CN1956371B - Packet transmission method of wireless network - Google Patents

Abstract

A packet transmission method of wireless network first judges whether the packet to be transmitted is a real-time communication packet. When the packet is a real-time communication packet, whether a retransmission mechanism is started for the packet is determined according to the transmission state of the wireless network.

Description

Packet transmission method of wireless network

technical field

The present invention relates to a packet transmission method, and in particular to a wireless network packet transmission method. the

Background technique

In recent years, wireless network systems (Wireless Network) such as wireless local area network (WLAN) and wireless metropolitan area network (WMAN) have been developed one after another, and the establishment of networks has been completed and provided services one after another. Among them, packet voice and packet video (PacketVoice/Video ) is regarded as one of the most important application service items on the wireless network system. However, providing instant messaging services (Real-time Communication Services) on wireless network systems faces many challenges. For example, most wireless handheld devices are powered by batteries, and the problem of power consumption needs to be overcome; Most of the data are generated regularly and are small packets, which will have a considerable impact on the bandwidth utilization of the wireless network system. the

On the other hand, the design of the wireless network system is mostly based on the transmission of data packets (Data Packet), and has not been optimized for the delivery of instant communication packets (Real-Time Packet). The characteristics of instant messaging packets cannot be fully utilized in the design of wireless network systems. For example, instant messaging can tolerate a certain degree of packet loss, and using extra bandwidth to achieve reliable transmission will not be the most important consideration when transmitting voice packets. Therefore, if the usage capacity of the network bandwidth can be increased and the power consumption of the handheld device can be improved, it will help to develop the instant messaging service in the wireless network environment. the

The operation process of the standard 802.11 is shown in Figure 1. When a mobile communication device (MobileStation, MS) transmits a packet, if the wireless medium is being used by other mobile communication devices, the mobile communication device will wait until the wireless medium is not in use, and then Wait for a distributed cooperation interframe space (DCF Interframe Space, DIFS), and start counting down the contention window (Contention Window, CW). When the contention window counts down to 0, it starts to send, such as request to send (RTS), confirm to send (CTS) and other control packets, or data (Data) and fragmentation (Fragmentation) packets (such as Frg#1 and Frg#2). After the receiving end receives the correct packet, it will send a response (ACK) packet to the sending end after a short interframe space (ShortInterframe Space, SIFS). the

Please refer to FIG. 2 , which is a structural diagram of a system using instant messaging to serve a wireless network. As shown in FIG. 2 , at the wireless network end, one or more wireless network devices 202 , 204 are connected to the wired network end through a wireless network access device (Access Point) 210 to access the Internet (Internet) 230 . Taking an uplink real-time frame as an example, the packet is first sent to the router (Router) 220 of the same LAN through the wireless network access device 210, and then the router 220 sends the packet to the other end through the Internet 230 to communicate with it A node (correspondent node) 240 for instant messaging service. As for the downlink real-time frame, the packet is first sent to the router 220 through the Internet 230, and then the router 220 sends the packet to the wireless network device 202 or 204 through the wireless network access device 210. the

According to the current technology, when using the wireless network environment to transmit instant messaging packets, the easiest way is to always activate the network card so that it can always send and receive packets. But such a design will make the network card still need to consume power even when it is not transmitting packets. One way to improve power consumption is to start the wireless network in a sleep state, and wake up the wireless network device to transmit when there is a packet to be transmitted. This method is generally called the PS-Poll transmission mechanism. Please refer to FIG. 3 , which is a packet sequence diagram and corresponding energy consumption diagram of transmitting real-time packets in the wireless network through the PS-Poll mechanism. As shown in FIG. 3 , the wireless network device (STA) can transmit uplink and downlink instant messaging packets after performing related connection registration operations. After the uplink instant messaging packet (UL Voice) is sent, the wireless network device needs to continue to wait for the response packet (ACK) from the wireless network access device (AP) because it needs to judge whether the packet should be resent. In addition, since the wireless network device is in the power saving mode, for the downlink instant communication packet (DL Voice), the packet stored in the buffer of the wireless network access device needs to be retrieved through PS-Poll. Similarly, in order for the wireless network access device to judge whether the packet should be resent, the wireless network device still needs to send a response packet to the wireless network access device to confirm that the packet is correctly received. Accordingly, in order to achieve reliable transmission of instant messaging packets, two additional SIFS and two response packets will be consumed, thus limiting the improvement of power consumption and network bandwidth usage capacity. the

