CN103326844B - Based on 802.11 agreement resource allocation methods in composite mode - Google Patents

Abstract

The invention relates to network data transmission technology, in particular to a method for uplink access and resource allocation based on 802.11 protocol mixed mode. The main technical solution of the method of the present invention is: identify the rate category of the access terminal through the access point, the rate category includes high-rate terminals and low-rate terminals, and then according to the rate category of the access terminal, the access point The data transmission time or transmission opportunity of the access terminal is allocated, and part of the transmission time or transmission opportunity of the low-rate terminal is allocated to the downlink data transmission of the high-rate terminal or the access point. The beneficial effect of the present invention is that by automatically identifying the terminal type, when the terminal STA accesses the AP, the AP side controls the uplink channel access opportunity and TXOP resource allocation time of each terminal to ensure the fairness of resources, thereby effectively improving the throughput and end-user perceptions. The present invention is especially applicable to the resource allocation method in the hybrid mode.

Description

Resource Allocation Method Based on Mixed Mode of 802.11 Protocol

technical field

The invention relates to network data transmission technology, in particular to a method for uplink access and resource allocation based on 802.11 protocol mixed mode.

Background technique

WLAN is the product of the combination of computer network and wireless communication technology. It uses wireless channels to access the network and provides a method for the mobility of communication. WLAN can be used as an extension of the traditional wired network, and WLAN is playing an increasingly important role due to its high flexibility, mobility, low cost and increasing transmission capacity, becoming one of the mainstream forms of future network development.

At present, there are mainly four types of wireless network standards that have been commercialized, namely 802.11n, 802.11a, 802.11g, and 802.11b. 802.11b can support a data rate of up to 11Mbps, and operates in the 2.4GHz ISM frequency band. The modulation technology uses complementary code keying (CCK) technology. The transmission speed of 802.11b cannot meet the wireless transmission requirements of large-capacity data, so the 802.11a and 802.11g. 802.11a works in the 5GHz frequency band, and adopts Orthogonal Frequency Division Multiplexing (OFDM) technology, and the speed reaches 54Mbps. Compared with 802.11b, 802.11a suffers less interference. modulation technique, so the two are incompatible. 802.11g adopts the 2.4GHz working frequency spectrum and uses Orthogonal Frequency Division Multiplexing (OFDM) technology to increase the transmission rate to 54Mbps. 802.11g is compatible with 802.11b. Since 802.11g signals can penetrate walls and floors, 802.11g can transmit signals farther than 802.11a. Therefore, 802.11g not only provides higher network bandwidth, but also protects the original investment, thus becoming the current market leader. mainstream. In order to achieve high-bandwidth and high-quality WLAN services and make WLAN reach the performance level of Ethernet, 802.11n is produced. The 802.11n protocol is a dual-frequency working mode, which can work at 2.4GHz and 5GHz. The combination of Multiple Input Multiple Output (MIMO) and Orthogonal Frequency Division Multiplexing (OFDM) technology not only improves the quality of wireless transmission, but also enables 802.11n to achieve a transmission rate of 300Mbps or even as high as 600Mbps. In the 802.11n draft, it is required that 802.11n products can operate in a mixed mode including 802.11a, 802.11g, and 802.11b, and have backward compatibility.

Hybrid networking, that is, through the effective integration of multiple networking technologies, network bandwidth is increased and signal coverage is expanded, so that users can obtain maximum bandwidth and support for multimedia applications. However, in a mixed networking scenario, for example, there are 802.11b, 802.11g, and 802.11n among commercialized wireless network standards. 802.11b can support a maximum data rate of 11Mbps, 802.11g's transmission rate is increased to 54Mbps, and 802.11n protocol can achieve a transmission rate of 300Mbps or even as high as 600Mbps. When these three modes exist in the hybrid network at the same time, the time required to send the same amount of data is different. As shown in Figure 1, 11n users can send the data in a short time, but due to the access of each terminal APs (Access Points) have equal opportunities, that is, the opportunities to obtain time resources are the same, resulting in 11n mode users having to wait for a long time before sending data, wasting too much time resources, and making the allocation of resources unsatisfactory. Reasonable, thus greatly reducing the system throughput and user experience. Therefore, we need to design a method to control the uplink channel access opportunity and TXOP resource allocation time of each terminal when the terminal STA accesses the AP in the mixed networking scenario to ensure the fairness of resources, thereby effectively improving the throughput. and end-user experience.

Contents of the invention

The technical problem to be solved by the present invention is to provide a resource allocation method based on the mixed mode of the 802.11 protocol based on the current IEEE802.11 protocol.

The technical solution adopted by the present invention to solve the above-mentioned technical problems is: a resource allocation method based on the 802.11 protocol mixed mode, which is characterized in that it includes:

The access point identifies a rate class of the access terminal, the rate class including a high rate terminal and a low rate terminal;

According to the rate category of the access terminal, the access point allocates the data transmission time or transmission opportunity of the access terminal, and allocates part of the transmission time or transmission opportunity of the low-rate terminal to the downlink data of the high-rate terminal or the access point transmission.

Specifically, the access point identifies the rate category of the access terminal, including:

The access point sets the statistical table to record the connection parameters of the connected terminal, which is used to identify the access terminal as a high-speed terminal or a low-speed terminal.

Specifically, the access point allocates the data transmission time or transmission opportunity of the access terminal, including:

After the access point receives the request transmission message control frame sent by the access terminal to request time resources, it judges the transmission permission control frame according to the identified rate category of the access terminal and sends it to the access terminal or the access point itself .

Specifically, the judging according to the identified rate category of the access terminal that the control frame is allowed to be sent is sent to the access terminal or the access point itself, including:

Determine whether the access terminal is a high-rate terminal or a low-rate terminal. If it is a high-rate terminal, the access point directly sends a control frame to allow sending, and allocates time resources to the access terminal for data transmission;

If it is a low-speed terminal, the access point will generate a random number and compare it with the preset probability number. If the random number is smaller than the probability number, the access point will modify the address of the receiving station in the control frame that is allowed to be sent to the access point. The address of the access point itself, giving the opportunity of data transmission to the access point itself;

If the random number is greater than the probability number, the access point directly allocates time resources to the access terminal for data transmission.

Specifically, the random number is a random number between 0 and 1.

Specifically, the probability number is 1/3.

Specifically, the judging according to the identified rate category of the access terminal that the control frame is allowed to be sent is sent to the access terminal or the access point itself, including:

Determine whether the access terminal is a high-rate terminal or a low-rate terminal. If it is a high-rate terminal, the access point directly allocates time resources for data transmission;

If it is a low-speed terminal, the access point obtains the time length field in the control frame of the request transmission message, shortens the time length according to a certain shortening ratio, and then sends the permission to send control frame to allocate time resources to the access terminal to allow access terminal for data transmission.

Specifically, the shortening ratio is 1/6.

The beneficial effect of the present invention is that by automatically identifying the terminal type, when the terminal STA accesses the AP, the AP side controls the uplink channel access opportunity and TXOP resource allocation time of each terminal to ensure the fairness of resources, thereby effectively improving the throughput and end-user perceptions.

Description of drawings

FIG. 1 is a schematic diagram of time resource distribution of each user in a hybrid networking mode;

Fig. 2 is a schematic diagram of the composition and workflow of the scene system adopting the present invention;

FIG. 3 is a schematic diagram of distribution on the time axis of signaling interaction in an embodiment;

Figure 4 is a schematic diagram of the RTS frame format;

FIG. 5 is a schematic diagram of a CTS frame format;

Fig. 6 is a schematic diagram of the frame format of the data frame;

FIG. 7 is a schematic diagram of the frame format of the ACK frame;

Fig. 8 is a schematic diagram of the flow of the first AP side of the embodiment;

Fig. 9 is a schematic diagram of the second AP side flow of the embodiment;

Among them, M represents a number generated randomly, and P represents a known and determined probability number.

detailed description

Currently, in the hybrid mode scenario, low-rate terminals and high-rate terminals have equal opportunities to access the channel, causing time resources to be allocated unfairly when multiple terminal types coexist, resulting in poor quality of service for high-rate terminals. Degradation of user experience. Therefore, the basic idea of the present invention is to introduce TXOP donation, that is, a low-rate terminal donates a part of its own transmission duration or transmission opportunity for downlinking of a high-rate terminal or AP. The details are as follows: When a terminal needs to access the AP, the terminal will send an RTS control frame to the AP to request time resources. Usually, the AP will send a CTS to the terminal to allow sending control frames, and allocate time resources to the terminal. However, regarding the above questions we raised, we hope that time resources can be used more reasonably to ensure the fairness of resources. Therefore, the AP determines whether to send CTS to the original terminal or send CTS-to-Self by identifying the type of terminal , allocating time resources to the AP itself, that is, allocating the uplink time slot to downlink data transmission. Alternatively, the second method is to reasonably modify the time length field in the CTS frame format, so as to control the time resource allocation of low-rate devices. According to this idea, let the low-rate terminal donate part of its own time resource, TXOP, to the high-rate terminal, thus ensuring the rationality of resource allocation and improving the overall throughput of the hybrid networking scenario.

Below in conjunction with accompanying drawing and embodiment, describe technical solution of the present invention in detail:

Example:

As shown in Figure 2, the scenario includes one AP and three terminals: STA1, STA2 and STA3. STA1 is a low-rate user and plans to send data to the AP, but STA2 and STA3 have not sent data. The AP keeps a table (as shown in Table 1) for the terminal STA in the connected state under its jurisdiction, which is used to identify whether the terminal is a high-speed terminal or a low-speed terminal. In the example in Figure 2, the AP receives the request from STA1 to send uplink data, and through identifying STA1, selects how much to perform terminal access control or resource (duration) allocation.

