CN103220761B - Distributed AP power dynamic adjusting method under intensive WLAN environment - Google Patents

Abstract

Distributed AP power dynamic adjusting method under the invention discloses a kind of intensive WLAN environment, mainly solves prior art can not adapt to network change in real time deficiency to reduction access point AP energy consumption aspect.Its step realized is: terminal sets up access-in point information table; Under the condition meeting service quality, access point AP adjusts the transmitting power of oneself according to the current terminal be connected with it; Access point AP receives new connection request, responds this request and adjusts oneself transmitting power; Access point AP receives releasing connection request, responds this request, and carries out switching differentiation and power-save operation; Wait for a period of time, if do not receive any request, access point then initiatively carries out switching and differentiates and power-save operation.Access point of the present invention can according to the behavioral trait of terminal in network, dynamically its transmitting power is adjusted, adapt to the change of network timely, the energy ezpenditure of AP can better be reduced, reduce the signal disturbing between AP, can be used in the wlan network of the intensive layout of AP.

Description

Distributed AP power dynamic adjusting method under intensive WLAN environment

Technical field

The invention belongs to communication technical field, in particular to the power dynamic adjusting method of a kind of access point AP, be applicable to the WLAN (wireless local area network) WLAN of intensive laying, under the condition ensureing user's access service ability, reduce the energy ezpenditure of network side, reduce the interference of signal between access point AP.

Background technology

In recent years, wireless local area network technology obtains and develops rapidly, particularly in order to meet the high bandwidth of user, and the mobility of user, and the reliability requirements of information, occur on a large scale at the wlan network of enterprise, office or school intensive layout AP thereupon.

Mobile subscriber is entered the Internet by WLAN, for it provides miscellaneous service, and such as voice-over-net phone, business VoIP, multimedia and video etc.In order to the stability of above-mentioned business can be realized, continual and steady network insertion becomes inevitable requirement, so at the beginning of the network planning, in order to meet the demand of user, the layout of all AP is all carry out the planning of AP according to the peak traffic of a certain zone user, but because the behavior of user has certain regularity, such as, in the WLAN (wireless local area network) of arranging at dining room or coffee-house, only within certain period, user just can reach peak traffic, and the traffic carrying capacity within other periods is lower, in particularly about morning, traffic carrying capacity is 0 substantially.Relevant research also shows that network occurs that the time period of peak traffic is little, and wherein the AP most of the time is all be in idle state.So arranging in the WLAN of AP according to peak traffic, the unnecessary energy consumption that on the one hand caused network side to occur, is also causing the interference ratio between AP and neighbor AP more serious on the one hand.

Due to the very fast development of modern communication technology, the energy consumption in information and communication technology (ICT) field has become a very important problem.In some countries, the energy consumption of access network has accounted for more than 50% of whole communications field energy consumption, and especially in the field of wireless communication, the energy consumption of access network has accounted for more than 80%.Swift and violent in the WLAN number growth rate of enterprise or other local layouts, cause the number of AP exponentially to increase every year.No matter be must pay attention to energy ezpenditure from economic aspect or environmental protection aspect, so while lifting network performance, the energy consumption reducing network side radio access point AP has attracted the concern of more and more people.

For the above-mentioned energy consumption problem about the Access Network in intensive WLAN, there is relevant solution in the last few years, main thought is all turn off the AP of a part, or reduce the transmitting power of AP, the network service that WLAN can be provided is relevant to user's request, and concrete solution has RoD(resource on-demand) and ILP (integer linear programming).In RoD scheme, by the AP cluster in network, according to the traffic carrying capacity of current network, dynamic unlatching or closedown AP.In ILP scheme, the business demand of modelling network, utilizes the thought of linear programming to solve the lowest energy consumption of network in section sometime.But these schemes all also exist certain deficiency.In RoD scheme, the overlayable user of AP all in bunch is identical, and bunch in all AP identical with the channel gain between the user that this bunch covers, this model very idealized, the operability in the network of reality is poor.In ILP model, if network size is comparatively large, the amount of calculation solving linear programming can become very large thereupon, and time cost also can become very high, causes this algorithm can not meet the requirement of network dynamic.

