CN100452740C

CN100452740C - Method for speech communicating in radio local network

Info

Publication number: CN100452740C
Application number: CNB2006100889745A
Authority: CN
Inventors: 陆洋; 张超; 陆建华; 林孝康
Original assignee: Tsinghua University
Current assignee: Tsinghua University
Priority date: 2006-07-28
Filing date: 2006-07-28
Publication date: 2009-01-14
Anticipated expiration: 2026-07-28
Also published as: CN1889489A

Abstract

A voice communication method of WLAN includes fetching type and subtype bit of data frame head by access point when new data frame is arrived at access point of WLAN, judging whether it is voice frame or not and sending data frame to send queue tail if it is not, seeking whether voice frame with the same address as newly arrived voice frame is in send queue or not if it is, combining two said voice frame and waiting to send it out if it is or otherwise sending newly arrived voice frame to send queue tail.

Description

The method of voice communication in a kind of WLAN (wireless local area network)

Technical field

The present invention relates to the method for voice communication in a kind of WLAN (wireless local area network), belong to network communications technology field.

Background technology

WLAN (wireless local area network) (hereinafter to be referred as WLAN) is to utilize radio-frequency technique to carry out the local area network (LAN) of transfer of data, and it is replenishing of cable LAN and extends.Wireless local area network technology has a lot of standards, and different standards has different application, and at present popular have IEEE 802.11 standards, bluetooth standard (Bluetooth) and a HomeRF standard, and wherein IEEE 802.11 standards are the most general.The WLAN (wireless local area network) of 802.11 standards of IEEE has two kinds of network organization forms, i.e. Ad Hoc and Infrastructure.Under Ad Hoc networking mode, need not access point, the autonomous equity work of all nodes is carried out direct communication in point-to-point mode; Under the Infrastructure networking mode, must there be a WAP (wireless access point) (hereinafter to be referred as AP) in the network, realize communication between each wireless device by AP.AP and wireless terminal come competitive channel according to distributed coordination function (hereinafter to be referred as the DCF) agreement of avoiding (hereinafter to be referred as CSMA/CA) based on carrier sense/conflict, in addition, also stipulated another kind of channel contention mechanism among the IEEE 802.11, be point coordination function (hereinafter to be referred as PCF), but still do not have extensive use at present.

Summary of the invention

The objective of the invention is to propose the method for voice communication in a kind of WLAN (wireless local area network),, make it can improve WLAN (wireless local area network) and insert IP speech (hereinafter to be referred as VoIP) message capacity under the environment by improving the design of existing wireless local network connecting point.In order to increase the VoIP message capacity, when new speech frame arrives medium access control sublayer (hereinafter to be referred as the MAC) formation of access point, itself and already present voice packet with same source and destination address are merged compression MAC formation; In order in multiple business, to distinguish the VoIP business, utilize the reserved field in the IEEE 802.11b mac frame form to identify.

The method of voice communication in the WLAN (wireless local area network) that the present invention proposes may further comprise the steps:

(1) when new medium access control sublayer Frame arrives the access point of WLAN (wireless local area network), access point reads its head " type " and " subtype " bit, whether to it is that speech frame is judged, if not, then this Frame is sent into the afterbody of medium access control sublayer transmit queue, if then carry out step (2);

(2) in the medium access control sublayer transmit queue, search the source address speech frame identical that whether exists and newly arrive speech frame with destination address, and its length is no more than predefined threshold value, if exist, then newly arrived speech frame and this speech frame that finds are merged, etc. to be sent, if do not exist, then newly arrived speech frame is sent into the afterbody of medium access control sublayer transmit queue.

The method of voice communication is characterized in being primarily aimed at the voice communication under the Infrastructure networking mode in the WLAN (wireless local area network) that the present invention proposes.A plurality of terminal uses are arranged in WLAN (wireless local area network), the user can pass through the AP access network, with the mode and the user under the same AP of VoIP business, be connected user, cable telephone network (PSTN) user on the Internet or mobile communication terminal user carries out voice communication.Because channel capacity is limit, each AP can only support the WLAN terminal user of some to insert.No matter be with same AP under other telex networks, still communicate by letter with other network users, the VoIP voice packet is at first delivered to AP, and then is transmitted by AP.AP is when receiving the VoIP voice packet, the VoIP voice packet that in itself and the formation is already present same source and destination address is merged according to certain rule, compression AP queue length, effectively reduce expense simultaneously, increase power system capacity, the method is not introduced extra wait time delay, has reduced average queuing delay, improves quality of voice transmission.

