CN102869127B - WLAN (wireless local area network) based antenna switching system and switching method - Google Patents

Abstract

The invention discloses a WLAN-based antenna switching system and a switching method, which mainly solve the problems of antenna switching and data collision in the communication process between an access point AP and multi-region users. The system includes: a queue buffer module, a MAC module, a PHY module, an antenna and a controller; the MAC module and the queue buffer module extract the user address of the data packet and send it to the controller. The antenna type is calculated to obtain the switching time of the day, and the MAC module is controlled to send the CTS frame and the beacon frame, and the PHY module is controlled to connect to the coaxial antenna or the common antenna. During working hours, it reduces the collision probability of multi-area users sending data to the AP at the same time, increases the throughput of the wireless network, facilitates intelligent management of users in multiple areas, improves the spatial multiplexing rate, and can be used for cross-area wireless communication.

Description

Antenna switching system and switching method based on WLAN

technical field

The present invention relates to the technical field of wireless communication, in particular to a WLAN-based antenna switching system and switching method, which can be used for distinguishing and identifying users in different areas in a wireless local area network, and switching control of communication within the area.

Background technique

Wireless local area network WLAN based on IEEE802.11 standard uses unlicensed 2.4GHz or 5.8GHz radio frequency band for wireless data transmission. According to different network topologies, WLAN can be divided into ad hoc networks and infrastructure networks.

In the infrastructure network, the wireless access point AP acts as the control center of the network, which has the function of integrating wired and wireless LANs and coordinating wireless user STAs. The coverage of a traditional AP is similar to a sphere. No matter where the user is in the sphere, the AP sends out signals omnidirectionally, which easily causes waste of signal power and seriously affects the performance improvement of the WLAN system.

In order to meet the bandwidth requirements of users, some patents have proposed smart antenna technology, which concentrates the limited signal energy of APs in the direction of users, and uses multiple directional beams to provide data transmission services for users, which not only expands the coverage of APs, but also improves network throughput. However, the transmission loss of wireless signals in the air is relatively large, and obstacles and electromagnetic interference will affect wireless signals, resulting in a decrease in signal quality.

Based on the wireless propagation loss problem mentioned above, some patents propose the combination of AP and coaxial cable, such as the method of using cable TV coaxial cable to realize broadband wireless access, connecting one end of the coaxial cable to the antenna interface of the AP, and the other One end is connected to a common antenna, as shown in Figure 1. In this way, cross-regional transmission of wireless signals is realized, and external interference is reduced. However, because the coaxial cable simply pulls the AP signal far away, users covered by different antennas cannot detect each other's existence, and it is easy to cause multiple user signals to collide at the AP, which increases the data transmission delay and seriously affects performance of the wireless network.

Contents of the invention

Aiming at the defects or deficiencies in the prior art, the purpose of the present invention is to provide a WLAN-based antenna switching system and switching method, which combines smart APs with cable TV coaxial cables and remote antennas. Certain rules are used to switch between ordinary antennas and coaxial antennas, so that APs can provide users with wireless data service services through traditional ordinary antennas, and can also use coaxial cables to enable wireless signals to pass through obstacles and communicate with specific spaces. Users communicate, thereby improving power utilization and spatial multiplexing.

Technical scheme of the present invention is realized like this:

1. Terminology

Period: It refers to the period from when the AP starts to work on the coaxial antenna, switches to the common antenna, and until the AP switches to the coaxial antenna again, which is set to 100ms.

Coaxial antenna: An antenna connected to an AP through a coaxial cable.

Ordinary antenna: refers to the antenna directly connected to the AP without a coaxial cable in the middle.

Two, the antenna switching system based on WLAN of the present invention includes:

The queue buffer module is responsible for storing the data packet sent by the upper layer, extracting the user address of the data packet, sending it to the control module, and receiving the control signal of the control module, sending or buffering or clearing the data packet;

The medium access control MAC module receives the data packet sent by the upper layer and the data packet uploaded by the physical layer PHY module, extracts the user address of the uplink data packet, sends it to the controller, and decides whether to broadcast the clear send CTS frame and signal according to the control signal of the controller. frame;

The physical layer PHY module is used to connect the medium access control MAC module and the antenna, and decide whether to switch between the coaxial antenna and the common antenna according to the control signal of the controller;

Antennas, including coaxial antennas and ordinary antennas, are used to receive or send data packets;

The controller is used to connect with the queue buffer module, the media access control MAC module and the physical layer PHY module respectively, check the user address of the data packet, establish and update the user entry and memory parameters, and calculate the distance between the coaxial antenna and the common antenna Switching time, setting control signal.

