CN101431510B - Multicast method in wireless local area network - Google Patents
Multicast method in wireless local area network Download PDFInfo
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Abstract
A method for performing multicast-transmission in media access control layer of wireless network comprises steps: transmitting party multicasts to receiving group of MRTS containing data packet indicating transmitting to receiving group or not, and waits for MCTS from receiving group member; after transmitting party has received MCTS from all members of receiving group, the transmitting party multicasts data packet to member of receiving group and records the serial number of data packet transmitted for the present; after every member of receiving group has received MRTS packet, records serial number for indicating newest received data packet at every MCTS packet, transmits the MCTS packet but not ACK packet to transmitting party in predetermined time period; the transmitting party judge if data packet is lost from serial number of data packet newly received and recorded in MCTS of every member, and then retransmits the data packet if the data packet is lost and transmits new data packet later.
Description
Technical field
The present invention relates to a kind of multicasting method in wireless network, particularly, relate to the method for in WLAN (wireless local area network), carrying out reliably multicast transmission, can improve the efficient of multicast protocol, and reduce the expense of control bag.
Background technology
In the WiMAX access technology, IEEE 802.11 has just become a kind of very general selection.At present, a lot of important application on WLAN (wireless local area network) (WLAN) all are based on multicast transmission.These application include, but are not limited to multimedia conferencing, Sharing Whiteboard, long-distance education, in many ways game and Distributed Calculation etc.
Multicast (being also referred to as multicast) refers to packet is sent to a plurality of destinations from a source, and the copy of information is sent to a group address, arrives all and wants to receive its recipient.Compare with clean culture, the efficient of multicast is very high.This is because any given link is extremely once multiplex, thereby can save bandwidth of network and resource.Because the advantage of multicast transmission on resource utilization, at present, it has received considerable concern.
Yet, in the multicast design of present internet, usually all be based on the multicast protocol in the IP layer.Much multicast protocol cleverly also only concentrates on the multicast routing Design.At media access control (MAC) layer, whether usually do not consider the multicast bag.Therefore, in the MAC layer, do not provide the multicast design, process and only packet is used as broadcast packet.In the situation, when the multicast of IP layer wraps in the upper transmission of WLAN, following problem can appear like this.On the one hand, increase extra IP processing expenditure.This is because present MAC layer is not supported the multicast bag, therefore not distinguish what receive at the MAC layer be multicast bag or broadcast packet to the terminal among the WLAN, the multicast bag of not supporting can not be masked, be forwarded to without exception after the IP layer but should wrap, just judged whether to receive this bag by receiving terminal according to multicast address.Will inevitably increase so the unnecessary processing expenditure of IP layer.On the other hand, multicast wraps in when transmitting among the WLAN, does not have RTS (request send grouping)/CTS (clear to send grouping) interaction mechanism of shaking hands to come channel reservation, does not also have retransmission mechanism to correct mistake, so causes the reliability transmitted lower.Like this, will cause the multicast bag to be lost because of link error or conflict.
In addition, exist multiple terminal among the WLAN, for example, portable computer, mobile phone, personal digital assistant (PDA).There is isomerism between these terminals.In addition, different terminals has different requirements for different application to QoS (quality of service).Therefore, at present the multicast bag of IP layer directly in WLAN transmission can run into the problems referred to above.Because these problems, the Reliable Multicast Protocols of design MAC layer is very important.
Reliable multicasting method has been proposed in the prior art.For example, the article that is entitled as " Reliable multicast in Multi-Access Wireless LANs " that J.Kuri and S.K.Kasera deliver is (referring to ACM/Kluwer Wireless Networks Journal, vol.7, no.4, pp.359-369, the article that is entitled as " Reliable multicast MACProtocol for Wireless LANs " that August 200S.K.S.Gupta, V.Shankar deliver is (referring to ICC 2003, pp93-pp97,2003); The article (referring to Proc.IEEE MILCOM 2001, pp.1008-1013, Oct.2001) that is entitled as " MAC Reliable Broadcast in AdHocNetworks " that K.Tang and M.Gerla deliver; The article (referring to Proc.ofICPP, pp.527-536, Aug.2002) that is entitled as " Reliable MAC layer multicast inIEEE 802.11 wireless networks " that M.T.Sum, L.Huang deliver; And Hrishikesh Gossain, the article (referring to LCN ' 04,2004) that is entitled as " SupportingMAC layer Multicast in IEEE 802.11Based MANETs:Issues and Solutions " that Nagesh Nandiraju delivers.