Description of drawings

Fig. 1 is the FB(flow block) of the inventive method.

Fig. 2 is a mac frame form schematic diagram used in the present invention.

Fig. 3 is to use the network system schematic diagram of the inventive method.

Embodiment

The method of voice communication in the WLAN (wireless local area network) that the present invention proposes, its FB(flow block) as shown in Figure 1, when new medium access control sublayer Frame arrives the WAP (wireless access point) of WLAN (wireless local area network), whether WAP (wireless access point) reads its head " type " and " subtype " bit, be that speech frame is judged to it.If not, then this Frame is sent into the afterbody of medium access control sublayer transmit queue, if, then in the medium access control sublayer transmit queue, search and whether exist and the new source address speech frame identical that arrives speech frame with destination address, and its length is no more than predefined threshold value, if exist, then formation is compressed, newly arrived speech frame and this speech frame that finds are merged, etc. to be sent, if do not exist, then newly arrived speech frame is sent into the afterbody of medium access control sublayer transmit queue.

In the said method,, may further comprise the steps newly arrived speech frame and the method that the speech frame that finds merges:

(1) will newly arrive the rear portion that data in the speech frame are inserted into data field in the speech frame that finds, form a new speech frame;

(2) revise speech frame head duration field according to the length of the data field of above-mentioned new speech frame;

(3) Frame Check Sequence of the amended speech frame of calculating is inserted the Frame Check Sequence that calculates the respective field of revising the speech frame head.

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

Referring to Fig. 1, be WAP (wireless access point) workflow diagram of the present invention.When new data arrived, before entering transmit queue, AP read " type " and " subtype " bit of mac frame head earlier, judged whether that speech frame arrives.If then in formation, search and whether exist and the new speech frame source address speech frame identical that arrive with destination address; If existence and its length are no more than predefined threshold value, then carry out the formation compression algorithm, itself and newly arrived speech frame are merged.During merging, at first the data field of newly arrived speech frame is partly inserted the data field rear portion of the speech frame that finds, recomputate frame duration and Frame Check Sequence according to new frame length and channel speed then, and revise the respective field of this speech frame head.Under other all situations, newly arrived mac frame all directly enters transmit queue.Because therefore mac frame payload length limited (being no more than 2312 bytes) needs before merging to check whether the frame length of carrying out after merging can exceed restriction.Consider other factors, such as retransmission cost etc., it is low slightly that threshold value also can be provided with.

Referring to Fig. 2, be mac frame form schematic diagram used in the present invention.Wherein, " frame control " field length is 2 bytes, is used to indicate some necessary control informations of mac frame.In " frame control " field, indicate the type of mac frame with " type " and " subtype " bit, " type " is that 10 expressions are Frames, " subtype " is 0000 to be expressed as general data, and 0001～0111 is used for the PCF agreement, and 1000～1111 keep and do not use.In the present invention,, increase therefore that to use " subtype " be 1010 expression speech businesses, distinguish mutually with 0000 represented general data business because channel competition adopts the DCF pattern.

Seeing also Fig. 3, is network system schematic diagram of the present invention.The WLAN terminal inserts Internet by AP, and normal telephone also can link to each other with Internet by voip gateway with mobile phone, thereby forms interconnecting of multiple network.By voip technology, between the WLAN terminal under the same AP, can carry out voice communication between WLAN terminal and the other-end.In WLAN, the business that mails to any destination from terminal all must send to AP earlier, is transmitted by AP then.At down direction, all send according to IEEE 802.11DCF agreement by AP from the data of any service source.

Claims

1, the method for voice communication in a kind of WLAN (wireless local area network) is characterized in that this method may further comprise the steps:

(1) when new media access control sublayer Frame arrives the WAP (wireless access point) of WLAN (wireless local area network), WAP (wireless access point) reads its head " type " and " subtype " bit, whether to it is that speech frame is judged, if not, then this Frame is sent into the afterbody of medium access control sublayer transmit queue, if then carry out step (2);

2, the method for claim 1 is characterized in that the subtype bit of wherein said medium access control sublayer data frame header, and definition 1010 is a speech frame.

3, the method for claim 1 is characterized in that wherein saidly with newly arrived speech frame and the method that the speech frame that finds merges, and may further comprise the steps: