CN1211966C - Method and system for fast synchronization of uplink and receiver for base station's access channel - Google Patents

Abstract

The present invention relates to a method for quickly synchronizing an up link in a synchronizing code division multiple access communication system. The present invention is characterized in that the method comprises the following procedures that (1) a mobile station is divided into a plurality of access time slots from access channels comprising an up link according to information sent by a base station, and a free access time slot is selected; (2) the mobile station sends access codes at a certain moment in the free access time slot; (3) a base station detects the access codes, and determines delay adjusting information of the mobile station; (4) the base station sends the delay adjusting information to the mobile station; (5) the mobile station adjusts the sending time of the thereof according to the received delay adjusting information, so that a subsequently sent signal arrives at the base station in standard access time.

Description

Uplink fast synchronization method and system

technical field

The present invention relates to a wireless communication system, in particular to a synchronous code division multiple access (CDMA) communication system, and more particularly to a method and system for quickly synchronizing an uplink in the synchronous code division multiple access communication system.

Background technique

In recent years, wireless communication has become the most active aspect in the field of communication, and the CDMA system has made it It emerged, developed rapidly, and became the technology of choice for third-generation cellular systems.

CDMA is a modulation and multiple access connection technology based on spread spectrum communication. In the CDMA communication system, the signals used by different users to transmit information are distinguished by their own different coding sequences. Since the CDMA system uses different code patterns to distinguish channels, these channels overlap each other in terms of frequency domain and time domain, or they all occupy the same frequency band and time, so the performance of the CDMA system is largely Depending on the characteristics of the code pattern, that is, the degree of mutual interference between multiple channels will be an important factor for determining the channel capacity and characteristics of the CDMA system.

Referring to Fig. 1, it shows a schematic diagram of a cellular mobile communication system, a cell is inside the hexagon, and wireless communication is carried out between a base station and a mobile station inside a cell. There is a base station and multiple mobile stations inside the cell, and each mobile station uses an independent channel, that is, a different spread spectrum address code, and communicates wirelessly with the base station at the same time. It is generally defined that from a base station to a mobile station is a downlink (downlink), whereas from a mobile station to a base station is called an uplink (uplink).

In the CDMA system, the channels are distinguished from each other by means of different codes adopted, so the correlation between the codes is very important. That is to say, the independence between such channels is guaranteed if and only if the codes assigned to the respective channels are not correlated with each other. When receivers use a given signal to recover its associated signal, these receivers should not be affected by channels using other codes.

However, in traditional CDMA systems, such as the IS95 system, the spreading codes used are generated by the pseudo-noise code sequence Walsh codes with the minimum cross-correlation value and the maximum auto-correlation value. Since the IS95 system is an asynchronous CDMA system, its uplink channel, that is, the signals sent by all mobile stations to the base station are transmitted asynchronously, because the pseudo-noise sequences from different mobile stations cannot be synchronized, and the pseudo-noise code sequences of different mobile stations are mutually incompatible. It cannot be orthogonal, so spread spectrum signals in the same frequency band and at the same time will form great interference with each other, that is, multiple access interference, which not only greatly reduces the channel capacity, but also increases the complexity of power control.

In order to eliminate the multiple access interference of the above-mentioned asynchronous communication system, it is required to use spreading codes with zero cross-correlation values, that is, orthogonal codes (not only orthogonal but also zero-correlation windows!), and due to the The orthogonality characteristic of C is established under the premise of complete synchronization of code sequences, so complete synchronization between these code sequences is required. Therefore, in a synchronous CDMA system, the synchronization of uplink and downlink is very important.

In a CDMA system, downlink synchronization is easy to achieve because all signals are sent from a single base station. However, the realization of uplink synchronization is much more difficult. The distance between each mobile station and the base station is different, and the delay of sending signals is also different, and the mobile station does not know the distance between itself and the base station, so it cannot adjust the time of sending signals, thus causing The signal sent by the mobile station arrives at the base station asynchronously. Especially, due to the unavoidable multipath fading and shadowing effects in wireless communication, it becomes more difficult to establish the synchronization of the uplink.

In recent years, several technical solutions have been proposed in the prior art to realize the uplink synchronization of the CDMA system. For example, Chinese patent 97118934 discloses a scheme for establishing and maintaining uplink synchronization in a synchronous CDMA system, but this The method is cumbersome, and it uses complex frame structure and control instructions to solve the uplink synchronization establishment process, and it cannot quickly make multiple mobile stations simultaneously establish synchronization.