Summary of the invention

The object of the invention is to for the deficiencies in the prior art, under the condition ensureing user's cut-in quality, distributed AP power dynamic adjusting method under proposing a kind of intensive WLAN environment, to reduce the energy ezpenditure of network side AP, reduces the signal disturbing between AP.

For achieving the above object, technical scheme of the present invention comprises the steps:

(1) in the network incipient stage, the access point AP in network at random according to the transmitting power work of a certain grade, and launches beacon frame with the interval of 100ms and maximum transmitting power, and is 0 by the mark position of beacon frame;

(2) a jth terminal t in network _jscanning channel, receives the beacon information that access point AP sends, and utilizes the beacon frame received to set up terminal t _jaccess-in point information, terminal t _jaccess-in point information comprise: terminal t _jaccess point set A _j, set A _jin all access point AP cover terminal t _jminimum emissive power, terminal t _jselect the access point a connected _swith alternate access point set B _j, concrete method for building up describes in dependent claims 1, wherein j=1, and 2 ...., n;

(3) access point a _i, i=1,2 ...., m is the stand-by period from receiving the time of previous association request frame, access point a in this time period T _iwait for the access of terminal, and judge access point a in time period T _iwhether receive connection request:

If access point a _ido not receive connection request, calculate access point a _icover set T _iin the minimum emissive power of all terminals adjustment access point a _icurrent transmitting power is wherein T _icurrent with access point a _ithe set of all terminals connected, wherein l _i,jfor access point a _icover terminal t _jminimum emissive power, complete after jump to step (4);

If access point a _ireceive connection request, then turn back to step (3);

(4) access point a _iregularly carry out information interaction with its neighboring access point AP, the current transmitting power of acquisition neighboring access point AP;

(5) access point a is judged _iwhether receive new connection request, if do not receive new connection request to perform step (6), if receive new connection request, to access point a _ibe handled as follows in two kinds of situation:

If (5a) a _icover new terminal t _n+1minimum emissive power l _{i, n+1}be less than or equal to a _icurrent transmitting power new terminal t _n+1directly and a _iconnect, after complete, forward step (5) to;

If (5b) a _icover new terminal t _n+1minimum emissive power l _{i, n+1}be greater than a _icurrent transmitting power respond this request, adjustment a _icurrent transmitting power value be l _{i, n+1}, namely step (5) is forwarded to after complete;

(6) access point a is judged _iwhether receive releasing connection request, if do not receive the request removed and connect, perform step (7), if receive the request removed and connect, respond this request, and to access point a _ido following process:

(6a) by the mark position 1 of beacon frame, access point a _iafter sending this beacon, immediately the flag bit of beacon frame is reduced to 0.

(6b) access point a _ireceive set T _iin terminal send the Frame comprising access-in point information of terminal, obtain set T _iin the access-in point information of each terminal;

(6c) access point a _iaccording to set T _ithe access-in point information of middle terminal is determined and access point a _ithe null terminator Null set U connected _i, set U _iin terminal meet: calculate access point a _icover set T _i-U _ithe minimum emissive power of middle terminal with difference: wherein for access point a _icover set T _iin the minimum emissive power of all terminals

(6d) access point a _iaccording to the terminal t received _uaccess-in point information, computing terminal t _ube linked into access point a _lafter, access point a _itransmitting power is relative to terminal t _uaccess point a when not accessing _lthe changing value of transmitting power: wherein t _u∈ U _i, a _l∈ B _u, B _ufor terminal t _uaccess point set, for access point a _lcurrent transmit power, l _l,ufor access point a _lcover terminal t _uminimum emissive power; In set B _uin, obtain terminal t _ucorresponding minimum power changing value

(6e) according to the method process set U of step (6d) _iin all terminals, obtain the minimum power changing value that each terminal is corresponding;

(6f) according to the value of trying to achieve in step (6c) and step (6e), the power change values that all access point AP of computing network is total: and determine U according to the size of D _ithe switching of middle terminal:

If D > 0, then U _iin terminal can be switched to alternate access point AP, perform step (6g);

