CN1414715A - Method of regulating modulation code according to area - Google Patents

Abstract

The invention discloses a method for adjusting the modulation and coding scheme according to the area, which comprises the following steps: (a) the base station divides all modulation and coding schemes (MCS) currently used into more than one MCS group; (b) the user terminal measures the channel in the cell channel quality and path loss, and transmit the information to the base station; (c) the base station updates and maintains the channel information table according to the received information, and calculates the distance between the user and the base station according to the path loss value, and calculates the distance between the user and the base station according to the distance between the user and the base station Determine the MCS group to which the user belongs by distance; (d) select a suitable channel and MCS combination for data transmission according to the channel information table of the user and the MCS group corresponding to the user; (e) return if the user's location changes (b). Using this method enables users to determine the modulation and coding levels and transmission channels used according to different locations, so as to ensure the best transmission quality and improve the overall performance of the system.

Description

A Method for Adjusting Modulation and Coding Schemes by Area

technical field

The present invention relates to a coding scheme adjustment technology, in particular to a method for adjusting a modulation and coding scheme according to an area in which a corresponding coding scheme is allocated according to different positions of users in a cell.

Background of the invention

At present, in the enhanced technology of the third generation mobile communication system, a method of adaptively changing the modulation and coding scheme (AMC) is proposed. This method is to divide the modulation and coding levels into eight levels, as shown in Table 1. When When channel conditions change, the modulation and coding sequence (MCS) level will also be automatically adjusted up or down according to the channel conditions to ensure good signal transmission performance. The specific working principle of this method is: the base station selects the modulation and coding scheme of the user according to the channel information fed back by the user, that is, selects a higher-order modulation and coding scheme and a higher coding rate in a place with good channel conditions, and selects a higher-order modulation and coding scheme and a higher coding rate in a place with good channel conditions. The bad place is to choose a low-order modulation and coding scheme and a lower coding rate. Table 1 shows eight optional modulation and coding schemes: encoding level modulation scheme Coding scheme (information bits/total bits) 1 Quadrature Phase Shift Keying (QPSK) 1/4 2 Quadrature Phase Shift Keying (QPSK) 1/2 3 Quadrature Phase Shift Keying (QPSK) 3/4 4 8 Phase Shift Keying (8PSK) 3/4 5 16-order quadrature amplitude modulation (16QAM) 1/2 6 16-order quadrature amplitude modulation (16QAM) 3/4 7 64-order quadrature amplitude modulation (64QAM) 1/2 8 64-order quadrature amplitude modulation (64QAM) 3/4

Table 1 Modulation and coding scheme

The number "1/4" in the encoding scheme in Table 1 means that a total of 4 bits are transmitted, of which 1 bit is an information bit, and the remaining 3 bits are redundant bits; similarly, "1/2" means a total of 2 bits are transmitted, and 1 bit is Information bits, 1 bit is a redundant bit; others can be deduced by analogy.

No matter how many levels the MCS adopts, there is an adjustment problem. However, in practical applications, there are several influencing factors between the user and the base station: distance, interference, channel conditions, etc., what standards should be used and how to proceed The adjustment of the coding scheme, that is to say, which coding scheme to use under what circumstances is better and can better guarantee the transmission quality of user signals, has not yet been determined to realize it. Moreover, it is likely that frequent adjustments to the coding scheme due to inaccurate measurements will degrade the transmission quality; or excessive modulation and coding levels will be used at inappropriate locations due to channel measurement errors, causing interference among users, thereby reducing system capacity. decline.

Contents of the invention

In view of this, the main purpose of the present invention is to provide a method for adjusting the modulation and coding scheme according to the region, so that the user can decide the modulation and coding level and the transmission channel according to the location, so as to ensure that it has the best transmission quality, thereby improving overall system performance.

In order to achieve the above object, the technical solution of the present invention is specifically realized in the following way:

A method for adjusting a modulation and coding scheme according to a region, which at least includes the following steps:

a. The base station divides all modulation and coding schemes (MCS) currently used into more than one MCS group;

b. The user (UE) side measures the channel quality and path loss of the channel in the cell, and transmits the information to the base station;

c. The base station updates and maintains the channel information table according to the received information, calculates the distance between the user and the base station according to the path loss value, and determines the MCS group to which the user belongs according to the distance between the user and the base station;

d. Select a suitable channel and MCS combination for data transmission according to the channel information table of the user and the MCS group corresponding to the user;

e. If the user's location changes, return to step b.