Preferably, the controller includes:

The monitoring module is used to control and update user entries and parameters in the memory, record the antenna switching time, and detect whether the switching time arrives, and output the current working antenna type of the access point AP;

The calculation module is used to calculate the parameters in the user entry and the memory, obtain the switching time between the coaxial antenna and the common antenna, and send it to the monitoring module, and output the updated parameters to the user entry and the memory;

The user entry is used to store and update user parameters, which include user address, antenna type, number of data packets, and number of silent periods;

The memory is used to store the number of data packets of different antenna types in the user entry.

Preferably, the switching time between the coaxial antenna and the common antenna is determined by the number of data packets of different antenna types in the memory, and the memory outputs the data packet numbers of different antenna types to the computing module to calculate the time between the coaxial antenna and the common antenna. The switching time T:

$\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 100</span>}<span\; class="notranslate">\; \&times;</span>\frac{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; N</span>}}\mathrm{<span\; class="notranslate">\; ms</span>}<span\; class="notranslate">\; ,</span>$

Wherein, M is the number of data packets of the coaxial antenna, and N is the number of data packets of the common antenna.

Three, the antenna switching method based on WLAN of the present invention comprises the following steps:

(1) The switching time initial value T of setting coaxial antenna and common antenna is 50ms, and the number of data packets in the setting user entry, the silent cycle number are all _zero ;

(2) Detect whether the initial value T ₀ of the switching time between the coaxial antenna and the common antenna is reached, if the initial value T ₀ of the switching time is not reached, perform step (3), otherwise, perform step (8);

(3) Detect whether the access point AP has an uplink or downlink data packet to arrive, if the access point AP has a downlink data packet to arrive, perform step (4), if the access point AP has an uplink data packet to arrive, perform step (6) ), if the access point AP has no uplink or downlink data packet arrival, then return to step (2);

(4) Extract the user address of the data packet, and search in the user entry, if the user address exists in the user entry, perform step (5), otherwise, clear the data packet and return to step (2);

(5) Check whether the user antenna type of the data packet matches the current antenna type of the access point AP, if the two match, then add 1 to the number of data packets of the user in the user entry, and send the data packet, otherwise, Put the data packet into the queue buffer corresponding to the antenna type, and return to step (2);

(6) Find the user address of the data packet in the user table entry, if the user address exists in the user table entry, perform step (7), otherwise, set up the user's address, antenna type, and data packet number in the user table entry , silent cycle number, perform step (7);

(7) Update user entry: add 1 to the number of data packets of this user, the antenna type is set to the coaxial antenna or common antenna of the current work of the access point AP, and returns to step (2);

(8) Detect the antenna type of the access point AP. If the access point AP is working on a coaxial antenna, it will broadcast a clear send CTS frame, switch to a common antenna, and broadcast a beacon frame. If the access point AP works on a common Antenna, then count the number of data packets of the coaxial antenna and the common antenna in the user entry, and store it in the memory, and perform step (9);

(9) compare the number of data packets of the coaxial antenna and the ordinary antenna in the memory, the number of data packets is the mean value of H cycles, and calculate the switching time of the coaxial antenna and the ordinary antenna M is the number of data packets of the coaxial antenna, and N is the number of data packets of the common antenna; the switching time T of updating is sent to the monitoring module, making T ₀ =T, and performing step (10);

(10) Set the number of silent periods: if the number of data packets of a user is non-zero, then its silent period number is still 0, otherwise, its silent period number is added by 1, and step (11) is performed;

(11) Clear the number of all data packets in the user table entry, the access point AP broadcasts the clear send CTS frame, switches to the coaxial antenna, and broadcasts the beacon frame, and returns to step (2).