If the Unscheduled-Automatic Power Saving Delivery (U-APSD) defined by 802.11e is used to deliver instant messaging packets, the power consumption of the PS-Poll transmission mechanism can be further improved. Please refer to FIG. 4 , which is a packet sequence diagram and a corresponding energy consumption diagram of transmitting real-time packets in a wireless network using the U-APSD mechanism. Compared with Fig. 3, the mechanism shown in Fig. 4 has one less PS-Poll packet, and the rest is similar to Fig. 3, and will not be described in detail here. the

In order to achieve a better power-saving effect, in addition to the above-mentioned power-saving transmission mechanism, many related media control technologies have been further developed. Among them, there may be those who reduce the synchronization signal and interval between the mobile communication device and the wireless network access device (Access Point, AP); or those who reduce the problem of hiding the mobile communication device, reduce interference and collision, and reduce the probability of retransmitting packets; Or someone who observes the transmission status of the current wireless medium to reduce redundant sending and receiving actions; or someone who predicts the time point of the next packet sending and receiving through data statistics or prediction; or someone who analyzes the packet for a long time (Long Term) or short time (Short Term) transmission behavior to control transmission to avoid unnecessary power consumption; or a transmission mechanism that modifies the standard Carrier Sense Multiple Access and Collision Avoidance (CSMA/CA); or reduces the transmission of fragmented packets Those who control the packet; or have added protection mechanisms to reduce the probability of long packets colliding during transmission; or have added or modified feedback information (Feedback Message) to help adjust the transmission power; or have reduced retransmission of packet data Unit or Response Packer. In addition, there are many other power saving techniques, such as: reducing detection in sleep mode, reducing system power consumption when receiving short control packets, quality of service (QoS) related power saving mechanisms, using TDMA ( Time Division Multiple Access, TDMA), using Packet Reservation Multiple Access (Packet Reservation Multiple Access), and reducing the transmission of network control information (Control Message), etc. the

However, many of the aforementioned power-saving mechanisms will be modified to the 802.11 transmission mechanism and are not compatible with the standard; some are limited by the results of detection or evaluation and have different power-saving effects; some are for saving a certain part of power consumption And cause power consumption of other parts; some cause other impacts to achieve power saving effects, such as reduced transmission performance (Throughput) or disconnection.

In other words, all current efforts to save power have their drawbacks. In particular, some power-saving mechanisms will cause inconvenience in use due to incompatibility with the standard. Therefore, existing technologies cannot effectively solve the problems encountered in instant messaging. the

In order to make the above and other objects, features and advantages of the present invention more comprehensible, preferred embodiments are specifically cited below and described in detail with accompanying drawings. the

Contents of the invention

According to the above, the object of the present invention is to provide a packet transmission method of wireless network, this packet transmission method transmits the packet of instant communication service through the multicast mechanism defined by the 802.11 standard, and is compatible with the standard in terms of compatibility At the same time, it will not be affected by the accuracy of evaluation or detection, and will not increase the power consumption of other parts to achieve power saving effects, and will not cause other impacts on mobile devices. Through the power saving of this proposal In addition to saving power, the technology can also increase the bandwidth usage capacity of the entire network system. the

To achieve the above object, the present invention proposes a wireless network packet transmission method, which firstly determines whether the packet to be transmitted is an instant messaging packet. And when the packet is an instant messaging packet, it is determined whether to enable the retransmission mechanism for the packet according to the signal strength of the wireless network or the loss rate of the received packet. the

