Patent Application
20130176870
1. Technical Field
The present disclosure relates to an antenna array control method, in particular, to an antenna array control method for selecting a best radiation pattern to perform a communication, and the access point using the same.
2. Description of Related Art
Recently, the wireless communication technology develops rapidly, and thus the client can communicate with the access point served as the wireless hotspot, such as Wireless Fidelity (Wi-Fi) hotspot, to share data and browse the web page. The client is for example a smart phone, a pad, a notebook, or any other mobile device having the communication ability. The access point is for example a smart phone served as the mobile station, an indoor access point, an outdoor access point, or any other communication device allowing the client to establish a link to access the internet.
The radiation strength of the omni-directional antenna is distributed uniformly for all directions (or angles), and thus each of the most conventional access points adopts the omni-directional antenna to communicate with the clients of the different directions. Unfortunately, the omni-directional antenna has the dispersed antenna radiation energy, the low radiation efficiency, and the limited coverage.
For each of specific directions, the directional antenna has stronger radiation strength and the farer coverage. Thus, in order to increase the efficiency of antenna radiation energy and the coverage, each of some conventional access points adopts the directional antennae to communicate with the clients of the different directions. However, the conventional access point of this type, must know the specific position of the client during wireless communication, and the antenna array must be manually configured, such that the conventional access point can use the matched radiation pattern to communicate with the client.
In short, most conventional access points themselves are multiple input multiple output (MIMO) systems, and can select a best radiation pattern by using a conventional antenna array control method to communicate with the client of the specific direction. In other words, the beam forming is performed by the conventional access points. It is a pity that the conventional antenna array control method has the longer executing time and lower accuracy.
An exemplary embodiment of the present disclosure discloses an antenna array control method comprising the following steps. At least a packet is selected as at least a probing packet every probing period. One of the radiation patterns to be probed in an antenna array is used to transmit the probing packet. Packet error rates of the radiation patterns to be probed in the antenna array are calculated. The radiation pattern with a minimum packet error rate among all of the radiation patterns is selected as a best radiation pattern.
An exemplary embodiment of the present disclosure discloses an antenna array control method comprising the following steps. Whether a plurality of radiation patterns to be probed of an antenna array must be probed or not is determined, so as to choose at least a packet as at least a probing packet. If the radiation patterns to be probed of the antenna array must be probed, whether a minimum probing packet transmitting number of the radiation patterns to be probed is less than a probing packet transmitting window value is determined. If the minimum probing packet transmitting number of the radiation patterns to be probed is less than the probing packet transmitting window value, the antenna array is controlled to use the radiation pattern with the minimum probing packet transmitting number to transmit the probing packet. If the minimum probing packet transmitting number of the radiation patterns to be probed is not less than the probing packet transmitting window value, the probing packet transmitting numbers of the radiation patterns to be probed are attenuated, the antenna array is controlled to use the radiation pattern with a minimum packet error rate to transmit the probing packet, and a best radiation pattern is set to be the radiation pattern with the minimum packet error rate.
An exemplary embodiment of the present disclosure discloses an access point comprising an antenna array, a radiation pattern controller, a radio frequency (RF) circuit, and an antenna array control method execution unit. The radiation pattern controller is electrically coupled to the antenna array, the radio frequency circuit is electrically coupled to the antenna array, and the antenna array control method execution unit is electrically coupled to the radio frequency circuit and the radiation pattern controller. The antenna array has a plurality of radiation patterns. The radiation pattern controller is used to select one of the radiation patterns of the antenna array according to a radiation pattern selection signal. The antenna array control method execution unit is used to select at least a packet as at least a probing packet every probing period, control the access point to use one of the radiation patterns to be probed to transmit the probing packet through generating the radiation pattern selection signal, calculate packet error rates of the radiation patterns to be probed, and control the access point to select the radiation pattern with a minimum packet error rate among all of the radiation patterns as a best radiation pattern of the antenna array.
To sum up, the antenna array control method and access point according to exemplary embodiments of the present disclosure can fast and accurately find the best radiation pattern which is used to communicate with client.
In order to further understand the techniques, means and effects the present disclosure, the following detailed descriptions and appended drawings are hereby referred, such that, through which, the purposes, features and aspects of the present disclosure can be thoroughly and concretely appreciated; however, the appended drawings are merely provided for reference and illustration, without any intention to be used for limiting the present disclosure.
The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.
Reference will now be made in detail to the exemplary embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or similar parts.
