The present invention relates to the field of wireless data transmission, and particularly to a device, system and method for multilink wireless data transmission.
In a wireless local area network (WLAN) system, a wireless communication module (referred to as WLAN client herein) running in a client mode interacts with an access point (referred to as AP hereinafter). With the development of technology, the size of the wireless communication module is becoming smaller and smaller, and the power consumption is becoming lower and lower as well. Therefore, a plurality of such WLAN clients can be integrated into one device, thereby forming a multilink WLAN system.
Since two or more WLAN clients are included on one device and each WLAN client can perform data transmission, when compared to a device including only one WLAN client, applying a multilink wireless local area network can increase the data throughput transmitted by each device and improve the flexibility of data transmission. However, when two or more WLAN clients are located on an identical device, there must be mutual interference among the two or more WLAN clients.
Generally, in order to avoid co-channel interference, different wireless communication modules work on different channels. However, in practical applications, the interference among wireless communication modules working on different channels is still very serious. For example, using inaccurate channel filters in wireless communication modules can bring interference. In addition, the distance between two wireless communication modules or two radio frequency (RF) components corresponding to two wireless communication modules being too close and the absence of appropriate RF shielding will also bring heavy interference. The interference above will result in a great loss of data throughput, degenerate system functions, and even cause the performance of the multilink wireless local area network degraded to the level of a single-link wireless local area network. Therefore, the interference problem among wireless communication modules seriously restricts the application of the multilink wireless local area network.
In order to solve the interference problem, an existing method is to increase the distance between a plurality of wireless communication modules on an identical device, or employ more effective RF shielding among the plurality of wireless communication modules. However, when the space on the device is limited, it is impossible to make the distance between the plurality of wireless communication modules far enough. In addition, employing more effective RF shielding will significantly increase the costs. Another existing method is to re-design antennas for a plurality of wireless communication modules to make sure that there is no interference among the signals of a plurality of antennas. However, in practical applications, it is hard to avoid the interference among a plurality of antennas. It is thus clear that the existing solutions for avoiding the interference among a plurality of wireless communication modules can only be applied in specific situations such as when device volume is large, but cannot be universally applied in the multilink wireless local area network.
Systems, methods and devices of the present invention for multilink wireless data transmission can effectively avoid the interference among two or more WLAN clients, thereby improving the stability and reliability of the multilink wireless local area network. In order to solve the technical problem above, the following technical solutions are provided:
According to one aspect of the present invention, a multilink wireless data transmission device comprises a control module and two or more WLAN clients, wherein the control module is constructed to control the WLAN clients to enable the data transmission states of those of the WLAN clients, which are not in an idle state, to be the same, and wherein the data transmission states comprise a receiving state and a sending state.
The control module is configure to control the WLAN clients which need to receive data to switch to the receiving state when a downlink triggering condition is met, and to control the WLAN clients which need to send data to switch to the sending state when an uplink triggering condition is met. Furthermore, the control module is configured to control the WLAN clients which need to receive data to send downlink transmission instructions to respectively corresponding access points thereof and receive downlink messages from the access points when the WLAN clients have finished sending all uplink messages or meet a first timing condition. Furthermore, the control module is configured to control the WLAN clients which need to send data to send uplink messages to respectively corresponding access points thereof when the WLAN clients have finished receiving all downlink messages or meet a second timing condition.
According to another embodiment of the present invention, a multilink wireless data transmission method for controlling the wireless data transmission between two or more WLAN clients and respectively corresponding access points thereof, comprises enabling the data transmission states of those of the WLAN clients, which are not in an idle state, to be the same, wherein the data transmission states comprise a receiving state and a sending state.
The enabling the data transmission states of the WLAN clients, which are not in an idle state, to be the same comprises switching the WLAN clients, which need to receive data, to the receiving state from the sending state when the downlink triggering condition is met, and switching the WLAN clients, which need to send data, to the sending state from the receiving state when the uplink triggering condition is met.
Furthermore, the downlink triggering condition is that the WLAN clients have finished sending all uplink messages or it is the first timing condition. Furthermore, switching the WLAN clients, which need to receive data, to the receiving state from the sending state comprises controlling the WLAN clients, which need to receive data, to send downlink transmission instructions to the access points and receive the downlink messages from the access points.
Furthermore, the uplink triggering condition is that the WLAN clients have finished receiving all downlink messages or it is the second timing condition. Furthermore, switching the WLAN clients, which need to send data, to the sending state from the receiving state comprises controlling the WLAN clients, which need to send data, to send uplink messages to the access points.
According to another embodiment of the present invention, a wireless communication system comprises a multilink wireless data transmission device and at least two access points respectively corresponding to the WLAN clients.
The access points are configured to send downlink messages to the WLAN clients only when receiving the downlink transmission instructions sent from the corresponding WLAN clients.
Furthermore, the WLAN clients send first reply messages to the access points corresponding thereto after receiving the downlink messages, and the access points send second reply messages to the WLAN clients corresponding thereto after receiving the uplink messages.
According to another embodiment of the present invention, a computer-readable medium store computer-readable codes used for implementing the multilink wireless data transmission method.
According to yet another embodiment of the present invention, a computer program product contains computer-readable codes used for implementing the multilink wireless data transmission method above.
The advantages of the present invention are that two or more WLAN clients only perform uplink data transmission or only perform downlink data receiving within a time period, avoiding the situation where the uplink data transmission and the downlink data receiving of two or more WLAN clients are overlapped. Therefore, the interference problem among two or more WLAN clients can be effectively solved, thereby improving the stability and reliability of the multilink wireless local area network.
In order to make objectives, technical solutions and advantages of the embodiments of the present invention more apparent, the embodiments of the present invention will be further described in detail hereinafter by way of example.
By carefully analyzing the multilink wireless local area network, the inventors discovered that the interference among two or more WLAN clients generally occurs in the situation where the uplink data transmission and downlink data receiving performed by two or more WLAN clients are overlapped. For example, for two WLAN clients, when one thereof sends uplink data while another receives downlink data, the stronger transmission power of the link sending uplink data will interfere with the link receiving downlink data with a lower power. However, when two WLAN clients are performing the uplink data transmission simultaneously or performing the downlink data receiving simultaneously, the interference among different wireless communication modules is smaller.
Therefore, as long as each wireless communication module is not in the states of receiving data and sending data simultaneously, the interference among them can be reduced greatly. The wireless communication module generally has three states: idle state, receiving data state and sending data state. Since the wireless communication module in an idle state neither receives data nor sends data, it will not interfere with other communication modules. Then, when the data transmission states of various wireless communication modules which are not in an idle state are the same, i.e. they are in a receiving state simultaneously or in a sending state simultaneously, the interference among these modules can be reduced greatly.
The technical solution of the present invention separates the uplink data transmission process and the downlink data receiving process of two or more WLAN clients, thereby making two or more WLAN clients only perform uplink data transmission (sending state) simultaneously or only perform downlink data receiving (receiving state) simultaneously, and thereby avoiding the situation where the uplink data transmission and downlink data receiving of two or more WLAN clients are overlapped. Consequently, the interference problem among different WLAN clients can be solved effectively, improving the stability and reliability of the multilink wireless local area network.
In the following paragraphs, the presently preferred embodiments of the present invention will be explained in detail in conjunction with the drawings.
For the sake of simplicity, the present embodiment comprises two WLAN clients; however, the device of the present invention can include two or more WLAN clients. For the situations involving more than two WLAN clients, it can be learned by those skilled in the art according to the present embodiment and other parts of this description how to apply the principle and technical solution of the present invention under such situations, and such applications would not depend on inventive effort beyond the present invention.
As shown in
For the present embodiment, the control module 50 is configured to control the first and second WLAN clients 10 and 20 to enable them to be in the same data transmission state when the first and second WLAN clients 10, 20 are not in an idle state. The data transmission state comprises a receiving state and a sending state.
Referring to the principle of the present invention described above, when the data transmission states of the first WLAN client 10 and the second WLAN client 20 are the same, i.e., they are in a receiving state simultaneously or in a sending state simultaneously, the interference among these modules can be reduced greatly.
Again in accordance with the principle of the present invention mentioned above, in an embodiment in which the device 100 includes more than two WLAN clients (such as three or more), it is possible that one or a part of the WLAN clients is possibly in an idle state. In that case, the control module 50 controls other WLAN clients, which are not in an idle state, to be in same data transmission states, i.e., to be in a sending state simultaneously or in a receiving state simultaneously.
Referring to
The downlink triggering condition comprises when the first and second WLAN clients 10 and 20 have finished sending both uplink messages, or when it is a first timing condition. The uplink triggering condition comprises when the first and second WLAN clients 10 and 20 have finished receiving both downlink messages, or when it is a second timing condition.
Controlling the WLAN clients to switch to the receiving state from the sending state includes, in one embodiment, controlling the WLAN clients to send uplink transmission instructions to the respectively corresponding access points thereof, and receive downlink messages from the respectively corresponding access points. Controlling the WLAN clients to switch to the sending state from the receiving state includes, in one embodiment, controlling the WLAN clients to send uplink messages to the two or more access points.
Therefore, the control module 50 is configured to control the WLAN clients to send downlink transmission instructions to the respectively corresponding access points and receive downlink messages therefrom when the WLAN clients have finished sending the uplink messages or meet the first timing condition.
Furthermore, it is also configured to control the WLAN clients to send uplink messages to the two or more access points when the WLAN clients have finished receiving the downlink messages or meet the second timing condition. Having finished receiving the downlink messages can mean that receiving of the longer one of the downlink messages received by the first WLAN client and second WLAN client is finished, or receiving of the last one of the received downlink messages is finished. Having finished sending all the uplink messages can mean that sending of the longer one of the uplink messages sent by the first and second WLAN clients is finished, or sending of the last one of the uplink messages which is sent is finished. How to determine having finished receiving all the downlink messages or having finished sending all the uplink messages will be described in conjunction with examples hereinafter.
In the manner above, the duration of each sending state or receiving state of the WLAN clients may be different, depending on the length of the uplink messages or downlink messages, the initiation time of the receiving or sending, etc.
An alternative method is to send or receive in a fixed time period, which is equivalent to performing temporal synchronization among the WLAN clients. In such a situation, each WLAN client is set as: sending data in sending time periods, and receiving data in receiving time periods. Such sending time periods and receiving time periods are alternately spaced. Thus, the first timing condition refers to the end moments of the sending time periods, and the second timing condition refers to the end moments of the receiving time periods. It can be understood by those skilled in the art according to the description herein that the temporal synchronization mechanism used in the present invention can be implemented by applying any of the existing appropriate techniques without additional inventive work.
Thus, when a transmission error occurs (such as an error in sending a downlink message from an access point, or an access point not having an idle bandwidth), the WLAN clients will not wait until they have finished receiving the downlink messages, but send uplink messages to the access points directly when meeting the second timing condition.
It can be learned by those skilled in the art according to the description above that for the implementation comprising more than two WLAN clients, the control module can control these WLAN clients in the same way.
In another embodiment of the present invention, a multilink wireless data transmission method includes controlling the wireless data transmission between two or more WLAN clients (e.g., the WLANs shown in
Furthermore, the enabling the data transmission states of the WLAN clients, which are not in an idle state, to be the same comprises switching the WLAN clients to the receiving state from the sending state when the downlink triggering condition is met, and switching the WLAN clients to the sending state from the receiving state when the uplink triggering condition is met.
Specifically, the uplink and downlink triggering conditions are identical to those in the description of the device shown in
The method of the present embodiment will be described in detail hereinafter in conjunction with
In order to facilitate understanding, description is carried out in conjunction with
In step 210, two WLAN clients (C1 and C2) simultaneously send initial uplink messages to the two access points corresponding to themselves (AP1 and AP2).
The drivers of the two WLAN clients can provide a control interface, and an external controller (such as the control module 50 of the embodiment in
In a WLAN system, having finished sending the uplink data, a WLAN client can automatically generate a sending success interrupt, then when all the WLAN clients have sent the sending success interrupt, this indicates that the sending of all the uplink messages has been finished.
As shown in step 220, when the sending of all the uplink messages in two WLANs has been finished, i.e., meeting the downlink triggering condition, then the two WLAN clients send downlink transmission instructions (shown as TC in
As shown in
As stated above, for example, for the embodiment shown in
After sending the downlink transmission instructions TC, the two WLAN clients C1 and C2 respectively receive the downlink messages from the two access points AP1 and AP2, as shown in step 230.
After having received the downlink transmission instructions, the two access points AP1 and AP2 start to transmit the downlink messages to the respectively corresponding WLAN clients. Since the transmission actions of the access points are triggered by the WLAN clients, it is ensured that the access points cannot transmit downlink messages to the WLAN clients when the WLAN clients are sending uplink messages.
In step 240, having finished receiving all the downlink messages, the two WLAN clients send another uplink message to the corresponding access points.