Table 1 Access terminal high and low rate identification table

The specific signaling control process is shown in Figure 2 and Figure 3. STA1 prepares to send data to the AP, and first sends a request to send message RTS (Request to Send, RTS control frame format is shown in Figure 4), because RTS is robustly modulated, Therefore, AP, STA2, and STA3 will all receive the RTS sent by STA1. Among them, STA2 and STA3 will modify their NAV according to the duration field in the RTS (RTS control frame format is shown in Figure 4), thereby reducing the occurrence of collisions. After receiving the RTS frame, the AP will judge the type of STA1 through Table 1, select the corresponding decision to allocate time resources (the specific decision-making process is described in Section 3), and send the permission to send the message CTS (CleartoSend, CTS control The frame format is shown in Figure 5). Because the CTS frame is also robustly modulated, STA1, STA2 and STA3 will all receive it. If the AP chooses to allocate time resources to the AP itself, STA1, STA2, and STA3 will modify their own NAV values according to the duration field of the CTS, and the AP will transmit downlink data. If the AP chooses to allocate time resources to STA1, STA2 and STA3 will modify their NAV values according to the duration field of the CTS. STA1 obtains time resources by analyzing the duration field in the CTS frame and transmits data to the AP. The data frame format is as follows: As shown in FIG. 6 , the format of the ACK frame is shown in FIG. 7 .

Processing flow on the AP side: After the AP receives the RTS sent by STA1, there are two methods for the AP to choose.

Method 1 is shown in Figure 8:

After the AP receives an RTS control frame sent by STA1, it judges that STA1 is a high or low rate user according to the high and low rate identification table 1 established on the AP side in advance.

If STA1 is a high-speed user, the AP directly sends a CTS control frame to allocate time resources to this terminal for data transmission.

If STA1 is a low-rate user, the AP will generate a random number between (0,1) and compare it with the determined probability P, for example: P=1/3.

If the random number is less than this probability, the AP will modify the RA and duration fields in the CTS control frame, modify the receiving station address (RA) in the CTS control frame to the address of the AP, and give the opportunity of data transmission to the AP itself, that is, change for downlink transmission.

If the random number is greater than this probability, the AP directly allocates time resources to the terminal STA1 for data transmission.

The second solution is shown in Figure 9:

After the AP receives the RTS control frame sent by STA1, it judges that STA1 is a high or low rate user according to the high and low rate identification table 1 established on the AP side in advance.

If STA1 is a high-speed user, the AP directly allocates time resources for data transmission.

If STA1 is a low-rate user, the AP first obtains the duration field in the RTS control frame. After obtaining the duration field, the AP shortens the duration according to a certain ratio K, such as shortening to 1/6 of the original, K=1/6, Then send a CTS to allocate time resources to the terminal to allow the terminal to perform data transmission.

Claims (4)

1., based on 802.11 agreement resource allocation methods in composite mode, it is characterized in that, comprising:

The rate class that access points identification accesses terminal, described rate class comprises two-forty terminal and low rate terminal;

According to the rate class accessed terminal, access points distributes the data transmission period accessed terminal or transmission opportunity, the fractional transmission duration of low rate terminal or transmission opportunity are distributed to the downlink data transmission of two-forty terminal or access points, described access points distributes the data transmission period accessed terminal or transmission opportunity, comprising:

After access points receives the request transmission message control frame of the request time resource sent that accesses terminal, the rate class accessed terminal according to identifying judges permission transmission control frame to send to access terminal or access points itself, and concrete grammar comprises:

Judge that to access terminal be two-forty terminal or low rate terminal, if two-forty terminal, then access points directly sends permission transmission control frame, time resource is distributed to this and accesses terminal and carry out transfer of data;

If low rate terminal, then access points produces a random number, compare with the probability number preset, if random number is less than probability number, then the address of access points self is revised as in the destination address allowed in transmission control frame by access points, by the chance of transfer of data to access points self;

If random number is greater than probability number, then time resource is directly distributed to and is accessed terminal by access points, carries out transfer of data.

2. according to claim 1ly it is characterized in that based on 802.11 agreement resource allocation methods in composite mode, the rate class that described access points identification accesses terminal, comprising:

Access points arranges statistical table, the Connecting quantity being in the terminal of connected state of record access, accesses terminal as two-forty terminal or low rate terminal for identifying.

3. according to claim 1ly it is characterized in that based on 802.11 agreement resource allocation methods in composite mode, described random number is the random number between 0 ~ 1.

4. according to claim 3ly it is characterized in that based on 802.11 agreement resource allocation methods in composite mode, described probability number is 1/3.