CN104052569B - Method and apparatus for switching MCS - Google Patents

Abstract

The invention discloses a method and a device for switching MCS, wherein the method comprises the following steps: detecting whether MCS used for communication between a first communication node and a second communication node needs to be switched or not; and if so, performing the switching through a direct connection channel between the first communication node and the second communication node. The invention solves the technical problems of larger time delay and higher error rate caused by the MCS switching through the network management system in the related technology, and achieves the technical effects of reducing the MCS switching time delay and reducing the error rate.

Description

Method and apparatus for switching MCS

technical field

The present invention relates to the field of communications, and in particular, to a method and apparatus for switching modulation coding schemes (Modulation Coding Scheme, MCS for short).

Background technique

Microwave communication, together with optical fiber communication and satellite communication, are known as the three main means of modern communication transmission. Microwave communication generally adopts the point-to-point transmission mode, which is currently mainly used in 2G or 3G mobile bearer networks to provide mobile operators with the transmission of voice and data services. It has large transmission capacity, stable long-distance transmission quality, low investment, and construction It has the advantages of short cycle and convenient maintenance. The typical network topology of microwave communication applied to mobile bearer network is shown in Figure 1. The point-to-point scenario can be used for backbone transmission between base stations or between base stations and base station control stations or access gateways.

Generally, the microwave communication node is shown in Figure 2, which consists of a modulation and demodulation unit and a radio frequency transceiver unit. Among them, the modulation and demodulation unit includes: a baseband interface and a modulation and demodulation unit, which is generally placed indoors, so it is also called an indoor unit (In-Door Unit, IDU for short). The radio frequency transceiver unit mainly implements the radio frequency transceiver function, and is generally placed on the tower together with the antenna, so it is also called the Out-Door Unit (ODU for short).

With the development of mobile wireless network and Ethernet technology, microwave transmission has gradually developed from traditional time division multiplexing (TDM) service transmission to today's hybrid service transmission (such as time division multiplexing, E1, Ethernet, etc. The mode of mixing various types of data), and the transmission capacity is gradually increasing. The data from different interfaces are uniformly scheduled and packaged into data frames, then modulated by the modem unit, and sent out through the radio frequency unit. Due to the transmission method of microwave point-to-point wireless communication, the requirements for the environment are relatively high. It is necessary to adjust the modulation method and code rate according to the influence of the environment to adapt to the current channel conditions. When the communication environment is good, a higher modulation method is generally used. The throughput is larger; otherwise, a lower modulation method is used.

At present, when MCS switching is required, the processing method is shown in Figure 3. After the system is powered on, the transceivers of Node A and Node B both work in the default Modulation Coding Scheme (MCS) and code rate. Down. As the environment changes, when the current modulation method and code rate cannot meet the channel requirements, the receivers of node A and node B will send a request to the local central processing unit (Central Processing Unit, CPU for short) to switch the MCS. The command is notified to the CPU of the opposite end through the upper-layer network management system, and the switching command is sent to the local external receiving unit and Modem (modulation and demodulation unit), as well as the external receiving unit and Modem of the source node, thus ensuring the system The switching of the corresponding MCS is performed at the position of the same frame data.

However, when the above method is used for processing, the following problems will mainly occur:

1) Send the switching request to the CPU, and then upload it to the upper-layer network management system, which will cause a large switching delay. Generally, the switching delay will roughly reach 10ms to 20ms;

2) It is difficult to ensure that the external receiving units and Modem of node A and node B perform corresponding MCS switching at the same frame data position, resulting in bit errors;

3) The coordination of external network management is required, and the code required for implementation is relatively large.

For the above problems, no effective solution has been proposed yet.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide a method and device for switching MCS, so as to at least solve the technical problems of large delay and high bit error rate caused by MCS switching through a network management system in the prior art.

According to an aspect of the embodiments of the present invention, there is provided a method for switching an MCS, including: detecting whether the MCS used for communication between a first communication node and a second communication node needs to be switched; in the case of determining yes, The above-mentioned switching is performed through the direct channel between the above-mentioned first communication node and the above-mentioned second communication node.

Preferably, performing the switching through the direct connection channel between the first communication node and the second communication includes: when the first communication node determines that the switching needs to be performed, the first communication node to the first communication node to the first communication node. The second communication node sends an MCS request message, wherein the above-mentioned MCS request message is used to notify the above-mentioned second communication node to use a new MCS for communication on a predetermined frame.

Preferably, the MCS request message is carried in the MCS_type field data frame.

Preferably, after the first communication node sends the MCS request message to the second communication node, the method further includes: the second communication node receives the MCS request message; the sending AMC control module of the second communication node detects that After the frame header indication signal sent by the external receiving unit of the second communication node, the MCS request message is notified to the external receiving unit of the second communication node, so as to notify the external receiving unit of the second communication node that it is receiving When the M-1 th frame after the MCS request message is reached, the above-mentioned new MCS is used for communication, wherein M is a positive integer.

Preferably, after notifying the MCS request message to the external receiving unit of the second communication node, the method further includes: the modulation and demodulation unit of the second communication node and the external receiving unit of the second communication node from the first communication node When the second communication node receives the Mth frame after the MCS request message, it uses the new MCS to communicate.

Preferably, after notifying the MCS request message to the external receiving unit of the second communication node, the method further includes: the receiving AMC control module of the first communication node after the second communication node receives the MCS request message The above-mentioned MCS request message sent by the modulation and demodulation unit of the above-mentioned second communication node is received on the M-1th frame of the above-mentioned second communication node, which is used to notify the above-mentioned first communication node to use the above-mentioned new MCS to communicate; the modulation and demodulation unit of the above-mentioned first communication node The demodulation module starts to use the above-mentioned new MCS to communicate in the next frame after receiving the above-mentioned MCS request message; the external receiving unit of the above-mentioned first communication node receives the above-mentioned second communication node after receiving the above-mentioned MCS request message. When the frame header of the next frame indicates the signal, the above-mentioned new MCS is used for communication.

Preferably, detecting whether the MCS used for communication between the first communication node and the second communication node needs to be switched includes: when the mean square error MSE is greater than a first predetermined threshold and/or the block error rate BLER is greater than a second predetermined In the case of the threshold value, it is determined that the above-mentioned handover needs to be performed between the above-mentioned first communication node and the above-mentioned second communication node.

Preferably, the above method is applied in a microwave communication system.

According to another aspect of the embodiments of the present invention, an apparatus for switching MCS is provided, which is located in a peer communication node and includes: an adaptive modulation and coding AMC engine module, configured to detect a device used for communication with another communication node. Whether the MCS needs to be switched; the originating AMC control module is configured to perform the above switching through the direct connection channel with the above-mentioned another second communication node in the case of determining yes.

Preferably, the above-mentioned originating AMC control module is further configured to send an MCS request message to the receiving-end AMC control module of the above-mentioned another communication node in the case of determining yes, wherein the above-mentioned MCS request message is used to notify the above-mentioned another communication node in the A new MCS is used for communication on a predetermined frame.

In the embodiment of the present invention, in a point-to-point peer-to-peer communication system, if it is detected that the MCS used between two peer-to-peer communication nodes cannot meet the current system requirements, and a new MCS needs to be used for communication, the The direct channel switching between the two peer-to-peer communication nodes is performed without switching through a third-party network management system other than the two peer-to-peer communication nodes, which solves the relatively long delay caused by the MCS switching through the network management system in the related art. The technical problems of large and high bit error rate have achieved the technical effect of reducing the MCS switching delay and reducing the bit error rate.

