Background technology
WLAN (wireless local area network) (WLAN) technology based on IEEE802.11 consensus standard is widely applied.Wireless user's premises equipment (CPE) is a kind of wireless terminal device receiving WiFi signal, is a kind of novel wireless terminal accessing device that can replace the terminal equipments such as wireless network card.For rural area, the so spacious environment in suburb, if deployment-specific transmission line, then cost is large, long construction period.And wireless CPE is equipped with directional antenna, make CPE transmitting power higher than common client device, thus do not need to use dedicated transmissions circuit, decrease the loss on line transmission, therefore greatly can improve entire system performance when wireless base station covers on a large scale.The mode of Power over Ethernet (PoE) can be used to power to CPE, like this, be convenient to install while good performance is provided for user, short construction period.In addition, people always wish that the coverage of wireless base station is the bigger the better, but the transmission range of wireless communication system is simultaneously relevant to the performance of wireless terminal.The ascending power of standard WiFi client is limited, and therefore, no matter the descending power of wireless base station has much, and the Top Runby of standard WiFi client all receives the restriction of ascending power, and distance is very limited.
IEEE802.11 agreement specifies, after sender sends a frame, recipient needs transmission Acknowledgement (ACK) frame to reply, and represents and successfully receives data.If sender does not receive the ACK frame of recipient within one period of scheduled time, sender can think this data transmission fails, and can resend this frame by comparatively low rate.This scheduled time is called as acktimeout.When adopting CPE, even if the uplink transmit power of CPE is higher than common client device, but be applied in rural area, this kind of situation in cities and towns, along with the increase of transmission range, signal strength signal intensity reduces, and the frame transmission time is corresponding increase also, according to fixing acktimeout, the re-transmission of mass data frame will inevitably be caused, have a strong impact on the throughput of system.
Along with the increase of transmission range, the communication between wireless device there will be increasing retransmission frame, and lower speed can be used between wireless device to communicate.In order to the throughput of not influential system, most wireless device provides the mechanism of amendment equipment acktimeout.Usually, common client cannot arrange acktimeout, but CPE can be arranged acktimeout, and this compensate for the deficiency of normal client end equipment in long range communication.At present, the acktimeout of the wireless CPE of transmission range situation manual configuration according to wlan system is needed.Usually, can be configured according to the acktimeout of coverage at that time to wireless base station.But, if run into the environment of more complicated, then the trial carried out repeatedly may be needed could to obtain a rational acktimeout.If there is several wireless base station, this will increase the workload of attendant greatly, can expend attendant's more time and energy, is not easy to very much management.For CPE client device, manual configuration acktimeout is more difficult, this is because user does not possess professional knowledge and cannot configure, even if having certain professional knowledge, do not understand the communication conditions of CPE client device and wireless base station, cannot complete configuration without any foundation yet.
Summary of the invention
The present invention adopts dynamic mode automatically to adjust the acktimeout of wireless base station and wireless terminal device, to improve the throughput of long-distance transmission.
According to an aspect of the present invention, provide a kind of ACK method of adjustment for wireless base station, comprising: (a) counts the ACK frame received from the wireless terminal device associated with wireless base station; B () checks the ACK frame count of the wireless terminal device received in the given time, if unreceived ACK frame count is greater than predetermined value, then obtain the transmitted power of wireless terminal device; (c) transmitted power calculating wireless terminal device based on wireless terminal device and the current distance of wireless base station; If d current distance that () calculates is relative to the change overrate of the first front distance of wireless base station and wireless terminal device, then based on the response time-out time acktimeout of the current distance adjustment wireless base station calculated.
According to an aspect of the present invention in the ACK method of adjustment of wireless base station, in step (c), wireless base station calculates the distance between wireless terminal device and wireless base station according to following formula: Si=Pout-Ct+Gt-PL+Gr-Cr; PL=32.4+20 × LogF
mhz+ 20 × LogR
kmwherein, Si represents the signal strength signal intensity that wireless base station receives, Pout represents the transmitted power of wireless terminal device, Ct and Cr represents the decay of the cable of the wireless terminal device as transmitting terminal and the wireless base station as receiving terminal respectively, Gt and Gr represents the gain of the antenna of the wireless terminal device as transmitting terminal and the wireless base station as receiving terminal respectively, and PL is space attenuation, F
mhzrepresent carrier frequency, R
kmrepresent the distance between wireless terminal device and wireless base station.
