Systems and methods for improved data throughput in communications networks

System and method for improving data volume in communication network

The present invention generally relates to communication networks, and more specifically relates to systems and methods for increasing the amount of data in communication networks.

The demand for multimedia applications including audio and video data is growing rapidly. Some of the more popular uses of multimedia are real-time interactive applications, such as video and audio streaming, Internet Protocol TV (IPTV), transmission of speeches or speeches to remote audiences, and animation simulations. Even when data compression is used, multimedia applications require a lot of bandwidth.

In an IEEE 802.11 wireless local area network (LAN), broadcast or multicast packet transmission enables over-band multimedia applications to simultaneously transmit audio and video data packets to each receiving node associated with a wireless LAN group. Broadcast packets are transmitted to all receiving nodes of the wireless LAN, and multicast packets are transmitted to two or more (but less than all) of the receiving nodes of the wireless LAN.

In this wireless LAN, a source node can transmit (for example, via Ethernet) multicast packets to an access point with a multicast function, and the access point has identified itself via wireless transmission Send the multicast packet for the destination receiving node that is part of the multicast group.

The access point of the wireless LAN can also support unicast packet transmission. For unicast transmission in a wireless LAN, the access point transmits one or more unicast packets to a receiving node identified by a desired destination address included in the unicast packets. After receiving the unicast packet, the receiving node transmits (about 9 μs later) an 802.11 acknowledgment (ACK) packet to the access point. The 802.11 ACK mechanism provides reliable data transmission in a typical high-interference 802.11 wireless network by confirming to the access point that the unicast packet has been received.

One limitation of transmitting multicast packets in a wireless LAN is that the 802.11 ACK does not provide a reliable mechanism to ensure that the receiving nodes actually receive the multicast packets. For example, if the 802.11 access point will transmit one or more multicast packets to many receiving nodes, and each of the receiving nodes will respond with 802.11 ACK packets basically synchronously, then The multiple ACK packets received by the access point during the synchronized 802.11 ACK period will contain "noise". For the access point, the multiple synchronized 802.11 ACKs are not interpretable. This situation can be called a "multiple ACK problem".

Another limitation of transmitting multicast packets is that the wireless LAN may be limited by the bandwidth used for multicast packets. Because of the multiple ACK problem, the IEEE 802.11 specification for multicast indicates that the transmission of multicast packets occurs at a minimum permitted physical data rate. Because receiving nodes can be at different distances from the transmission source and can encounter different interference levels, transmitting at the minimum permitted physical data rate improves the possibility of receiving multicast packets by each receiving node. For example, an 802.11 access point transmits multicast packets at a minimum permitted physical data rate of 1 Mbps for 802.11b and 6 Mbps for 802.11a. These receiving nodes do not transmit 802.11 ACK packets to confirm the reception of multicast packets. Therefore, if there is no such 802.11 ACK mechanism, there is no confirmation of receiving multicast packets.

In addition, transmission at the minimum permitted physical data rate cannot make full use of the available bandwidth in the wireless LAN, otherwise the available bandwidth can support a higher data rate. In addition, transmission at the minimum permitted physical data rate may make wireless LAN unsuitable for applications requiring high-speed communication, such as multimedia applications.

The present invention solves the above-mentioned problems by providing a system and method for improving the amount of data in a communication network. An access point of the communication network of an embodiment receives multicast or broadcast packets from a source. The access point converts the multicast or broadcast packet into a unicast packet with a certain address to a station associated with the access point. The access point then transmits the unicast packet from the access point to the station via the communication network. By converting multicast or broadcast packets into one or more unicast packets, the access point can improve the amount of data in the communication network by sending the unicast packets at a data rate that is higher than Otherwise, it will be possible to transmit multicast or broadcast packets to the station at a higher data rate. In addition, the unicast packet prepares for reliable transmission of data in the multicast or broadcast packet in the communication network, and the unicast packet is confirmed in the communication network.

In some embodiments, the communication network includes an 802.11 wireless network. The access point can determine the station from a list of one or more stations associated with the access point. The access point can determine a minimum data rate, the access point can use the minimum data rate to transmit multicast or broadcast packets to the station, and determine a valid unicast to transmit unicast packets to the station Send rate. If the effective unicast rate does not exceed the minimum data rate, the access point may then transmit the multicast or broadcast packet to the station instead of transmitting the unicast packet to the station.