As shown in
In other embodiments, if the two WLAN clients do not perform receiving synchronously, then having finished receiving all the downlink messages can also mean having finished sending the last one of the two uplink messages. For example, if there is an error in the time when the two access points receive the downlink transmission instructions, or after receiving the downlink transmission instruction, a certain access point does not send a downlink message immediately but waits until the downlink thereof is idle then starts to send the downlink messages, thereby a possible result is that the downlink message sending by the two access points is not completely synchronized.
In a WLAN system, after having received the downlink data, a WLAN client can automatically generate a receiving success interrupt. Therefore, when all the WLAN clients have generated the receiving success interrupt, then the two WLAN clients send uplink messages, if meeting the uplink triggering condition.
That is, only when all the WLAN clients have finished receiving all the downlink messages, the WLAN clients continue to send the uplink messages to the respective access points thereof. By setting the uplink triggering condition, it can be ensured that in a plurality of WLAN clients, only uplink data transmission is performed without receiving downlink messages, avoiding the interference between uplink data transmission and downlink data receiving.
According to the description above, it is clear that the WLAN clients only perform uplink data transmission or only perform downlink data receiving within a time period.
Referring to
As shown in
As shown in
It can be understood by those skilled in the art, for the situation of taking having finished receiving all the downlink messages and having finished sending all the downlink messages as the triggering condition (as in the example shown in
As a result, it can be seen apparently from
As mentioned above, the downlink triggering condition can be the first timing condition, while the uplink triggering condition can be the second timing condition. In such a situation, the first time period can be set as sending data, and the second time period as receiving data. At this moment, the timing diagram of the process is similar to
For example, it is set that both WLAN clients C1 and C2 are starting to send uplink messages at the moment of t0. When the moment of t1 arrives, the sending of uplink messages will be paused; in turn the downlink transmission instructions TC are sent, then receiving the downlink messages transmitted from the access points is started. At the moment of t2, the receiving of downlink messages is paused; in turn uplink messages are sent. As such, the processes above are performed alternately.
In the situation of using timing as the triggering condition, the WLAN clients can record the location where the uplink messages and downlink messages are paused, whereby the uplink messages can be sent continuously from the paused location, or the corresponding access points are notified to transmit downlink messages from the paused location. Also, a shorter length of messages can be set or a longer timing duration can be set, so as to complete the uplink message sending or downlink message receiving within each time period. Such a data transmission method of resuming from breakpoint is common knowledge of those skilled in the art, and it is not the content to be described in the present invention, and accordingly it will not be described in detail.
It is described in the timing diagram in
In the situation shown in
In addition, as stated above, when there are three or more WLAN clients, some WLAN clients may be in an idle state. Whereas when the WLAN clients, which were originally in an idle state, switch to a non-idle state, such as similarly shown in
In another embodiment, a wireless communication system comprises a multilink wireless data transmission device stated above (such as device 100 shown in
In the current wireless communication system, when a WLAN client needs to receive a downlink message from an access point, the WLAN client generally transmits a sending request to the access point first, then the access point transmits data to the WLAN client according to the situation thereof. That is, the access point controls the process of transmission, while the WLAN client only performs receiving. Thus, if an access point (such as AP1 in
Therefore, in the system of the present embodiment, only when all the access points have received the downlink transmission instructions TC from the WLAN clients, downlink messages are transmitted to the WLAN clients, instead of sending data all the time after receiving the sending request. Of course, it can be understood by those skilled in the art that if the access point itself does not have an idle bandwidth, sending will not be performed either.
Describing in conjunction with
It can be seen that since the access points of the system in the present embodiment only send downlink data after receiving the downlink transmission instructions of the WLAN clients, the overlapping of downlink data transmission and uplink data receiving is avoided, which can effectively solve the interference problem among a plurality of WLAN clients, and improve the stability and reliability of the wireless local area network with multiple wireless communication links.
It can be understood by those skilled in the art that the example of the system comprising a multilink wireless data transmission device with more than two WLAN clients and more than two access points is similar to the example described above in conjunction with
It is well known that during the running of the system in the present embodiment, various data transmission errors may appear, resulting in the failure of sending uplink messages or the failure of receiving downlink messages by the WLAN clients. For this reason, the WLAN clients in the present system can be configured to send first reply messages to the corresponding access points after receiving the downlink messages successfully; and when receiving the uplink messages successfully, the access points send second reply messages to the corresponding WLAN clients.
