CN101466137B - TD-SCDMA terminal and automatic gain control method thereof - Google Patents
TD-SCDMA terminal and automatic gain control method thereof Download PDFInfo
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Abstract
The invention provides a TD-SCDMA terminal and an automatic gain control method. The method includes the following steps: step A, when the terminal receives a business time slot downwards transmitted by a network side at the first time, the initial value which is used for receiving the AGC gain of the current subframe business time slot is set according to the relationship between the received signal intensity of the downlink pilot frequency time slot in the current subframe and the preset signal intensity range; wherein, the business time slot is the downlink time slot for loading business in the subframe, the preset signal intensity range is that the signal intensity scope when the business time slot signal processed by the network side power control reaches the terminal; step B, the terminal receives the business time slot in the current subframe according to the initial value of the AGC gain. According to the method, the UE can obtain the proper initial value of the AGC gain used for receiving the business time slot when discontinuously receiving the time slot, so as to speed up the AGC constringency of the business time slot, thus obtaining the fine communication property.
Description
Technical Field
The present invention relates to the field of wireless communication technologies, and in particular, to a Time-Division-synchronous Code Division Multiple Access (TD-SCDMA) terminal and an Automatic Gain Control (AGC) method thereof.
Background
In a mobile communication system, since channel conditions are affected by multipath effects, shadowing effects, fading, and the like, the received signal level varies widely. In order to ensure good receiving effect, the received signal strength must be ensured in a certain input range, so that an automatic gain control module needs to be added in the receiver (terminal) to stabilize the received signal level at a proper amplitude.
The physical channel of TD-SCDMA adopts four-layer structure: system frame number, radio frame, subframe, and slot/code. Referring to fig. 1, a TDMA radio frame is 10ms long and is divided into two 5ms subframes, each of which is divided into 7 regular time slots (TS0-TS6) and 3 special time slots (TS 6) of 675 us: a Downlink Pilot Time Slot (DwPTS), a guard interval (GP), and an Uplink Pilot Time Slot (UpPTS).
In the TD-SCDMA mobile communication system, the system frame structure is composed of a plurality of time slots, for each downlink time slot, the automatic gain control module of the user terminal (UE) respectively counts the signal energy, then generates the received signal gain (AGC gain) of the time slot corresponding to the next sub-frame according to the AGC algorithm, and receives the corresponding time slot in the next sub-frame according to the received signal gain. In an ideal case: the network side continuously transmits signals, the user terminal continuously receives the signals, and after a period of convergence, the gain of the received signals is stabilized around a relatively ideal value.
However, in TD-SCDMA mobile communication systems, there are a lot of situations that do not satisfy the above conditions:
1) from the network side, signals of common control channels (such as a paging channel PCH, a forward access channel FACH, a paging indicator channel PICH, a fast physical access channel FPACH and the like) are transmitted discontinuously, and the subframes occupied by the signals are usually not continuous;
2) from the perspective of the UE, in the case that the UE performs operations such as cell switching, cell reselection, or service channel reconfiguration to another cell, if the establishment of the wireless connection between the UE and the network side has not been successful, no data is transmitted in the service timeslot, and the UE cannot continuously receive the service timeslot signal to obtain a stable AGC gain.
In the above case 1, the traffic slot is transmitted discontinuously on the subframe; in case 2, the traffic slot has not started to transmit continuously on the subframe. Under these conditions, a general automatic gain control algorithm in the prior art cannot meet the requirements, so that AGC of a service timeslot cannot be converged timely, thereby affecting the working performance of the UE.
Disclosure of Invention
The technical problem to be solved by the present invention is to provide a TD-SCDMA terminal and an automatic gain control method thereof, so that when UE discontinuously receives a service timeslot, it can obtain a suitable initial value of AGC gain for receiving the service timeslot, thereby accelerating AGC convergence of the service timeslot to obtain good communication performance.
In order to solve the technical problems, the invention provides the following scheme:
an automatic gain control AGC method of TD-SCDMA terminal includes:
step A, when a terminal receives a service time slot issued by a network side for the first time, setting an initial value of AGC gain for receiving the service time slot in the current subframe according to the relationship between the received signal strength of a downlink pilot time slot in the current subframe and a preset signal strength range, wherein the service time slot is a downlink time slot for bearing services in the subframe, and the preset signal strength range is a signal strength range when a service time slot signal subjected to power control processing by the network side reaches the terminal;
and step B, the terminal receives the service time slot in the current sub-frame according to the initial value of the AGC gain.
