mobile phone that occupies Slot4 moves to the wave beam orientation No. 3 with 301a among Fig. 3 a, promptly with Fig. 3 a in 303a at once, catch snapshot with oscilloscope.
Waveform 1301 is inside of base station transmitting-receiving control signal waveforms, and this waveform signal is corresponding with a frame signal shown in Figure 5; Waveform 1302 is time slot control signal waveforms in the base station, and each time slot is 625 microseconds; Waveform 1303 is the real-time wave beam control number of different time-gap, i.e. 3 bits.
Measure of merit of the present invention:
The control signal waveform that two mobile subscribers are conversed by base station of the present invention grasps snapshot, and when a pair of mobile phone was put through, they had taken time slot Slot2 and time slot Slot4 respectively; Move two mobile phones then respectively, when the mobile phone that occupies the Slot2 time slot moves on to the wave beam orientation No. 1, promptly corresponding and mobile phone that occupy Slot4 moves to the wave beam orientation No. 3 with 301a among Fig. 3 a, promptly with Fig. 3 a in 303a at once, the waveform of catching snapshot with oscilloscope is as shown in figure 12.Waveform 1301 is inside of base station transmitting-receiving control signal waveforms among the figure, and this waveform signal is corresponding with a frame signal shown in Figure 5; Waveform 1302 is time slot control signal waveforms in the base station, and each time slot is 625 microseconds; Waveform 1303 is the real-time wave beam control number of different time-gap, i.e. 3 bits.From the corresponding relation between wave beam orientation, the described mobile subscriber of Figure 12 place and the working control wave beam number as can be seen: the wave beam control number that Slot2 is corresponding is 1, and the wave beam control number of Slot4 correspondence is 3, and they are corresponding fully with the orientation at mobile phone place.In fact, when mobile phone was mobile in coverage, waveform 1303 can real-time tracking and is adjusted to the orientation at mobile phone place.Can search for, follow the tracks of user location just because of the base station, and only on user location, carry out the transmitting-receiving of wireless signal.Make the receiving sensitivity of the inventive method and base station be improved, and have good antijamming capability, anti-multipath decline ability, thereby improved communication quality.