Therefore, a method for quickly synchronizing the uplink is urgently needed in the prior art.

Contents of the invention

The first object of the present invention is to provide a method for quickly synchronizing the uplink in a synchronous code division multiple access communication system, so as to solve the above-mentioned problems and defects in the prior art.

The second object of the present invention is to provide a system for quickly synchronizing uplink in a synchronous code division multiple access communication system.

For realizing above-mentioned first purpose, the present invention provides a kind of method that uplink is carried out fast synchronization in synchronous code division multiple access communication system, it is characterized in that comprising the following steps:

(1) The mobile station selects an idle access slot from a plurality of access slots into which the access channel included in the uplink is divided according to the information sent by the base station;

(2) The mobile station sends an access code at a certain moment in the idle access time slot;

(3) The base station detects the access code, and determines the delay adjustment information of the mobile station;

(4) The base station sends the delay adjustment information to the mobile station;

(5) The mobile station adjusts its sending time according to the received delay adjustment information, so that the signal sent subsequently reaches the base station at the standard access time.

In order to achieve the above-mentioned second purpose, the present invention provides a system for quickly synchronizing the uplink in a synchronous code division multiple access communication system, and the synchronous code division multiple access communication system includes at least one mobile station and at least one base station ,

The fast synchronization system is characterized in that:

The at least one mobile station includes:

means for selecting an idle access slot from a plurality of access slots into which the access channel included in the uplink is divided according to information sent by the base station;

means for sending an access code at some point within said free access slot;

The at least one base station includes:

means for detecting said access code and determining delay adjustment information for a mobile station;

means for sending said delay adjustment information to a mobile station; and

The at least one mobile station also includes:

A device for adjusting the signal transmission time according to the received delay adjustment information so that the transmitted signal reaches the base station at the standard access time.

Wherein, the means for detecting the access code and determining the delay adjustment information of the mobile station includes:

a demodulator for demodulating an access code signal sent by the mobile station in an access channel included in the uplink;

A low-pass filter is used to low-pass filter the demodulated signal;

A matched filter is used to perform a correlation operation on the low-pass filtered signal and the pre-stored access code sequence;

The maximum value search circuit is used to determine the threshold value of the output signal of the matched filter according to relevant parameters;

a limiter, configured to output a valid signal according to the threshold value;

a sliding correlator configured to calculate the time elapsed for the access code from the mobile station to the base station based on the active signal; and

An offset calculation module, configured to compare the elapsed time with a standard time, and calculate a time offset.

According to the method or system for quickly synchronizing the uplink in the synchronous code division multiple access communication system of the present invention, the synchronous reception between the uplink signals of multiple mobile stations can be quickly realized at the same time, thereby reducing the communication between channels Interference, increase the channel capacity of the system, and because of the unique access code and special matched filter structure, the synchronization accuracy is very high, the number of adjustments is small, and it can ensure that the synchronization establishment of the uplink is fast and effective, and the method is simple ,Easy to implement.

Figure overview

The above and other features and advantages of the present invention will be more apparent through the detailed description of the best embodiments of the present invention in conjunction with the accompanying drawings.

Fig. 1 is a structural representation of a cellular mobile communication system;

Fig. 2 is a flow chart of a method for fast synchronization of an uplink in a synchronous code division multiple access communication system according to the present invention;

Fig. 3 is a detailed flowchart of the base station detecting the access code and determining the delay adjustment information;

Fig. 4 is a structural schematic diagram of an uplink access channel from a mobile station to a base station applied in the present invention;

Fig. 5 shows a schematic diagram of characteristics when an access code passes through a matched filter for storing the same access code;

Fig. 6 shows a schematic diagram of characteristics when the access code passes through a matched filter for storing different access codes;

FIG. 7 is a schematic structural diagram of a base station access channel receiver used in a system for performing fast synchronization on an uplink in a synchronous code division multiple access communication system according to the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

The best mode for carrying out the present invention will be described in detail below.

Fig. 2 is a flow chart of a method for fast synchronization of an uplink in a synchronous code division multiple access communication system according to the present invention.

After the mobile station is turned on, the mobile station user first receives the information sent by the base station from the downlink, performs frequency correction, frame synchronization and bit synchronization with the system, and obtains information on available access channel time slots. In step 201, the mobile station selects an idle access slot from a plurality of access slots into which the uplink access channel is divided according to the information of the available access channel slots. Then, at step 202, the mobile station transmits a fixed access code at a certain time within the selected free time slot. The specific structure of the access channel will be described later with reference to FIG. 4 .