The access point can also determine an antenna configuration to transmit to the station on the antenna configuration; and determine a physical data rate to transmit to the station at the physical data rate. The access point can then transmit unicast packets from the access point to the station via the wireless network on the antenna configuration and at the physical data rate. In a further embodiment, the access point determines that the station serves as the source and does not transmit the unicast packet to the station. The access point can query the station to determine an address of the station and can map an address of the multicast or broadcast packet to the address of the station. The access point can also associate the station to an address of a multicast or broadcast packet based on a joining request transmitted from the station to the source.

Provide a package that includes receiving a multicast or broadcast packet from a source to an access point and converting the multicast or broadcast packet into a unicast packet with a certain address to the station associated with the access point method. The method also includes transmitting unicast packets from the access point to the station via the communication network. The multicast or broadcast packet may include a user data protocol (UDP) network message. The multicast or broadcast packet may also include a multicast control packet.

An alternative method includes receiving a multicast or broadcast packet from a source to an access point in a communication network; determining a first rate, and the access point can communicate with the one by the first rate The first station associated with the access point transmits the multicast or broadcast packet; a second rate is determined, and the access point can use the second rate to transmit the multicast to a second station associated with the access point Sending or broadcasting a packet; and transmitting the multicast or broadcasting packet to the first station and the second station at the lower of the first rate and the second rate. Advantageously, the access point can determine a higher data rate than a minimum physical data rate designated for the communication network, and the access point can send the higher data rate to the first station and the second station. The station transmits multicast or broadcast packets.

In one embodiment, a first node of the communication network used for transmission to a second node of the communication network is configured to determine a first rate for transmitting multicast or broadcast packets. The first node also determines a second rate, which is used to transmit to the second node one or more unicasts generated by converting multicast or broadcast packets into the one or more unicast packets Send the packet. If the second data rate exceeds the first data rate, the first node then transmits one or more unicast packets to the second node, otherwise it transmits multicast or broadcast packets to the second node.

Advantageously, when appropriate, the first node converts the multicast or broadcast packet into one or more unicast packets at a higher rate than the minimum physical data rate designated for multicast or broadcast transmission The data rate is used to sequentially transmit the unicast packet(s) to the second node. The first node may include an access point with a multicast function. In some embodiments, the first node determines a third rate, and the first node can use the third rate to transmit multicast or broadcast packets to a third node of the communication network; and via the communication network The multicast or broadcast packet is transmitted to the second node and the third node at the lower of the first rate and the third rate.

Therefore, these systems and methods can provide reliable multicast or broadcast packets via wireless LAN by converting multicast or broadcast packets into one or more unicast packets and serving the corresponding confirmation packets from the station. transmission. An additional advantage is that the systems and methods can determine not to convert multicast or broadcast packets, and can transmit the multicast via the wireless LAN at a data rate higher than the minimum physical data rate that the station can reliably receive Send or broadcast packets.

The system and method disclosed in this article enable the amount of data in the communication network to be greater than the amount of data provided in the prior art. For example, the systems and methods disclosed in this article support over-band multimedia applications via wireless LAN. In the present disclosure, the nodes of the communication network can be referred to as a host, a source, a destination, a node, a receiving node, an access point, and a station. Since it should be understood that the present invention is by no means limited to the illustrated embodiments, such references should not be considered in a limited sense. For example, the "receiving node" is by no means limited to receiving functions. In addition, the term packet group includes a multicast packet, a broadcast packet and any packet whose destination address indicates one or more addresses and/or nodes of the communication network.

According to one embodiment, a wireless local area network (LAN) includes an access point configured to receive multicast or broadcast packets from a source. The multicast or broadcast packet is addressed to a group including one or more nodes of the communication network (for example, stations associated with the access point of the wireless LAN). The access point determines whether to convert a multicast or broadcast packet into one or more unicast packets for sequential transmission to one or more nodes, or whether to transmit the multicast or broadcast packet to the group. If the access point transmits the multicast or broadcast packet without conversion, the access point can determine a minimum common denominator data rate based on the data rate used to transmit the multicast or broadcast packet to one or more nodes , And transmit the multicast or broadcast packet to the group at the lowest common denominator rate.