In an embodiment of the present invention, a multicast media access control (MAC) address shared by the wireless access node and the wireless network device is further configured. The multicast MAC address can be obtained through information exchange between the wireless access node and the wireless network device, or can be obtained by converting the unicast network address of the wireless network device. the

In one embodiment of the present invention, when converting the unicast network address of the wireless network device to the multicast MAC address, a standard conversion of converting the unicast network address to the unicast MAC address is first performed program, and then convert the specific field of the network address in the specification standard into a multicast media access control address, so that the unicast media access

In another embodiment of the present invention, after judging that the packet to be transmitted is an instant messaging packet, before deciding whether to enable the retransmission mechanism for this packet, multiple instant messaging packets can be integrated into a downlink chain packet, and the The downlink chain packet is a transmission unit for packet transmission. the

In one embodiment of the present invention, when a plurality of instant messaging packets are integrated into a downlink chain packet, for each instant messaging packet added to the downlink chain packet, it is first converted into a multicast media storage according to the unicast network address. A sub-header is generated by fetching the specific byte used for the control address and the length of the corresponding MAC packet data unit, and then combining the sub-header and the corresponding MAC packet into a sub-packet. After multiple sub-packets are combined, each sub-packet is chain-combined through the sub-header interface. Finally, before the result of the chain combination of these sub-packets, a standard MAC header is added to thereby generate the aforementioned downstream chain packet. the

The present invention detects and separates instant messaging packets and non-instant messaging packets, and dynamically starts and closes the retransmission mechanism of instant messaging packets when dealing with instant messaging packets, so it can effectively reduce the Detect instant messaging packet retransmission and the bandwidth of retransmission packets, and thereby improve the network bandwidth utilization capacity of the wireless network system and the power consumption of the handheld device. the

In order to make the above and other objects, features and advantages of the present invention more comprehensible, preferred embodiments are specifically cited below and described in detail with accompanying drawings. the

Description of drawings

Figure 1 shows the operation flow of the standard 802.11. the

Fig. 2 is a system structure diagram of a wireless network using instant messaging services. the

FIG. 3 is a packet sequence diagram and a schematic diagram of corresponding energy consumption for transmitting real-time packets in a wireless network using the PS-Poll mechanism. the

FIG. 4 is a packet timing diagram and a schematic diagram of corresponding energy consumption for transmitting real-time packets in a wireless network using the U-APSD mechanism. the

FIG. 5 is a schematic diagram of unicast MAC addresses and multicast MAC addresses according to the IPv4 network standard. the

FIG. 6 is a schematic diagram of a packet structure in which multiple instant messaging packets with unicast IP addresses are combined into a downlink chain packet. the

FIG. 7A is a flowchart of operations performed by a router when receiving data from a node according to an embodiment of the present invention. the

FIG. 7B is a flow chart of operations performed by the router when receiving data from the wireless network access device according to an embodiment of the invention. the

FIG. 8A is a flowchart of operations performed by a wireless network device when receiving data from a wireless network access device according to an embodiment of the invention. the

FIG. 8B is a flow chart of operations performed by the wireless network device when uploading data to the wireless network access device according to an embodiment of the present invention. the

Marking description of main components

202, 204: wireless network device

210: Wireless network access device

220: Router

230: Internet

240: node

600, 620, 640: packets with unicast IP addresses

610, 630, 650: headers

612, 632, 652: specific bytes

660: Downlink chain packet

670: Header of Downlink Chain Packet

672a, 672b, 672c: Subheaders

680a, 680b, 680c: MAC packet data unit

S700～S720: implementation steps of an embodiment of the present invention

S730～S746: Implementation steps of an embodiment of the present invention

S800～S818: Implementation steps of an embodiment of the present invention

S830～S848: Implementation steps of an embodiment of the present invention

Detailed ways

In the following, a wireless local area network (WLAN) will be used for illustration, but the content of the present invention is applicable to various wireless network systems, and is not limited to be used in a wireless local area network. And the embodiment will take the dynamic correspondence and allocation method of multicast/unicast addresses as an example to describe in detail the specific technical means to achieve the separation of instant messaging packets and non-instant messaging packet retransmission mechanisms, but it is also possible to activate and close voice packets dynamically through other methods. A retransmission mechanism is used to achieve the effects described in the present invention. the

