TWI481221B - Selecting method for modulation and coding scheme, communication module of base station, and communication module of user equipment - Google Patents

Description

Modulation coding scheme selection method, base station communication module and user equipment communication module

A Modulation and Coding Scheme (MCS) selection method, a base station communication module, and a Customer Premise Equipment (CPE) communication module, in particular, a carrier-to-interference and noise ratio (carrier) To Interference plus Noise Ratio (CINR) selection method of modulation coding scheme, base station communication module and user equipment communication module.

The Modulation and Coding Scheme (MCS) is a key feature of Worldwide Interoperability for Microwave Access (WiMAX) technology to ensure base station (BS) and customer premises equipment ( Communication quality between Customer Premise Equipment, CPE). In the MCS supported by WiMAX, there are three types of modulation: Quadrature Phase Shift Keying (QPSK), 16 Quadrature Amplitude Modulation (QAM), and 64QAM. The BS changes the modulation mode according to the increase and decrease of the carrier carrier and interference to noise ratio (CINR) of the communication quality represented by the CPE.

But in fact, not in the same channel environment between BS and CPE, the same MCS will be applied under the same CINR. The CINR is only an average signal quality factor, so it is not appropriate to refer to the CINR for MCS selection in the actual channel environment. If the CINR is overestimated, the BS adopts a higher modulation and coding mode, which causes a large number of packet errors, which in turn reduces the transmission efficiency. on the contrary, If the CINR is underestimated, wireless resources will be wasted due to the use of modulation and coding methods with lower transmission rates.

In order to solve the above problems, the present invention provides a Modulation and Coding Scheme (MCS) selection method, a base station (BS) communication module, and a Customer Premise Equipment (CPE) communication module. The base station communication module and the client device communication module can be used to perform the MCS selection method.

The MCS selection method is the following steps. Receiving a plurality of first packets in a first period, and calculating a packet error rate (PER) according to the first packets. Determine if the packet error rate is greater than an error rate threshold. When the packet error rate is greater than the error rate threshold, perform the following steps. Obtain a carrier-to-interference plus noise ratio (CINR) return value. An adjustment procedure is performed to obtain a CINR adjustment value. An actual return value is calculated based on the CINR return value and the CINR adjustment value. Select one of the multiple MCSs based on the actual reward value.

The base station communication module includes a first communication unit, a CINR adjustment unit, and an MCS selection unit. The first communication unit is configured to receive the plurality of first packets during the first period. The CINR adjustment unit is configured to perform the following steps. The packet error rate is calculated based on these first packets. Determine if the packet error rate is greater than the error rate threshold. When the packet error rate is greater than the error rate threshold, perform the following steps. Get the CINR return value. Perform an adjustment procedure to get the CINR adjustment value. The actual return value is calculated based on the CINR return value and the CINR adjustment value. The MCS selection unit is used to select the actual return value. Take one of the multiple MCSs.

The client device communication module communicates with the base station communication module, and the client device communication module includes a second communication unit and a CINR adjustment unit. The communication unit is configured to receive the plurality of first packets during the first period. The CINR adjustment unit is configured to perform the following steps. The packet error rate is calculated based on these first packets. Determine if the packet error rate is greater than the error rate threshold. When the packet error rate is greater than the error rate threshold, perform the following steps. Get the CINR return value. Perform an adjustment procedure to get the CINR adjustment value. The actual return value is calculated based on the CINR return value and the CINR adjustment value. The actual return value is sent to the base station communication module, so that the base station communication module selects one of the plurality of MCSs according to the actual reward value.

In summary, the MCS selection method, the BS communication module, and the CPE communication module calculate the actual return value of the actual return to the BS according to the packet error rate and the CINR return value, and then the BS selects the MCS according to the actual return value. Therefore, the selected MCS can more accurately reflect the instant messaging environment and ensure sufficient use of wireless resources.

The detailed features and advantages of the present invention are set forth in the Detailed Description of the Detailed Description of the <RTIgt; </ RTI> <RTIgt; </ RTI> </ RTI> </ RTI> <RTIgt; The objects and advantages associated with the present invention can be readily understood by those skilled in the art.