According to an aspect of the present invention in the ACK method of adjustment of wireless base station, in step (d), according to the aerial propagation velocity of electromagnetic wave, modulation system, ACK frame sign and 802.11 mark spaces calculate acktimeout.
According to an aspect of the present invention in the ACK method of adjustment of wireless base station, in step (b), wireless base station sends the claim frame for asking transmitted power to wireless terminal device, receive the response frame of wireless terminal device, and from response frame, obtain the transmitted power of wireless terminal device.
According to an aspect of the present invention in the ACK method of adjustment of wireless base station, in step (c), distribution situation according to the quantity of all wireless terminal devices of wireless base station coverage and the distance between each wireless terminal device and wireless base station calculates distance average, and adjusts the acktimeout of wireless base station based on the distance average calculated.
According to an aspect of the present invention, additionally provide the device that a kind of ACK for wireless base station adjusts, comprising: counter, the ACK frame received from the wireless terminal device associated with wireless base station is counted; Power detecting unit, checks the ACK frame count of the wireless terminal device received in the given time, if unreceived ACK frame count is greater than predetermined value, then obtains the transmitted power of wireless terminal device; Computing unit, the transmitted power based on wireless terminal device calculates the current distance of wireless terminal device and wireless base station; Adjustment unit, if the current distance calculated is relative to the change overrate of the first front distance of wireless base station and wireless terminal device, then based on the acktimeout of the current distance adjustment wireless base station calculated.
According to an aspect of the present invention, power detecting unit controls wireless base station and sends for asking the claim frame of transmitted power and receiving the response frame of wireless terminal device to wireless terminal device, and from response frame, obtain the transmitted power of wireless terminal device.
According to an aspect of the present invention, computing unit calculates distance average according to the distribution situation of the quantity of all wireless terminal devices of wireless base station coverage and the distance between each wireless terminal device and wireless base station, and adjustment unit is based on the acktimeout of the distance average adjustment wireless base station calculated.
According to a further aspect in the invention, additionally provide a kind of ACK method of adjustment for wireless terminal device, comprising: (a) counts the ACK frame received from wireless base station; B () checks the ACK frame count of the wireless base station received in the given time, if unreceived ACK frame count is greater than predetermined value, then obtain the transmitted power of wireless base station; (c) transmitted power calculating wireless terminal device based on wireless base station and the current distance of wireless base station; If d current distance that () calculates is relative to the change overrate of the first front distance of wireless base station and wireless terminal device, then based on the acktimeout of the current distance adjustment wireless terminal device calculated.
According to an aspect of the present invention in the ACK method of adjustment of wireless terminal device, in step (c), wireless terminal device calculates the distance between wireless terminal device and wireless base station according to following formula: Si=Pout-Ct+Gt-PL+Gr-Cr; PL=32.4+20 × LogF
mhz+ 20 × LogR
kmwherein, Si represents the signal strength signal intensity that wireless terminal device receives, Pout represents the transmitted power of wireless base station, Ct and Cr represents the decay of the cable of the wireless base station as transmitting terminal and the wireless terminal device as receiving terminal respectively, Gt and Gr represents the gain of the antenna of the wireless base station as transmitting terminal and the wireless terminal device as receiving terminal respectively, and PL is space attenuation, F
mhzrepresent carrier frequency, R
kmrepresent the distance between wireless terminal device and wireless base station.
According to an aspect of the present invention in the ACK method of adjustment of wireless base station, in step (b), wireless terminal device sends the claim frame for asking transmitted power to wireless base station, receive the response frame of wireless base station, and from response frame, obtain the transmitted power of wireless base station.