Thereafter, in step 203, the base station detects the access code sent by the mobile station, and determines the delay adjustment information of the mobile station.

In step 204, the base station sends the delay adjustment information to the mobile station.

In step 205, the mobile station adjusts its sending time according to the received delay adjustment information, so that the signal sent subsequently reaches the base station at the standard access time.

Fig. 3 is a detailed flow chart of the base station detecting the access code and determining delay adjustment information. The process shown in FIG. 3 constitutes step 203 in FIG. 2 .

As shown in FIG. 3, in step 2031, demodulation, low-pass filtering, matched filtering and correlation operations are performed on the received signal. In step 2032, the threshold value of the signal is determined by using the maximum value search circuit and related parameters. In step 2033, by comparing with the threshold value, a valid signal is output by the limiter. In step 2034, the time elapsed for the access code to arrive at the base station from the mobile station is calculated using the sliding correlator. In step 2035, the elapsed time is compared with the standard time, and a time offset is calculated as the delay adjustment information.

Fig. 4 is a schematic diagram of the structure of the uplink access channel from the mobile station to the base station applied in the present invention. As shown in Figure 4, the access channel is divided into M time slots. When a mobile station tries to access, each mobile station is assigned to a time slot for access, and finally the user signal arrives at the base station at this time A standard position in the slot, in order to reach the base station synchronously with each mobile station signal in the uplink. In order to ensure that the mobile station accesses at the standard position, the mobile station must send an N-bit long code word (occupancy NT _C ) in one time slot. Since a time slot allocated to the access channel is KT _C (T _C =1/f _C , f _C is the chip rate: 1.2288Mcps), so the range of the starting position of the code word sent by the mobile station is 0-(KN)Tc between. No signal is sent at T _C other than sending N-bit codewords.

The access code that the present invention uses is a kind of unique spreading code in addition, and this access code is made up of three parts, and the access code length is N bits, so the front N/3 bits are defined as sequence 1, and the back N/3 The bit is sequence 2, the middle complements N/3 bits 0, and there is an orthogonal complement between sequence 1 and sequence 2.

For users in a cell, a fixed set of access codes can be used to access, but different time slots can be selected.

Every time the mobile station accesses, it sends a fixed access code in one time slot (KT _C ) among the M time slots allocated to the access channel. Because the user does not know whether his signal is the standard position for access after the signal arrives at the base station when he starts to access, so the transmission time (the transmission time of the first bit of the N-bit codeword) is set as a fixed value S.

Secondly, the base station access channel receiver calculates the deviation of the signal sent by the mobile station once per time slot (KT _C ) as a unit. The access channel receiver of the base station calculates the arrival time of the mobile station signal by receiving the signal energy of each mobile station user in each different access time slot, and compares it with the standard time to calculate the user signal arrival time and The standard access position gap is then transmitted to the mobile station through the downlink to transmit time delay adjustment information. Through the delay adjustment information, the controller of the mobile station user adjusts the transmission time of the user's next access code word until the time when the user access signal arrives at the base station is the standard time.

Fig. 5 shows a schematic diagram of characteristics after the access code passes through the matched filter used to store the same access code, it can be seen that the secondary peaks are all less than or equal to 0, while the main peak is very large.

Fig. 6 shows a schematic diagram of the characteristics of the access codes after they pass through the matched filter used to store different access codes. It can be seen that the cross-correlation peak is very small compared to the main auto-correlation peak.

By describing the method of the present invention in conjunction with Fig. 2 and Fig. 3, those skilled in the art can easily imagine that the system for fast synchronization of the uplink in the Synchronous Code Division Multiple Access communication system of the present invention has The following characteristics.

The at least one mobile station included in the synchronous code division multiple access communication system includes:

means for selecting an idle access slot from a plurality of access slots into which the access channel included in the uplink is divided according to information sent by the base station;

means for sending an access code at a certain time within the free access slot;

The at least one base station included in the synchronous code division multiple access communication system includes:

means for detecting an access code and determining delay adjustment information for a mobile station;

means for sending the delay adjustment information to a mobile station; and

The above at least one mobile station also includes:

A device for adjusting the signal transmission time according to the received delay adjustment information so that the transmitted signal reaches the base station at the standard access time.