If D≤0, then U _iin terminal can not be switched to alternate access point AP, turn back to step (5);

(6g) to set U _iin terminal all carry out active handover operation, make terminal t _uthe access point be switched to is for trying to achieve D _ucorresponding access point, wherein terminal t _u∈ U _i; After having switched, adjustment access point a _icurrent transmitting power turn back to step (5);

(7) access point a _iin the past the time of a transmitting power adjustment starts to wait for, if do not receive connection request or remove connection request in time period T1, then performs step (6a) ~ (6g); If only receive connection request, then perform step (5); If only receive releasing connection request, then perform step (6), if receive connection request and remove connection request, then preferential answering connection request simultaneously.

The present invention compared with prior art tool has the following advantages:

1. the present invention is according to the characteristic of channel between access point AP and terminal, the transmitting power of adjustment access point AP, make access point AP with the covering of minimum emissive power realization to terminal, thus access point AP can be realized with minimum power work, reduce the energy ezpenditure of AP;

2. the present invention is according to the behavioral trait of terminal, set up three kinds of different trigger mechanisms, access point AP adjusts its transmitting power in a different manner according to different trigger conditions, achieve the dynamic conditioning of access point AP transmitting power, thus reduce the energy ezpenditure of AP further, reduce the signal disturbing between AP.

Accompanying drawing explanation

Fig. 1 is the network model figure that the present invention uses;

Fig. 2 is overview flow chart of the present invention;

Fig. 3 is the sub-process figure of dynamic conditioning switch-in point transmitting power in the present invention.

Embodiment

Below in conjunction with accompanying drawing, content of the present invention is described in detail.

As shown in Figure 1, in the network model that the present invention uses, the coverage of its access point AP is relevant to its transmitting power, in the present invention, the transmitting power of access point AP adopts multiple centrifugal pump, the emitting power grade that different values is corresponding different, the emitting power grade set K={1 of access point AP, 2,, k} represents; In the present invention, i-th access point in network is designated as a _i, in network, all access point AP are A={a _i| i=1,2 ...., m}; A jth terminal is designated as t _j, the middle terminal of network is designated as T={t _j| j=1,2 ...., n}.

With reference to Fig. 2, performing step of the present invention is as follows:

Step 1: in the network incipient stage, the access point AP in network at random according to the transmitting power work of a certain grade, and launches beacon frame with the interval of 100ms and maximum transmitting power, and is 0 by the mark position of beacon frame;

The present invention, on the basis of 802.11 standards, with the addition of " transmitting power of beacon " information to beacon frame; The form of this information is as follows:

Message length accounts for five bytes altogether, and be divided into four fields, the length shared by each field as shown in Table 1; Wherein the value of Element id field is 43, shows that this information is the transmitting power of beacon; Length in Length field shared by this information; The value of flag bit is 0 or 1, when the value of this flag bit is 0, terminal utilizes newly arrived beacon frame to set up or the access-in point information of more new terminal, when the value of flag bit is 1, terminal upgrades after access-in point information according to this beacon frame, sends the access-in point information of this terminal to its current connected access point AP; The transmission power level of beacon is the double type of double precision, and unit is dBm.

The additional information of table one beacon frame

Element ID	Length	Flag bit	The transmitting power of beacon frame
				1	1	1	2

Step 2: the terminal t in network _j, j=1,2 ...., n scans channel, receives the beacon that access point AP sends, and utilizes the beacon frame received to set up terminal t as follows _jaccess-in point information:

(2.1) according to the received power of the beacon frame received, terminal t is determined _jaccess point set A _jif: terminal t _jreceive i-th access point a _ithe received power of the beacon frame sent is more than or equal to minimum receive threshold p _th, then access point a _ifor terminal t _jan access point, otherwise access point a _ican not as terminal t _jaccess point;

(2.2) terminal t is used _jall access points form access point set A _j: A _j={ a _i| p _i,j>=p _th, i=1,2 ...., m}, wherein p _i,jfor terminal t _jreceive a _ithe received power value of the beacon frame launched, p _th=-95dBm;

(2.3) set of computations A _jin all access point AP cover terminal t _jminimum emissive power: a _i∈ A _j, wherein, l _i,jfor access point a _icover terminal t _jminimum emissive power, p _ifor access point a _ilaunch the performance number of beacon frame;

Described set A _jin access point and access point cover terminal t _jminimum emissive power constitute terminal t _joriginal access-in point information, terminal t _jaccess-in point information as shown in Table 2, have recorded set A in table two _jin APN and this access point cover terminal t _jminimum emissive power.

Table two terminal t _joriginal access-in point information

APN	Access point covers terminal t jMinimal power values
		a i,a i∈A j	l i,j
……	……

Step 3: terminal t _jdetermine that this terminal selects the access point a connected according to original access-in point information _swith alternate access point set B _j, and with access point a _sconnect;

(3.1) terminal t is determined _jselect the access point a connected _swith alternate access point set B _j:

By set A _jin, p _s,jcorresponding access point is as access point a _s, terminal t _jto access point a _sthe received power p of the beacon sent _s,jmeet:

Alternate access point set: B _j=A _j-{ a _s;

(3.2) terminal t _jto access point a _ssend association request frame, with access point a _sconnect, simultaneously terminal t _jcontinue the beacon frame more new terminal t according to receiving _jin the A described in step (2.2), (3.1) _j, l _i,j, B _jinformation;

A described in step (2.2) _j, l _i,jwith the B described in step (3.1) _jform terminal t _jaccess-in point information;

Described association request frame is on the association request frame in 802.11 standards, with the addition of " minimum emissive power that access point covers terminal " information; The form of this information is as follows:

Message length accounts for four bytes altogether, and be divided into three fields, the length shared by each field as shown in Table 3; The value of field Element ID is 44, shows that this information is the minimum emissive power that access point covers terminal; Length in Length field shared by this information; The value of the minimum emissive power of access point covering terminal is the double type of double precision, and unit is dBm.

Step 4: access point a _i, i=1,2 ...., m is the stand-by period from receiving the time of previous association request frame, access point a in this time period T _iwait for the access of terminal.

The additional information of table three association request frame

Element ID	Length	Access point covers the minimum emissive power of terminal
			1	1	2

Step 5: judge access point a in time period T _iwhether receive connection request, and according to differentiation result to access point a _ibe handled as follows respectively:

If access point a _ido not receive connection request, calculate access point a _icover set T _iin the minimum emissive power of all terminals and adjust access point a _itransmitting power be: wherein T _ifor current with access point a _ithe set of all terminals connected, has adjusted rear execution step (6);

If access point a _ireceive connection request, then return step (4), access point a _icontinue the access waiting for terminal.

Step 6: according to the behavioral trait of terminal, the transmitting power of dynamic adjustment access point AP.

With reference to Fig. 3, being specifically implemented as follows of this step:

(6a) access point a _iregularly carry out information interaction with its neighboring access point AP, the current transmitting power of acquisition neighboring access point AP.

(6b) access point a is judged _iwhether receive new connection request, if receive new connection request, perform step (6c); If do not receive new connection request, perform step (6d).

(6c) a is judged _icover new terminal t _n+1minimum emissive power l _{i, n+1}with a _icurrent operating power magnitude relationship, according to judged result to access point a _ibe handled as follows respectively:

If a _icover new terminal t _n+1minimum emissive power l _{i, n+1}be less than or equal to a _icurrent operating power then new terminal t _n+1directly and a _iconnect, turn back to step (6b); If a _icover new terminal t _n+1minimum emissive power l _{i, n+1}be greater than a _icurrent operating power new terminal t _n+1with a _iconnect, and adjust value be: step (6b) is returned after having adjusted.