The invention provides a Modulation and Coding Scheme (MCS) selection method, a base station (BS) communication module and a Customer Premise Equipment (CPE) communication module, wherein the MCS selection The method can be implemented as a BS communication module or a CPE communication Module.

Please refer to "FIG. 1" first, which is a communication diagram of a base station communication module and a user equipment communication module of an embodiment. A BS BS communication module 20 can simultaneously communicate with a plurality of CPE CPE communication modules in a wireless manner, 30 of which can be used for Worldwide Interoperability for Microwave Access (WiMAX) or Long Term Evolution (Long Term Evolution). , LTE) and other wireless communication protocols.

The CPE can be an electronic device such as a mobile phone, a notebook computer, a tablet computer or a portable game machine, and can communicate with the BS through the CPE communication module communication 30 to obtain wireless Internet access or call service.

The MCS selection method can select a suitable MCS according to the communication quality between the BS communication module 20 and the CPE communication module 30, and can integrate a carrier to interference plus noise ratio (CINR) return value. And a Packet Error Rate (PER) to determine the quality of the communication. Simply put, the MCS selection method adjusts the CINR return value based on the packet error rate to more accurately represent the communication quality.

Next, please refer to "FIG. 2", which is a schematic flow chart of the selection method of the MCS of an embodiment. The BS communication module 20 or the CPE communication module 30, which is used to implement the MCS selection method, is hereinafter referred to as a working module. The working module can perform the following steps S100 to S700 to count once every other time. Packet the error rate and select the MCS for this period of time.

The working module first receives the plurality of first packets in a wireless manner in a first period, and calculates a packet error rate according to the received first packets (step S100). for To ensure the validity of the calculated packet error rate, the total number of received packets can be accumulated to a certain amount before the packet error rate is calculated. Please refer to "FIG. 3" for a flow chart of step S100 of an embodiment.

The working module receives the plurality of first packets in the first period (step S110), and determines whether the number of received first packets is less than a threshold number of packets (step S120). For example, the working module can receive the first packet from the BS communication module 20 or the CPE communication module 30 within 5 seconds or 10 seconds, and calculate the total number of the first packets received during the period.

When the number of the first packets is greater than the threshold of the number of packets, the working module may directly calculate the packet error rate of the first period according to the first packets (step S130). However, when the number of the first packet is less than or equal to the threshold of the packet, the working module may continue to receive the second packet in a second period, and calculate the first packet according to the first packet and the second packet. The packet error rate for the period and the second period (step S140). According to an embodiment, the working module may continuously receive the first packet and the second packet, regardless of whether the number of the first packet is greater than a threshold of the number of packets. If the number of the first packets is greater than the threshold of the number of packets, the working module may perform the subsequent steps S200 to S700 while continuing to receive the second packet.

Furthermore, after the end of the second period, the working module can also confirm whether the received first packet and the total number of the second packet are greater than the packet threshold. If not, the packet can continue to be received until the total number of received packets is greater than the threshold of the number of packets, and the packet error rate is calculated based on the received packets. Similarly, the working module may be continuously receiving the packet regardless of whether the total number of the first packet and the second packet is greater than the threshold of the number of packets. If the total number of the first packet and the second packet is large In the packet threshold, the working module can perform the subsequent steps S200 to S700 while continuing to receive other packets. In addition, when the BS communication module 20 and the CPE communication module 30 are reconnected, the packet error rate can be reset to zero.

After obtaining the effective packet error rate, the working module determines whether the packet error rate is greater than an error rate threshold (step S120) to determine how to adjust the CINR return value. When the packet error rate is greater than the error rate threshold, it indicates that the quality of the wireless communication is poor, and the following steps S300 to S600 may be performed.

The work module may first obtain a CINR return value (step S300), and then perform an adjustment procedure to obtain a CINR adjustment value (step S400). For each channel of wireless communication, the working module can continuously perform channel measurement and obtain a CINR return value. The CINR return value can be obtained from an estimation operation of a physical wafer of a physical layer (PHY layer) of the working module. Traditionally, the CPE periodically obtains the CINR return value and directly reports the CINR return value to the BS. However, the MCS selection method adjusts the CINR return value according to the packet error rate to more accurately express the communication quality.