The method that proposes in the above-mentioned prior art can be divided into two classes: the first kind is based on (NCTS/NACK) mechanism of negative feedback, another kind of (CTS/ACK) mechanism that is based on asserts feedback.Usually, higher based on the efficient of the multicast protocol of negative feedback, but its reliability is relatively poor.Usually the method that adopts comprises based on degenerative multicast protocol, for example: LBP (based on the agreement of representative), DBP (based on the agreement of random delay) and PBP (agreement of Based on Probability), and based on the multicast protocol of positive feedback, for example: BMW (broadcast medium window agreement and BMMM), and batch processing multicast protocol.
LBP (based on the representative agreement: leader based protocol) on the basis of IEEE 802.11, expanded RTS/CTS handshake mechanism and the response ACK mechanism for correcting errors, thereby can support reliably multicast transmission.In this method, need from one group of recipient, to specify in advance a representative (leader).Source (transmit leg) at first sent a multicast RTS bag (MRTS) to all group members before sending multicast packets.For the representative in the reception group, if it has been ready to receive data, just respond MCTS (multicast clear to send grouping), otherwise, then do not make response.For other group members in the reception group, if be not ready for receive data, just respond NCTS (negative CTS), otherwise, then do not make response.In this handshake procedure, if the representative in the reception group has been ready to receive and responded the CTS bag, and a certain group member is not ready for, and has responded the NCTS bag, so, this NCTS bag will with the reception group in the CTS packet conflict that sends of representative.And in a single day source listens to the CTS bag, just thinks and has successfully obtained channel, and begin to send multi-case data.Receive after the packet, correct if packet receives for the representative in the reception group, then respond ACK, otherwise, then send NACK; For other group members in the reception group, if successfully receive, then do not respond, otherwise, response NACK.
Therefore, the LBP method is being applied in the situation of IEEE 802.11, is existing the recipient and be difficult to judge the problem that how to feed back.This problem is present in all based in the degenerative agreement.In IEEE 802.11, if clash or link error, the recipient can not correctly receive bag, certainly also just can not extract carry in the bag such as wrapping type, the header packet information of the source address of bag, destination address etc. and so on.Therefore, as recipient correctly during the receive data bag, whether its is difficult to decision needs to provide negative feedback, and provides which kind of negative feedback.For example, being difficult to determine is feedback NACK or feedback NCTS.In order to address this problem, need to do extra work again to revise the IEEE802.11 agreement.
In addition, the LBP method being applied in the situation of IEEE 802.11, after source is sent multi-case data, if receive after the erroneous packets as the group member of the representative in non-reception group, it will send NACK grouping, and the ACK packet collisions of sending with the representative in the reception group.This collision will cause source can't hear the ACK grouping that the representative in the reception group feeds back, thereby retransmit this packet.Therefore, cause transmit leg to carry out unnecessary re-transmission.When the transmission of packet made a mistake at certain group member place, this group member be because can't obtain the sequence number of packet, and can not judge the packet whether this packet retransmits.Therefore, whether this group member is no matter successfully received this packet before, without exception to source feedback NACK grouping.Like this, will cause source to carry out unnecessary re-transmission.
In addition, in the situation that the LBP method is applied to IEEE 802.11, also can produce capture effect.So-called capture effect refers to that when a node is received two bags simultaneously that has the packet than strong cohesiveness receipts power correctly to be caught.Suppose under a kind of environment, the representative in the reception group from access point (AP) very close to, AP is distant for another nodal distance.So as AP response CTS, and during another node response NCTS, this NCTS should clash with CTS originally, but because capture effect, the CTS that AP sends has correctly been received by source, and is not correctly received away from the NCTS response that the node of AP sends.This just causes source to think that mistakenly this can send data.