An exemplary embodiment of the present disclosure provides an access point of executing an antenna array control method, such that the access point can use the best radiation pattern to communicate with the client. The antenna array control method periodically chooses a packet to be transmitted as a probing packet to find the packet error rates of the radiation patterns to be probed, and determines a probing range of the radiation patterns to be probed (i.e. the set of the radiation patterns to be probed), a probing period, and a statistic range of the packet error rate (i.e. the total sample number of the packet error rate, which is corresponding to a statistic attenuation value) by performing a statistic operation on the received signal strength indicator (RSSI) variation associated with the best radiation pattern.
In short, the antenna array control method utilizes the statistic information of the transmission, such as the packet error rates of the radiation patterns to be probed, the received signal strength indicator variation of the best radiation pattern, and so on. Thus, the accuracy and execution time of the antenna array control method for finding the best radiation pattern are respectively increased and shortened. In addition, the throughput of the access point using the above antenna array control method can be further enhanced. The following descriptions illustrate the details of the exemplary embodiments of the access point and the antenna array control method.
The access point 1 comprises an antenna array control method execution unit 11, a radiation pattern controller 12, an antenna array 13, and radio frequency circuit 14. The antenna array control method execution unit 11 is electrically coupled to the radiation pattern controller 12. The radiation pattern controller 12 is electrically coupled to the antenna array 13. The antenna array 13 is electrically coupled to the radio frequency circuit 14. The radio frequency circuit 14 is electrically coupled to the antenna array control method execution unit 11.
The antenna array control method execution unit 11 comprises an antenna array control algorithm storage unit 111, a memory unit 112, and a processor 113. The processor 113 is electrically coupled to the antenna array control algorithm storage unit 111 and the memory unit 112.
The antenna array control algorithm storage unit 111 stores an algorithm associated with the antenna array control method, and for example can be the non-volatile memory apparatus. The processor 113 performs the antenna array control method according to the algorithm stored in the antenna array control algorithm storage unit 111, and transmits the statistic information (such as packet error rates of the radiation pattern, the packet transmitting number, a received signal strength indicator of each packet, and a received signal strength indicator variation and sample number of the best radiation pattern) obtained from the execution of the antenna array control method to the memory unit 112. The memory unit 112 stores the statistic information, and can for example be a volatile or non-volatile memory apparatus.
In the exemplary embodiment of
The antenna array 13 has a plurality of antennas which provides a plurality of radiation patterns to the radio frequency circuit 14, and thus the radio frequency circuit 14 can use selected one of the radiation patterns to transmit or receive the packet. The radiation pattern controller 12 indicates the antenna array 13 to select one of the radiation patterns according to the radiation pattern selection signal generated by antenna array control method execution unit 11.
The antenna array control method execution unit 11 selects at least a packet as at least a probing packet every probing period, and use one of the radiation patterns to be probed to transmit the probing packet. In addition, the other packets not selected as the probing packets are transmitted by using the best radiation pattern. Furthermore, in the exemplary embodiment of the present disclosure, the antenna array 13 may set the radiation pattern for receiving the packet to be the radiation pattern for transmitting the packet.
According to the majority of communications standards, when the client receives a packet, the client will transmit a confirm signal (for example, the acknowledge signal ACK) back to the access point 1, or equivalently, when the client does not receive the packet for a specific time, the client will transmit the non-confirm signal (for example, the non-acknowledge signal NACK) back to the access point 1. Thus, the access point 1 can know whether the probing packet is successfully transmitted to the client or not, and the antenna array control method execution unit 11 can further obtain the packet error rates of the radiation patterns to be probed.
To be specific, to enhance the comparability of the packet error rates, the antenna array control method execution unit 11 can make the probing packet transmitting numbers of radiation patterns to be probed be identical to each other. During the probing process, the antenna array control method execution unit 11 selects the radiation pattern to be probed with the minimum probing packet transmitting number to transmit the probing packet. Then, the antenna array control method execution unit 11 generates the radiation pattern selection signal corresponding to the radiation pattern to be probed with the minimum probing packet transmitting number to the radiation pattern controller 12. Thus, the radiation pattern controller 12 can control the antenna array 13 to select the radiation pattern to be probed with the minimum probing packet transmitting number.
When the probing packet transmitting numbers of the radiation patterns to be probed are equal to the probing packet transmitting window value (i.e. a specific threshold value), the antenna array control method execution unit 11 may reset the probing packet transmitting numbers of the radiation patterns to be probed, and select the radiation pattern with the minimum packet error rate among the radiation patterns as the best radiation pattern. Then, the antenna array control method execution unit 11 may generate the radiation pattern selection signal corresponding to the best radiation pattern to the radiation pattern controller 12, such that the radiation pattern controller 12 can control the antenna array 13 to select the radiation pattern.