Please refer to "Figure 4" for a flow chart of the adjustment procedure of an embodiment. The adjustment program compares the product of the packet error rate with the minor repair coefficient and a first adjustment value upper limit, and takes the lower one as a first adjustment value (step S410).

In other words, the adjustment program may first calculate the product of the packet error rate and the down-cut coefficient, and then compare the product with the first adjustment value upper limit, and use the lower of the product and the first adjustment value as the first adjustment value. . The down-cut factor can be a preset constant and can be set by the user.

The CINR return estimated by the physical layer in the case of a large packet error rate The value accuracy rate is low, and the obtained CINR return value should be revised to meet the actual communication quality. Therefore, basically, the larger the packet error rate, the larger the first adjustment value. However, in order to avoid too much down-cutting, the subsequent selected MCS is too low to reduce the transmission efficiency, or even cause the jitter of the transmission amount. You can set the upper limit of the first adjustment value to limit the maximum that can be adjusted each time. value.

Then, the adjustment program compares the sum of the previous adjustment value and the first adjustment value and the second adjustment value upper limit, and takes the lower one as the CINR adjustment value (step S420). In more detail, the working module can count the packet error rate every time period (for example, the first period), and calculate the CINR adjustment value corresponding to the time period. After the adjustment is completed, the current CINR adjustment value will be recorded as the previous adjustment value for use in the next adjustment. In general, the first adjustment value calculated in step S410 may be added to the previous adjustment value as the final CINR adjustment value. Similarly, in order to maintain the stability of the communication state, the adjustment procedure can refer to the second adjustment value upper limit to avoid excessive CINR adjustment value. The first adjustment value upper limit and the second adjustment value upper limit may all be preset constants, and may be set by the user.

After the working module obtains the CINR adjustment value, the actual reward value is calculated based on the CINR return value and the CINR adjustment value (step S500). According to an embodiment, the difference between the CINR return value and the CINR adjustment value may be directly used as the actual return value. Finally, one of the plurality of MCSs may be selected based on the actual reward value (step S600).

According to an embodiment, when the packet error rate is less than or equal to the error rate threshold, the working module may obtain the CINR return value (step S300), and directly use the previous adjustment value as the CINR adjustment value (step S700).

According to another embodiment, if the packet error rate is equal to the error rate threshold value representation The current communication quality is good, so the MCS selection method can reduce the CINR adjustment value. Please refer to "figure 5", which is a schematic flow chart of a method for selecting an MCS of another embodiment. When the packet error rate is less than or equal to the error rate threshold, the working module may first determine whether the packet error rate is equal to zero (step S250). When the packet error rate is not equal to zero, the CINR return value is obtained (step S300), and the previous adjustment value is directly used as the CINR adjustment value (step S700).

When the packet error rate is equal to zero, the current communication quality is very good, but the transmission rate of the MCS currently in use may be too low. Then, the working module can compare the difference between the previous adjustment value and the upper adjustment coefficient and a lower limit of the adjustment value, and take the higher one as the CINR adjustment value (step S800). The working module can first calculate the previous adjustment value minus the upper repair coefficient to obtain a difference, and then compare the difference with the lower limit of the adjustment value, and use the higher of the difference and the lower limit of the adjustment value as the CINR adjustment value. The upper repair factor can be a preset constant and can be set by the user.

It should be noted that the CINR adjustment value can be positive or negative. When the CINR adjustment value is positive, the actual return value is smaller than the CINR return value; otherwise, when the CINR adjustment value is negative, the actual return value is greater than the CINR return value. Therefore, the MCS selection method can increase or decrease the actual return value according to the packet error rate, and may select different MCSs accordingly.

In addition, generally, the upper limit of the first adjustment value and the upper limit of the second adjustment value are both positive values, for example, 5 dB; the lower limit of the adjustment value is a negative value, for example, -2 dB. By setting the upper limit of the first adjustment value, the upper limit of the second adjustment value, and the lower limit of the adjustment value, it can be ensured that when the MCS selection method is repeatedly executed, the actual return value is not increased or lowered indefinitely to obtain the entire communication. The situation is stable.