Please refer to the network structure shown in FIG. 2 again for a clear understanding of the subsequent description. When the present invention is used in the PS-Poll mechanism, the wireless network device 202 or 204 will first perform the relevant connection registration operation on the wireless network access device 210 and the router 220, and communicate with the node 240 on the other end for instant messaging service Establish an instant messaging connection. Through this part of the action, the wireless network access device 210 will enable the support for the dynamic correspondence and distribution method of the multicast/unicast address of the wireless network device 202 or 204, and provide the router 220 with the ability to distinguish instant communication packets from non-instant communication packets. Necessary parameters of the communication packet. Then, the wireless network device 202 or 204 can judge whether to use the multicast address for uplink and downlink IM packet transmission according to the current communication quality or packet loss situation, so as to disable the retransmission mechanism. the

In an IPv4 embodiment of the present invention, when performing the relevant connection registration operation between the wireless network device 202 or 204 and the wireless network access device 210 and the router 220, the wireless network device 202 or 204 first needs to generate a valid The multicast address (represented here by the multicast media access control address MAC MA). This multicast address can be generated by combining the last 23 bits of the unicast address of the wireless network device 202 or 204 (represented by the unicast media access control address MAC STA here) with the standard prefix of the multicast address MAC MA (prefix) generated. Of course, other technologies that can achieve multicast address generation can also be used in this case. Next, the wireless network device 202 or 204 makes a connection request to the wireless network access device 210 . In this connection request, the wireless network device 202 or 204 will carry the multicast address MAC MA as a parameter, and the wireless network access device 210 can update this parameter in the current wireless network device connection table after receiving the request middle. Alternatively, these multicast addresses MAC MA can be directly generated by the wireless network access device 210 according to the unicast address MAC STA of the wireless network device 202 or 204, so that no additional information or data exchange operations are required. the

In order for the router 210 to transmit the downlink instant messaging packet sent to the wireless network device 202 or 204 using the multicast address of the wireless network device, the wireless network device 202 or 204 needs to use the Address Resolution Protocol (ARP, Address Resolution Protocol) to update the ARP list of the router 210. At this time, the network (IP) address of the wireless network device 202 or 204 will correspond to its multicast address MAC MA and unicast address MAC STA at the same time. Finally, in order to make the router 210 distinguish between instant messaging packets and non-instant messaging packets, a simple method for identifying instant messaging packets and non-instant messaging packets can be accomplished through port numbers (Port Number), that is, router 210 can pass The session description protocol (Session Description Protocol, SDP) information brought when the wireless network device 202 or 204 establishes an instant messaging connection invitation with the other end instant messaging node 240, records the port number used by the instant messaging connection for subsequent identification Whether it is used for instant messaging packets. In addition, for example, whether the packet uses a specific address header, whether the packet is carried out according to a specific information exchange method (such as the aforementioned SDP), etc., can also be used as the basis for judging whether the packet is an instant messaging packet. the

After the aforementioned packet transmission preparatory work is completed, the actual packet transmission can be started. According to the technology of the present invention, the packet transmission at this time can be easily divided into two types: instant messaging packets and non-instant messaging packets. For non-IM packets, no special processing is performed in this embodiment. However, this does not mean that these non-instant messaging packets cannot be changed in any transmission, which is well known to those skilled in the art and will not be repeated here. On the other hand, for the instant messaging packet, the present invention will determine whether to enable the retransmission mechanism according to the transmission state of the wireless network. For example, the wireless network device 202 or 204 can divide its transmission behavior on the time axis into several time periods with a time length t, and use the signal strength (RSSI) or the packet loss rate (Packet Lost Rate) and other parameters to judge the current network status. In other words, in the present invention, the wireless network device 202 can be made to check the signal strength every predetermined time t, and turn off the retransmission mechanism of the instant messaging packet when the signal strength is greater than a default value. Alternatively, it is also possible to confirm the packet loss rate at intervals of a predetermined time t, and enable the retransmission mechanism of instant messaging packets when the packet loss rate is higher than a default value. the