It is noted that, the antenna array control method execution unit 11 attenuates the probing packet transmitting numbers of the radiation patterns to be probed according to the statistic attenuation value to reset the probing packet transmitting numbers of the radiation patterns to be probed.
In addition, when the antenna array control method execution unit 11 currently uses the best radiation pattern to transmit the probing packet, the antenna array control method execution unit 11 can perform a statistic operation on the received signal strength indicator of each probing packet. When the sample number of the received signal strength indicators being counted is enough, the antenna array control method execution unit 11 calculates the received signal strength indicator variation of the best radiation patterns according to the received signal strength indicators.
When the antenna array control method execution unit 11 currently does not use best radiation pattern to transmit the probing packet, if the best radiation pattern does not change, the antenna array control method execution unit 11 cannot calculate the received signal strength indicator variation of the currently used radiation pattern. By contrast, if the best radiation pattern changes, the antenna array control method execution unit 11 can calculate the received signal strength indicator variation of the best radiation pattern of the previously used best radiation pattern so as to obtain the statistic attenuation value, the probing period, and the probing range of the radiation patterns to be probed. Then, the antenna array control method execution unit 11 can reset the received signal strength indicator variation of the best radiation pattern.
Based upon the foregoing description, in the exemplary embodiment of the present disclosure, the antenna array control method executed by the antenna array control method execution unit 11 can be divided into two main steps which are respectively the probing packet transmission step and the probing packet statistic calculation step. The following description gives illustrations of the probing packet transmission step and the probing packet statistic calculation step.
Referring to
At step S204, since the probing process is not required (i.e. the packet is not served as the probing packet), the antenna array control method execution unit 11 controls the antenna array 13 to use the best radiation pattern to transmit the packet through the radiation pattern controller 12. At step S204, the antenna array control method execution unit 11 further sets the best radiation pattern to be the radiation pattern of the antenna array for receiving the packet.
At step S202, the antenna array control method execution unit 11 determines whether the minimum probing packet transmitting number among the radiation patterns to be probed is less than the probing packet transmitting window value. If the minimum probing packet transmitting number is less than the probing packet transmitting window value, the step S203 is executed. If the minimum probing packet transmitting number is equal to the probing packet transmitting window value (i.e. the probing packet transmitting number of the radiation patterns to be probed are equal to the probing packet transmitting window value), the step S205 is executed.
At step S203, the antenna array control method execution unit 11 determines the antenna array 13 to use the radiation pattern with the minimum probing packet transmitting number to transmit the probing packet through the control of the radiation pattern controller 12. In addition, at step S203, the antenna array control method execution unit 11 further sets the radiation pattern of the antenna array 13 for receiving the packet to be the radiation pattern with the minimum probing packet transmitting number.
At step S205, the antenna array control method execution unit 11 attenuates the probing packet transmitting number of the radiation patterns to be probed according to the statistic attenuation number. Next, at step S206, the antenna array control method execution unit 11 determines the antenna array 13 to use the radiation pattern with the minimum packet error rate to transmit the probing packet through the control of the radiation pattern controller 12, and updates the best radiation pattern to be the radiation pattern with the minimum packet error rate. In addition, at step S206, the antenna array control method execution unit 11 further sets the radiation pattern of the antenna array 13 for receiving the packet to be the radiation pattern with the minimum packet error rate.
Moreover, it is noted that, the probing range of the radiation patterns to be probed, the probing period, and the statistic attenuation value is determined according to the received signal strength indicator variation of the best radiation pattern. When the received signal strength indicator variation of the best radiation pattern is smaller, the probing range of the radiation to be probed and the statistic attenuation value is smaller, and the probing period is longer. By contrast, when the received signal strength indicator variation of the best radiation pattern is larger, the probing range of the radiation to be probed and the statistic attenuation value is larger, and the probing period is shorter. Thus, the accuracy of the antenna array control method is guaranteed, and the execution time and the probing consumption are reduced.
Please refer to
First, at step S301, antenna array control method execution unit 11 determines whether the currently transmitting packet is the probing packet. If the currently transmitting packet is not the probing packet, the step S302 will be executed. If the currently transmitting packet is the probing packet, the step S305 will be executed.
At step S302, the antenna array control method execution unit 11 performs a statistic calculation on the received signal strength indicator of the packet. Then, at step S303, the antenna array control method execution unit 11 determines whether the sample number of the received signal strength indicators being counted is enough. If the sample number of the received signal strength indicators being counted is enough, the step S304 will be executed. If the sample number of the received signal strength indicators being counted is not enough, the probing packet statistic calculation step will be ended. It is noted that, at step S303, whether the sample number of the received signal strength indicators being counted is enough can be determined by whether the statistic period used to perform the statistic calculation on the received signal strength indicator.