According to a further aspect in the invention, provide the device that a kind of ACK for wireless terminal device adjusts, comprising: counter, the ACK frame received from wireless base station is counted; Power detecting unit, checks the ACK frame count of the wireless base station received in the given time, if unreceived ACK frame count is greater than predetermined value, then obtains the transmitted power of wireless base station; Computing unit, the transmitted power based on wireless base station calculates the current distance of wireless terminal device and wireless base station; Adjustment unit, if the current distance calculated is relative to the change overrate of the first front distance of wireless base station and wireless terminal device, then based on the response time-out time acktimeout of the current distance adjustment wireless terminal device calculated.
According to a further aspect in the invention, power detecting unit controls wireless terminal device and sends to wireless base station for asking the claim frame of transmitted power and receiving the response frame of wireless base station, and from response frame, obtain the transmitted power of wireless base station.
Embodiment
Below with reference to accompanying drawings exemplary embodiment of the present invention is described.
Fig. 1 illustrates according to an exemplary embodiment of the present invention for the flow chart of the ACK method of adjustment of wireless base station.
First, in step 110, the quantity of wireless base station to the ACK frame received from wireless terminal device counts.
Next, in step 120, the ACK frame count of the wireless terminal device that wireless base station inspection receives in the given time.Have a timer according to the wireless base station of exemplary embodiment of the present invention creates, this timer can travel through all states being associated in the counting of the ACK frame of the wireless terminal device of this wireless base station.If in the given time, the count value of the ACK frame of the wireless terminal device do not received does not exceed the threshold value of setting, then count value resets by wireless base station; If exceed threshold value, then wireless base station is determined to need arranging response time-out time acktimeout.
If determine to need to arrange acktimeout in step 120, then proceed to step 130.In step 130, wireless base station obtains the transmitted power of wireless terminal device.According to embodiments of the invention, wireless base station is by sending Action frame to wireless terminal device and obtaining from wireless terminal device the transmitted power that response frame obtains wireless terminal device.
Fig. 2 shows according to an exemplary embodiment of the present invention for obtaining the Action frame of transmitted power.By expanding the Action frame obtained according to the embodiment of the present invention to the Action frame of 802.11 standards.As shown in Figure 2, after Action field, there is power interaction fields 20 for the Action frame obtaining transmitted power according to the embodiment of the present invention.Power interaction fields 20 comprises 1 Req/Resp field and 1 Txpower field, and Req/Resp field instruction Action frame is for asking transmitted power or for response (reply) transmitted power.Such as, when the value of Req/Resp field is 0, represents that this Action frame is the frame for asking transmitted power, and when the value of Req/Resp field is 1, represent that this Action frame is the frame for responding transmitted power.Txpower field is used to indicate the value of transmitted power.
Wireless base station can receive the response Action frame from wireless terminal device after the Action frame of request transmitted power is sent to wireless terminal device subsequently, and obtains the transmitted power of wireless terminal device from response Action frame.
Referring back to Fig. 1, next, in step 140, wireless base station calculates the current distance between wireless terminal device and wireless base station based on the transmitted power of wireless terminal device.Here, according to one embodiment of the invention, distance between wireless terminal device and wireless base station can be calculated according to following equation:
Si=Pout-Ct+Gt-PL+Gr-Cr equation (1)
PL=32.4+20 × LogF
mhz+ 20 × LogR
kmequation (2)
Wherein, Si represents the signal strength signal intensity that wireless base station receives, Pout represents the transmitted power of wireless terminal device, Ct and Cr represents the decay of the cable of the wireless terminal device as transmitting terminal and the wireless base station as receiving terminal respectively, Gt and Gr represents the gain of the antenna of the wireless terminal device as transmitting terminal and the wireless base station as receiving terminal respectively, PL is space attenuation, F
mhzrepresent carrier frequency, R
kmrepresent the distance between wireless terminal device and wireless base station.Here, usual Ct, Cr, Gt and Gr can be preset.