According to an embodiment, the MCS selection method can be implemented in the BS communication module 20. Please refer to FIG. 6 , which is a block diagram of a BS communication module of an embodiment. The BS communication module 20 can include a first communication unit 22, a CINR adjustment unit 24, and an MCS selection unit 26. For example, the BS communication module 20 can be an uplink module or a downlink module in the BS.

The first communication unit 22 is configured to continuously and wirelessly transmit and receive packets during the first period, the second period, or the subsequent period. And the first communication unit 22 can count the total number of packets that have been received so far, and the total number of packets that have occurred so far.

In the beginning, the CINR adjustment unit 24 may wait (wait, or call idle) for a first period, and query the total number of packets that the first communication unit 22 has received so far and the total number of packets in which the error occurred. Then, the CINR adjusting unit 24 can compare the data of the current inquiry and the previous inquiry, and then calculate the packet error rate of the first period. However, if the number of the first packet is less than the threshold of the packet number, the CINR adjustment unit 24 may continue to wait for a second period, then query the first communication unit 22 and calculate the total number of the first packet and the second packet, and may The packet error rate during the first period plus the second period is calculated.

The CINR adjustment unit 24 also performs the above steps S200, S250, S300, S400, S500, S700, and S800 to calculate an actual reward value based on the CINR return value and the packet error rate. If the BS communication module 20 is the downlink link module of the BS, the CINR adjustment unit 24 can calculate the packet error rate by using a Hybrid Automatic Repeat ReQuest (HARQ) technique. If BS communication module 20 is the uplink link module of the BS, and the CINR adjustment unit 24 can calculate the packet error rate by using the HARQ or the Packet Cyclic Redundancy Check (packet CRC) technique.

After receiving the actual reward value from the CINR adjustment unit 24, the MCS selection unit 26 performs step S600 to select an appropriate MCS, and causes the first communication unit 22 to communicate with the CPE communication module 30 according to the selected MCS.

According to an embodiment, the MCS selection method can also be implemented in the CPE communication module 30. Please refer to FIG. 7 , which is a block diagram of a communication module of a client device according to an embodiment. The CPE communication module 30 can include a second communication unit 32 and a CINR adjustment unit 34. For example, the CPE communication module 30 can be an uplink module in the CPE.

The second communication unit 32 is configured to continuously and wirelessly transmit and receive packets during the first period, the second period, or the subsequent period, and can communicate with the first communication unit 22. And the second communication unit 32 can count the total number of packets that have been received so far, and the total number of packets that have occurred so far.

Similar to the CINR adjustment unit 34, the CINR adjustment unit 34 may wait for a first period, inquire the second communication unit 32 to encapsulate the relevant data, and calculate the packet error rate for the first period. If the number of the first packet is less than the threshold of the packet number, the CINR adjustment unit 34 may continue to wait for a second period, and then calculate the packet error rate during the period of the first period plus the second period.

The CINR adjustment unit 34 can be configured to perform the above steps S200, S250, S300, S400, S500, S700, and S800 to calculate an actual reward value according to the CINR return value and the packet error rate. If the CNR communication module 30 is an uplink link module of the CPE, The CINR adjustment unit 34 can calculate the packet error rate using the HARQ or packet CRC techniques.

In step S500, the CINR adjustment unit 34 of the CPE communication module 30 can send the actual reward value to the BS communication module 20, so that the MCS selection unit 26 of the BS communication module 20 selects an appropriate MCS according to the actual reward value. For example, the CPE communication module 30 can cause the channel quality information channel (CQICH) to report the calculated actual return value, thereby affecting the selection of the downlink link module of the BS for the MCS.

For example, it is assumed that the working module is the BS communication module 20, and it is the downlink link module of the BS. Assume that the BS communication module 20 obtains a CINR return value of 28 decibels (dB), correspondingly selects the MCS to be 64QAM-5/6, and communicates with the CPE communication module 30 according to the 64QAM-5/6 rule. When the packet error rate of the packet continuously received by the BS communication module 20 is greater than the error rate threshold, the actual return value may be lowered according to the above steps S300 to S500.

If the packet error rate in a plurality of consecutive first periods is greater than the error rate threshold, the CINR adjustment value will gradually increase and will rise to a positive value, and the actual return value will gradually decrease. The MCS selection unit 26 will select a modulation mode lower than 64QAM-5/6, for example, select MCS to be 64QAM-3/4, and then communicate with the CPE communication module 30 under the rules of 64QAM-3/4.

