Network and method for voice and data wireless communications

The present invention relates to a wireless local area network (LAN), and more particularly to a wireless local area network that carries mixed traffic of voice and data.

Wireless local area networks are typically used for applications where wired equipment is not available and include portable computers. Such applications include warehouse inventory tracking, portable store point-of-sale (POS) terminals, shipping and receipt, package tracking, and the like.

The IEEE 802.11 communication standard has been used by certain manufacturers to provide interoperability between wireless local area network devices. The IEEE 802.11 communication standard defines a protocol for transmitting information in packets. This standard defines functions such as packet size, packet content information, data transfer rate, and roaming. The main forms of information that were first transmitted in a system designed for the published IEEE 802.11 communication standard were barcode information, POS information, package tracking information, and so on. In this known system, many remote terminals can communicate with a single access point in order to send and receive information such as bar code information, POS information, and package tracking information. Published standards define communication media shared by transmitters (eg, access points and one or more remote terminals).

In addition, this standard defines variable packet sizes. A remote terminal with a relatively long transmit packet needs to occupy a shared communication medium for a longer time than a remote terminal with a relatively short transmit packet. In the past, due to the format of information transmitted by this system, delays in communication packets were generally not important for at least partial communication. In general, information such as barcode information, package tracking information, etc. remains valid until the next incremental event occurs (eg, until the barcode information changes, or where the package is next to the route). Tracked up to etc.). Moreover, such information generally does not affect system communication, even if delivered with some delay.

In certain known systems, the transmitted packets are simply transmitted in the order in which they were received. In these known systems, the transmitted packet is repeatedly transmitted a predetermined number of times without proper reception confirmation from the designated receiver, but the transmission of the remaining other packets is delayed. If the proper receipt confirmation cannot be received, the packet is retransmitted a predetermined number of times, after which the transmitter can transmit the remaining packets.

In recent years, there has been an increasing demand for providing mixed voice and data traffic in wireless local area networks. Currently, the IEEE 802.11 communication standard does not provide specifications for voice communication. In general, information for performing voice communication requires more time than information such as barcode information and package tracking information. Communication for performing voice communication generally requires a larger amount of information to be carried by the system than when the system communicates regarding information carried by a wireless local area network. Furthermore, the quality of voice communication depends on the speed of information exchange. In data communication such as package tracking communication, the speed of information exchange is not important because communication quality is generally not a factor for evaluating the effectiveness of communication.

<p> Certain known wireless local area networks carry voice signals as part of their communication traffic, but this system is insufficient to effectively meet the requirements for mixed communications as described above. Further, it is necessary to meet the requirements of the existing system without substantially increasing the complexity, structure, design, cost, etc. of the system.</p>

<p> According to the principles of the present invention, transmitters and networks for mixed voice and data communication traffic are provided. The communication network may be a wireless local area network that uses packet communication. The communication network can include at least one access point, which receives voice and other communications for transmission to the terminal associated with the access point.</p><p> To manage packet transmission, the transmitter can prioritize packets. Prioritization includes data communication, based on when each packet was received, based on whether the packet contains voice communication, and based on whether the packet contains network management communication. Whether the packet was sent using a particular communication protocol, based on whether or not the packet was directed to a device capable of voice communication (eg, communication other than for voice or network management). It is done based on whether or not.</p><p> A transmitter such as an access point can prioritize transmitted packets based on which receiver terminal the packet is addressed to. Packets can be separated into queues, each queue storing received packets sent to a particular terminal. Packets may be further prioritized within each queue.</p><p> The prioritized packets give each terminal a fair opportunity and can be transmitted in such an order that each terminal can receive the same number of packets. For example, packets can be sent in a round fashion. In each round, the highest priority packet can be sent to each terminal (for example, a method of sending one packet per round for each terminal). In each round, the same number of packets can be sent to each terminal (eg, one for each packet).</p><p> In connection with each transmission packet, a reception confirmation (for example, reception confirmation packet) from the receiving terminal for each transmission packet is performed before the transmitter discards the transmission packet or transmits the next packet to the terminal. Can be requested. The transmitter can iteratively transmit a particular packet until it is acknowledged or the retry threshold (eg, the total number of times the packet is transmitted) is reached. The retry threshold can be determined based on whether the retransmitted packet is for voice communication. The retry threshold for voice communication may be smaller than the threshold for other communications. In a communication network using frequency hopping spread spectrum communication, a packet can be retransmitted when the number of transmissions reaches the initial retry threshold. If the reception confirmation is reached without receiving the initial retry threshold, the retransmission can be interrupted until the frequency hop in the modulation ends. Retransmission can then be resumed until a receipt confirmation is received or all retry thresholds are reached. The initial and total retry thresholds can vary based on whether the packet being retransmitted is for voice communication.</p><p> New packets that are received and prioritized may have a higher priority than packets that have not been confirmed. If a packet with a higher priority than the packet being retransmitted is received, the retransmission of the unconfirmed packet is replaced. If it is determined that the new received packet has a higher priority than the other packets, the transmitter terminates the previous received packet to the same terminal and sends the new received packet to a particular terminal. After that, the packets that have not been confirmed to be received are retransmitted in the subsequent rounds.</p>

<p> While giving a higher priority to a packet for voice communication than a packet for data communication, it prevents the transmission of data communication from being substantially disturbed. Moreover, this system and method meets the complex requirements of a mixed communication traffic environment without substantially increasing the structure, complexity, cost, processing delay, etc. of known wireless local area network systems and methods. Can be executed. Further features, essence, and various advantages of the present invention will become more apparent from the following detailed description with reference to the accompanying drawings. Throughout the accompanying drawings, the same reference numbers refer to the same parts.</p>

The present invention improves mixed traffic voice communication for wireless local area networks (LANs) by substantially satisfying the aforementioned communication requirements. Packets transmitted in the wireless local area network via the half-duplex communication medium are transmitted in order of priority. The priority can be determined at least based on whether or not the specific packet is for voice communication. One technique for determining whether a packet is for voice communication is to determine whether the designated recipient of the packet is identified for voice communication, and the transmitted packet is a specific communication protocol (eg, for example). , A commonly used protocol for sending voice) to determine if it was received. Other techniques for prioritizing transmitted packets and determining which packet is for voice communication will be described below.

Giving a high priority to voice communication interferes with the transmission of other non-voice communication packets. This interference can be substantially prevented by distributing the packets fairly. Distribute fairly by transmitting one packet (eg, the highest priority packet) to all recipients (eg, remote terminals) in each transmission round, and packet transmission in multiple rounds. Can be done. In the case of a transmission packet that has not been confirmed to be received by the designated recipient, the next transmission is made unless the latest transmission packet to the same terminal, which has a higher priority than the packet that has not been confirmed to be received, is being received. Can be resent in rounds. The latest received packet with high priority will be transmitted before the unconfirmed packet is transmitted. The number of times a packet is retransmitted can be determined based on whether or not the packet performs voice communication. Also, voice communication can be prioritized by using a technique described below that gives the sender who is trying to transmit a packet for voice communication greater access to the communication medium.

Referring to FIG. 1, the wireless local area network (LAN) 20 can include a plurality of cells 22. For the sake of brevity and clarity, the wireless local area network 20 will be illustrated exemplarily primarily assuming that the local area network has one cell 22. Cell 22 can include access point 24 (sometimes referred to as a wireless local bridge). Cell 22 can include remote terminal 26. Each terminal 26 may be a mobile terminal, a portable terminal, or a fixed terminal. Each terminal 26 may be a desktop workstation, a laptop computer, a palmtop computer, a handheld personal computer, a pen input computer, a personal digital assistant, a handheld scanner, a data collector, a handheld printer, or the like. Each terminal 26 can include a wireless network interface resource configured to perform two-way radio or infrared signal communication. Such resources can include interface cards (or external modems), software drivers, and antennas. Other suitable resources may be used, but for the sake of brevity and clarity, wireless network interface resources will be described primarily in the context of interface cards, software drivers, and antennas. The interface card can be configured to use a standard computer bus interface (eg, ISA, PCMCIA, etc.) or a standard computer port (eg, RS232, RS422, etc.) to provide convenient access to the terminal equipment.

A network operating system can be implemented in each terminal 26. At each terminal 26, the interface card can be coupled to a network OS application that uses software drivers. The interface card for each remote terminal 26 may be a network communication interface. Typically, the network interface card for each remote terminal 26 is implemented to modulate the communication signal using a spread sequence using a carrier sense access protocol.

The access point 24 may be an interface for communicating between the wireless network 20 and the wired network. The access point 24 can be configured to provide a communication gateway between each terminal 26 in cell 22 or between a wired network and terminal 26. The access point 24 includes resources (eg, software, hardware, or a combination thereof) configured to connect the access point to a wired network (eg, on an Ethernet® network, Token Ring network, etc.). be able to. Typically, the access point 24 is configured to convert signals between a wired communication medium and a wireless communication medium. This conversion allows the access point to pass communication information between the wired network and the wireless remote terminal 26.

Typically, the access point operates according to the IEEE 802.11 standard (eg, provides 802.11 roaming, standard 802.11 data speeds) and has sufficient processing power, hardware to provide additional functionality developed by the manufacturer. Equipped with hardware, software, etc. The access point 24 can be realized by using a personal computer (for example, Power PC, IBM compatible computer), a server, a workstation, or the like having an appropriate operating system, wireless network interface resource, wired network interface resource, network OS application, or the like.

The access point 24 and the remote terminal 26 can be configured to communicate using spread spectrum modulation techniques (eg, direct sequence spread spectrum modulation, frequency hopping spread spectrum modulation). The IEEE802.11 standard defines the format and content of communication packets. The communication packet, which is also called a frame, may have a variable size in which each packet size is identified by the packet header information. In certain embodiments, each packet body may be variable from 0 to 2312 octets.

When activated, when one of the terminals 26 is first powered on, the terminal 26 works with the access point 24 to locate the merged cell 22. The remote terminal 26 becomes associated with the access point 24 after a preliminary exchange of communication between the access point 24 and the terminal 26. A plurality of terminals 26 can be associated with each access point 24. Each terminal 26 may have different communication performance and requirements. The access point 24 can manage the communication traffic between the terminal 26 and the wired network. The access point 24 can manage the communication traffic by controlling when the packet is transmitted to each remote terminal 26 in the cell 22. Communication traffic in cell 22 includes data packets (eg, signals carrying packets for data communication), voice packets (eg, signals carrying packets for voice communication), real-time packets (eg, multimedia). Alternatively, it may include a signal that carries a packet for real-time communication such as voice communication), a management packet (for example, a signal that carries a packet for performing network management communication), and the like.

The wired network coupled to the access point 24 may include a device 23 configured to perform the wired network. Wired networks can connect to external networks (PBX, PSTN, Internet, etc.).

The access point 24 can manage communication traffic by prioritizing packets transmitted to the associated remote terminal 26. FIG. 2a shows exemplary steps for managing communication traffic for use with access points such as the access point 24 shown in FIG. In step 40, the access point can receive a signal carrying a packet transmitted to a remote terminal (eg, a packet addressed to an individual terminal 26 in cell 22 of FIG. 1). In step 42, the access point can prioritize the transmitted packets it receives. The access point decides which remote terminal to send the packet to, and which of the packets sent to that remote terminal is the packet to be sent next. Prioritize. Prioritization can be performed between access points receiving packets. For example, prioritization can be performed at regular intervals. Each packet can be prioritized based on reception time, packet content, packet address information, message protocol, fairness to each terminal, and the like.

For clarity, the management of packet communication traffic will be described primarily in relation to queues. Similarly, other techniques than using queuing may be used to manage packet communication traffic. The exemplary queues 44, 46, 48, 50, and 52 shown in FIG. 2b are provided based on the exemplary steps of FIG. 2a. Queue 44 contains exemplary packets in the order received by the access point. Packets in queue 44 may be received from a remote terminal associated with the access point or from a wired network. The packet in queue 44 is a packet destined for the four terminals T1, T2, T3, and T4. Queues 44, 46, 48, 50, and 52 can include packets from queue 44 if the packets are prioritized by the access point. Each of the queues 44, 46, 48, 50, and 52 is a queue associated with each of the terminals T1, T2, T3, and T4. In each of the queues 44, 46, 48, 50, and 52, packets can be prioritized based on the time the packet was received.

Each packet shown in queue 44 has a terminal address and a packet number. Here, for convenience of explanation, the packet number is used to indicate the order in which the access points received the packets. In queues 44, 46, 48, 50, and 52, packets with lower numbers are received earlier and have higher transmission priority.

Packets can be sent on a priority basis. FIG. 3a shows an exemplary step for packet transmission. In step 54, the access point prioritizes outgoing packets. In step 56, for example, based on priority, based on fairness, based on fairness and priority, based on fairness to each terminal, based on one packet per terminal communication sequence. By transmitting, the prioritized packets are distributed. If desired, fairness may be determined as part of step 54 when the access point prioritizes packets.

The exemplary queues 58, 60, 62, 64, and 64 of FIG. 3b are provided based on the exemplary steps of FIG. 3a. Each queue 58, 60, 62, 64, and 64 is associated with terminals T1, T2, T3, and T4, respectively. Transmission packets to terminals T1, T2, T3, and T4 are received by the access point. In each queue, packets are prioritized based on receive time. For fairness, the access point can send packets in a round fashion. In each round, the access point can send packets of the same number (eg, one packet) to each terminal.

Queue 66 includes packets from queues 58, 60, 62, 64, and 64, in the order in which the packets are sent. This order is divided into multiple rounds, each round containing one packet per terminal. As shown, each of the first and second rounds contains one, or four, packets for each terminal associated with the access point. After the first two rounds have been successfully transmitted, queue 62 has no packets to send to terminal T3, so the third round contains three packets.

The access point can select and transmit packets for each terminal in each round in the order in which the access point received the packets for that terminal. Further referring to FIG. 3b, in the first round, the access points are the first packets, each contained in queues 58, 60, 62, 64, and 64, packet numbers 2, 3, 6, And 1 are sent. In the second round, the access points transmit packet numbers 4, 8, 7, and 5, which are each the next packet received for their respective terminals T1, T2, T3, and T4, respectively. In each round, one packet from each queue is sent without competition between each queue for position within the round. An exemplary packet in Figure 3b (and other drawings) is a variable size packet. For the sake of brevity, the packets are shown as fixed length packets.

The access point prioritizes packets based on which packets are for voice communication. FIG. 4a shows an exemplary step associated with prioritizing packets based on which packets are for voice communication. In step 68, the access point determines which of the packets to be transmitted is a voice communication packet.

The voice communication packet is a packet that carries digitized voice communication. As mentioned above, voice communication typically has stricter communication requirements than other communications such as inventory management data, point of sale information, etc. The access point can determine which packet is for voice based on the message flag of the packet, based on the packet addressed to the terminal capable of voice communication, or based on the message protocol (described later). At step 70, the packets can be prioritized. The voice communication packet may have a higher priority than other packets.

The exemplary queues 72, 74, 76 of FIG. 4b can be provided based on the exemplary steps of FIG. 4a. The queue 72 may include transmission packets received by the access point to terminals T1 and T2. Queue 72 includes packets (packet numbers 1, 4, and 6) transmitted to perform voice communication. Since the voice communication packet has a higher priority than the other packets in the queues 74 and 76, these voice packets are transmitted before the other packets. The queue 74 for terminal T1 includes voice packet number 6, which has a higher priority than packet numbers 3 and 5 received before packet number 6. Queue 76 for terminal T2 includes voice packet numbers 1 and 4, which have a higher priority than packet numbers 2 and 7 for other communications. Within each queue, voice packets are prioritized to be sent before other packets. In addition, all packets in the queue are prioritized to be sent based on the time the access point received each packet.

The access point can prioritize packets based on network management requirements. Figure 5a shows exemplary steps associated with prioritizing packets based on network management requirements. At step 78, the access point determines which packet should be sent to manage network operation. The packet is determined to be a network management packet based on the message flag and the message length. In step 80, the packets are prioritized based on which packets are for network management.

The exemplary queues 82, 84, and 86 of FIG. 5b can be provided based on the exemplary steps of FIG. 5a. The received packet queue 82 may include packet numbers 1, 4, and 6 transmitted for network management. Management packets may have a higher priority than other packets to protect the integrity of network operation. Queues 84 and 86 can be run for terminals T1 and T2, respectively. Management packet numbers 1 and 4 have a higher priority than other packets in the queue for terminal T1 (that is, they are placed first in the queue), and management packet number 6 is in the queue for terminal T2. Higher priority than other packets. Higher priority packets in each queue are sent before lower priority packets in the queue.

In wireless local area networks, packet traffic can be managed with different levels of priority. Figure 6a shows exemplary steps associated with prioritizing packets by different levels of precedence. In step 88, the access point determines which packet is for voice communication, network management communication, or other communication. In step 90, the network-activated management packet is given the highest priority. In step 92, the voice communication packet is given the second highest priority. In step 94, the other communication packets are given the third highest priority.

The exemplary queues 96, 98, 100, and 102 of FIG. 6b can be provided based on the exemplary steps of FIG. 6a. The queue 96 can include received packets, including voice communication packets, management communication packets, and other communication packets transmitted to terminals T1, T2, and T3. Queues 98, 100, and 102 can be run for terminals T1, T2, and T3, respectively. In queues 98, 100, and 102, management packets have the highest priority (ie, higher than voice and other communications), voice packets have the second highest priority, and other communications packets have priority. The ranking is the third highest. The priority between packets for the same type of communication can be based on the reception time. Packets can be transmitted from the access point in the order of packet priority for each remote terminal.