Parameters of user address, antenna type, number of data packets and number of silent periods are stored in the user entry.

In the present invention, by adding controllers for coaxial antennas and ordinary antennas to the existing access point AP, the access point AP flexibly allocates the working time of the coaxial antenna and the ordinary antenna according to the data grouping through the coaxial antenna or the ordinary antenna , to meet the business needs of users to the greatest extent; at the same time, effectively reduce the collision probability of data transmission between the access point AP and users in multiple areas, increase the throughput of the wireless network, and realize the multi-area user's communication to a certain extent Intelligent management.

Description of drawings

Fig. 1 is the signal coverage area of existing access point AP;

Fig. 2 is a system block diagram of the present invention;

Fig. 3 is a controller block diagram of the present invention;

FIG. 4 is a flow chart of antenna switching in the present invention.

detailed description

In order to make the purpose and technical method of the present invention clearer and easier to understand, the present invention will be further described in detail below with reference to the accompanying drawings.

Referring to FIG. 2 , the system of the present invention includes: a queue buffer module 10 , a medium access control MAC module 20 , a physical layer PHY module 30 , an antenna 40 and a controller 50 . The queue buffer module 10 is bidirectionally connected with the media access control MAC module 20 and the controller 50, the controller 50 is bidirectionally connected with the media access control MAC module 20, the controller 50 is unidirectionally connected with the physical layer PHY module 30, and the antenna 40 is connected with the physical layer Module 30 is bidirectionally connected. in,

Described queue cache module 10, comprises the queue cache of coaxial antenna and the queue cache of common antenna, is used for storing the data packet that upper layer sends, extracts the user address of data packet, and submits to controller 50, according to controller 50 output Control information A, control information B, and control information C determine to send data packets or store data packets in the queue buffer of the corresponding antenna type: if control information A is 01, send data packets; if control information A is 10, store data packets To the queue buffer of the coaxial antenna; if the control information A is 11, store data packets to the queue buffer of the common antenna; if the control information B is 01, release the queue buffer of the coaxial antenna; if the control information B is 10, release the common antenna The queue cache; if the control information C is high level, clear the data packet.

The medium access control MAC module 20 extracts the user address of the uplink data packet, and sends it to the user entry 502, and broadcasts a clear-to-send CTS frame and a beacon frame under the control of the control signal B: if the control signal B is 01 or 10, Then the medium access control MAC module 20 broadcasts the clear-to-send CTS frame and the beacon frame; otherwise, does not broadcast the clear-to-send CTS frame and the beacon frame.

The physical layer PHY module 30 determines whether to switch between the coaxial antenna and the common antenna according to the control information B of the controller 50: if the control signal B is 01 or 10, the PHY module 30 controls switching to the coaxial antenna or the common antenna ; Otherwise, do not switch between the coaxial antenna or the common antenna.

The antenna 40 includes a coaxial antenna and an ordinary antenna, and is used for receiving or sending data packets.

The controller 50 is used to detect the data packets in the queue buffer module 10 and the MAC module 20, control the storage and release of the data packets in the queue buffer module 10, and control the switching between the coaxial antenna and the common antenna.

Referring to FIG. 3 , the controller 50 includes: a monitoring module 501 , a user entry 502 , a computing module 503 and a memory 504 . The monitoring module 501 is unidirectionally connected to the user entry 502 and the memory 504, and bidirectionally connected to the computing module 503, and the computing module 503 is bidirectionally connected to the user entry 502 and the memory 504, respectively. in,

The monitoring module 501 sends the current working antenna type of the access point AP to the operation module 503, detects whether the switching time T ₀ between the coaxial antenna and the common antenna is reached, and sets the control signal B: if the switching time T ₀ is reached, and The currently working antenna type is a common antenna, and the control signal B is set to 01; if the switching time T ₀ is reached, and the current working antenna type is a coaxial antenna, the control signal B is set to 10.

The user entry 502 searches and outputs the parameters of the user entry 502 according to the user address of the data packet, sets the control signal C, and updates the parameters of the user entry 502 according to the calculation result of the operation module 503 . Among them, the parameters of the user entry 502 include user address, antenna type, number of data packets, and number of silent periods, as shown in Table 1.