Preferably, in the above method, in the step a, the setting an initial value of an AGC gain used for receiving a service slot in a current subframe specifically includes:
when the received signal strength of the downlink pilot time slot in the current subframe is smaller than the lower limit of the preset signal strength range, setting the initial value as a first gain value, wherein the first gain value is an AGC gain adopted by the terminal when the terminal receives a service time slot signal of which the signal strength is the lower limit;
when the received signal strength of the downlink pilot time slot in the current subframe is greater than the upper limit of the preset signal strength range, setting the initial value as a second gain value, wherein the second gain value is an AGC gain adopted by the terminal when the received signal strength of the terminal is the service time slot signal of the upper limit;
and when the received signal strength of the downlink pilot time slot in the current sub-frame is between the first preset value and the second preset value, setting the initial value as the AGC gain adopted by the terminal for receiving the downlink pilot time slot in the current sub-frame.
Preferably, in the above method, the terminal continuously receives a downlink pilot timeslot sent from the network side, and determines, according to an AGC convergence algorithm, an AGC gain for receiving the downlink pilot timeslot in a next subframe when receiving the downlink pilot timeslot in the current subframe.
Preferably, in the above method, the network side transmits the traffic slot in a plurality of consecutive subframes, and the method further includes:
and step C1, the terminal receives the service time slot in each sub-frame in the continuous sub-frames, and performs convergence processing on the AGC gain of the service time slot.
Preferably, in the above method, the convergence processing includes:
receiving the service time slot in the current sub-frame according to the AGC gain used for receiving the service time slot in the current sub-frame;
comparing the received signal strength of the service time slot in the current subframe with a preset threshold value to obtain a comparison result;
and adjusting the AGC gain for receiving the service time slot in the next subframe according to the comparison result.
Preferably, in the above method, the network side transmits the traffic slot in multiple discontinuous subframes, and the method further includes:
step C2, after receiving the service time slot for the first time, when the terminal receives the service time slot for the nth time, determining the AGC gain g (N) for receiving the service time slot according to the following formula, and receiving the service time slot according to the AGC gain g (N):
G(N)＝G(N-1)+(S(N)-S(N-1))
wherein, N is more than or equal to 2, S (N) represents the received signal intensity of the downlink pilot frequency time slot in the subframe of the Nth received service time slot.
The invention also provides a TD-SDCMA terminal, which comprises:
a service time slot gain initialization module, configured to set an initial value of an AGC gain for receiving a service time slot in a current subframe according to a relationship between a received signal strength of a downlink pilot time slot in the current subframe and a predetermined signal strength range when the terminal receives the service time slot issued by a network side for the first time, where the service time slot is a downlink time slot for carrying a service in the subframe, and the predetermined signal strength range is a signal strength range when a service time slot signal subjected to power control processing by the network side reaches the terminal;
a service time slot receiving module, configured to receive the service time slot in the current subframe according to the initial value of the AGC gain set by the service time slot gain initialization module when the terminal receives the service time slot for the first time
Preferably, in the terminal, the service timeslot gain initialization module is further configured to: when the received signal strength of the downlink pilot time slot in the current subframe is smaller than the lower limit of the preset signal strength range, setting the initial value as a first gain value, wherein the first gain value is an AGC gain adopted by the terminal when the terminal receives a service time slot signal of which the signal strength is the lower limit; when the received signal strength of the downlink pilot time slot in the current subframe is greater than the upper limit of the preset signal strength range, setting the initial value as a second gain value, wherein the second gain value is an AGC gain adopted by the terminal when the received signal strength of the terminal is the service time slot signal of the upper limit; and when the received signal strength of the downlink pilot time slot in the current sub-frame is between the first preset value and the second preset value, setting the initial value as the AGC gain adopted by the terminal for receiving the downlink pilot time slot in the current sub-frame.
Preferably, the terminal further includes:
and the downlink pilot time slot receiving module is used for continuously receiving the downlink pilot time slot sent from the network side, and determining AGC gain for receiving the downlink pilot time slot in the next subframe according to an AGC convergence algorithm when receiving the downlink pilot time slot in the current subframe.
Preferably, in the above terminal, the service time slot receiving module is further configured to receive the service time slots in multiple consecutive subframes, respectively, and perform convergence processing on AGC gain values of the service time slots.