In an embodiment of the present invention, the function of controlling whether to enable the retransmission mechanism of the instant messaging packet is determined by controlling whether the instant messaging packet becomes a multicast packet. According to the current network transmission specification, the multicast packet will not have a packet retransmission mechanism, so if the instant messaging packet can be converted from unicast to multicast, the overall time of instant messaging packet transmission can be reduced. Different from other conversion mechanisms, when it is necessary to convert packets from unicast to multicast, the present invention converts packets that are still in unicast state at the network layer (IP layer) when entering the data link layer (Data Link Layer) , change the header of its Media Access Control (Medium Access Control, MAC) address, so that the MAC address of the above-mentioned packet can be converted into a multicast mode. the

Please refer to FIG. 5 , which is a schematic diagram of unicast MAC addresses and multicast MAC addresses according to the IPv4 network standard. As shown in FIG. 5 , for current network transmission specifications, the difference between a unicast MAC address and a multicast MAC address lies in that the front end of the address has different values. Therefore, as long as the content of the specific field of the unicast MAC address in the specification standard (in the specification standard of IPv4, it refers to the first 25 bits of the MAC address here, while in the specification standard of IPv6, it refers to the Or it is the first 16 bits of the MAC address) into the content of a specific field of the multicast media access control address, and the unicast MAC address can be easily converted into a multicast MAC address. According to this point, after obtaining an instant communication packet with a unicast network (IP) address, the standard conversion procedure of converting the unicast network address into a unicast MAC address can be carried out earlier (these standard conversion procedures are different due to different network standards are different, but their conversion should be well known to those skilled in the art, so details will not be repeated here). the

After the unicast MAC address is converted, the standard content of the specific field of the unicast MAC address in the network specification standard must be converted into the standard content of the specific field of the multicast MAC address according to the method shown in Figure 5, so that A unicast MAC address becomes a multicast MAC address. Finally, in order to prevent unicast instant messaging packets from being mistaken for multicast instant messaging packets when decoding, in this embodiment, a predefined multicast address group can be used, that is, the MAC address belongs to this group The address within is regarded as an instant communication packet, and if it is not in this address group, it is regarded as a general multicast packet. the

In addition, it is possible to further integrate instant messaging packets with the same attribute into a downlink chain packet, and use the downlink chain packet as a transmission unit for packet transmission. Among other things, these attributes may be power consumption, quality of service (QoS), security, delivery delay or delay jitter, and the like. Please refer to FIG. 6 , which is a schematic diagram of a packet structure combining multiple instant messaging packets 600 , 620 and 640 with unicast IP addresses into a downlink chain packet 660 . In this embodiment, the specific bytes 612, 632, and 652 discarded when converting the unicast IP address to the multicast MAC address are used, and the length of the subsequent MAC packet data unit (680a, 680b, and 680c) is added to generate A new sub-header (Sub-Header) 672a, 672b, and 672c, plus MAC packet data units 680a, 680b, and 680c are combined to form a sub-packet (Sub-Packet). That is, 672a and 680a are combined into one subpacket, 672b and 680b are combined into one subpacket, and 672c and 680c are combined into one subpacket. Then, multiple sub-packets are combined into a long packet by sub-headers in a chained manner, and a standard multicast MAC header 670 is added to generate a downlink chained packet 660 . the

In the above process, the content of the sub-header can be changed according to the IP version, and the length of the sub-packet can be changed according to the actual length of the MAC packet data unit. Other data packets can also operate according to the original conversion and transmission methods without any influence. Using this technology, multiple packets with the same attributes, including power consumption, QoS, and security, can be chained into a single MAC packet for transmission. Transmission contention between packets. In this mechanism, packets with the same type will be transmitted using the same type of transmission method, such as transmission delay (Delay), delay jitter (Jitter), or other attributes, and cooperate with the algorithm to run. the