Table 1 Parameters of user entries

Wherein, the number of silent periods indicates whether the user sends or receives data packets within one period. If the number of silent periods is 0, it means that the user receives or sends data packets; if the number of silent periods is not 0, it means that the user does not receive or send data packets.

The calculation module 503 counts the number of data packets of the coaxial antenna and the common antenna, and sends it to the memory 504, and calculates the antenna switching time T: M is the number of data packets of the coaxial antenna, N is the number of data packets of the common antenna, and is updated to the monitoring module 501; the updated antenna type, the number of data packets and the number of silent periods are output to the user entry 502, and the antennas of the data packets are compared Type and the antenna type of the access point AP is currently working, set the control signal A: If the antenna type of the data packet is a coaxial antenna, the access point AP is currently working on the coaxial antenna, set the control signal A to 01; if the data packet The antenna type of the group is a coaxial antenna, the access point AP is currently working on a common antenna, and the control signal A is set to 10; if the antenna type of the data group is a common antenna, the access point AP is currently working on a coaxial antenna, set The control signal A is 11; if the antenna type of the data packet is a common antenna, and the access point AP is currently working on a coaxial antenna, set the control signal A to 00.

The memory 504 stores and updates the number of data packets of different antenna types in H cycles, as shown in Table 2, the number of data packets of different types of antennas in the H+1th cycle covers the number of data packets in cycle 1, and so on, and the number of data packets in the first cycle The number of data packets of different types of antennas of H+2 periods covers the number of data packets of the second period, and so on, ensuring that the memory 504 always stores the number of data packets of the latest H periods.

Table 2 Memory structure

Number of groups cycle 1 cycle 2 cycle 3 cycle 4 .... Cycle H The number of data packets of the coaxial antenna The number of data packets for common antennas

The working principle of the entire antenna switching system is: after the access point AP starts to work, the queue buffer module 10 or the media access control MAC module 20 extracts the user address of the data packet, searches and outputs the corresponding data packet number and Antenna type, set the control signal C, the operation module 503 compares the antenna type of the data packet with the current antenna type of the access point AP, sets the control signal A, and sends the updated data packet number and antenna to the user entry 502 type. When the monitoring module 501 detects that the switching time T ₀ between the coaxial antenna and the common antenna arrives, the control signal B is set according to the current working antenna of the access point AP, the PHY module 30 switches to the coaxial antenna or the common antenna, and the MAC module 20 broadcasts and clears Send the CTS frame and the beacon frame, the calculation module 503 counts the number of data packets of different antenna types in the user entry 502, updates them in the memory 504, and calculates the number of data packets of different antenna types in the memory 504 at the same time in H cycles, and obtains the antenna The switching time T is updated to the monitoring module 501, and T ₀ =T. The access point AP operates cyclically according to the above content.

Referring to Fig. 4, the antenna switching method based on WLAN of the present invention includes the following implementation steps:

In step 1, an initial value T ₀ of switching time between the coaxial antenna and the common antenna is set.

In this example, the parameters of the user entry in the controller and the number of groups in the memory are cleared, and the initial value T ₀ of the switching time of the monitoring module in the controller is set to 50ms. Wherein, the parameters of the user entry include user address, antenna type, number of data packets and number of silent periods.

Step 2, check whether the antenna switching time T ₀ is reached, if not, execute step 3, otherwise, execute step 8.

In this example, the monitoring module in the controller is used to detect whether the switching time T ₀ of the antenna has arrived.

Step 3, check whether there is a data packet arriving, if there is a downlink data packet arriving, perform step 4; if there is an uplink data packet arriving, if there is an uplink data packet arriving, perform step 6; if there is no downlink or uplink data packet Arrived, return to step 2.

In this example, the queue buffer module detects whether a downlink data packet arrives, and the media access control MAC module detects whether a downlink data packet arrives.

Step 4, extract the user address of the data packet, search for the antenna type and the number of data packets related to the data packet, if they cannot be found, clear the data packet, and perform step 5.