The difference of DBP method and LBP method is: it only preengages channel with CTS (1).(2) it avoids the conflict of a plurality of CTS with a random timer.
The course of work of DBP method is described below.At first, source starts an overtime timer, then sends MRTS and preengages channel.The cycle that can suppose timer is T.The group member of all recievers is listening to MRTS (multicast request send grouping) afterwards, will start a timer (timing cycle can from 1,2 ..., select at random among the L}).Timer then before, if node A listens to the CTS grouping that other nodes send, then the own timer of cancellation does not send CTS and divides into groups.If node A does not listen to the CTS grouping, work as timer then so, just send the CTS response.Source waits the T time, if receive the CTS grouping, just begins to send data.Recipient's group members correctly receive and do not send response after the data.If find the error in data of reception, then send the NACK grouping and make response.PBP method and DBP method are very alike, and unique difference is that the PBP method utilizes probability to avoid the conflict of CTS.
Compare with the LBP method, PBP and DBP method need to be spent more time channel reservation.On the other hand, if want to select the probability of optimum PBP response and the at random timing cycle of DBP, need to know the size of this multicast group, and can't obtain the size of multicast group in this stage.Therefore in order to obtain optimum probability or the parameter value of timing cycle and so at random, must obtain and outer information.This also is PBP and the existing defective of DBP method.
In addition, for the method based on positive feedback that proposes in the prior art, usually adopt BMW (broadcast medium window agreement) and BMMM (batch processing multicast protocol) method.These methods based on positive feedback have overcome the defective in the above-mentioned feedback method, but have produced other problem.For example, the BMW method is just simply regarded a multicast process as a plurality of clean cultures, so its efficient is lower.In order to raise the efficiency, the BMMM method has been proposed.In the BMMM method, in order to coordinate recipient group member's ACK, introduced a new bag type (RAK: the request positive acknowledgement).The RAK grouping is arranged on before the ACK grouping, and the group member who is used to indicate the recipient sends ACK in order.Fig. 1 shows the groundwork process of BMMM method.In the BMMM method, if having a transmit leg and n recipient to carry out multi-casting communication, early stage through n RTS/CTS alternately after, transmit leg begins to send packet (DATA).Send after the DATA, each recipient's poll ground of sending direction sends the RAK grouping.The recipient receives after the RAK grouping, sends ACK to transmit leg.Although the BMMM method is more reliable than BMW method, in transmission course, need to have n mutual and n is mutual to RAK/ACK to RTS/CTS, the expense (RTS, CTS, RAK and ACK) that its control is wrapped is very large.Following table 1 has provided the expense of physical layer control bag and the expense of packet.
Table 1
| RTS | CTS | DATA | ACK |
| 40 time slots | 40 time slots | 15 time slots | 40 time slots |
Compared the expense of physical layer control bag and the expense of packet in the table 1, wherein hypothesis needs to transmit the packet of 512 bytes.We can see from table 1, and the transmission of data bag has taken 15 time slots, and (RTS, CTS and ACK) taken 120 time slots, and the resource of the transmission of data bag is less than 10% of whole resource.
Summary of the invention
In view of the above problems, made the present invention.The purpose of this invention is to provide a kind of method of in the MAC of wireless network layer, carrying out multicast transmission, can improve the efficient of multicast protocol, reduce the expense of control bag, and avoid the conflict of a plurality of MRTS.
According to an aspect of the present invention, the method of carrying out multicast transmission in a kind of media access control (MAC) layer in wireless network is provided, comprise step: the multicast of sending direction reception group comprises the multicast request transmission grouping (MRTS) that indicates whether to have the packet that will send to the reception group, and waits for from the multicast clear to send grouping (MCTS) that receives the group membership; Transmit leg to receiving group membership's multicast packets, and records the sequence number of the packet of current transmission after receiving the MCTS that organizes all members from reception; Each member in the reception group is after receiving the MRTS bag, and the sequence number of the packet of up-to-date reception indicated in record in MCTS bag separately, and the backward transmit leg transmission of predetermined time cycle MCTS bag, and does not send positive acknowledgement (ACK) bag; Transmit leg judges whether to occur data-bag lost from the sequence number from the packet of the up-to-date reception of record each member's the MCTS bag, and is occurring in the situation of data-bag lost, the packet of retransmission of lost, and send subsequently new packet.