The method further includes: the base station sets up a channel information table for each user in advance, and the table contains information about all channels currently available to the user in the cell. The method also includes: the base station obtains relevant idle and available channels from the radio network controller (RNC), and obtains relevant channel quality information obtained in its idle time slots from the user (UE), updates the channel information table and maintain. The maximum number of available channels is the number of all channels that can be used in a cluster of cells under the jurisdiction of the radio network controller (RNC).

Wherein, step d further includes: the base station firstly selects the best channel among the idle and available channels of the user, and establishes a one-to-one correspondence with all MCSs of the MCS group, and when the communication quality deteriorates, sequentially selects the best channel from the channel information table of the user Select the channel with the highest current priority and its corresponding MCS combination for data transmission.

The method further includes: when there are not enough channels allocated to users in all areas, preferentially allocate channels to users closer to the base station.

After the base station calculates the current user location, it first needs to judge whether it has an idle channel according to the channel information table of the user. If not, the user keeps the original MCS and the channel used.

When the channel selected by more than one user conflicts, the channel is allocated to the user who is closer to the base station.

The UE detects the correctness and error of the data block transmission in real time and reports the information to the base station, and the base station counts the number of erroneous transmissions; when the same data block of the user has two consecutive transmission errors, the base station reselects the current channel and the next channel in sequence. A combination of MCS; if the combination of the current channel and each MCS is not applicable, the channel with the next highest priority in the channel information table of the user is sequentially selected.

The division of the MCS groups is jointly determined by the path loss principle and the transmit power principle. Users located at the edge of the cell can only use modulation and coding schemes up to QPSK 3/4.

As can be seen from the above scheme, the key of the present invention is: the base station calculates the distance between them by measuring the path loss between itself and the user terminal (UE); The base station determines the modulation and coding level and the corresponding channel that the user can use by pre-dividing the modulation and coding groups according to the area.

During this process, the base station stores a channel information table for each user, and the base station obtains relevant free available channels from the radio network controller (RNC) and obtains other channels obtained in its free time slots from the UE. channel quality information, update and maintain the table. In this way, it can ensure that the UE can obtain the channel with the best channel quality and the most suitable modulation and coding scheme available at a certain position, which not only simplifies the complexity of modulation and coding level adjustment, reduces the interference between users in the system, but also improves system performance.

Because the characteristic of time division duplex (TDD) system is: the user divides the time slot to transmit data, so, the user just can measure the quality of other channels in the cell in the time slot that it does not transmit, therefore, the present invention is more suitable for TDD system.

It can be seen that the method for adjusting the modulation and coding schemes by region provided by the present invention groups all the modulation and coding schemes in the cell according to the distance from the base station, and classifies the channels and modulation and coding levels available to the user according to the distance between the user and the base station. Carry out one-to-one correspondence, and establish a channel information table, so that users can obtain information about the channel and modulation and coding levels at the same time. Adjusting the modulation and coding scheme by region can not only ensure that the user transmits with the best transmission path, but also simplify the adjustment process of the modulation and coding level, reduce the interference between users in the cell, and improve system performance and signal transmission quality and reduce the occurrence of wrong adjustments.

Description of drawings

Fig. 1 is the flowchart of the realization of the method of the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

It is assumed that the mobile communication system adopts an eight-level modulation and coding scheme; and the channel numbers of the channels are set to a~h. In practical applications, the number of channels can be randomly selected, and the maximum number of channels can be used in a cluster of cells under the jurisdiction of the RNC. The number of all channels; suppose the distance between the user and the base station is D, and the radius of the cell is R.

In this embodiment, the base station divides the modulation and coding schemes into three groups: group A uses all modulation and coding schemes, that is, M=8; group B uses modulation and coding schemes up to 16QAM 3/4, that is, sets N=6; Group C uses a modulation and coding scheme up to QPSK 3/4, that is, L=3. In practical applications, the division of MCS groups is considered according to the communication quality of users in the actual environment. Due to the problem of path loss and transmission power, users at the cell boundary generally cannot use high-order modulation such as 64QAM and 16QAM. The two principles of path loss and transmission power will determine the grouping of MCS.