Preferably, in the above terminal, the service timeslot receiving module is further configured to receive the service timeslots in a plurality of discontinuous subframes, respectively, wherein when receiving the service timeslot N times, an AGC gain g (N) for receiving the service timeslot is determined according to the following formula, and the service timeslot is received according to the AGC gain g (N):
G(N)＝G(N-1)+(S(N)-S(N-1))
wherein, N is more than or equal to 2, S (N) represents the received signal intensity of the downlink pilot frequency time slot in the subframe of the Nth received service time slot.
It can be seen from the above description that, in the TD-SCDMA terminal and the automatic gain control method thereof provided by the present invention, when the UE receives the service time slot for the first time, according to the relationship between the received signal strength of the downlink pilot time slot in the current subframe and the predetermined signal strength range, the UE sets the initial value of the AGC gain for receiving the service time slot in the current subframe, and then receives the service time slot in the current subframe according to the initial value of the AGC gain, so that the appropriate initial value of the AGC gain can be obtained when the service time slot signal is received discontinuously, and the receiving performance of the first service time slot is improved. In the invention, for the service time slot of discontinuous transmission, the AGC gain of the service time slot of the last receiving period is added with the wireless channel fading between two receiving periods to obtain the initial AGC gain of the current receiving period, and the discontinuous service time slot is received by using the AGC gain, thereby reducing the calculation amount of the terminal, leading the receiving of the terminal side to be more real-time and rapid and improving the receiving efficiency. In addition, for the service time slot continuously transmitted in a plurality of subframes, the present invention can utilize the existing various AGC algorithms to carry out convergence processing on the basis of the initial value of the AGC gain of the first service time slot, can accelerate the convergence of the AGC of the service time slot, improve the receiving quality of the service time slot and obtain good communication performance.
Drawings
FIG. 1 is a schematic diagram of a TD-SCDMA frame structure;
FIG. 2 is a diagram illustrating signal strength of each time slot in a subframe;
FIG. 3 is a diagram illustrating the relationship between the UE-to-Node B distance and the UE received signal strength;
FIG. 4 is a diagram illustrating the relationship between the downlink pilot timeslot signal and the traffic timeslot signal strength when the UE is at the cell boundary;
FIG. 5 is a diagram showing the relationship between the downlink pilot time slot signal and the traffic time slot signal strength when the UE is close to the Node B;
FIG. 6 is a flow chart of an automatic gain control method according to an embodiment of the present invention;
figure 7 is a schematic diagram of FACH discontinuous reception;
fig. 8 is a schematic structural diagram of a TD-SCDMA terminal according to an embodiment of the present invention.
Detailed Description
When UE receives discontinuous service time slot, the invention compares the received signal intensity of the downlink pilot frequency time slot in the current sub-frame with the preset signal intensity range to further determine an appropriate AGC gain initial value, and receives the service time slot in the current sub-frame according to the initial value, so that the UE can obtain the appropriate AGC gain initial value when the service time slot signal is received discontinuously, thereby accelerating the AGC convergence of the service time slot and obtaining good communication performance. The present invention will be described in detail below with reference to specific embodiments in conjunction with the accompanying drawings.
In this embodiment, the service timeslot is a downlink timeslot for carrying a service in a subframe.
In case 1 described in the background, the traffic slots are transmitted discontinuously on the sub-frame; in case 2, the traffic slot has not started to transmit continuously on the subframe. In these cases, it is necessary to determine an appropriate initial value of the AGC gain, so that the UE can receive the first traffic slot better according to the initial value, and can accelerate the convergence of the AGC of the traffic slot.
As can be seen from the frame structure of the TD-SCDMA mobile communication system, only the downlink pilot time slot is transmitted in each sub-frame, that is, in the above two cases, the UE usually receives the downlink pilot signal continuously in each sub-frame, and when receiving the downlink pilot time slot in the current sub-frame, the UE generates AGC gain (the unit of gain is dB) for receiving the downlink pilot time slot in the next sub-frame through an AGC algorithm. Since the channel fading experienced by the pilot time slot and other non-pilot time slots are substantially the same, there is some correlation between their signal strengths. In order to keep synchronization with the network side, the downlink pilot timeslot signals are usually received continuously, so that the AGC gain variation of the downlink pilot timeslot can substantially reflect the signal strength variation of the cell in which the pilot timeslot is located. When the mobile terminal receives the non-pilot time slot signal discontinuously, the mobile terminal can select a proper initial AGC gain value for receiving the non-pilot time slot signal of the cell according to the intensity change of the pilot time slot signal of the corresponding cell so as to accelerate the convergence of the non-pilot time slot AGC.
In TD-SCDMA mobile communication system, the downlink pilot is transmitted in omni-directional broadcast, and the traffic time slot carrying traffic is usually processed by power control, fig. 2 shows an example of the transmission signal strength of the downlink pilot time slot and the transmission signal strength of the traffic time slot under power control (here, the downlink traffic time slot may be TS0, TS 2-TS 6).
As shown in fig. 3, in an ideal case, the downlink pilot signal strength is inversely proportional to the distance between the UE and the Node B, and the closer the UE is to the Node B, the greater the received downlink pilot signal strength is; the farther the UE is from the Node B, the smaller the received downlink pilot signal strength. In the prior art, at the network side, the service time slot carrying the service is continuously controlled by power, so that the received signal strength of the service time slot at the UE side is kept within a predetermined signal strength range [ T1, T2] no matter how far the distance between the UE and the Node B is; on the UE side, for signals with received signal strength within [ T1, T2], the UE processes the traffic timeslot signal by using an AGC gain corresponding to the received signal strength, so that the processed signals meet the requirements of subsequent analysis processing. That is, corresponding to the traffic slot signals with the received signal strength within [ T1, T2], the UE side has an AGC gain corresponding to the signal strength.
In this embodiment, when selecting the AGC gain for receiving the first service timeslot, the following factors are considered:
1. when the terminal is at the boundary of the current resident cell, the signal strength of the pilot time slot signal after long-distance fading is relatively low, and due to the action of network side power control, the signal strength of the service time slot signal carrying the service will be relatively stable when reaching the UE, as shown in fig. 4, where TSn represents the service time slot. Therefore, the power of the downlink pilot time slot received by the UE and the power of the service time slot have a large difference, the signal strength of the pilot time slot is much smaller than that of the service time slot, and if the current AGC gain of the downlink pilot time slot is directly used to receive the service time slot, the received signal is easily saturated, and a good receiving effect cannot be achieved;
2. when the terminal is closer to the Node B, the pilot timeslot signal is stronger. The traffic timeslot carrying the traffic will be relatively stable under the action of power control, and the signal strength at this time is as shown in fig. 5. Therefore, the power of the downlink pilot time slot received by the UE and the power of the traffic time slot also have a large difference, and the strength of the pilot time slot signal is much greater than that of the traffic time slot signal. At this time, if the current AGC gain of the downlink pilot timeslot is directly used to receive the service timeslot, it is usually not guaranteed that the received service timeslot has sufficient gain, and a better receiving effect cannot be achieved.
According to the above analysis, when receiving the service slot for the first time in this embodiment, the initialization process of the service slot AGC gain can be specifically divided into the following 3 cases:
1. when the received signal strength of the downlink pilot time slot is in the range of [ T1, T2], namely greater than or equal to T1 and less than or equal to T2, directly using the current AGC gain of the downlink pilot time slot as the initial value of the AGC gain of the received service time slot;
2. the received signal strength of the downlink pilot time slot is greater than T2: in this case, if the current AGC gain of the downlink pilot timeslot is used to receive the service timeslot, the signal gain of the service timeslot is too weak to ensure normal reception. Therefore, when the received signal strength of the downlink pilot timeslot is greater than T2, G2 is used as the initial value of the AGC gain of the received traffic timeslot in this embodiment, where G2 is the received AGC gain corresponding to the downlink signal strength T2, that is, the AGC gain adopted by the UE when receiving the signal strength T2;
3. the received signal strength of the downlink pilot time slot is less than T1: in this case, the AGC gain of the current downlink pilot timeslot is too strong for the non-pilot timeslot, and if the service timeslot is received by using the AGC gain of the downlink pilot timeslot, signal saturation is easily caused, and a better receiving performance cannot be achieved. Therefore, when the signal strength of the downlink pilot timeslot is less than T1, G1 is used as the initial value of the AGC gain of the received traffic timeslot, where G1 is the received AGC gain corresponding to the downlink signal strength T1, that is, the AGC gain adopted by the UE when receiving the signal strength T1.
Therefore, the automatic gain control method of TD-SCDMA terminal described in this embodiment, as shown in fig. 6, includes the following steps:
and step 12, the terminal receives the service time slot in the current sub-frame according to the initial value of the AGC gain.