According to the present invention, provide a kind of reliable MAC layer multicast transmission method.The method has adopted a kind of extendible implicit expression to confirm (EIA) method.Utilize the method, in the MCTS bag, by carrying the mode of confirmation, removed the transmission of ACK bag.In addition, each member in the reception group has distributed priority, makes each member feed back CTS according to priority.
In addition, in the method for the invention, owing to removed the transmission of ACK bag, thereby eliminated the probability of ACK/NAK packet loss and collision, on the other hand, by in MCTS, carrying the sequence number of the nearest packet that successfully receives of indication, solved the problem of the unnecessary re-transmission that exists in other agreements.
Description of drawings
By below in conjunction with description of drawings the preferred embodiments of the present invention, will make of the present invention above-mentioned and other objects, features and advantages are clearer, wherein:
Fig. 1 is the schematic diagram of groundwork process of the BMMM method of expression prior art;
Fig. 2 is the schematic diagram of the frame format of expression RTS of the prior art;
Fig. 3 is that expression is according to the schematic diagram of the frame format of MRTS in the multicast transmission of the embodiment of the invention;
Fig. 4 is that expression is according to the schematic diagram of the frame format of MCTS in the multicast transmission of the embodiment of the invention;
Fig. 5 is the schematic diagram of carrying out an example of multicast among the expression WLAN;
Fig. 6 is that expression is according to the schematic diagram of the transmission course of the affirmation of the implicit expression expanded in the multicast transmission of the embodiment of the invention;
Fig. 7 is the message workflow diagram figure that expression is confirmed according to the implicit expression expanded of the embodiment of the invention.
Embodiment
With reference to the accompanying drawings embodiments of the invention are described in detail, having omitted in the description process is unnecessary details and function for the present invention, obscures to prevent that the understanding of the present invention from causing.
Fig. 2 shows the schematic diagram of the frame format of RTS of the prior art.As shown in Figure 2, in 802.11, comprise frame control (frame control) territory in the RTS frame of the prior art of definition, duration (duration) territory, DA (destination address) territory, TA (transmitting terminal address) territory, and CRC (CRC).Wherein, the frame control domain is mainly used to indicate the type of frame, and duration field is used for preengaging channel, and the CRC territory is used for judging whether the frame that receives is correct.
Fig. 3 shows according to the schematic diagram of the embodiment of the invention in the frame format of the MRTS of MAC layer execution multicast transmission.As shown in Figure 3, according to unique difference of the RTS frame format of the frame format of the MRTS of present embodiment and prior art shown in Figure 2 be will indication destination address the DA territory change into and be used to indicate the RA territory that receives group address.This change does not need to change the formation form of frame.Should be noted that this group address converts according to IP multicast address.Known in the artly be, there are 32 bits the IP address, and MAC Address then has 48 bits.IP multicast address all belongs to Class D IP address, and its Gao Siwei is 1110, and therefore 28 remaining bits can be used to be mapped as the multicast address of MAC layer.As an example, can regard these 28 bits as decimal number, then convert thereof into 16 system numbers, the result has been exactly the MAC Address of needs.
Fig. 4 shows according to the schematic diagram of the embodiment of the invention in the frame format of the MCTS of MAC layer execution multicast transmission.CTS frame format difference according to the prior art that defines among the frame format of the MCTS of present embodiment and the IEEE802.11 is to have increased a Seq field, and simultaneously, it also needs to resemble and changes the RA field the MRTS.The content of filling in this Seq field is the sequence number of the packet of the up-to-date correct reception of recipient.By this Seq field, source just can judge the present reception situation of recipient, thus the ACK field in annulling the agreement alternately, and improve efficiency of transmission.
Fig. 5 is the schematic diagram of carrying out an example of multicast among the expression WLAN.As shown in Figure 5, the source node in the residential quarter 1 will send data to the multicast group in the residential quarter 2.The multi-case data that source node produces is transferred to the multicast group G in the residential quarter 2 at last via the access point AP1 in the residential quarter 1 and the access point AP2 in the residential quarter 2.