FIG. 1 illustrates a block diagram of a system 100 for multicast packet transmission in a wireless local area network according to an embodiment of the present invention. The system 100 includes a source node 110, a network link 115, an access point 120, receiving nodes 130, 140, and 150, wireless links 135, 145, and 155, and a system that includes two or more of these receiving nodes A group 160 of more than two (for example, receiving nodes 130 and 140). The source node 110 is configured to communicate with the access point 120 via the network link 115. The access point 120 is configured to communicate with the receiving nodes 130 to 150 via the wireless links 135 to 155 that form the wireless LAN.

The source node 110 is any device capable of performing network communication including unicast or multicast packet transmission with the access point 120 via the network link 115. The source node 110 may include, for example, a personal computer, a server, a network attached storage device, or a network video distribution device. The source node 110 can support network protocols such as Transmission Control Protocol/Internet Protocol (TCP/IP), User Data Sheet Protocol (UDP/IP) and/or Internet Group Management Protocol (IGMP), and can support Unicast, multicast and/or broadcast packet transmission of network data.

The source node 110 is configured to transmit one or more packet groups (eg, one or more multicast or broadcast packets) addressed to the group 160 via the network link 115. The network link 115 can be a wired or wireless network link. In one embodiment, the network link 115 includes a UDP/IP connection. In one example, the source node 110 includes an IPTV video server (not shown) that transmits multicast packets, and provides a remote video stream to the group 160 through the access point 120. Although discussed with regard to multicast transmission, the packet group may include a packet whose destination address designates all nodes among the receiving nodes 130 to 150 (that is, broadcast) or less than all nodes (that is, broadcast). That is, multicast).

Each of the receiving nodes 130 to 150 includes any device capable of receiving network communications from the source node 110 via the access point 120 via the wireless links 135 to 155. The receiving nodes 130 to 150 may include devices such as personal computers, PDAs, mobile phones, and/or TVs with Internet functions. In one example, the receiving nodes 130 to 140 of the group 160 may include TV video converters configured to receive a video stream provided by the IPTV server at the source node 110 to the group 160. Although described as the source node 110 and the receiving nodes 130 to 150, it should be noted that the source node 110 can also be the destination node of a data packet and the receiving nodes 130 to 150 can also be the source node of a data packet.

As further described herein, the access point 120 is configured to simultaneously transmit the video stream as a multicast packet to the receiving node 130 and the receiving node 140, or to use it as one or more unicast packets. It is transmitted to each of the receiving nodes 130 and 140 sequentially. The access point 120 is essentially any device that can act as a bridge in a point-to-point connection in a wireless LAN or as a bridge between a network link 115 and wireless links 135 to 155. As discussed further with respect to FIG. 2, the access point 120 can be configured to convert a multicast packet into one or more unicast packets. The access point 120 may include a processor, a memory, and additional circuits that provide or assist in providing the bridge and/or the multicast packet conversion. The access point 120 may use an IEEE 802.11 protocol (such as 802.11a or 802.11b) to communicate with the receiving nodes 130 to 150. It will be understood that the access point 120 can incorporate other wireless protocols such as 802.11g, 802.16 or Bluetooth.

The access point 120 can support a multicast control protocol (such as IGMP), and can be configured as a router with a multicast function. A multicast control protocol enables the access point 120 to determine from the receiving nodes (for example, receiving nodes 130 to 150) which group (for example, group 160) the receiving nodes 130 to 150 are associated with. Some examples of multicast control protocols are IGMP, protocol independent multicast (PIM), real-time streaming protocol (RTSP), multi-protocol border gateway protocol (MBGP), and multicast source finding protocol (MSDP) , Simple Service Discovery Protocol (SSDP) and Source Specific Multicast (SSM). For example, the receiving node 130 may send a multicast control protocol packet to the access point 120 to change the channel used for an IPTV multicast stream received from the source node 110. The multicast control protocol packet informs the access point 120 that the receiving node 130 focuses on receiving the packet group for the selected channel.

The access point 120 of some embodiments is further configured to maintain information about "associated nodes". The associated node is a device that has negotiated a wireless communication link (for example, wireless link 135) with the access point 120. For example, when the receiving node 130 initially associates with the access point 120 to negotiate the wireless link 135, the receiving node 130 provides a media access control (MAC) or hardware address that uniquely identifies the receiving node 130. The receiving node 130 can also provide a list of permitted physical data rates (for example, 1 Mbps to 54 Mbps), which can communicate with the access point 120 at this rate. For example, the access point 120 can store the information about the associated node in the memory.