The base station sets up a channel information table for each user in advance, which contains information about all channels currently available to the user in the cell, and sorts the channels according to channel transmission performance, that is, whether the channels are good or bad. As for the judgment of the quality of the channel, the user measures the channel quality when it is not transmitting data and reports it to the base station, and then the base station sorts the available channels according to this information.

Then, referring to shown in Figure 1, the realization of the method of the present invention specifically includes the following steps:

1) The UE measures the quality of the channel in the cell in the time slot when it does not transmit data. At the same time, the UE also needs to measure the path loss, which is achieved through the common control physical channel (P-CCPCH) and the downlink pilot channel (DwPTS). obtained, and transmit the channel quality and path loss measurement information back to the base station. This step should be continuously carried out during the whole communication process and detected in real time.

2) The base station maintains the user's channel information table according to the received data, that is, sorts the available channels in the cell; then, the base station calculates the distance between the UE and the base station NodeB according to the path loss value provided by the UE. distance; and make the following judgments according to the distance between the user and the base station:

① When the user is close to the base station, that is, when D<1/3R, the base station selects an idle channel a with the best quality from the user's channel information table to correspond to the MCS of group A, that is, use the best quality The channels correspond to the eight MCS levels one by one, as shown in Table 2: priority level channel number modulation coding scheme 1 A 8 2 A 7 3 A 6 4 A 5 5 A 4 6 A 3 7 A 2 8 A 1

Table 2 Correspondence between channel a and MCS when the user is in D<1/3R

Wherein, the numbering of the corresponding MCS coding scheme follows the numbering in Table 1.

If all combinations of channel a cannot be used, that is, all MCS levels of channel a are not suitable, then interrupt the service of the user, or take out another channel, such as the next best channel b, repeat the above operations, as shown in Table 3 : priority level channel number modulation coding scheme 1 b 8 2 b 7 3 b 6 4 b 5 5 b 4 6 b 3 7 b 2 8 b 1

Table 3 Correspondence between channel b and MCS when the user is in D<1/3R

Wherein, the numbering of the corresponding MCS coding scheme follows the numbering in Table 1.

If the various MCS levels of channel b are not applicable to the user's channel, the service is interrupted or the channel with the highest priority in the user's channel information table is sequentially selected for data transmission, and so on. Wherein, the so-called inapplicability of the channel and the MCS means that multiple transmission errors occur when a certain combination of the channel and the MCS is used to transmit data. The base station generally selects a channel and MCS combination according to the priority order from high to low, and if it is not suitable, selects the next one.

② When the user is in the middle of the base station, that is, 1/3R≤D<2/3R, the base station selects the best idle channel from the user's channel information table to correspond to each MCS of group B, The corresponding method is the same as in ①, as shown in Table 4: priority level channel number modulation coding scheme 1 c 6 2 c 5 3 c 4 4 c 3 5 c 2 6 c 1

Table 4 Correspondence between channel c and MCS when the user is in 1/3R≤D<2/3R

Wherein, the numbering of the corresponding MCS coding scheme follows the numbering in Table 1.

If the current channel a is the best channel, and channel c is the second best channel; at this time, the users at D<1/3 and the users at 1/3≤D<2/3 both think that a is the best channel , according to the principle of giving priority to users who are closer to the base station, the channel a is preferentially allocated to users who are closer to the base station, and the second-best channel c is allocated to users relatively far from the base station.

③ When the user is far away from the base station, that is, D≥2/3R, the base station selects the best idle channel from the user's channel information table to correspond to the three MCSs of group C, and the corresponding method is the same as in ① . priority level channel number modulation coding scheme 1 d 3 2 d 2 3 d 1

Table 5 Correspondence between channel d and MCS when the user is in D≥2/3R

Wherein, the numbering of the corresponding MCS coding scheme follows the numbering in Table 1.

Similarly, if two users think that the same channel is the best at the same time, the channel will be assigned to the user who is closer to the base station, and the other user will choose second.

In the above three cases, it is assumed that there is an idle channel. In fact, after the base station calculates the location of the user, it first needs to judge whether there is an idle channel according to the channel information table of the user. If not, the user maintains the original communication channel and MCS scheme. If there are not enough channels allocated to the users in the three areas in the entire cell, according to the principle of maximum capacity and minimum transmission power, the users who are closer to the base station will be given priority, that is, the base station will give priority to the current idle available channels to the users with the closest distance. user.