Wherein, the access point AP2 in the residential quarter 2 utilizes multicast protocol of the present invention to transmit to the reception group.For convenience of description, table 2 has been listed the implication that needs some numerical value of using in description.
Table 2
| Numerical expression | Implication |
| R | Number of members in the multicast group |
| Rcvd_MCTS_number | AP wait to be feedback in, the number of the MCTS that receives bag |
| Frametx_seq | The sequence number of the packet that AP sends recently |
| Framerv_seq[i] | Priority is the group membership of i, the sequence number of the packet that successfully receives recently. |
| SIFS | Short frame period |
| T MCTS | Send MCTS and wrap the needed time |
When the MAC of the AP2 in the residential quarter 2 layer received multicast packets from the upper strata, it at first translated into the multicast address of IP layer the group address of MAC layer.Then, prepare to initiate the MRTS/MCTS handshake mechanism and come channel reservation.Before sending MRTS, AP2 at first judges in the output queue of oneself whether mail in addition the packet of reception group G.If any, AP2 then is made as 0000 (this value is reserved) to the subtype value of the frame control domain (frame control) in the MRTS bag in IEEE 802.11, be used to indicate the packet that will mail in addition reception group G.Otherwise if there is not to mail to the packet of reception group G, AP2 then is made as 0001 (this value is also reserved) to the subtype value of the frame control domain in the MRTS bag in IEEE 802.11, be used to indicate the packet that does not have to mail to reception group G.Passed through conflict and avoided process, when available free channel, AP2 begins multicast MRTS.
Receive after the MRTS bag from AP2, each group membership in the reception group records the Subtype value among the MRTS, then responds the MCTS bag.Because a plurality of members are arranged in the reception group, so AP2 may receive a plurality of MCTS bags.For fear of the conflict of these bags, the group membership needs the priority (will be described later the setting of priority) according to oneself, and order is to AP2 response MCTS bag.AP2 has successfully received after the MCTS bag of all group membership's responses, begins to send multi-case data, records simultaneously the sequence number of the packet that sends, Frametx_seq.Subsequently, receive the group membership and receive multi-case data, extract the subtype value among the MRTS, the subtype value that records in the frame control domain in MRTS before this according to AP2 determines whether that needs respond ACK.Only having the subtype value of working as is 0001, when namely indication does not have to mail to the packet of reception group G, the group membership just can send ACK, otherwise, if the subtype value is 0000, indication AP2 will mail to the packet of reception group G in addition, and the group membership does not then send ACK, and only records the sequence number Framerv_seq of the packet that successfully receives.
Can suppose that AP2 has a plurality of packets will send to multicast group G, so the subtype among the AP2 MRTS is set to 0000.When multicast group G detected this and arranges from the MRTS that receives after receiving MRTS, the group membership just knew the packet that will send in addition, does not therefore need to respond ACK.Through after the conversation procedure (MRTS/MCTS/DATA), AP2 does not also know whether packet is successfully received by all nodes.After this, AP2 begins to initiate the handshake procedure of MRTS/MCTS so that channel reservation for next packet.Receive after this MRTS bag that the group membership of multicast group G can will in the MCTS bag of AP2 transmission, then send to AP2 to the before this Framerv_seq value lift-launch of record.If the Framerv_seq that certain group membership X feeds back is less than the sequence number of the nearest packet that sends of AP2, namely Frametx_seq means that then group membership X has received wrong packet.AP2 has received after all MCTS bags, begins to judge whether that all group memberships have successfully received packet.If all Framerv_seq that feed back equal Frametx_seq, mean that then AP2 can send new packet; Otherwise AP2 needs retransmission data packet may.