According to the above process, when the UE receives the service slot for the first time, setting an initial value of an AGC gain for receiving the service slot in the current subframe according to a relationship between a received signal strength of a downlink pilot slot in the current subframe and a predetermined signal strength range [ T1, T2], wherein the predetermined signal strength range [ T1, T2] is a signal strength range when a service slot signal subjected to power control processing by the network side reaches the UE side; then, the UE receives the service time slot in the current sub-frame according to the initial value of the AGC gain, thereby obtaining the proper initial value of the AGC gain when the service time slot signal is received discontinuously, and improving the receiving performance of the first service time slot.
For the two cases described in the background art, this embodiment may further include, after the step 12, another step of receiving the traffic slot after the first traffic slot. For the case 1, as shown in fig. 7, the traffic slot is discontinuously transmitted in a subframe, the FACH that the UE wants to receive the discontinuous transmission is received, or the UE operates in a Multi-Frame (Multi Frame) network environment. In fig. 7, there is FACH transmission on a certain traffic slot of only one subframe in each period P1(P1 includes multiple subframes). In FIG. 7, the N-1 FACH is received in the first P1 cycle, and then the N FACH is received in the next P1 cycle. And between two receiving repetition periods, the network side does not perform power control processing on the service time slot corresponding to the FACH. Here, N.gtoreq.2. In this case, the embodiment may further track the change of the wireless channel in real time according to the change of the downlink pilot signal strength to obtain a suitable AGC gain, and specifically, the automatic gain control method for the TD-SCDMA terminal according to the embodiment may further include the following step after step 12:
step 13, assuming that the received signal strength of the downlink pilot timeslot in the subframe where the nth-1 service timeslot is located is S (N-1), and the received signal strength of the downlink pilot timeslot in the subframe where the nth service timeslot is located is S (N), then (S (N) -S (N-1)) may reflect the channel fading from the nth-1 service timeslot to the nth service timeslot, so that when the terminal receives the nth service timeslot, the AGC gain g (N) used is:
G(N)＝G(N-1)+(S(N)-S(N-1))，N≥2
wherein, G (N-1) is the AGC gain adopted by the terminal to receive the N-1 th service time slot.
In the above formula, the unit of S (N) is dBW or dBMW, and the unit of (S (N) -S (N-1)) is dB.
As shown in fig. 7, after receiving the N-1 th FACH, until the next receiving period P1, the service timeslot corresponding to the FACH is no longer received, and in the process, the pilot timeslot is continuously received (there is a pilot timeslot in each subframe, but there is not necessarily a service timeslot corresponding to the FACH), and after processing by the downlink synchronization apparatus, the terminal can obtain the continuously converged AGC gain of the downlink pilot timeslot while maintaining synchronization with the network side. At the beginning of the next receiving period P1, the signal strength of the downlink pilot time slot is assumed to be stable as s (n). Between two receiving periods, because the service time slot of FACH is not continuously received, the change of the wireless channel condition cannot be monitored, so before the next receiving period starts, the AGC gain value of the original service time slot of FACH cannot adapt to the current channel change, and AGC needs to be initialized according to the above formula to obtain a new receiving AGC gain g (n).
For the service time slot of discontinuous transmission, the AGC gain of the service time slot of the last receiving period is added with the wireless channel fading between two receiving periods, and then the initial AGC gain of the current receiving period can be obtained. And the difference of the downlink pilot signal strength between the two receiving periods reflects the fading condition of the wireless channel. Thus, an appropriate AGC gain can be obtained using the above formula, and the traffic slot continues to be received in the subframe after the first traffic slot.
In the above formula, the difference between the downlink pilot signal strengths of the two receiving periods is used for calculation, and the AGC gain of the downlink pilot time slot between the two receiving periods is not used for calculation. Since the AGC gain is usually obtained by calculation based on signal strength: for example, after the received signal strength of the downlink pilot timeslot in the subframe where the nth service timeslot is located is obtained as s (N), s (N) needs to be compared with a specific threshold, and then the corresponding AGC gain is obtained through smoothing processing. Since the difference between the downlink pilot signal strengths can reflect the fading condition of the wireless channel, in this embodiment, the calculation is performed directly according to the signal strength in the above formula, and after the received signal strength is obtained as s (n), the calculation of g (n) can be started, so that the receiving process at the terminal side is more real-time and faster, and the receiving efficiency is improved.