As described further herein, because the access point 120 of an embodiment is configured to convert multicast packets addressed to the group 160 into unicast packets addressed to one or more of the receiving nodes 130 to 140, the The system 100 improves the amount of multicast data in the wireless LAN. The access point 120 can sequentially transmit one or more unicast packets to the receiving nodes 130 to 140 at a higher data rate than the minimum data rate used for 802.11 multicast transmission. In addition, because the access point 120 will be able to serve the 802.11 ACK packets generated by the receiving nodes 130 to 140, the access point 120 in this embodiment ensures reliable transmission of the converted multicast packets. In some embodiments, the access point 120 may decide not to convert the multicast packet into one or more unicast packets, but instead may be a minimum permitted entity for 802.11 multicast packet transmission A relatively higher data rate is used to transmit multicast packets to the receiving nodes of the group 160.

FIG. 2 illustrates an exemplary method for multicast or unicast transmission in the wireless local area network of FIG. 1 according to an embodiment of the present invention. The steps of the exemplary method are described as occurring in a specific order, but it will be understood that certain steps can be rearranged to provide a similar result. This method determines whether to convert a multicast packet into one or more unicast packets, or whether to transmit the multicast packet. The method also determines the rate at which the multicast packet and the unicast packet or packets are transmitted. The method starts with the access point 120 that has been associated with the receiving nodes 130-150.

In step 205, the access point 120 receives from the first receiving node (for example, the receiving node 130) a first joining request (for example, an IGMP joining request such as an IGMP joining request) containing a first address of one of the receiving nodes 130. Multicast control protocol packet). The access point 120 uses the joining request to associate the addresses of the receiving node 130 and the group 160 with each other. In IGMP, a multicast user (e.g., receiving node 130) joins a multicast group (e.g., group 160) to enable group reception of a multicast traffic stream. When the access point 120 receives the IGMP splicing request from the receiving node 130, the access point 120 checks the IGMP packet and determines the required splicing information.

In this embodiment, the access point 120 itself does not use the IGMP protocol. In any case, the system 100 utilizes the fact that the IGMP joining request from the receiving node 130 to 140 to the source node 110 passes through the access point 120. The access point 120 "sucks in" or samples the IGMP joining requests to map the hardware (MAC) addresses of the receiving nodes 130 and 140 with the addresses of the group 160. In some embodiments, the access point 120 "speaks" the IGMP protocol. The access point 120 can map the IP addresses (instead of the MAC addresses) of the receiving nodes 130 and 140 to the addresses of the group 160.

In the process of selecting to inhale or speak the IGMP or other control protocols from the receiving nodes 130 to 150, the access point 120 may maintain a map containing all or all of the receiving nodes 130 to 150 associated with the access point 120 A subset of hardware addresses. The access point 120 can use the mapping to query the receiving nodes 130 to 150 to determine which of the receiving nodes 130 to 150 are interested in receiving multicast traffic addressed to the group 160. The mapping of MAC addresses or IP addresses allows the access point 120 to convert the multicast packets received from the source node 110 and addressed to the group 160 into one or more of the receiving nodes 130 to 140 addressed to the group 160. On-demand packet delivery.

In step 210, the access point 120 maps the first address of the receiving node 130 from the IGMP packet to the address of the group 160. In step 215, the access point 120 receives a second engagement request (for example, a second IGMP engagement request) from a second receiving node (for example, the receiving node 140). In step 220, the access point 120 maps a second address of the receiving node 140 to the address of the group 160.

In step 225, the access point 120 receives the multicast packet addressed to the group 160. In step 230, the access point 120 determines a first data rate (for example, 54 Mbps), and the access point 120 can use the first data rate to reliably transmit to the receiving node 130 (for example, including the 802.11 ACK mechanism) One or more military-on-demand packets. In step 235, the access point 120 determines a second data rate (for example, 24 Mbps), and the access point 120 can reliably transmit one or more unicasts to the receiving node 140 at the second data rate. Packet. Although not depicted, in some embodiments, the access point 120 can determine an additional (e.g., a third or more) data rate, and the access point 120 can use the additional data rate to transfer a second data rate. Three receiving nodes (for example, receiving node 150 that will be part of group 160) reliably transmit one or more unicast packets.