Fig. 6 shows the transmission course of confirming according to the implicit expression expanded in the multicast transmission of the embodiment of the invention.As shown in Figure 6, a transmit leg and n recipient are arranged in the multicast group.When transmit leg sends data, usually there are a plurality of packets will outwards send (4 packets have been shown among Fig. 6).Before sending first packet, transmit leg at first sends MRTS in the first dialog procedure, and the recipient sends MCTS and carries out alternately.The recipient has been shown among Fig. 6 has replied in order MCTS, to avoid sending conflict.After MRTS/MCTS finished alternately, transmit leg began to send first packet (among Fig. 6 with hatched, sequence number be 1 packet).So far, first dialog procedure finishes.
In other agreement, in order to confirm transmitting, after receiving each packet, the recipient sends the ACK bag, to confirm to receive the packet that is sent.Different from other agreement, in the present invention, before packet did not send, the recipient had removed the ACK bag for each Packet Generation.After this, in the second dialog procedure, in order to send second packet, need to carry out equally MRTS/MCTS alternately to carry out initialization.Transmit leg has sent in the second dialog procedure after the MRTS bag, and the recipient wants feedback MCTS bag.As previously mentioned, the MCTS of feedback this moment is changed, and wherein includes the Seq field of the nearest up-to-date packet sequence number that successfully receives of indication.Tentation data bag 1 is correctly received by all recipients, and the value of the Seq field of the MCTS of each recipient's feedback bag equals 1 in the second dialog procedure.When transmit leg finds that the value of the Seq field in the MCTS bag of all recipient's feedbacks all equals 1, can judge that then all recipients receive correct packet, and beginning the transmission of data bag 2.Send after the packet 2, transmit leg is ready for sending packet 3 in the 3rd dialog procedure.Equally, before sending packet 3, it is mutual to carry out MRTS/MCTS between transmit leg and the recipient.Since packet 2 may be in transmission certain node loss, after transmit leg sends the MRTS bag, recipient's feedback MCTS bag, at this moment, the value of the Seq field in the MCTS of some the recipient's feedback bag may the factor data packet loss but 1, and the value that successfully receives the Seq field in the MCTS bag of recipient's feedback of packet is 2.Transmit leg finds that the value of the Seq field in the MCTS bag of some recipient's feedback is at 1 o'clock, can judge that this recipient has lost packet 2.In this case, transmit leg at first sends packet 2 in the 3rd dialog procedure, then send packet 3.The rest may be inferred, until send all packets in the 4th dialog procedure.
According to the present invention, utilize the MCTS of next DATA bag to wrap to be confirmed whether correctly to receive previous packet, thereby saved the expense of ACK bag.In addition, the new data packets that send and the packet that sends are previously sent in same dialog procedure, saved thus a part of mutual expense.
Fig. 7 is the message workflow diagram figure that expression is confirmed according to the implicit expression expanded of the embodiment of the invention.At first, at step S701, transmit leg (AP) starts, multicast MRTS bag in the wireless network.In addition, the timer of transmit leg in step S702 startup transmit leg, the cycle that timer is set is T=T
MCTS+ SIFS (having listed the concrete meaning of each parameter in the table 2), and the MCTS of wait recipient feedback.The recipient receives after the MRTS bag, and at step S703, each group member calculates oneself and how long should wait for before response MCTS according to the priority of oneself.Each group member is calculated as follows the stand-by period: T
2=m * SIFS+ (m-1) * T
MCTS(wherein, m is the priority of each node).Each group member calculates the stand-by period according to self, and the timing cycle that the timer of self is set is T
2After this, at step S704, each group member is carried the Framerv_seq value of the sequence number of the packet of indicating up-to-date reception in the Seq field of MCTS bag.If not yet receive packet, it is 0 that Framerv_seq then is set.At timer then, namely pass through T
2After time, send the MCTS bag.