Conversely, if the packet error rate in a plurality of consecutive first periods is greater than the error rate threshold, the CINR adjustment value will gradually decrease and will fall to a negative value, and the actual reward value will gradually increase, so that the MCS selects Unit 26 has the opportunity to choose a higher modulation mode.

In summary, the MCS selection method, the BS communication module, and the CPE communication module combine the reference CINR and the packet error rate to select the MCS. Therefore, it is possible to avoid MCS that is suitable for the transmission quality of the immediate environment due to overestimation or underestimation of the CINR, thereby improving the efficiency of use of the radio resources.

The above detailed description of the preferred embodiments of the present invention is intended to provide a further understanding of the scope of the invention. On the contrary, the intention is to cover various modifications and equivalent arrangements within the scope of the invention as claimed.

20‧‧‧Base Station Communication Module

22‧‧‧First communication unit

24‧‧‧CINR adjustment unit

26‧‧‧MCS selection unit

30‧‧‧Customer Equipment Communication Module

32‧‧‧Second communication unit

34‧‧‧CINR adjustment unit

FIG. 1 is a schematic diagram of communication between a base station communication module and a user equipment communication module of an embodiment.

Figure 2 is a flow chart showing the selection method of the MCS of an embodiment.

FIG. 3 is a schematic flow chart of step S100 of an embodiment.

Figure 4 is a flow chart showing the adjustment procedure of an embodiment.

Figure 5 is a flow chart showing the selection method of the MCS of another embodiment.

Figure 6 is a block diagram of a base station communication module of an embodiment.

Figure 7 is a block diagram of a communication module of a client device of an embodiment.

Claims (15)