Description of drawings

The accompanying drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the attached image:

1 is a schematic diagram of a microwave point-to-point transmission scenario according to the related art;

2 is a schematic diagram of the composition of a microwave transmission system according to the related art;

Fig. 3 is the microwave adaptive modulation coding processing block diagram according to the related art;

4 is a preferred flowchart of a method for switching MCS according to an embodiment of the present invention;

5 is a schematic diagram of a modulation and coding frame structure of microwave adaptive modulation and coding according to an embodiment of the present invention;

6 is a preferred structural block diagram of an apparatus for switching MCS according to an embodiment of the present invention;

FIG. 7 is a block diagram of a preferred processing of microwave adaptive modulation and coding according to an embodiment of the present invention.

Detailed ways

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings and in conjunction with embodiments. It should be noted that the embodiments in the present application and the features of the embodiments may be combined with each other in the case of no conflict.

An embodiment of the present invention provides a preferred method for switching MCS. As shown in FIG. 4 , the method includes the following steps:

Step S402: Detecting whether the MCS used for communication between the first communication node and the second communication node needs to be switched;

Step S404: In the case of determining yes, perform the handover through the direct connection channel between the first communication node and the second communication node.

In the above preferred embodiment, in a point-to-point peer-to-peer communication system, if it is detected that the MCS used between the two peer-to-peer communication nodes cannot meet the current system requirements, and a new MCS needs to be used for communication, the The direct channel switching between the two peer-to-peer communication nodes is performed without switching through a third-party network management system other than the two peer-to-peer communication nodes, which solves the relatively long delay caused by the MCS switching through the network management system in the related art. The technical problems of large and high bit error rate have achieved the technical effect of reducing the MCS switching delay and reducing the bit error rate.

In the above step S402, it can be determined whether the switching of the MCS needs to be performed in the following manner. ) is greater than a second predetermined threshold, it may be determined that the handover needs to be performed between the first communication node and the second communication node. Preferably, the above judgment may be made at the first communication node or at the second communication node. Of course, which node makes the judgment, which node triggers the above handover process. In practical applications, there may be multiple MCSs, and each current MCS should correspond to two of the above-mentioned thresholds (the size of the thresholds can be configured by software). Preferably, in order to ensure no codeless handover, the selection of the threshold can leave some margin, that is, when the set threshold value is a threshold value interval, the corresponding handover is performed when it is greater than any value in this interval.

In the above-mentioned step S404, in order to enable the switching directly through the direct channel between the two communication nodes, the corresponding switching request message may be carried through the data frame transmitted between the two communication nodes. In a preferred embodiment, the switching through the direct channel between the first communication node and the second communication includes: when the first communication node determines that the switching is required, the first communication node sends a request to the second communication node. The second communication node sends an MCS request message (that is, the first communication node triggers the subsequent handover process), wherein the MCS request message is used to notify the second communication node to use a new MCS for communication on a predetermined frame. For example, the MCS request message can be carried in the MCS_type field data frame as shown in FIG. 5 , preferably, a segment in the data frame can be preset to carry the MCS request message, for example, the MCS request message can be carried in the MCS_type field in the upper bits of the data frame.

In order to realize that the external receiving unit and the modulation and demodulation unit of the first communication node and the second communication node can switch to the new MCS for communication in the same frame, the synchronization between the two communication nodes can be realized in the following way: After a communication node sends the MCS request message to the second communication node, the second communication node receives the MCS request message; however, the MCS request message is not immediately sent to the external receiving unit of the second communication node, but at the second communication node. After the sending AMC control module of the communication node detects the frame header indication signal (sync) sent by the external receiving unit of the second communication node, it notifies the MCS request message to the external receiving unit of the second communication node. Notifying the external receiving unit of the second communication node to use the new MCS for communication in the Mth frame after the second communication node receives the MCS request message, where M is a positive integer. That is, the two communication nodes configure the value M in advance, and then instruct the external bearer unit of the second communication node to switch to the new MCS for communication at the M-1th frame after receiving the request message. Preferably, M can be configured when the entire communication system is initially powered on. That is, the modulation and demodulation unit of the second communication node and the external receiving unit of the second communication node simultaneously use the new MCS for communication when receiving the Mth frame after the MCS request message from the second communication node.

In a preferred embodiment, the modulation and demodulation unit of the second communication node sends an MCS request message to the receiving AMC control module of the first communication node on the M-1th frame after it receives the MCS request message, to notify The first communication node uses the new MCS to communicate; the modulation and demodulation module of the first communication node starts to use the new MCS to communicate in the next frame after receiving the MCS request message; the external receiving unit of the first communication node When the frame header indication signal of the next frame is received, the communication using the new MCS is started.

Because the external receiving unit of the second communication node has already started to send the first frame when it receives the MCS request message (request mcs), therefore, the external receiving unit can only start counting from the head of the next frame, but the modem is directly from the The current frame starts to be counted at the same time, so the Mth frame counted by the modem is the previous frame of the Mth frame counted by the external receiving unit. The receiving unit, the modem unit of the second communication node, and the external receiving unit of the second communication node can perform MCS switching in the same frame.

In each of the above-mentioned preferred embodiments, the above-mentioned method can be applied to, but not limited to, a microwave communication system.

In this embodiment, a device for switching MCS is also provided, which is located in a peer-to-peer communication node, and the device is used to implement the above-mentioned embodiments and preferred implementations, and what has been described will not be repeated. As used below, the term "unit" or "module" may be a combination of software and/or hardware that implements a predetermined function. Although the apparatus described in the following embodiments is preferably implemented in software, implementations in hardware, or a combination of software and hardware, are also possible and contemplated. FIG. 6 is a preferred structural block diagram of an apparatus for switching MCS according to an embodiment of the present invention. As shown in FIG. 6 , it includes: an adaptive modulation and coding (Adaptive Modulation and Coding, AMC for short) engine module determination unit 602 and an originating AMC The structure of the control module 604 will be described below.

An adaptive AMC engine module 602, configured to detect whether the MCS used for communication with another communication node needs to be switched;

The originating AMC control module 604, coupled with the adaptive modulation and coding engine module 602, is configured to perform the handover through the direct connection channel with the another second communication node in the case of determining yes.

In a preferred embodiment, the above-mentioned sending end AMC control module 604 is further configured to send an MCS request message to the receiving end AMC control module of the other communication node in the case of determining yes, wherein the MCS request message is used for The other communication node is notified to communicate using the new MCS on a predetermined frame.

The above-mentioned device for switching the MCS is located in the first communication node, and the above-mentioned receiving end AMC control module is located in the second communication node. However, it is worth noting that the first communication node and the second communication node are peer-to-peer The communication node, the first communication node and the second communication node all have an adaptive AMC engine module, an originating AMC control module and a receiving AMC control module at the same time.

The present invention is further explained below with a specific preferred system switching structure of adaptive coding and modulation in a point-to-point wireless communication system, but it is worth noting that this preferred embodiment is only for better description of the present invention, and It does not constitute an unreasonable limitation of the present invention.

Through the following embodiments, the peer-to-peer wireless communication system can timely respond to changes in the wireless channel in real channels, and quickly adjust the Modulation Coding Scheme (MCS) without errors to adapt to the current channel. The system switching structure of the adaptive coding and modulation can support the switching of the modulation mode and the coding mode, the hardware implementation structure is relatively simple, only some corresponding judgment conditions need to be added, and the resource overhead is small. The specific description of its implementation process is as follows, as shown in Figure 7:

S1: The Adaptive Modulation and Coding (AMC) engine module of Node B (equivalent to the above-mentioned first communication node) is based on the mean square error (Mean Square Error, MSE) and block error rate (Block Error). Ratio (abbreviated as BLER) to judge the change of the current link (preferably, the judgment condition can be configured through software); when the value of MSE or the value of BLER exceeds a predetermined threshold, it can be determined that switching is required To the corresponding MCS, each current MCS corresponds to two predetermined thresholds (the thresholds can be configured through software). Preferably, in order to ensure no codeless handover, the selection of the threshold can leave some margin, that is, when the set threshold value is a threshold value interval, the corresponding handover is performed when it is greater than any value in this interval.