Next, at step S705, transmit leg is judged the cycle T at timer
1Whether receive the MCTS bag of recipient's feedback before expiring.If judge in cycle T at step S705
1Do not receive the MCTS bag, transmit leg then turns back to step S701 before.If in cycle T
1Receive the MCTS bag of feedback, transmit leg then proceeds to step S706, eliminates current timer before, extracts the value of Framerv_seq from the Seq field that the MCTS that receives wraps, and this value is inserted array Framerv_seq[] in.In addition, transmit leg starts timer, and it is T that its timing cycle is set
1, wait for receiving next MCTS bag.After this, at step S707, transmit leg judges whether to receive the MCTS bag of all recipient's feedbacks.If judge the MCTS bag that does not receive all recipient's feedbacks at step S707, flow process is then returned step S702, waits for other MCTS bag.If judge the MCTS bag that has received all recipient's feedbacks at step S707, flow process then proceeds to step S708.At step S708, namely judge after the Rcvd_MCTS_number=R array Framerv_seq[that it is R that transmit leg obtains a size].The sequence number of the packet that this array indication recipient receives.Then, flow process proceeds to step S709, according to array Framerv_seq[] sequence number of the packet that receives of the recipient of indication judges whether to occur data-bag lost.If array Framerv_seq[] minimum value equal Frametx_seq, show that then the recipient has correctly received the packet of transmission.In this case, flow process proceeds to step S711, and transmit leg sends new packet, and Frametx_seq=Frametx_seq+1 is set.Otherwise, if judge array Framerv_seq[at step S709] minimum value be not equal to Frametx_seq, then show data-bag lost to occur.In this case, flow process proceeds to step S710, the packet of transmit leg retransmission of lost.
As previously mentioned, owing in the multicast group a plurality of members are arranged, transmit leg may be received a plurality of MCTS bags.For fear of the conflict of these bags, the multicast group membership needs the priority according to oneself, and order is sent the MCTS response to transmit leg.
Recipient group member's priority setting is described below.Can suppose a terminal when adding or leaving a multicast group, at first need to send a clear and definite adding group (join-group) or leave group (leave-group) message to access point (AP).At the AP place, keep a tabulation that has comprised group address, group membership priority, shown in following table 3.When a terminal T sends adding group (join-group) message, require to add multicast group G
iThe time, AP at first checks tabulation, finds out multicast group G
iInterior existing greatest priority P
MaxThen, AP notification terminal T, its priority is P
Max+ 1.
The tabulation that table 3 AP safeguards
| Group number | Member's linking layer address | Priority |
| G 1 | A 1 | 1 |
| G 1 | A 2 | 2 |
| G 1 | A 3 | 3 |
| …… | …… | …… |
| G 2 | A i | 1 |
| G 2 | A i+1 | 2 |
When a terminal T will leave the multicast group, it at first sends left group (leave-group) message.AP receives after this message that checking tabulates judges whether terminal T has greatest priority.If so, AP can be T deletion from tabulation.If not, AP can send one and change priority (change-priority) message, notifies other members to change the priority of oneself.In message, the priority of emblem egress T.Receive change priority message after, if the priority of acceptance point less than the priority of T, then node does not change own priority.If the priority of acceptance point is greater than the priority of T, then node subtracts 1 in the priority basis of oneself.
According to the present invention, removed in the prior art, the recipient need to receive the ACK bag that sends behind each packet, thereby has avoided the probability of ACK/NAK packet loss and collision.On the other hand, in the MCTS of receive direction transmit leg response bag, carry the Framerv_seq field of the sequence number of the packet of indicating up-to-date reception, solved the problem of the unnecessary re-transmission that exists in other agreements.
So far invention has been described in conjunction with the preferred embodiments.It should be appreciated by those skilled in the art that in the situation that does not break away from the spirit and scope of the present invention, can carry out various other change, replacement and interpolations.Therefore, scope of the present invention should not be understood to be limited to above-mentioned specific embodiment, and should be limited by claims.
Claims (9)
1. carry out the method for multicast transmission in media access control (MAC) layer in wireless network, comprise step:
The multicast of sending direction reception group comprises the multicast request transmission grouping that indicates whether to have the packet that will send to the reception group, and waits for from the multicast clear to send grouping that receives the group membership;
Transmit leg to receiving group membership's multicast packets, and records the sequence number of the packet of current transmission after receiving the multicast clear to send grouping of organizing all members from reception;
Each member in the reception group is after receiving multicast request transmission grouping, the sequence number of the packet of the up-to-date reception of record indication in multicast clear to send grouping separately, and the backward transmit leg transmission of predetermined time cycle multicast clear to send grouping, and do not send positive acknowledgement (ACK) bag;
Transmit leg judges whether to occur data-bag lost from the sequence number from the packet of the up-to-date reception of record each member's the multicast clear to send grouping, and is occurring in the situation of data-bag lost, the packet of retransmission of lost, and send subsequently new packet.