A method for selecting a modulation coding scheme includes: receiving a plurality of first packets in a first period, and calculating a packet error rate according to the first packets; determining whether the packet error rate is greater than an error rate threshold; And when the packet error rate is greater than the error rate threshold, performing the following steps: obtaining a carrier to interference plus noise ratio (CINR) return value; performing an adjustment procedure to obtain a CINR adjustment value Calculating an actual return value according to the CINR return value and the CINR adjustment value; and selecting one of the plurality of modulation coding schemes according to the actual reward value; wherein the adjusting procedure comprises: comparing the packet error rate with the minor repair coefficient And a first adjustment value upper limit, taking the lower one as a first adjustment value; and comparing the sum of a previous adjustment value and the first adjustment value and a second adjustment value upper limit, whichever is lower CINR adjustment value. The method for selecting a modulation coding scheme according to claim 1, wherein the step of receiving the first packets in the first period and calculating the packet error rate according to the first packets comprises: Receiving the first packets during the period; Determining whether the number of the first packets is less than a threshold of the number of packets; when the number of the first packets is greater than the threshold of the number of packets, calculating the packet error rate of the first period; When the number of the first packets is less than or equal to the threshold of the number of packets, the plurality of second packets are continued to be received in a second period, and the packet error rate of the first period and the second period is calculated. The method for selecting a modulation coding scheme according to claim 1, further comprising: when the packet error rate is less than or equal to the error rate threshold, performing the following steps: determining whether the packet error rate is equal to zero; when the packet error rate is When the value is equal to zero, the following steps are performed: obtaining the CINR return value; comparing the difference between a previous adjustment value and a repair coefficient and a lower limit of the adjustment value, and taking the higher one as the CINR adjustment value; according to the CINR return value and the The CINR adjustment value calculates the actual reward value; and selects one of the modulation coding schemes according to the actual reward value. The method for selecting a modulation coding scheme according to claim 3, further comprising: when the packet error rate is not equal to zero, performing the following steps: obtaining the CINR return value; and using the previous adjustment value as the CINR adjustment value. The method for selecting a modulation coding scheme according to claim 1, wherein the step of calculating the actual reward value according to the CINR return value and the CINR adjustment value comprises: subtracting the CINR return value from the CINR adjustment value as a difference The actual return value. A base station communication module includes: a first communication unit, configured to receive a plurality of first packets during a first period; and a CINR adjustment unit, configured to perform the following steps: calculating a packet error according to the first packets And determining whether the packet error rate is greater than an error rate threshold; and when the packet error rate is greater than the error rate threshold, performing the following steps: obtaining a CINR return value; performing an adjustment procedure to obtain a CINR adjustment value; And calculating an actual reward value according to the CINR return value and the CINR adjustment value; and a modulation coding scheme selection unit, configured to select one of the plurality of modulation coding schemes according to the actual reward value; wherein the adjustment procedure includes Comparing the product of the packet error rate with the minor repair coefficient and a first adjustment value upper limit, taking the lower one as a first adjustment value; and comparing the sum of the previous adjustment value and the first adjustment value and a second Adjust the upper limit of the value and take the lower one as the CINR adjustment value. The base station communication module of claim 6, wherein in the step of calculating the packet error rate according to the first packets, the CINR adjustment unit performs the following steps: determining whether the number of the first packets is smaller than a packet threshold value; when the number of the first packets is greater than the threshold of the packet number, calculating the packet error rate of the first period; and when the number of the first packets is less than or equal to the When the threshold is thresholded, the second period is waited for, and the packet error rate of the first period and the second period is calculated according to the plurality of second packets received by the first communication unit in the second period. The base station communication module according to claim 6, wherein the CINR adjustment unit further performs the following steps: when the packet error rate is less than or equal to the error rate threshold, performing the following steps: determining whether the packet error rate is equal to zero; When the packet error rate is equal to zero, the following steps are performed: obtaining the CINR return value; and comparing a difference between a previous adjustment value and an upper repair coefficient and a lower limit of the adjustment value, taking the higher one as the CINR adjustment value; The CINR return value and the CINR adjustment value calculate the actual return value. The base station communication module of claim 8, further comprising: when the packet error rate is not equal to zero, performing the following steps: obtaining the CINR return value; and using the previous adjustment value as the CINR adjustment value. The base station communication module of claim 6, wherein the CINR adjustment unit subtracts the CINR return value from the CINR adjustment value as the actual reward value. A user equipment communication module communicates with a base station communication module, the user equipment communication module includes: a second communication unit, configured to receive a plurality of first packets in a first period; and a CINR The adjusting unit is configured to: calculate a packet error rate according to the first packets; determine whether the packet error rate is greater than an error rate threshold; and when the packet error rate is greater than the error rate threshold, perform the following Step: obtaining a CINR return value; performing an adjustment procedure to obtain a CINR adjustment value; calculating an actual return value according to the CINR return value and the CINR adjustment value; and transmitting the actual reward value to the base station communication module, Having the base station communication module select one of a plurality of modulation coding schemes according to the actual reward value; The adjusting procedure includes: comparing a product of the packet error rate with the minor repair coefficient and a first adjustment value upper limit, taking the lower one as a first adjustment value; and comparing the previous adjustment value with the first adjustment value And a second adjustment value upper limit, which is taken as the CINR adjustment value. The user equipment communication module of claim 11, wherein in the step of calculating the packet error rate according to the first packets, the CINR adjustment unit performs the following steps: determining whether the number of the first packets is If the number of the first packets is greater than the threshold of the number of packets, the packet error rate of the first period is calculated; and when the number of the first packets is less than or equal to When the number of packets is thresholded, the second period is waited for, and the packet error rate of the first period and the second period is calculated according to the plurality of second packets received by the second communication unit in the second period. The CERA adjustment unit further performs the following steps: when the packet error rate is less than or equal to the error rate threshold, performing the following steps: determining whether the packet error rate is equal to zero; When the packet error rate is equal to zero, perform the following steps: obtain the CINR return value; Comparing the difference between a previous adjustment value and an upper adjustment coefficient and a lower adjustment value, taking the higher one as the CINR adjustment value; and calculating the actual return value according to the CINR return value and the CINR adjustment value. The user equipment communication module of claim 13, further comprising: when the packet error rate is not equal to zero, performing the following steps: obtaining the CINR return value; and using the previous adjustment value as the CINR adjustment value. The client device communication module of claim 11, wherein the CINR adjustment unit subtracts the CINR return value from the CINR adjustment value as the actual reward value.