S2: The AMC engine module of the node B informs the sending AMC control module of the node to carry the corresponding MCS request message (request mcs message) in the next frame. Preferably, the request mcs message can be inserted into the Send in the high bits of the MCS_tpye field in the frame format;

S3: The sending AMC control module of node B sends a data frame carrying the corresponding request mcs message;

S4: After the receiving AMC control module of the A node (equivalent to the above-mentioned second communication node) receives the requestmcs message, it notifies the request mcs message to the sending AMC control module of the A node;

S5: When the sending AMC control module of node A notifies the external receiving unit of node A of the received request mcs after detecting the frame header indication signal (sync) sent by the external receiving unit of node A, for the external receiving unit of node A For the receiving unit, this request mcs indicates the MCS that should be used on the pre_notice number frame, and the pre_notice number (equivalent to the above M) pre-notified frame number can be configured by software at the initial power-on;

S6: When it is detected that the request mcs at this time is different from the last received request mcs, the counter is started, the external receiving unit switches to the new MCS when the pre_notice number frame is counted, and the modem counts the pre_notice number frame. When the request mcs message is carried in the lower part of the MCS type (MCS_tpye) field in the frame format as shown in Figure 5, the request mcs message is sent to the B node. Because sync is the indication signal of the frame header, the external receiving unit receives the request mcs The first frame has already started to be sent, so the external receiving unit can only start counting from the head of the next frame, and the modem starts counting at the same time, so the frame pre_notice number counted by the modem is the frame pre_notice number counted by the external receiving unit. previous frame. The issuance of the above-mentioned pre-notification frame ensures that the fast switching is reduced by a few frames compared with the traditional implementation method, which is equivalent to a reduction of 4-8 milliseconds;

S7: After parsing the request mcs message, the receiving AMC control module of node B notifies the external receiving unit of node B to switch to a new MCS in the next frame, and starts to start a new MCS when the external receiving unit receives the frame header signal MCS, thereby ensuring synchronous switching with the modem.

In the above steps S5 and S6, the MCS pre-notification to the sending end of the external receiving unit is completed, and the two parties switch the corresponding MCS at the position of the frame specified by pre_noticenumber, thereby ensuring that no errors are generated during the switching process. If the pre_noticenumber is configured as 1, the sending AMC control module immediately notifies the received request mcs to the external receiving unit after detecting the frame header indication signal (sync) sent by the external receiving unit, so that the external receiving unit can quickly After completing the switching of MCS, the longest delay in the whole process is only 4ms. Since the change of the channel is a gradual process, the delay of 8ms can keep up with the change of the channel. In the above step S7, the receiving end of the MCS pre-notification of the external receiving unit is completed, and the receiving end is required to receive the switched data at the fastest speed. This switching method not only ensures error-free switching of the system and faster response to current channel changes, but also reduces the switching delay and requires less code for hardware implementation.

In the above preferred embodiment, the channel adjustment information is fed back by node B for the MCS adjustment of the unidirectional link from A to B. Because A and B are peer nodes, the same is true for the channel adjustment information fed back by node A. At the same time, the two make their own adjustments without affecting each other.

In another embodiment, a software is also provided, and the software is used to execute the technical solutions described in the foregoing embodiment and the preferred implementation manner.

In another embodiment, a storage medium is also provided, in which the above-mentioned software is stored, and the storage medium includes but is not limited to: an optical disk, a floppy disk, a hard disk, a rewritable memory, and the like.

From the above description, it can be seen that the present invention achieves the following technical effects: in a point-to-point peer-to-peer communication system, if it is detected that the MCS used between two peer-to-peer communication nodes cannot meet the current system needs, When a new MCS needs to be used for communication, switching is performed through the direct connection channel between the two peer communication nodes, instead of switching through a third-party network management system other than the two peer communication nodes. The technical problems of large delay and high bit error rate caused by MCS switching in the network management system have achieved the technical effect of reducing MCS switching delay and reducing bit error rate.