2. method according to claim 1 comprises that further transmit leg is sending the multicast request and at first the multicast address of IP layer is translated into before sending grouping the step of the group address of media access control layer.
3. method according to claim 1, wherein transmit leg judges whether that the step that data-bag lost occurs comprises the sequence number of extracting the packet of the up-to-date reception of each member of recording from the multicast clear to send grouping from each member, and in the sequence number of the current transmission packet of the sequence number of the packet of the up-to-date reception of described record and described record not simultaneously, judge the step that data-bag lost occurs.
4. method according to claim 3 further is included in transmit leg and judges that when the recipient had correctly received the packet of transmission, transmit leg sent the step of new packet.
5. method according to claim 1, comprise that further each member in the reception group is according to separately priority, calculate the time cycle that to wait for from before transmission multicast clear to send grouping response, and sequentially send the step that the multicast clear to send is divided into groups to transmit leg.
6. method according to claim 5, further be included in receive change priority message after, if the priority of receiving node less than the priority of the terminal of leaving the multicast group, then described receiving node does not change own priority; If the priority of receiving node is greater than the priority of the terminal of leaving the multicast group, then described receiving node subtracts 1 step in the priority basis of oneself.
7. method according to claim 1, if the member of wherein reception group does not receive packet, the value of sequence number that the packet of the up-to-date reception of multicast clear to send grouping indication then is set is zero.
8. method according to claim 1 further is included in transmit leg and indicates in the situation of the packet that will not send, after the member in the reception group receives the packet of last transmission, to the step of transmit leg feedback positive acknowledgement bag.
9. method according to claim 1 further comprises in the frame control domain of transmit leg in multicast request transmission grouping and records the step whether packet that will send to the reception group is arranged.
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| CN 200710186021 CN101431510B (en) | 2007-11-09 | 2007-11-09 | Multicast method in wireless local area network |
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| CN103841002B (en) * | 2012-11-22 | 2018-08-03 | 腾讯科技（深圳）有限公司 | Voice transmission method, terminal, voice server and voice-transmission system |
| US11422907B2 (en) | 2013-08-19 | 2022-08-23 | Microsoft Technology Licensing, Llc | Disconnected operation for systems utilizing cloud storage |
| US9451417B2 (en) * | 2013-11-27 | 2016-09-20 | Qualcomm Incorporated | System and method for multicast communications in Wi-Fi networks |
| CN103716137B (en) * | 2013-12-30 | 2017-02-01 | 上海交通大学 | Method and system for identifying reasons of ZigBee sensor network packet loss |
| CN107920054B (en) * | 2016-10-11 | 2020-11-17 | 华为技术有限公司 | Data transmission method and related equipment thereof |
| CN114422626B (en) * | 2022-01-28 | 2022-11-08 | 北京秒如科技有限公司 | Protocol transmission method, device and system |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2005119969A1 (en) * | 2004-06-02 | 2005-12-15 | Matsushita Electric Industrial Co., Ltd. | Radio transmission method |
| CN1871806A (en) * | 2003-10-24 | 2006-11-29 | 索尼株式会社 | Wireless communication system, wireless communication device and wireless communication method, and computer program |
| CN1933460A (en) * | 2006-09-30 | 2007-03-21 | 中兴通讯股份有限公司 | Equipment, system and realizing method for wireless local network transmission group broadcasting frame |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1871806A (en) * | 2003-10-24 | 2006-11-29 | 索尼株式会社 | Wireless communication system, wireless communication device and wireless communication method, and computer program |
| WO2005119969A1 (en) * | 2004-06-02 | 2005-12-15 | Matsushita Electric Industrial Co., Ltd. | Radio transmission method |
| CN1933460A (en) * | 2006-09-30 | 2007-03-21 | 中兴通讯股份有限公司 | Equipment, system and realizing method for wireless local network transmission group broadcasting frame |
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