More specifically, the above-mentioned means for detecting the access code and determining the delay adjustment information of the mobile station include:

a demodulator for demodulating received signals;

A low-pass filter is used to low-pass filter the demodulated signal;

A matched filter is used to perform a correlation operation on the low-pass filtered signal and the pre-stored access code sequence;

The maximum value search circuit is used to determine the threshold value of the output signal of the matched filter according to relevant parameters;

The limiter outputs a valid signal according to the threshold value;

a sliding correlator for calculating the time elapsed for the access code to arrive at the base station from the mobile station based on the valid signal; and

The offset calculation module is configured to compare the elapsed time with the standard time, and calculate a time offset, which is delay adjustment information.

The various components contained in the base station mentioned above can be arranged in a base station access channel receiver.

Fig. 7 schematically shows the structure of such an access channel receiver, which is used for fast synchronization of the uplink of the synchronous code division multiple access communication system.

As shown in Figure 7, reference numeral 601 represents a demodulator, 604 represents a low-pass filter, 607 represents a matched filter, 608 represents a limiter, 609 represents a maximum value search circuit, 610 represents a sliding correlator, and 611 represents a time offset computing module.

Assuming that the real part of the codeword sent by the user is x(t) and the imaginary part is y(t), the modulated signal is:

C(t)＝x(t)cos(ω _c t)+y(t)sin(ω _c t)

If the influence of noise is not considered, the signal received by the base station is:

C(t)＝x(t)cos(ω _c t)+y(t)sin(ω _c t)

After the access signal from the mobile station passes through the demodulator 601, the I-way signal 602 is:

$\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span><span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>$

$<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>$

After the low-pass filter 604, the high-frequency signal is filtered out, and the 605 signal is: $I\left(t\right)=\frac{1}{2}x\left(t\right)$ Similarly, after the access signal from the mobile station passes through the demodulator 601, the Q channel signal 603 is:

$\mathrm{<span\; class="notranslate">\; Q</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span><span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>$

$<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>$

After the low-pass filter 604, the high-frequency signal is filtered out, and the 606 signal is: $Q\left(t\right)=\frac{1}{2}\mathrm{the\; y}\left(t\right)$

The two-way signals after the low-pass filter are sent to a special matched filter 607, and the filter stores the access code sequence, then the output of the matched filter cancels all positive secondary peaks of the code word autocorrelation, so that the autocorrelation The associated subpeaks are zero, or negative.

The output signal of the matched filter passes through the maximum value search module 609 and the limiter 608 at the same time. The maximum value search module 609 finds the maximum value from the output signal of the matched filter 607 , and uses the product of its value and a parameter as the threshold value of the subsequent limiter 608 . After passing through the limiter 608 like this, the value greater than the threshold value in all input energy values is output as it is, and the amount smaller than this threshold value is filtered out, and the output is 0, which effectively reduces the autocorrelation secondary peak, The influence of cross-correlation peaks and noise on the calculation of the main peak position.

The output signal of the limiter 608 is sent to the next-stage sliding correlator (with a length of L) 610 for the purpose of finding the positions of the largest L adjacent values from the 2K values. That is, find the position of the last maximum value from the 2K values (if there are more than two equal maximum values in the 2K values, take the position of the last one), that is, the time when the user arrives at the base station.

The calculated user signal arrival time at the base station is compared with the standard position, and the offset is calculated in the time offset calculation module 611 to generate a delay control instruction DCC (Delay Control Command) command.

The delay control command (or delay adjustment information) is transmitted to the mobile station in the downlink. After receiving the information from the base station, the user of the mobile station adjusts its transmission time so that the signal arriving at the base station finally meets the standard access time.

When the value output from the sliding correlator deviates from the standard position within the allowable range, it indicates that the access is successful. If it successfully outputs a "1" signal, DCC outputs a special command at the same time to tell the user that the access is successful; if not successful, it outputs a "0" signal, and DCC is an adjustment command.

If the calculated position of the maximum energy window of the user access signal of the mobile station exceeds the adjustable range, it means that the adjustment fails. In this case, the base station needs to downlink send a special DCC command to the user, and the user sends an access pulse again for re-access.

The above description can clearly show that since the access channel is used in the uplink and divided into different time slots, more mobile stations can access the system at the same time, ensuring fast establishment of the uplink. In addition, due to the combination of the access code and the matched filter, the accuracy of calculating the delay deviation of the signal sent by the mobile station is guaranteed, and the synchronization establishment process of the uplink is accelerated.

Although the best embodiment of the present invention has been described in detail with reference to the accompanying drawings, various modifications and changes can be made by those skilled in the art without departing from the scope and spirit of the present invention. Accordingly, the scope of the present invention is limited only by the claims.