In step 240, the access point 120 determines an effective unicast rate. As discussed further in relation to Figure 3, the effective unicast rate corresponds to a combined rate that is used to convert the multicast packet into one or more unicast packets with the first and second (and third ...) The data rate is used to send one or more unicast packets to the receiving nodes 130 and 140 of the group 160. The effective unicast rate depends on the total number included in the unicast packets, including the extra burden of data packets (for example, the extra bits in the unicast packets compared to the multicast packets) . The effective unicast rate also depends on the calculation time associated with the conversion of a multicast packet into one or more unicast packets. The effective unicast rate is further based on the duration for receiving and processing the ACK packet from the receiving node of the group 160. In addition, because each additional receiving node in the group 160 reduces the effective unicast rate proportionally, the effective unicast rate is based on the number of receiving nodes in the group 160. In the title "System and Method for Transmission Parameter Control for an Antenna Apparatus with Selectable "Elements" also proposed a method for determining the effective unicast rate in the US patent application in the application, and the subject of the application is incorporated herein by reference.

Rather than converting a multicast packet into a unicast packet, as further described, the access point can transmit to the group 160 at a "lowest common denominator rate". For example, especially when a large number of receiving nodes in the group 160 each receive at a relatively high rate, the lowest common denominator rate may be higher than the effective unicast rate. For example, the group 160 may include receiving nodes 130, 140, and 150. The receiving node 130 can receive packets at a physical data rate of 54 Mbps, the receiving node 140 can receive packets at a physical data rate of 54 Mbps, and the receiving node 150 can receive packets at a physical data rate of 54 Mbps. The lowest common denominator rate of this example is 54 Mbps, which can be higher than the effective unicast rate. In step 245, the access point 120 determines the lowest common denominator rate (LCDR) for synchronously transmitting multicast packets to the receiving nodes of the group 160.

In steps 250 to 295, the access point 120 determines whether to transmit unicast packets or multicast packets, and at what rate to transmit the unicast or multicast packets. Specifically, in steps 250 to 275, the access point 120 may determine to convert the multicast packet into one or a plurality of first unicast packets addressed to the receiving node 130 and addressed to one of the receiving nodes 140 Or multiple second unicast packets for transmission. Alternatively, in steps 285 to 295, the access point 120 may determine to synchronously transmit the multicast packet to the receiving nodes 130 to 140 of the group 160 without converting the multicast packet into a unicast packet. In addition, in steps 285 to 295, if the minimum common denominator rate is higher than the minimum allowable physical data rate, the access point 120 determines whether to transmit at the minimum common denominator rate.

In step 250, the access point 120 determines whether the effective unicast rate exceeds the least common denominator rate. For example, in an 802.11a wireless LAN with receiving nodes 130, 140, and 150 in the group 160, the first data rate may be 54 Mbps, the second data rate may be 6 Mbps, and the third data rate may be 54 Mbps . For example, given the number of data bits in a unicast packet, additional burden on the packet, conversion processing time, and the like, the effective unicast rate can be 11.5 Mbps. Therefore, the effective military-on-demand rate of 11.5 Mbps exceeds the minimum common denominator rate of 6 Mbps (that is, the minimum permitted physical data rate of 802.11a), so in steps 255 to 275, the access point 120 will multicast The packet is converted into one or more unicast packets.

In step 255, the access point 120 converts the multicast packet into the first unicast packet with a certain address to the receiving node 130. In step 260, the access point 120 transmits the first unicast packet to the receiving node 130 at the first data rate and the first data rate. After transmitting the first unicast packet, before converting the multicast packet into a second unicast packet in steps 270 to 275 and transmitting the second unicast packet to the receiving node 140, in step 265 The access point 120 can be delayed by a predetermined delay period. The delay period is calculated to allow sufficient time for the receiving node 130 to generate an 802.11 ACK, and the access point 120 can receive the 802.11 ACK to confirm the reliable transmission and reception of the first unicast packet. The access point 120 can calculate the delay period based on several factors. For example, the access point 120 may calculate the delay based on the calculation time required for the access point 120 to convert the multicast packet into the first unicast packet. The delay may include the additional burden of the data packet (for example, the extra bits in the first unicast packet that reduces the first data rate to a relatively low "user" data rate). In addition, if the access point 120 does not receive the 802.11 ACK from the receiving node 130 for the first unicast packet, the access point 120 can retransmit the first unicast packet to the receiving node 130 and add it to the delay.