Obviously, those skilled in the art should understand that the above-mentioned modules or steps of the present invention can be implemented by a general-purpose computing device, which can be centralized on a single computing device, or distributed in a network composed of multiple computing devices Alternatively, they may be implemented in program code executable by a computing device, such that they may be stored in a storage device and executed by the computing device, and in some cases, in a different order than here The steps shown or described are performed either by fabricating them separately into individual integrated circuit modules, or by fabricating multiple modules or steps of them into a single integrated circuit module. As such, the present invention is not limited to any particular combination of hardware and software.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (6)

1. a method for switching modulation and coding mode MCS, is applied in the microwave communication system, is characterized in that, comprises: Detecting whether the MCS used for communication between the first communication node and the second communication node needs to be switched; In the case of determining yes, performing the handover through a direct channel between the first communication node and the second communication node; Wherein, performing the handover through the direct connection channel between the first communication node and the second communication node includes: when the first communication node determines that the handover needs to be performed, the The first communication node sends an MCS request message to the second communication node, wherein the MCS request message is used to notify the second communication node to use a new MCS to communicate on a predetermined frame; After the first communication node sends the MCS request message to the second communication node, the method further includes: the second communication node receives the MCS request message; the second communication node sends the AMC After detecting the frame header indication signal sent by the external receiving unit of the second communication node, the control module notifies the MCS request message to the external receiving unit of the second communication node, for notifying the second communication node The external receiving unit of the communication node uses the new MCS for communication when receiving the M-1 th frame after the MCS request message, where M is a positive integer. 2. The method according to claim 1, wherein the MCS request message is carried in an MCS_type field data frame. 3. The method according to claim 1, wherein after notifying the MCS request message to an external receiving unit of the second communication node, the method further comprises: When the modulation and demodulation unit of the second communication node and the external receiving unit of the second communication node receive the Mth frame after the MCS request message from the second communication node, the new MCS is used for communication . 4. The method according to claim 1, wherein after notifying the MCS request message to an external receiving unit of the second communication node, the method further comprises: The receiving AMC control module of the first communication node receives the information sent by the modem unit of the second communication node on the M-1th frame after the second communication node receives the MCS request message. the MCS request message, used to notify the first communication node to use the new MCS to communicate; The modulation and demodulation module of the first communication node starts to use the new MCS to communicate in the next frame after receiving the MCS request message; The external receiving unit of the first communication node starts to use the new MCS for communication when receiving the frame header indication signal of the next frame after the second communication node receives the MCS request message. 5. The method according to any one of claims 1 to 4, wherein detecting whether the MCS used for communication between the first communication node and the second communication node needs to be switched comprises: When the mean square error MSE is greater than the first predetermined threshold and/or the block error rate BLER is greater than the second predetermined threshold, it is determined that the handover needs to be performed between the first communication node and the second communication node. 6. A device for switching modulation and coding mode MCS, applied in a microwave communication system, characterized in that, being located in a peer-to-peer communication node, comprising: An adaptive modulation and coding AMC engine module for detecting whether the MCS used for communication with another communication node needs to be switched; an originating AMC control module, configured to perform the handover through a direct channel with the another second communication node in the case of determining yes; Wherein, the sending end AMC control module is further configured to send an MCS request message to the receiving end AMC control module of the other communication node in the case of determining yes, wherein the MCS request message is used to notify the other communication node The communication node uses the new MCS to communicate on a predetermined frame; Wherein, the other communication node is used to receive the MCS request message; the other communication node includes a sending AMC control module and an external receiving unit, and the sending AMC control module is used for detecting that the external receiving unit sends After receiving the frame header indication signal of the MCS request message, the MCS request message is notified to the external receiving unit to notify the external receiving unit to use the new MCS request message when the M-1th frame is received. MCS to communicate, where M is a positive integer.

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