In this example, the user address of the data packet is extracted through the queue buffer module and sent to the user entry, and the user entry sends the corresponding antenna type and the number of data packets to the calculation module. If there is no user address of the data packet in the user entry , antenna type, number of data packets and number of silent periods, then set the control signal C to a high level, that is, notify the queue buffer module to clear the data packets.

Step 5, compare the antenna type of the data packet with the current working antenna type of the access point AP:

If the two antenna types are the same, send the data packet, and at the same time, add 1 to the data packet number of the data packet, and return to step 2;

If the antenna types of the two are different, and the current working antenna of the access point AP is a common antenna, save the data packet and return to step 2;

If the two antenna types are different, and the current working antenna of the access point AP is a coaxial antenna, save the data packet and return to step 2.

In this example, the user entry in the controller sends the antenna type of the data packet to the computing module, and at the same time, the monitoring module sends the antenna type currently working on the access point AP to the computing module, and the computing module compares the two:

If both antenna types are the same, then set the control information A to be 01, that is, notify the queue buffer module to send the data packet, and meanwhile, add 1 to the data packet number of the data packet, update to the user entry, and return to step 2;

If the antenna types of the two are different, and the current working antenna of the access point AP is an ordinary antenna, set the control information A to 10, store the data packet in the queue buffer of the coaxial antenna, and return to step 2;

If the antenna types of the two are different, and the current working antenna of the access point AP is a coaxial antenna, set the control information A to 11, store the data packet in the queue buffer of the common antenna, and return to step 2.

Step 6, extract the user address of the data packet, search for the antenna type and the number of data packets related to the user address, if it cannot be found, save the user address of the data packet, the current working antenna type, and perform step 7.

In this example, the user address of the data packet is extracted through the MAC module of the media access control and sent to the user entry. The user entry searches and sends the corresponding antenna type and the number of data packets to the calculation module. If the user address does not exist in the user entry , the user address, antenna type, number of data packets, and number of silent periods of the data packet are added to the user entry.

Step 7, compare the antenna type of the data packet with the current working antenna type of the access point AP:

If the two antenna types are the same, add 1 to the data packet number of the data packet, and return to step 2;

If the antenna types of the two are different, and the current working antenna of the access point AP is a common antenna, then set the antenna type of the data packet to be a common antenna, and return to step 2;

If the antenna types of the two are different, and the current working antenna of the access point AP is a coaxial antenna, set the antenna type of the data packet as a coaxial antenna, and return to step 2.

In this example, the user entry in the controller sends the antenna type of the data packet to the computing module, and at the same time, the monitoring module sends the current antenna type of the access point AP to the computing module, and the computing module compares the two antenna types Compare:

If the two antenna types are the same, add 1 to the data packet number of the data packet, update the user entry, and return to step 2;

If the antenna types of the two are different, and the current working antenna of the access point AP is a common antenna, then set the antenna type of the data packet as a common antenna, update it to the user entry, and return to step 2;

If the antenna types of the two are different, and the current working antenna of the access point AP is a coaxial antenna, set the antenna type of the data packet to be a coaxial antenna, update it into the user entry, and return to step 2.

Step 8: Detect the type of antenna that the access point AP is currently working on. If it is a common antenna, set the control signal B to 01 and go to step 9. If it is a coaxial antenna, set the control signal B to 10 and go to step 12.

In this example, the monitoring module in the controller detects the antenna type of the access point AP currently working.

Step 9, counting and saving the number of data packets of the coaxial antenna and common antenna in one cycle respectively, updating the number of silent periods of the user, if the number of data packets received or sent by the user is not 0, set the number of silent periods to 0, otherwise, Increment the number of silent periods by 1, and go to Step 10.

In this example, the user address, antenna type, number of data packets, and number of silent periods of all users in the user entry are output, and the calculation module counts the number of data packets of the coaxial antenna and common antenna, and updates them to the memory. At the same time, the user entry The number of middle packets is reset to zero, and the number of silent periods is updated. If the number of data packets received or sent by the user is not 0, the number of silent periods is set to 0, otherwise, the number of silent periods is increased by 1.

Step 10, count the number of data packets of the coaxial antenna and the common antenna in H cycles, and calculate the new switching time T: M is the number of data packets of the coaxial antenna, N is the number of data packets of the common antenna; set T ₀ =T, and execute step 11.