In step 270, the access point 120 converts the multicast from the source node 110 into a second unicast packet with a certain address to the sink node 140. In step 275, the access point 120 transmits the second data packet to the receiving node 140 at the second unicast rate. In a similar manner to the method described above with respect to steps 260 to 265 for the first unicast packet, the access point 120 waits for an 802.11 ACK from the receiving node 140 to ensure that the second unicast packet is received Reliable transmission and reception. If the access point 120 does not receive the 802.11 ACK from the receiving node 140, the access point 120 can transmit the second unicast packet to the receiving node 140 again. Although not depicted, steps 265 to 275 may be repeated for an additional (eg, third...) receiving node in the group 160.

If necessary, the access point 120 can determine whether one of the receiving nodes of the group 160 includes a multicast data transmitter in step 260 and step 275. For example, if the receiving node 130 acts as the source node 110 to send multicast packets to the receiving nodes 140 and 150 of the group 160 via the access point 120, then the access point 120 does not need to send back the converted packet to the receiving node 130 again. One-on-demand packet delivery. Although sending the unicast packet back to the receiving node 130 is a legal action in 802.11, such an action consumes network bandwidth.

At step 250, if the effective unicast rate does not exceed the minimum common denominator rate, the access point 120 may determine not to convert the multicast packet into one or more unicast packets for delivery to each of the group 160 A receiving node performs sequential transmission. Therefore, in step 285, the access point 120 determines whether the LCDR exceeds the minimum allowable data rate. For example, if the receiving node 130 can receive at 54 Mbps and the receiving node 140 can receive at 24 Mbps, the LCDR of 24 Mbps exceeds the minimum allowable data rate of 6 Mbps. Therefore, in step 290, the access point 120 will use the 24 Mbps LCDR to transmit multicast packets to the group 160. Alternatively, at step 285, the receiving node 130 if, for example, 54 Mbps can be received and the receiving node 140 can only be received at 6 Mbps, the LCDR does not exceed the allowable minimum of 6 Mbps data rates of. Therefore, in step 295, the access point 120 will transmit multicast packets to the group 160 at the minimum permitted data rate of 6 Mbps.

With regard to the method described in FIG. 2, by converting the multicast packets in the access point 120 into one or more unicast packets that can be sequentially transmitted to each receiving node of the group 160 at a relatively higher data rate Packets are used to advantageously achieve higher data volume than traditional multicast transmission. In addition, because the unicast packets are confirmed by the ACK response from each receiving node of the group 160, converting the multicast packets into unicast packets can provide higher data transmission reliability. In addition, if the access point 120 decides not to convert multicast packets into unicast packets, then the access point 120 can transmit the multicast packets at the lowest common denominator rate, which is one ratio of IEEE 802.11 The minimum permitted physical data rate defined in the standard is the higher physical data rate.

Although FIGS. 1 and 2 generally describe the multicast data stream from the source node 110 to the group 160 (that is, from left to right in FIG. 1), the methods described in relation to FIG. 2 are effective in the opposite direction (For example, from right to left in Figure 1) streaming multicast control protocol packets are applicable. For example, the system 100 may include a source node (e.g., receiving node 130) configured to transmit a packet group to a destination node (e.g., access point 120). The receiving node 130 sends a multicast control protocol packet such as an IGMP join request to the access point 120 via the wireless link 135 to join a group (for example, group 160) that receives an IPTV multimedia multicast stream. In order to provide more efficient use of the available bandwidth of the wireless link 135 and to provide reliable transmission of multicast control protocol packets, the receiving node 135 may convert the multicast control protocol packets into one or more single The packet is sent on-demand for transmission to the access point 120 and confirmed by the access point 120.

In one example, the receiving node 130 determines a first data rate for transmitting the packet group and determines a second data rate based on converting the packet group into unicast packets with a certain address to the access point 120 . If the first data rate used to transmit the packet group is less than the second data rate used to transmit unicast packets, the receiving node 130 transmits the data to the access point 120 at the second data rate via the wireless link 135 On-demand packet delivery. As discussed herein, the receiving node 130 transmits unicast packets at a higher physical data rate than the rate designated for multicast transmission. Once the unicast packet is received, the access point 120 sends an ACK to confirm the reception of the unicast packet.