For the situation 1 in the background art, a network side sends a service timeslot in a plurality of consecutive subframes, and at this time, the automatic gain control method for a TD-SCDMA terminal in this embodiment may further include the following step after step 12:
and step 13', the terminal receives the service time slot in each subframe in a plurality of continuous subframes, and performs convergence processing on the AGC gain value of the service time slot. Wherein the convergence processing comprises: receiving the service time slot in the current sub-frame according to the AGC gain used for receiving the service time slot in the current sub-frame; comparing the received signal strength of the service time slot in the current subframe with a preset threshold value to obtain a comparison result; and determining the AGC gain for receiving the service time slot in the next subframe according to the comparison result.
It can be seen that when the service time slot is continuously transmitted in a plurality of subframes, the existing various AGC algorithms can be utilized to perform convergence processing on the AGC gain of the service time slot, so that the convergence of the AGC of the service time slot can be accelerated on the basis of the initial value of the AGC gain of the first service time slot, the receiving quality of the service time slot is improved, and good communication performance is obtained.
Based on the automatic gain control method of the TD-SCDMA terminal, this embodiment further provides a TD-SCDMA terminal, as shown in fig. 8, where the TD-SCDMA terminal includes:
and the downlink pilot time slot receiving module is used for continuously receiving the downlink pilot time slot sent to the network side and determining the AGC gain for receiving the downlink pilot time slot in the next sub-frame according to an AGC convergence algorithm when receiving the downlink pilot time slot in the current sub-frame.
A service time slot gain initialization module, configured to set an initial value of an AGC gain for receiving a service time slot in a current subframe according to a relationship between a received signal strength of a downlink pilot time slot in the current subframe and a predetermined signal strength range when the terminal receives the service time slot issued by a network side for the first time, where the service time slot is a downlink time slot for carrying a service in the subframe, and the predetermined signal strength range is a signal strength range when a service time slot signal subjected to power control processing by the network side reaches the terminal;
a service time slot receiving module, configured to receive the service time slot in the current subframe according to the initial value of the AGC gain set by the service time slot gain initialization module when the terminal receives the service time slot for the first time
Specifically, the service timeslot gain initialization module is configured to: when the received signal strength of the downlink pilot time slot in the current subframe is smaller than the lower limit of the preset signal strength range, setting the initial value as the first gain value, wherein the first gain value is an AGC gain adopted by the UE when the received signal strength is the service time slot signal of the lower limit; when the received signal strength of the downlink pilot time slot in the current subframe is greater than the upper limit of the preset signal strength range, setting the initial value as the second gain value, wherein the second gain value is an AGC gain adopted by the UE when the received signal strength is the service time slot signal of the upper limit; and when the received signal strength of the downlink pilot time slot in the current sub-frame is between the first preset value and the second preset value, setting the initial value as the AGC gain adopted for receiving the downlink pilot time slot in the current sub-frame.
Preferably, the service time slot receiving module may be further configured to receive the service time slots in multiple consecutive subframes, respectively, and perform convergence processing on AGC gain values of the service time slots.
Similarly, the foregoing service slot receiving module may be further configured to receive the service slots in a plurality of discontinuous subframes, respectively, where when receiving the service slot N times, an AGC gain g (N) for receiving the service slot is determined according to the following formula, and the service slot is received according to the AGC gain g (N):
G(N)＝G(N-1)+(S(N)-S(N-1))
wherein, N is more than or equal to 2, and S (N) represents the received signal strength of the downlink pilot frequency time slot in the subframe where the Nth received service time slot is located. In the above formula, the unit of S (N) is dBW or dBMW, and the unit of (S (N) -S (N-1)) is dB.
The above embodiments are described in more detail below in two application scenarios.
1) Cell handover or cell reselection:
after receiving the switching or reselection command, the UE starts to receive signals of a target cell;
if the target cell has not been measured or has not resided, the UE firstly receives the downlink pilot time slot of the target cell, keeps the synchronization with the target cell through a downlink pilot time slot receiving module and simultaneously obtains the signal intensity and the corresponding AGC gain of the downlink pilot time slot of the target cell;
after the AGC gain of the downlink pilot time slot of the target cell is obtained, an initial value of the AGC gain of the service time slot of the receiving target cell is obtained through a service time slot gain initialization module. The specific decision criterion is as described above, and the AGC gain used when receiving the service time slot for the first time is obtained by comparing the signal strength of the pilot time slot of the target cell with two thresholds T1 and T2.