In this example, the memory in the controller cyclically records the number of data packets of the coaxial antenna and the common antenna in H cycles, and the calculation module calculates the average value M of the data packets of the coaxial antenna in H cycles, and the coaxial antenna in H cycles The average number of data packets of the antenna N, using the formula The switching time T between the coaxial antenna and the ordinary antenna is calculated, saved and updated to the monitoring module, and T ₀ =T.

Step 11, broadcast clear to send CTS frame, switch to the coaxial antenna, broadcast beacon frame, release the data packet of the coaxial antenna, and return to step 2.

In this example, the medium access control MAC module broadcasts and clears to send the CTS frame and the beacon frame, the physical layer PHY module connects the coaxial antenna, disconnects the common antenna, and releases the data packets in the queue buffer of the coaxial antenna.

Step 12, update the switching time of the antenna, broadcast a clear-to-send CTS frame, switch to a common antenna, broadcast a beacon frame, release the data packet of the common antenna, and return to step 2.

In this example, the switching time of the monitoring module is updated, so that T ₀ =100-T, at the same time, the media access control MAC module broadcasts and clears sending CTS frames and beacon frames, the physical layer PHY module connects the common antenna, disconnects the coaxial antenna, releases Data packets in the coaxial antenna's queue buffer.

The above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto, and the method of the present invention is not limited to the realization of the system of the present invention. The modifications and variations of the methods for realizing the above functions are all within the spirit and principle of the present invention.

Claims (2)

1. A method for switching antennas based on WLAN, comprising the steps of: (1) The switching time initial value T of setting coaxial antenna and common antenna is 50ms, and the number of data packets in the setting user entry, the silent cycle number are all _zero ; (2) Detect whether the initial value T ₀ of the switching time between the coaxial antenna and the common antenna is reached, if the initial value T ₀ of the switching time is not reached, perform step (3), otherwise, perform step (8); (3) Detect whether the access point AP has an uplink or downlink data packet to arrive, if the access point AP has a downlink data packet to arrive, perform step (4), if the access point AP has an uplink data packet to arrive, perform step (6) ), if the access point AP has no uplink or downlink data packet arrival, then return to step (2); (4) Extract the user address of the data packet, and search in the user entry, if the user address exists in the user entry, perform step (5), otherwise, clear the data packet and return to step (2); (5) Check whether the user antenna type of the data packet matches the current antenna type of the access point AP, if the two match, then add 1 to the number of data packets of the user in the user entry, and send the data packet, otherwise, Put the data packet into the queue buffer corresponding to the antenna type, and return to step (2); (6) Find the user address of the data packet in the user table entry, if the user address exists in the user table entry, perform step (7), otherwise, set up the user's address, antenna type, and data packet number in the user table entry , silent cycle number, perform step (7); (7) Update user entry: add 1 to the number of data packets of this user, the antenna type is set to the coaxial antenna or common antenna of the current work of the access point AP, and returns to step (2); (8) Detect the antenna type of the access point AP. If the access point AP is working on a coaxial antenna, it will broadcast a clear send CTS frame, switch to a common antenna, and broadcast a beacon frame. If the access point AP works on a common Antenna, then count the number of data packets of the coaxial antenna and the common antenna in the user entry, and store it in the memory, and perform step (9); (9) compare the number of data packets of the coaxial antenna and the ordinary antenna in the memory, the number of data packets is the mean value of H cycles, and calculate the switching time of the coaxial antenna and the ordinary antenna M is the number of data packets of the coaxial antenna, and N is the number of data packets of the common antenna; the switching time T of updating is sent to the monitoring module, making T ₀ =T, and performing step (10); (10) Set the number of silent periods: if the number of data packets of a user is non-zero, then its silent period number is still 0, otherwise, its silent period number is added by 1, and step (11) is performed; (11) Clear the number of all data packets in the user table entry, the access point AP broadcasts the clear send CTS frame, switches to the coaxial antenna, and broadcasts the beacon frame, and returns to step (2). 2. The antenna switching method according to claim 1, wherein parameters of user address, antenna type, number of data packets and number of silent periods are stored in the user entry.