(6d) access point a is judged _iwhether receive releasing connection request, if do not receive the request removed and connect, perform step (6e), if receive the request removed and connect, respond this request, and to access point a _ido following process:

(6d1) by access point a _ithe mark position 1 of beacon frame, access point a _iafter sending this beacon, immediately the flag bit of beacon frame is reduced to 0;

(6d2) access point a _ireceive set T _iin terminal send the Frame comprising access-in point information of terminal, obtain set T _iin the access-in point information of each terminal;

(6d3) access point a _iaccording to set T _ithe access-in point information of middle terminal is determined and access point a _ithe null terminator Null set U connected _i, set U _iin terminal meet:

(6d4) access point a is calculated _icover set T _i-U _ithe minimum emissive power of middle terminal with difference D _i,k; wherein for access point a _icover set T _iin the minimum emissive power of all terminals set T _i-U _irepresent as set subclass U _iin terminal all disconnect and access point a _iconnection time, continue keep with access point a _ithe terminal set connected;

(6d5) access point a _iaccording to the terminal t received _uaccess-in point information, computing terminal t _ube linked into access point a _lafter, access point a _itransmitting power is relative to terminal t _uaccess point a when not accessing _lthe changing value d of transmitting power _u,l: wherein t _u∈ U _i, a _l∈ B _u, B _ufor terminal t _uaccess point set, for access point a _lcurrent transmit power, l _l,ufor access point a _lcover terminal t _uminimum emissive power;

(6d6) according to the method process set B of step (6d5) _uin all access points, and obtain terminal t _ucorresponding minimum power changing value:

(6d7) according to the method process set U of step (6d6) _iin all terminals, obtain the minimum power changing value that each terminal is corresponding;

(6d8) according to the D that step (6d4) is tried to achieve _i,kwith the minimum power changing value of trying to achieve in step (6d7), the power change values that all access point AP of computing network is total: and determine U according to the size of D _ithe switching of middle terminal:

If D > 0, then U _iin terminal can be switched to alternate access point AP, perform step (6d9);

If D≤0, then U _iin terminal can not be switched to alternate access point AP, turn back to step (6b);

(6d9) to set U _iin terminal all carry out active handover operation, make terminal t _uthe access point be switched to is for trying to achieve D _ucorresponding access point, wherein terminal t _u∈ U _i; After having switched, adjustment access point a _icurrent transmitting power be: turn back to step (6b).

(6e) access point a _iin the past the time of a transmitting power adjustment starts to wait for, and according to access point a _iin stand-by period section T1, whether receive connection request or remove connection request, being handled as follows respectively:

If do not receive connection request or remove connection request in stand-by period section T1, then perform step (6d1) ~ step (6d9);

If only receive connection request in stand-by period section T1, then perform step (6b);

If if only receive releasing connection request in stand-by period section T1, then perform step (6d);

If receive connection request and remove connection request, then preferential answering connection request simultaneously, perform step (6b).

Claims (1)

1. a distributed AP power dynamic adjusting method under intensive WLAN environment, comprises the steps:

(1) in the network incipient stage, the access point AP in network at random according to the transmitting power work of a certain grade, and launches beacon frame with the interval of 100ms and maximum transmitting power, and is 0 by the mark position of beacon frame;

(2) a jth terminal t in network _jscanning channel, receives the beacon information that access point AP sends, and utilizes the beacon frame received to set up terminal t _jaccess-in point information, carry out as follows:

(2a) terminal t is determined _jaccess point set A _jif, terminal t _jreceive i-th access point a _ithe received power of the beacon frame sent is more than or equal to minimum receive threshold p _th, then by access point a _ias terminal t _jan access point, otherwise access point a _ican not as terminal t _jaccess point, j=1,2 ...., n;

(2b) terminal t is used _jall access points form access point set A _j: A _j={ a _i| p _i,j>=p _th, i=1,2 ...., m}, wherein p _i,jfor terminal t _jreceive a _ithe received power value of the beacon frame launched, p _th=-95dBm;

(2c) set of computations A _jin all access point AP cover terminal t _jminimum emissive power l _i,j: a _i∈ A _j, wherein p _ifor a _ilaunch the performance number of beacon frame;

(2d) terminal t is determined _jselect the access point a connected _swith alternate access point set B _j:

Alternate access point set: B _j=A _j-{ a _s}

Will in set A _jin, terminal t _jaccess point corresponding time maximum to the received power of the beacon frame that access point sends is as access point a _s, i.e. terminal t _jto access point a _sthe received power p of the beacon sent _s,jmeet: $p_{s,j}=\underset{a_i\∈A_j}{\mathrm{Max}}\left(p_{i,j}\right);$