As shown in
The first reply message can be a data packet independent of the uplink message, or can be contained in an identical data packet with the uplink message. Likewise, the second reply message can be a data packet independent of the downlink message, or can be contained in an identical data packet with the downlink message. Although in
So, when the WLAN clients or access points do not receive messages due to transmission errors, reply messages will not be received, and can be re-sent in another time period, thus improving reliability. Improving the reliability by means of re-sending and how to realize data re-sending are common knowledge in the art, and the advantages and details thereof will not be described in detail herein.
As another example, the WLAN clients send the uplink messages when the receiving of all the downlink messages has been finished as described above. Therefore, when the WLAN client is in a receiving state (as in the time period t2 in
According to the description above, when meeting the second timing condition, the WLAN clients suspend receiving of downlink messages but directly send uplink messages to the access points, which can overcome the problem resulting from transmission errors. However, as stated above, taking timing condition as the triggering condition sending/receiving may result in incompletion of message transmission.
To solve the problem above, the timing condition can be combined with the message transmission condition. That is, for the downlink triggering condition, having finished sending all the uplink messages, the WLAN client enters the receiving state, but when it has not finished sending by the time the first timing condition is met, the sending will be paused, and the WLAN client enters the receiving state as well. Similarly, for the uplink triggering condition, when having finished sending all the downlink messages, the WLAN client enters the sending state, but when it has not finished receiving by the time the second timing condition is met, the receiving will be paused, and the WLAN client still enters the sending state.
Although the description above implies that the sending/receiving finish conditions are judged before the timing conditions, the judgment precedence of the two conditions can be chosen according to specific application environments.
In the case of not finishing receiving/sending, the method of resuming from breakpoint can be applied as stated above, or the re-sending mechanism above, or any other appropriate methods, or a combination of the methods stated above can be applied. In the embodiments above, each WLAN client corresponds to the access point one-to-one. In actual situations, in the cause of more than two WLAN clients, it is possible that a plurality of WLAN clients is connected to one access point. It can be understood by those skilled in the art that in such a situation, one access point can only communicate with one WLAN client at a certain moment.
For example, for the case of three WLAN clients C1, C2 and C3, and two access points AP1 and AP2, C1 and C2 and AP1 and AP2 are the WLAN clients and access points shown in
Also provided in the present invention is a storage medium readable by a machine (such as a computer), wherein instructions for making a machine execute a multilink wireless data transmission method described herein are stored therein.
Also provided in the present invention is a computer program product, containing computer readable instructions which can execute the multilink wireless data transmission method.
In particular, it is possible to provide a system or device provided with the storage medium on which software program codes performing the functions of any one of the abovementioned embodiments are stored, and to enable the computer (or CPU or MPU) of the system or device to read out and execute the program codes stored in the storage medium.
In this case, the program codes read from the storage medium per se are capable of performing the functions of any one of the abovementioned embodiments; thus the program codes and the storage medium storing the program codes constitute a part of the present invention.
The storage medium embodiments for providing the program codes include floppy disks, hard disks, magneto optical disks, compact disks (such as CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM, DVD-RW, DVD+RW), magnetic tape, nonvolatile storage card and ROM. Optionally, the program codes can be downloaded from a server computer via communication networks.
In addition, it should be clear that the functions of any one of the abovementioned embodiments can be performed not only by executing the program codes read by the computer but also by enabling the operation system operated on the computer, etc. to perform a part of or all of the actual operations based on the instructions of the program codes.
What are mentioned above are merely the preferable exemplary embodiments of the present invention, and they are not intended to limit the protection scope of the present invention. Appropriate improvements to the preferred embodiments of the present invention can be made during particular implementation processes to meet particular requirements of a particular situation. Therefore it can be understood that particular embodiments of the present invention described herein are merely demonstrations but not used for limiting the scope of protection of the present invention.
Number | Date | Country | Kind |
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CN201110341439.7 | Nov 2011 | CN | national |
This is a U.S. national stage of PCT Application No. PCT/EP2012/071538, filed on Oct. 31, 2012, which claims priority to Chinese Patent Application No. 201110341439.7, filed on Nov. 2, 2011, each of which is hereby incorporated in its entirety by reference.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP2012/071538 | 10/31/2012 | WO | 00 | 5/1/2014 |