2) DCH received FACH or discontinuous transmission:
in a TD-SCDMA communication system, the FACH is transmitted in a predetermined manner over a plurality of subframes that are not contiguous. A similar transmission procedure is also possible for DCH under Multi Frame network. If the time between two transmissions is long, and the influence of fading, multipath and the like on the wireless channel may change very severely in the time, when the next repetition period comes, the AGC gain used in the last reception cannot meet the requirement, and signal saturation or undersize may occur, causing a re-reception error.
By using the scheme of the invention, the downlink pilot signal is continuously received when the FACH/DCH is discontinuously received, so that the change of the wireless channel between two receiving periods can be represented by the change of the strength of the pilot signal. The AGC gain of the previous receiving period plus the channel fading between the two receiving periods, i.e. the difference between the pilot signal strengths of the two receiving periods, can obtain the initial AGC value of the next receiving period.
In summary, the automatic gain control method and the corresponding TD-SCDMA terminal provided in the embodiments of the present invention enable the terminal to obtain an appropriate initial value of AGC gain when receiving a discontinuous service timeslot, thereby accelerating the convergence of AGC, enabling the service timeslot to achieve a good receiving effect quickly, and thus establishing a connection with a network side quickly. Especially in the network environment of cell reselection, switching (including hard switching and relay switching), Multi-carrier and Multi-Frame, the time of AGC convergence can be obviously shortened by using the invention, and good communication performance can be obtained.
Finally, it should be understood that the above-mentioned embodiments are merely preferred embodiments of the present invention, and not intended to limit the present invention, and any modifications, equivalents, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (9)
1. An automatic gain control AGC method for a TD-SCDMA terminal, comprising:
step A, when a terminal receives a service time slot issued by a network side for the first time, setting an initial value of AGC gain for receiving the service time slot in the current subframe according to the relationship between the received signal strength of a downlink pilot time slot in the current subframe and a preset signal strength range, wherein the service time slot is a downlink time slot for bearing services in the subframe, and the preset signal strength range is a signal strength range when a service time slot signal subjected to power control processing by the network side reaches the terminal;
step B, the terminal receives the service time slot in the current sub-frame according to the initial value of the AGC gain;
in step a, the setting an initial value of an AGC gain for receiving a service slot in a current subframe specifically includes:
when the received signal strength of the downlink pilot time slot in the current subframe is smaller than the lower limit of the preset signal strength range, setting the initial value as a first gain value, wherein the first gain value is an AGC gain adopted by the terminal when the terminal receives a service time slot signal of which the signal strength is the lower limit;
when the received signal strength of the downlink pilot time slot in the current subframe is greater than the upper limit of the preset signal strength range, setting the initial value as a second gain value, wherein the second gain value is an AGC gain adopted by the terminal when the received signal strength of the terminal is the service time slot signal of the upper limit;
and when the received signal strength of the downlink pilot time slot in the current sub-frame is between the first preset value and the second preset value, setting the initial value as the AGC gain adopted by the terminal for receiving the downlink pilot time slot in the current sub-frame.
2. The method of claim 1, wherein the terminal continuously receives a downlink pilot slot transmitted from the network side, and determines an AGC gain for receiving the downlink pilot slot in a next subframe according to an AGC convergence algorithm when receiving the downlink pilot slot in a current subframe.
3. The method of any of claims 1 to 2, wherein the traffic slot is transmitted in a plurality of consecutive subframes by a network side, the method further comprising:
and step C1, the terminal receives the service time slot in each sub-frame in the continuous sub-frames, and performs convergence processing on the AGC gain of the service time slot.
4. The method of claim 3, wherein the convergence process comprises:
receiving the service time slot in the current sub-frame according to the AGC gain used for receiving the service time slot in the current sub-frame;
comparing the received signal strength of the service time slot in the current subframe with a preset threshold value to obtain a comparison result;
and adjusting the AGC gain for receiving the service time slot in the next subframe according to the comparison result.
5. The method of any of claims 1 to 2, wherein the traffic slot is transmitted in a plurality of discontinuous subframes by a network side, the method further comprising:
step C2, after receiving the service time slot for the first time, when the terminal receives the service time slot for the nth time, determining the AGC gain g (N) for receiving the service time slot according to the following formula, and receiving the service time slot according to the AGC gain g (N):
G(N)＝G(N-1)+(S(N)-S(N-1))
wherein, N is more than or equal to 2, S (N) represents the received signal intensity of the downlink pilot frequency time slot in the subframe of the Nth received service time slot.