(2e) terminal t _jto access point a _ssend association request frame, with access point a _sconnect, simultaneously terminal t _jcontinue the beacon frame more new terminal t according to receiving _jin the A described in step (2b), (2c), (2d) _j, l _i,j, B _jinformation;

(3) access point a _i, i=1,2 ...., m is the stand-by period from receiving the time of previous association request frame, access point a in this time period T _iwait for the access of terminal, and judge access point a in time period T _iwhether receive connection request:

If access point a _ido not receive connection request, calculate access point a _icover set T _iin the minimum emissive power of all terminals adjustment access point a _icurrent transmitting power is wherein T _icurrent with access point a _ithe set of all terminals connected, wherein l _i,jfor access point a _icover terminal t _jminimum emissive power, complete after jump to step (4);

If access point a _ireceive connection request, then turn back to step (3);

(4) access point a _iregularly carry out information interaction with its neighboring access point AP, the current transmitting power of acquisition neighboring access point AP;

(5) access point a is judged _iwhether receive new connection request, if do not receive new connection request to perform step (6), if receive new connection request, to access point a _ibe handled as follows in two kinds of situation:

If (5a) a _icover new terminal t _n+1minimum emissive power l _{i, n+1}be less than or equal to a _icurrent transmitting power new terminal t _n+1directly and a _iconnect, after complete, forward step (5) to;

If (5b) a _icover new terminal t _n+1minimum emissive power l _{i, n+1}be greater than a _icurrent transmitting power respond this request, adjustment a _icurrent transmitting power value be l _{i, n+1}, namely step (5) is forwarded to after complete;

(6) access point a is judged _iwhether receive releasing connection request, if do not receive the request removed and connect, perform step (7), if receive the request removed and connect, respond this request, and to access point a _ido following process:

(6a) by the mark position 1 of beacon frame, access point a _iafter sending this beacon, immediately the flag bit of beacon frame is reduced to 0;

(6b) access point a _ireceive set T _iin terminal send the Frame comprising access-in point information of terminal, obtain set T _iin the access-in point information of each terminal;

(6c) access point a _iaccording to set T _ithe access-in point information of middle terminal is determined and access point a _ithe null terminator Null set U connected _i, set U _iin terminal meet: calculate access point a _icover set T _i-U _ithe minimum emissive power of middle terminal with difference: wherein for access point a _icover set T _iin the minimum emissive power P of all terminals _i ^k;

(6d) access point a _iaccording to the terminal t received _uaccess-in point information, computing terminal t _ube linked into access point a _lafter, access point a _itransmitting power is relative to terminal t _uaccess point a when not accessing _lthe changing value of transmitting power: wherein t _u∈ U _i, a _l∈ B _u, B _ufor terminal t _uaccess point set, for access point a _lcurrent transmit power, l _l,ufor access point a _lcover terminal t _uminimum emissive power; In set B _uin, obtain terminal t _ucorresponding minimum power changing value

(6e) according to the method process set U of step (6d) _iin all terminals, obtain the minimum power changing value that each terminal is corresponding;

(6f) according to the value of trying to achieve in step (6c) and step (6e), the power change values that all access point AP of computing network is total: and determine U according to the size of D _ithe switching of middle terminal:

If D>0, then U _iin terminal can be switched to alternate access point AP, perform step (6g);

If D≤0, then U _iin terminal can not be switched to alternate access point AP, turn back to step (5);

(6g) to set U _iin terminal all carry out active handover operation, make terminal t _uthe access point be switched to is for trying to achieve D _ucorresponding access point, wherein terminal t _u∈ U _i; After having switched, adjustment access point a _icurrent transmitting power turn back to step (5);

(7) access point a _iin the past the time of a transmitting power adjustment starts to wait for, if do not receive connection request or remove connection request in time period T1, then performs step (6a) ~ (6g); If only receive connection request, then perform step (5); If only receive releasing connection request, then perform step (6), if receive connection request and remove connection request, then preferential answering connection request simultaneously.