Then, in step 150, the current distance that calculates in the step 140 change whether overrate relative to the first front distance of wireless base station and wireless terminal device is determined in wireless base station.If determine to change overrate, then in step 160, then wireless base station is according to the acktimeout of the current distance adjustment wireless base station calculated.Particularly, after the transmission range obtaining wireless terminal device and wireless base station, acktimeout can be calculated according to the aerial propagation velocity of electromagnetic wave, modulation system, ACK frame sign and 802.11 mark spaces.
Illustrate the example calculating acktimeout according to transmission range below.Usually, ACK frame can be sent out according to the speed of 6Mbps.In addition, 802.11g adopts OFDM technology, and 20Mhz carrier frequency has 52 subcarriers, wherein has 48 subcarriers for communicated data signal, and modulation system adopts BPSK, and each code element has 1bit.WLAN technology sends a symbol needs 3.2us.When 802.11g, mark space be 800ns to prevent neighbor isi, the code check of BPSK is 1/2.The bit number of each like this carrier wave coding is 1bit, totally 48 subcarriers, so total 48*1bit=48bit.The data bit of each symbol is 48bits*1/2=24bits.The size of ACK frame is 14bytes, needs use 5 symbols to send, and lead code and the transmission of PLCP head need need 20us.Therefore, ACK send time=20+5*4=40us, thus acktimeout can be calculated according to following equation (3):
Acktimeout=T
ack+ distance/c+a equation (3),
Wherein, T
ackrepresent the transmitting time of ACK frame, c represents the aerial propagation velocity of electromagnetic wave, and a represents compensation constant, can environmentally suitably adjust.A value is necessarily greater than 0, this is because receiving data frames also needs to consume part-time.
After adjustment acktimeout, the counting of ACK frame resets by wireless base station.If determine that change does not have overrate, then the counting of ACK frame directly resets by wireless base station.
According to embodiments of the invention, if there is multiple wireless terminal device in the coverage of wireless base station, then when step 160 adjusts acktimeout, can not only according to and the distance of one of them wireless terminal device determine the acktimeout of wireless base station, but need to choose a moderate value.Particularly, a distance average can be calculated according to the distribution situation of the quantity of all wireless terminal devices of wireless base station coverage and the distance between each wireless terminal device and wireless base station, and adjust the acktimeout of wireless base station based on the distance average calculated.In addition, according to quantity and the range distribution situation of wireless terminal device, the computational methods for distance average can be changes.
Illustrate according to an exemplary embodiment of the present invention for the ACK method of adjustment of wireless terminal device below with reference to Fig. 3.
First, in step 310, wireless terminal device counts the ACK frame received from wireless base station.
Next, in step 320, the ACK frame count of the wireless base station that wireless terminal device inspection receives in the given time.According to the wireless terminal device of exemplary embodiment of the present invention, there is a timer equally.If in the given time, the count value of the ACK frame of the wireless base station do not received does not exceed the threshold value of setting, then count value resets by wireless terminal device; If exceed threshold value, then wireless terminal device is determined to need arranging response time-out time acktimeout.
If determine to need to arrange acktimeout in step 320, then proceed to step 330.In step 330, wireless terminal device obtains the transmitted power of wireless base station.According to embodiments of the invention, wireless terminal device is by sending Action frame to wireless base station and obtaining from wireless terminal device the transmitted power that response frame obtains wireless terminal device.Action frame is identical with the Action frame of Fig. 2 as used herein, therefore, will no longer set forth.
Next, in step 340, wireless terminal device calculates the current distance between wireless terminal device and wireless base station based on the transmitted power of wireless base station.Here, according to one embodiment of the invention, distance between wireless terminal device and wireless base station can be calculated according to equation 1 and equation 2 equally:
Si=Pout-Ct+Gt-PL+Gr-Cr;
PL=32.4+20×LogF
mhz+20×LogR
Km,
Wherein, Si represents the signal strength signal intensity that wireless terminal device receives, Pout represents the transmitted power of wireless base station, Ct and Cr represents the decay of the cable of the wireless base station as transmitting terminal and the wireless terminal device as receiving terminal respectively, Gt and Gr represents the gain of the antenna of the wireless base station as transmitting terminal and the wireless terminal device as receiving terminal respectively, PL is space attenuation, F
mhzrepresent carrier frequency, R
kmrepresent the distance between wireless terminal device and wireless base station.