6. A TD-SDCMA terminal, comprising:
a service time slot gain initialization module, configured to set an initial value of an AGC gain for receiving a service time slot in a current subframe according to a relationship between a received signal strength of a downlink pilot time slot in the current subframe and a predetermined signal strength range when the terminal receives the service time slot issued by a network side for the first time, where the service time slot is a downlink time slot for carrying a service in the subframe, and the predetermined signal strength range is a signal strength range when a service time slot signal subjected to power control processing by the network side reaches the terminal;
a service time slot receiving module, configured to receive a service time slot in a current subframe according to an initial value of the AGC gain set by the service time slot gain initialization module when the terminal receives the service time slot for the first time;
wherein,
the service timeslot gain initialization module is further configured to: when the received signal strength of the downlink pilot time slot in the current subframe is smaller than the lower limit of the preset signal strength range, setting the initial value as a first gain value, wherein the first gain value is an AGC gain adopted by the terminal when the terminal receives a service time slot signal of which the signal strength is the lower limit; when the received signal strength of the downlink pilot time slot in the current subframe is greater than the upper limit of the preset signal strength range, setting the initial value as a second gain value, wherein the second gain value is an AGC gain adopted by the terminal when the received signal strength of the terminal is the service time slot signal of the upper limit; and when the received signal strength of the downlink pilot time slot in the current sub-frame is between the first preset value and the second preset value, setting the initial value as the AGC gain adopted by the terminal for receiving the downlink pilot time slot in the current sub-frame.
7. The terminal of claim 6, further comprising:
and the downlink pilot time slot receiving module is used for continuously receiving the downlink pilot time slot sent from the network side, and determining AGC gain for receiving the downlink pilot time slot in the next subframe according to an AGC convergence algorithm when receiving the downlink pilot time slot in the current subframe.
8. The terminal according to any of the claims 6 to 7,
the service time slot receiving module is further configured to receive the service time slots in multiple consecutive subframes, respectively, and perform convergence processing on AGC gain values of the service time slots.
9. The terminal according to any of the claims 6 to 7,
the service time slot receiving module is further configured to receive the service time slots in multiple discontinuous subframes, respectively, where when receiving the service time slot N times, an AGC gain g (N) for receiving the service time slot is determined according to the following formula, and the service time slot is received according to the AGC gain g (N):
G(N)＝G(N-1)+(S(N)-S(N-1))
wherein, N is more than or equal to 2, S (N) represents the received signal intensity of the downlink pilot frequency time slot in the subframe of the Nth received service time slot.
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| CN101848533B (en) * | 2010-04-28 | 2012-08-22 | 广州市广晟微电子有限公司 | Radio frequency self-loop automatic gain control method for TD-SCDMA terminal |
| WO2013004017A1 (en) * | 2011-07-07 | 2013-01-10 | 中兴通讯股份有限公司 | Method and system for implementing automatic gain control |
| CN103688579A (en) * | 2011-07-25 | 2014-03-26 | 高通股份有限公司 | Method and apparatus for automatic gain control for TD-SCDMA systems |
| WO2013091171A1 (en) * | 2011-12-20 | 2013-06-27 | 中兴通讯股份有限公司 | Method and system for realizing auto gain control |
| CN103379602B (en) * | 2012-04-12 | 2016-04-20 | 联芯科技有限公司 | Terminal auto gain control method under downlink multi-slot business and terminal |
| CN103379607B (en) * | 2012-04-17 | 2018-01-30 | 中兴通讯股份有限公司 | The gain control method and device of TD HSPA+ terminal devices |
| CN103973387B (en) * | 2013-01-30 | 2016-12-28 | 电信科学技术研究院 | A kind of method and device safeguarding time slot state information |
| CN106332228A (en) * | 2015-06-16 | 2017-01-11 | 联芯科技有限公司 | Frequency sweeping method and device according to frequency band |
| CN111399001B (en) * | 2020-03-31 | 2022-05-06 | 和芯星通科技(北京)有限公司 | Method and device for processing broadband interference |
| CN112689322B (en) * | 2020-12-18 | 2023-01-24 | 展讯通信（上海）有限公司 | Power control method, device and equipment |
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| CN1719751A (en) * | 2005-07-19 | 2006-01-11 | 凯明信息科技股份有限公司 | Burst receiving automatic gain controlling method for time division duplex mobile communication system |
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