If the first data rate for transmitting the packet group is greater than the second data rate for transmitting unicast packets, the receiving node 130 can transmit the packet group via the wireless link 135. As previously discussed, the receiving node 130 can transmit the packet group at the lowest common denominator rate. The access point 120 then receives the packet group and processes the multicast control protocol packet. Therefore, in these embodiments, the receiving node 130 and the access point 120 individually determine whether the transmission of the packet group or the conversion of the packet group into one or more unicast packets allows more effective bandwidth and reliable transmission. usage of.

FIG. 3 illustrates an exemplary sequence diagram of converting a multicast packet into one or more unicast packets as described in FIGS. 1 to 2 compared with a multicast packet transmission according to an embodiment of the present invention. A first time interval 310 instructs the access point 120 to convert the multicast packet received from the source node 110 into a first unicast packet and, for example, transmit the first unicast packet to the receiving node 130 at 54 Mbps. The time needed. It will be understood that the time interval 310 may be based on at least the first data rate, the number of data bits in the first unicast packet, and the conversion required by the access point 120 to convert the multicast packet into the first unicast packet Time changes and changes. After transmitting the first unicast packet to the receiving node 130, an ACK time interval 320 instructs the receiving node 130 to send back an 802.11 ACK in response to the first unicast packet and the access point 120 processes the 802.11 ACK packet The time required.

Similarly, a second time interval 330 instructs the access point 120 to convert the multicast packet received from the source node 110 into a second unicast packet and send it to the receiving node 140 at the second data rate (for example, 18 Mbps) The time required to transmit the second unicast packet. A second ACK interval 340 indicates the receiving node 140 to return an 802.11 ACK in response to the second unicast packet and the time required for the access point 120 to process the 802.11 ACK packet. In comparison, a multicast time interval 350 instructs the access point 120 to receive the multicast packet at the lowest common denominator rate or the smallest permitted physical data rate and to transmit the multicast packet to the receiving nodes 130 and 140 simultaneously. The duration.

Because the duration of the combined time intervals 310, 320, 330, and 340 is shorter than the duration of the multicast time interval 350, the system and method described in this article convert multicast packets into sequential The uni-cast packets are used to advantageously achieve a higher amount of data. In addition, for example, as the first and second data rates are lower due to interference in the wireless links 135 and 145 (FIG. 1), the duration of the time intervals 310 and 320 increases, and the time intervals 310, 320, The combined duration of 330 and 340 can exceed the multicast interval 350. In this case, the minimum common denominator rate can provide a higher data rate than the minimum permitted data rate. Therefore, another advantage is the moderate degradation of the overall data transmission rate with changes in the wireless LAN.

The embodiments discussed herein are illustrated as an example of the present invention. When referring to the description to describe the embodiments of the present invention, those skilled in the art can easily understand various modifications or adaptations to the described methods and/or specific structures. Relying on the teachings of the present invention and making the teachings promote all such modifications, adaptations or changes of the technology should be regarded as falling within the scope of the present invention. Therefore, these descriptions and illustrations should not be considered in a limited sense, but it should be understood that the present invention is by no means limited to the illustrated embodiments. Therefore, the scope of the present invention should not be determined with reference to the above description, but the scope of the additional patent application together with the full scope of its equivalents shall prevail.

<p>100. . . system</p><p>110. . . Source node</p><p>115. . . Network link</p><p>120. . . Access point</p><p>130, 140, 150. . . Receiving node</p><p>135, 145, 155. . . Wireless link</p><p>160. . . group</p><p>310. . . First time interval</p><p>320. . . First ACK interval</p><p>330. . . Second time interval</p><p>340. . . Second ACK interval</p><p>350. . . Multicast interval</p>

FIG. 1 illustrates a block diagram of a system for multicast transmission in a wireless local area network according to an embodiment of the present invention; FIG. 2 illustrates the wireless area used in FIG. 1 according to an embodiment of the present invention An exemplary method of multicast or unicast transmission in the network; and FIG. 3 illustrates an embodiment according to the present invention, and illustrates the conversion of multicast packets into unicast packets as described in relation to FIGS. 1 to 2 The illustrative timing diagram.