In the case of using downlink chain packets, in the network environment shown in FIG. 2, the operations of the mobile communication device 202 or 204 and the router 220 can be slightly modified for corresponding operation support. Please refer to FIG. 7A , which is a flow chart of operations performed by the router 220 or other network devices with Layer 3 processing capabilities when receiving data from the node 240 according to an embodiment of the present invention. When the device receives a TCP/IP packet sent from the external network (step S700), it first distinguishes whether the packet belongs to an instant messaging packet (steps S702, S704), if it is not an instant messaging packet, then use the general processing and transmission method Send (step S706). If it is an instant messaging packet, identify which service mechanism the packet belongs to (step S708). Then it is determined whether a sub-packet needs to be generated according to whether it belongs to the same type of service mechanism (step S710). If a sub-packet needs to be generated, the corresponding sub-header is generated through the conversion program (step S712), and then its packet data unit is added to generate a sub-packet (step S714). After the sub-packet does not need to be established or the sub-packet has been established, it is then judged by algorithm calculation whether the transmission time is reached (step S716). If the transmission time has not been reached, then this sub-packet is put into the process (Schedule) or queue (Queue), waiting for the time of transmission (step S720); otherwise, if the transmission time has been reached, a new service mechanism belonging to these service mechanisms is generated type of multicast MAC header, and concatenate the subpackets in the process or queue into a single packet and send it out (step S718). the

Next, please refer to FIG. 7B , which is a flow chart of operations performed by the router 220 or other network devices with Layer 3 processing capabilities when receiving data from the wireless network access device 210 according to an embodiment of the present invention. In this embodiment, when a packet is received from the wireless network access device 210, identification processing is performed on the header of the packet (step S730). If it is found to be a non-multicast packet after identification, then use the standard method for processing (step S732); otherwise, if it is found to be a multicast packet after identification, then process the header of the multicast packet (step S734), and identify whether Belongs to a predefined instant messaging package (step S736). If the identification of step S736 finds that it is not a predefined instant messaging packet, then use the general multicast method to process (step S738); otherwise, if it is a predefined instant messaging packet, then interpret the sub-header of the packet (step S740 ), then process the sub-packet data unit (step S742), then remove the sub-header and pass the packet to the upper layer for processing (step S744). Finally check whether there is a next batch of sub-packets (step S746), if yes, then do the same process (steps S740-S746), if not, then end this program. the

Next, please refer to FIG. 8A , which is a flowchart of operations performed when the wireless network device 202 or 204 receives data from the wireless network access device 210 according to an embodiment of the present invention. In this embodiment, when the mobile communication device 202 or 204 receives a packet transmitted from the external network through the wireless network access device 210, it will first determine whether it is a multicast packet (step S800), if not, then according to the standard The method processes the packet (step S802). If it is a multicast packet, process the header (step S804). Then it is judged whether the package belongs to the predefined instant messaging package (step S736), if not, then process according to the standard method (step S802); if so, then perform subsequent processing for the package. First, check the sub-header to judge whether this batch of sub-packets belongs to oneself (steps S808, S810), if not then ignore this batch of sub-packets (step S812), then check the next batch of sub-packets (S818); otherwise, if this The batch of subpackages belongs to oneself, then processing (step S814) for the subpackage, the subheader is removed and unwrapped after the subpackage data unit is delivered to the upper layer for processing (step S816), then check the next batch of subpackages (step S818 ) until the entire multicast packet has been interpreted. the

Next, please refer to FIG. 8B , which is a flowchart of operations performed when the wireless network device 202 or 204 uploads data to the wireless network access device 210 according to an embodiment of the present invention. Wherein, when the wireless network device has data to be transmitted (step S830), it first classifies the TCP/IP packet (step S832). If it is not a predefined instant messaging package, it will be processed and transmitted according to the general data processing principles (steps S834, S836); and if it is a predefined instant messaging package, it will be judged whether it belongs to which specific service mechanism (steps S834, S836). S838), and then generate the sub-header corresponding to the service mechanism (step S840), and then add the packet data unit to form a MAC sub-packet (step S842). Afterwards, calculate whether to send out (step S844) according to process or algorithm, if should send out, then this packet is sent out (step S846) according to the principle of multicast transmission; Or wait in the queue for transmission time (step S848). the