At step S304, the antenna array control method execution unit 11 calculates the received signal strength indicator variation of the best radiation pattern, and determines the statistic attenuation value, the probing period, and the probing range of the radiation patterns to be probed correspondingly, wherein the received signal strength indicator variation of the best radiation pattern is obtained according to the received signal strength indicators of the packets transmitted by using the best radiation pattern.
At step S305, the antenna array control method execution unit 11 updates the packet error rate of the currently used radiation pattern associated with the antenna array 13. At step S306, the antenna array control method execution unit 11 sorts the radiation patterns according to the packet error rates associated with the radiation patterns.
Next, at step S307, the antenna array control method execution unit 11 determines whether the best radiation pattern changes, i.e. determines whether the radiation pattern with the minimum packet error rate is still the previous best radiation pattern. If the best radiation pattern changes, the step S308 will be executed. By contrast, if the best radiation pattern doesn't change, the probing packet statistic calculation step will be ended.
At step S308, the antenna array control method execution unit 11 calculates received signal strength indicator variation of the previous best radiation pattern, and determines the statistic attenuation value, the probing period, the probing range of the radiation pattern to be probed correspondingly, wherein the received signal strength indicator variation of the previous best radiation pattern is obtained according to the received signal strength indicators of the packets transmitted by the previous best radiation pattern. Next, at step S309, the antenna array control method execution unit 11 resets the received signal strength indicator of the best radiation pattern, so as to recalculate the received signal strength indicator variation of the best radiation pattern.
Next, the details for determining the statistic attenuation value, the probing period, and the probing range of the radiation pattern are illustrated as follows. Referring to
The formula of the received signal strength change of the best radiation pattern is for example can be expressed as CR=PT0/2+(CR1+CR2)/4. The variable CR represents the received signal strength change of the best radiation pattern, and the variables CR1 and CR2 respectively represent the received signal received strength indicators of the previous two best radiation patterns. The variable PT0 is expressed as PT0=num(−r≦RSSIk−RA1≦r)/SampleNum, wherein the variable SampleNum represents the sample number of the received signal strength indicator, the variable r is a user defined positive integer, such as 1, the variable RA1 represents the average received signal strength indicator in the previous statistic period, the variable RSSIk is the received signal strength indicator in the previous statistic period, and the function num(−r≦RSSIk−RA1≦r) means the number which the difference between the received signal strength indicator and the average received signal strength indicator in the previous statistic period is not less than −r and not larger than r. In short, the variable PT0 represents the ratio of the number which the difference between the received signal strength indicator and the average received signal strength indicator in the previous statistic period is not less than −r and not larger than r, over the sample number of the received signal strength indicators.
However, it is noted that, the formula of the received signal strength indicator variation may be modified to meet the different requirements. The formula of the received signal strength indicator variation is not used to limit the present disclosure.
In the exemplary embodiment of
When the received signal strength indicator of the best radiation is larger than a % but less than and equal to b %, it means the received signal strength indicator variation has little variation. Meanwhile, the statistic attenuation value is ¼, the probing range of the radiation patterns to be probed is P/4, and the probing period is T/2, wherein the variable b is for example 15. When the received signal strength indicator of the best radiation is larger than b % but less than and equal to c %, it means the received signal strength indicator variation has normal variation. Meanwhile, the statistic attenuation value is ½, the probing range of the radiation patterns to be probed is P/2, and the probing period is T/3, wherein the variable b is for example 45. When the received signal strength indicator of the best radiation is larger than c %, it means the received signal strength indicator variation has extreme variation. Meanwhile, the statistic attenuation value is 1, the probing range of the radiation patterns to be probed is P, and the probing period is T/4.
In addition, it is noted that the table of
To sum up, the antenna array control method and access point of the exemplary embodiments can fast and accurately find the best radiation pattern to communicate with the client. Furthermore, compared to the conventional access point, the access point using the above antenna array control method has the increased wireless coverage, the enhanced data throughput, and the improved data transmission rate.
The above-mentioned descriptions represent merely the exemplary embodiment of the present disclosure, without any intention to limit the scope of the present disclosure thereto. Various equivalent changes, alternations or modifications based on the claims of present disclosure are all consequently viewed as being embraced by the scope of the present disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201210003562.2 | Jan 2012 | CN | national |