3) The base station monitors in real time whether the user's location changes according to the path loss uploaded by the user. If the user is in the three areas of the cell, that is, D<1/3, 1/3R≤D<2/3R, D≥2/ If the user moves between 3R, that is to say, if the location changes, return to step 1) and perform the corresponding operation again; otherwise, the user maintains the existing channel and corresponding MCS level.

The above execution process is carried out when there is no error in the user data transmission. In fact, in step 1), the UE side also monitors the correctness and error of the data transmission and reports the monitoring result to the base station. After the base station receives the information uploaded by the UE , which counts the number of error transmissions, and then judges whether the same data has two consecutive transmission errors according to the statistical information. If not, the user maintains the currently used channel and MCS; otherwise, the base station reselects a more suitable one from the channel information table. channel and MCS to transmit the data block, that is to say, sequentially select the next highest priority available channel and its corresponding MCS from the user's channel information table for data transmission. If the area where the user is located changes and the data transmission continues to make mistakes, firstly according to the change of the user's position, according to the change of the user's position, a new channel and corresponding modulation and coding scheme are reselected from the new user channel information table for transmission.

From the above process analysis, it can be seen that channel allocation mainly follows three principles:

a. When the number of channels is insufficient, give priority to users who are closer to the base station;

b. When the channel used by multiple users conflicts, give priority to the user who is closer to the base station;

c. When the same data block of a certain user has continuous transmission errors, reselect the corresponding available channel and MCS according to the channel information table of the user.

In a word, the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention.

Claims (11)

1, a kind of method of regulating modulation code according to area is characterized in that this method comprises the steps: at least

A. the base station is divided into more than one MCS group with all Modulation and Coding Scheme (MCS) of current employing;

B. user (UE) end is measured the channel quality and the path loss of channel in the sub-district, and sends this information to base station;

C. the distance of this user and base station is calculated according to path loss values simultaneously according to the information updating maintenance channel information table of being received in the base station, and determines that according to the distance of user and base station the MCS under this user organizes;

D. choosing suitable channel according to the MCS group of this user's channel information table and this user's correspondence is combined into line data with MCS and transmits;

If e. this user's position changes, then return step b.

2, method according to claim 1, it is characterized in that this method further comprises: a channel information table is set up for each user in advance in the base station, comprises the information of current these all available channels of user in this sub-district in this table.

3, method according to claim 2, it is characterized in that this method also comprises: the base station is by obtaining relevant idle available channel from radio network controller (RNC), and obtain the correlated channels quality information that in its idle time slot, obtains from user (UE) end, the channel information table is upgraded and safeguards.

4, method according to claim 1 and 2 is characterized in that: the number of described available channel is operable all numbers of channel in the cluster sub-district that radio network controller (RNC) administered to the maximum.

5, method according to claim 1, it is characterized in that steps d further comprises: the optimum channel in the idle available channel of this user is at first chosen in the base station, set up one-to-one relationship with all MCS of this MCS group, when the communication quality variation, then from this user's channel information table, choose the not highest channel of current priority and corresponding M CS thereof in proper order and be combined into the line data transmission.

6, method according to claim 1 is characterized in that this method further comprises: when not having enough channel allocation to give the user of All Ranges, then preferentially channel allocation is given and the nearer user of base station distance.

7, method according to claim 1, it is characterized in that this method further comprises: the base station is after calculating the active user position, at first will judge whether it has idle channel according to this user's channel information table, if do not have, then this user keeps original MCS and used channel.

8, method according to claim 1 is characterized in that this method further comprises: when the channel of user-selected usefulness more than one clashes, preferentially channel allocation is given and the nearer user of base station distance.

9, method according to claim 1 is characterized in that this method further comprises: the UE end detects correcting errors of transmission of data blocks in real time and this information is reported the base station, by the base station number of times of erroneous transmissions is counted; When the double generation error of transmission of this user's same data block, the base station order combination of selecting current channel and next MCS for use again; If the combination of current channel and each MCS is all inapplicable, then order is chosen the highest channel of next priority in this subscriber channel information table.

10, method according to claim 1 is characterized in that: the division of described Modulation and Coding Scheme (MCS) group is determined jointly by path loss principle and transmitting power principle.

11, according to claim 1 or 10 described methods, it is characterized in that: the user who is positioned at cell edge only adopts the Modulation and Coding Scheme that is up to QPSK 3/4.