It can be clearly known from the above descriptions that the present invention decides to enable or disable the packet retransmission mechanism by actively controlling whether the instant messaging packet is a multicast packet. One of the ways to control whether the instant messaging packet is a multicast type is to use the above-mentioned means of changing the MAC address to achieve. If the method provided by the present invention is used on the PS-Poll transmission mechanism, then because the multicast address is used for transmission on the uplink and downlink instant communication packet transmission, the retransmission mechanism can be closed to reduce the time of waiting for the response packet Time, by reducing two short interframe spaces and two response packets, the wireless network device can improve both power consumption and network bandwidth utilization. Similarly, the method provided by the present invention can also be applied to other instant messaging power-saving transmission methods such as U-APSD. At this time, because the multicast address is used to transmit the uplink and downlink instant messaging packet transmission, it can be transmitted. Turn off the retransmission mechanism to reduce the waiting time for the response packet. By reducing the space between two short frames and two response packets, it can also improve the power consumption and network bandwidth usage at the same time. According to the experimental results, the utilization rate of the network bandwidth can be increased by about 40%, and at the same time, the power consumption can be saved by about 40%. the

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make some modifications and improvements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be defined by the claims. the

Claims (24)

1. A packet transmission method of a wireless network, characterized in that it comprises the following steps: Judging whether a packet to be transmitted is an instant messaging packet; and When the packet is an instant messaging packet, it is determined whether to enable a retransmission mechanism for the packet according to the signal strength of the wireless network, wherein the multicast MAC address is used as the destination MAC address of the instant messaging packet to The retransmission mechanism is disabled, wherein the unicast MAC address is used as the destination MAC address of the instant messaging packet to enable the retransmission mechanism. 2. The packet transmission method of the wireless network according to claim 1, wherein the step of deciding whether to open the retransmission mechanism for the packet according to the signal strength of the wireless network comprises: confirming the signal strength at predetermined intervals; and When the signal strength is greater than the default value, turn off the retransmission mechanism for the packet. 3. The method for transmitting packets in a wireless network according to claim 1, further comprising setting a multicast MAC address commonly used by the wireless access node and the wireless network device. 4. The packet transmission method of wireless network according to claim 3, wherein the MAC address is set through the information exchange between the wireless access node and the wireless network device. 5. The wireless network packet transmission method according to claim 3, wherein the multicast MAC address is obtained by converting the unicast network address of the wireless network device. 6. The wireless network packet transmission method according to claim 5, wherein the step of converting the unicast network address of the wireless network device to obtain the multicast MAC address comprises: perform standard translation procedures for translating the unicast network address to a unicast media access control address; and converting the content of the specific field of the unicast MAC address into the content of the specific field of the multicast MAC address, so that the unicast MAC address becomes a multicast MAC address. 7. The packet transmission method of wireless network according to claim 1, characterized in that the original unicast MAC address is used as the destination MAC address of the non-IM packet to enable the retransmission mechanism. 8. The packet transmission method of wireless network according to claim 1, wherein the step of judging whether the packet to be transmitted is an instant messaging packet comprises: record the network port numbers, address headers and specific information exchange methods used when establishing instant messaging; and When it is found that the port number used to send the packet is the network port number, the packet uses the address header, and the packet is sent in the specific information exchange mode, it is determined that the packet is an instant messaging packet. 9. The packet transmission method of wireless network according to claim 1, characterized in that after judging that the packet to be transmitted is an instant messaging packet, before deciding whether to open the retransmission mechanism for the packet, the following steps are also carried out: Integrating multiple downlink instant messaging packets into downlink chain packets; and The downlink chain packet is used as a transmission unit for packet transmission. 