Then, in step 350, wireless terminal device determines the current distance that calculates in the step 340 change whether overrate relative to the first front distance of wireless base station and wireless terminal device.If determine to change overrate, then in step 360, then wireless terminal device is according to the acktimeout of the current distance adjustment wireless base station calculated.After adjustment acktimeout, the counting of ACK frame resets by wireless terminal device.If determine that change does not have overrate, then the counting of ACK frame directly resets by wireless terminal device.
Below with reference to Fig. 4, the device adjusted according to the ACK for wireless base station of the embodiment of the present invention and the device adjusted for the ACK of wireless terminal device are described.
As shown in Figure 4, the device 400 adjusted for the ACK of wireless base station comprises counter 410, power detecting unit 420, computing unit 430 and adjustment unit 440.Counter 410 is for counting the ACK frame received from the wireless terminal device associated with wireless base station.Power detecting unit 420 checks the ACK frame count of the wireless terminal device received in the given time, if unreceived ACK frame count is greater than predetermined value, then obtains the transmitted power of wireless terminal device.The transmitted power calculating wireless terminal device of computing unit 430 based on wireless terminal device and the current distance of wireless base station.If the current distance calculated is relative to the change overrate of the first front distance of wireless base station and wireless terminal device, then adjustment unit 440 is based on the acktimeout of the current distance adjustment wireless base station calculated.Wherein, computing unit 430 can calculate distance between wireless terminal device and wireless base station according to equation 1 and 2, will no longer be described in detail at this.In addition, when there is multiple wireless terminal device in wireless base station coverage, computing unit 430 calculates distance average according to the distribution situation of the quantity of all wireless terminal devices of wireless base station coverage and the distance between each wireless terminal device and wireless base station, thus adjustment unit 440 is based on the acktimeout of the distance average adjustment wireless base station calculated.Power detecting unit 420 sends for asking the claim frame of transmitted power and receiving the response frame of wireless terminal device to wireless terminal device by controlling wireless base station, obtains the transmitted power of wireless terminal device from response frame.
The device 500 adjusted for the ACK of wireless terminal device comprises: counter 510, power detecting unit 520, computing unit 530 and adjustment unit 540.Counter 510 is for counting the ACK frame received from wireless base station.Power detecting unit 520 checks the ACK frame count of the wireless base station received in the given time, if unreceived ACK frame count is greater than predetermined value, then obtains the transmitted power of wireless base station.The transmitted power calculating wireless terminal device of computing unit 530 based on wireless base station and the current distance of wireless base station.If the current distance calculated is relative to the change overrate of the first front distance of wireless base station and wireless terminal device, then adjustment unit 540 is based on the acktimeout of the current distance adjustment wireless terminal device calculated.Similarly, computing unit 530 can calculate distance between wireless terminal device and wireless base station according to equation 1 and 2, and power detecting unit 520 sends for asking the claim frame of transmitted power and receiving the response frame of wireless terminal device to wireless base station by controlling wireless terminal device, obtains the transmitted power of wireless terminal device from response frame.
The present invention can realize the automatic adjustment of the ACK time-out for wireless base station and wireless terminal device, thus the throughput of wireless system can be improved, and can judge that the decrease reason of throughput causes because of transmission range or other disturbing factor exactly.In addition, when adjusting the acktimeout of wireless base station, suitable acktimeout can be calculated according to the quantity of wireless terminal device and range distribution, thus can ensure that the throughput of whole wireless system is in optimal level.
Although illustrate and describe the present invention with reference to some exemplary embodiments of the present invention, but it should be appreciated by those skilled in the art that, when not departing from the spirit and scope of the present invention of claim and equivalents thereof, various change can be made in form and details.