Claims (8)

1. one kind is carried out synchronous method fast to up link in synchronous code division multiple access communication system, it is characterized in that may further comprise the steps:

(1) mobile radio station from a plurality of access slots that the access channel that is contained in up link is divided into, is selected an idle access slot according to the information that the base station sends;

(2) the sometime transmission access code of mobile radio station in described idle access slot;

(3) described access code is detected in the base station, determines the time delay adjustment information of described mobile radio station;

(4) base station sends described time delay adjustment information to mobile radio station;

(5) mobile radio station is adjusted its transmitting time according to the described time delay adjustment information of receiving, makes its signal that sends subsequently arrive the base station in the turn-on time of standard; Described step (3) is included in the following steps of carrying out on the base station:

The signal of receiving is carried out demodulation, low-pass filtering, matched filtering and related operation, output signal then;

Utilize maximum value search circuit and relevant parameter, determine the threshold value of described signal;

Energy value and described threshold value by described signal compare, amplitude limiter output useful signal;

Utilize sliding correlation detector to calculate described access code arrives described base station experience from described mobile radio station time according to described useful signal;

Time and standard time to described experience compare, computing time side-play amount, described time offset is described time delay adjustment information.

2. method according to claim 1 is characterized in that in the described step (2), and described access code is that the fixed time in described idle access slot sends.

3. method according to claim 1 is characterized in that the described step that the signal of receiving is carried out matched filtering comprises: with the described signal of receiving be stored in access code sequence in the matched filter in advance and carry out the step of related operation.

4. according to each method in the claim 1 to 3, it is characterized in that: described access code is a kind of N position spreading code, wherein before the N/3 position be sequence 1, back N/3 position is a sequence 2, middle N/3 position is 0, has the characteristic of orthogonal complement between sequence 1 and the sequence 2.

5. one kind is carried out synchronous system fast to up link in synchronous code division multiple access communication system, and described synchronous code division multiple access communication system comprises at least one mobile radio station and at least one base station,

Described quick synchro system is characterised in that:

Described at least one mobile radio station comprises:

A plurality of access slots that the information that is used for sending according to the base station is divided into from the access channel that is contained in up link are selected the device of an idle access slot;

Be used for the device that sends access code sometime in described idle access slot;

Described at least one base station comprises:

The device that is used to detect described access code and determines the time delay adjustment information of mobile radio station;

Be used for sending the device of described time delay adjustment information to mobile radio station; And

Described at least one mobile radio station also comprises:

Being used for adjusting signal sending time according to the described time delay adjustment information of receiving makes the signal that is sent arrive the device of base station in the turn-on time of standard;

Described mobile radio station and described base station are coupled;

A plurality of access slots that the described information that is used for sending according to the base station is divided into from the access channel that is contained in up link select the device of an idle access slot and the described device that sends sign indicating number sometime that is used in described idle access slot to be coupled, and send access code to described base station; Describedly be used to detect access code and determine that the device and the described device that is used for sending to mobile radio station described time delay adjustment information of the time delay adjustment information of mobile radio station are coupled, receive and detect described access code, and to described mobile radio station transmission delay adjustment information; Described mobile radio station receives the time delay adjustment information of described base station, and according to the time of described time delay adjustment information adjustment to described base station transmit signals.

6. system according to claim 5 is characterized in that describedly being used to detect described access code and determining that the device of the time delay adjustment information of mobile radio station comprises:

Demodulator is used for the signal of receiving is carried out demodulation;

Low pass filter is used for the signal after the demodulation is carried out low-pass filtering;

Matched filter is used for carrying out related operation through the signal of low-pass filtering and the access code sequence of storage in advance;

The maximum value search circuit is used for according to relevant parameter, determines the threshold value of the output signal of described matched filter;

Amplitude limiter, according to described threshold value, the output useful signal;

Sliding correlation detector is used for calculating described access code arrives described base station experience from described mobile radio station time according to described useful signal; And

The calculations of offset module is used for the time and the standard time of described experience are compared, computing time side-play amount, described time offset is described time delay adjustment information.

7. system according to claim 6 is characterized in that the described device that sends access code sometime that is used in described idle access slot sends access code at fixed time.

8. according to each system in the claim 5 to 7, it is characterized in that: described access code is a kind of N position spreading code, wherein before the N/3 position be sequence 1, back N/3 position is a sequence 2, middle N/3 position is 0, has the characteristic of orthogonal complement between sequence 1 and the sequence 2.

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