10. The packet transmission method of wireless network according to claim 9, characterized in that the step of integrating a plurality of downlink instant messaging packets into the downlink chain packet comprises: generating a sub-header according to the specific byte used when converting the downlink unicast network address into the multicast MAC address and the length of the corresponding MAC packet data unit; combining the sub-header and the corresponding MAC packet into a sub-packet; chain-combining each sub-packet via sub-header interfacing; and The downstream chained packet is generated by prepending the result of the chained combination of each sub-packet with a standard MBAC header. 11. The wireless network packet transmission method according to claim 9, characterized in that when a plurality of downlink instant messaging packets are integrated into the downlink chain packet, downlink instant messaging packets with the same attribute are integrated together. 12. The wireless network packet transmission method according to claim 11, wherein the same attribute includes one of power consumption, quality of service, security, transmission delay and delay jitter. 13. A packet transmission method of a wireless network, characterized in that it comprises the following steps: Judging whether a packet to be transmitted is an instant messaging packet; and When the packet is an instant messaging packet, determine whether to enable the retransmission mechanism for the packet according to the packet loss rate of the wireless network, wherein the multicast MAC address is used as the destination MAC of the instant messaging packet address to disable the retransmission mechanism, wherein the unicast MAC address is used as the destination MAC address of the instant messaging packet to enable the retransmission mechanism. 14. The packet transmission method of the wireless network according to claim 13, wherein the step of determining whether to open the retransmission mechanism for the packet according to the packet loss rate of the wireless network includes: confirming the packet loss rate at regular intervals; and When the loss rate of the sending and receiving packet is higher than the default value, the retransmission mechanism is enabled for the packet. 15. The method for transmitting packets in a wireless network according to claim 13, further comprising setting a multicast MAC address commonly used by the wireless access node and the wireless network device. 16. The packet transmission method of wireless network according to claim 15, wherein the MAC address is set through the information exchange between the wireless access node and the wireless network device. 17. The wireless network packet transmission method according to claim 15, wherein the multicast MAC address is obtained by converting the unicast network address of the wireless network device. 18. The wireless network packet transmission method according to claim 17, characterized in that the step of converting the unicast network address of the wireless network device to obtain the multicast MAC address comprises: perform standard translation procedures for translating the unicast network address to a unicast media access control address; and converting the content of the specific field of the unicast MAC address into the content of the specific field of the multicast MAC address, so that the unicast MAC address becomes a multicast MAC address. 19. The wireless network packet transmission method according to claim 13, wherein the original unicast MAC address is used as the destination MAC address of the non-IM packet to enable the retransmission mechanism. 20. The packet transmission method of wireless network according to claim 13, characterized in that the step of judging whether the packet to be transmitted is an instant messaging packet comprises: record the network port numbers, address headers and specific information exchange methods used when establishing instant messaging; and When it is found that the port number used to send the packet is the network port number, the packet uses the address header, and the packet is sent in the specific information exchange mode, it is determined that the packet is an instant messaging packet. 21. The packet transmission method of wireless network according to claim 13, characterized in that after judging that the packet to be transmitted is an instant messaging packet, before deciding whether to enable the retransmission mechanism for the packet, the following steps are also performed: Integrating multiple downlink instant messaging packets into downlink chain packets; and The downlink chain packet is used as a transmission unit for packet transmission. 22. The packet transmission method of wireless network according to claim 21, characterized in that the step of integrating a plurality of downlink instant messaging packets into the downlink chain packet comprises: generating a sub-header according to the specific byte used when converting the downlink unicast network address into the multicast MAC address and the length of the corresponding MAC packet data unit; combining the sub-header and the corresponding MAC packet into a sub-packet; chain-combining each sub-packet via sub-header interfacing; and The downstream chained packet is generated by prepending the result of the chained combination of each sub-packet with a standard MBAC header. 23. The packet transmission method of wireless network according to claim 21, characterized in that when a plurality of downlink instant messaging packets are integrated into the downlink chain packet, the downlink instant messaging packets with the same attribute are integrated together. 24. The packet transmission method of wireless network according to claim 23, wherein the same attribute includes one of power consumption, quality of service, security, transmission delay and delay jitter.

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