Certain wireless local area networks use the 7-tier Open Systems Interconnection (OSI) reference model established by the International Organization for Standardization (ISO). Open Systems Interconnection defines a complete set of network functions classified into seven layers. The 7 layers are the physical layer (1st layer), data link layer (2nd layer), network layer (3rd layer), transport layer (4th layer), session layer (5th layer), and presentation layer (5th layer). 6th layer) and application layer (7th layer). The network function is configured so that each OSI layer is supported by a layer below it.

The transport layer establishes and maintains communication between applications on different computers. Communication protocols such as Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) operate at the transport layer. TCP provides full-duplex connection services (eg, maintaining virtual communication connections between end users), while UDP provides connectionless services (eg, maintaining open connections between end users). To provide communication). A commonly used communication protocol for voice communication at the network layer is UDP.

Figure 7a relates to packet transmission for use in a wireless local area network configured to perform the transport layer of the 7-tier Open Systems Interconnection (eg, wireless local area network 20 in Figure 1). An exemplary step is shown. In step 104, the access point can determine which terminal is capable of voice communication. The access point can determine which terminal is capable of voice communication based on the message flag in the packet, the address assigned in advance for the terminal capable of voice communication, and the like. In step 106, the access point can receive the transmitted packet to the terminal. Step 106 can be performed before or after step 104, or during that step.

At step 108, the access point can prioritize packets. Prioritization can be based on multiple factors. Prioritization can be done based on which terminal the packet is directed to, based on the packet's communication protocol, whether the packet is for network management or not, and further on the basis of receive time. At step 110, the packet is transmitted. Packets can be sent on the basis of how they are prioritized and on the basis of fairness (eg, maintaining fairness by maintaining a uniform distribution of packets between each remote terminal).

The exemplary queues 112, 114, 116, 118, and 120 of FIG. 7b can be performed based on the exemplary steps of FIG. 7a. The queue 112 may be a queue of received packets that are placed in the queue 112 in the order in which they were received by the access point. Terminals T1, T2, and T3 may be associated with the access point when it receives the packet. Queues 114, 116, and 118 can be executed for terminals T1, T2, and T3, respectively, if received packets are prioritized. The access point may determine that terminal T1 is a voice-communicable terminal before the packets in queue 112 are received.

Packets sent to manage the wireless network can be given the highest priority. The queue 112 includes two management packets: packet number 1 to terminal T1 (eg, addressed to terminal T1) and packet number 9 to terminal T3. In queue 114 for terminal T1, packet number 1 has the highest priority in queue 114, and in queue 118 for terminal T3, packet number 9 has the highest priority in queue 118. There is.

Packets sent for voice communication have the second highest priority. The communication protocol of the OSI transport layer processes the packet without determining whether the packet is for voice communication. Certain networks run using the OSI transport layer use UDP for voice communication. The access point determines which packet is for voice communication based on the packet's communication protocol (eg UDP) and whether the packet is directed to a voice-enabled terminal. Communication protocols operating at the transport layer (ie, TCP and UDP) deliver messages between source systems (eg, external networks) and recipient systems (eg, wireless local area network 20 in Figure 1). To use Internet Protocol (IP) services at the network layer. The IP packet contains a protocol field indicating which protocol in the transport layer (eg, UDP, TCP, etc.) the enclosed packet is for.

Packets are shared between the access point and the remote terminal and can be received by the access point from a half-duplex communication medium (eg, a radio frequency channel) with which the remote terminal communicates with the access point. In addition, the packet can be received from other communication media on which the wired network communicates with the access point. Packets use the Internet Protocol for network layer communication (eg, using the IP packet format), and UPD, TCP, etc. for transport layer communication (eg, UDP packet format). (Using), sent to the access point. Therefore, the packet received by the access point from the remote terminal already meets the communication requirements for IP, UDP, TCP, and the like. If necessary (for example, when two remote terminals in a wireless LAN communicate), the access point may configure the packet to meet the 802.11 standard.

The access point can read the protocol field of the received IP packet to determine the transport layer communication protocol of the received packet. A packet processed using UDP and directed to a terminal capable of voice communication can be determined by the access point to include voice communication. The access point can determine in advance which terminal is capable of voice communication through previous interactions with the terminal. Previous interactions may occur when a remote terminal first searches for an access point to establish communication (eg, when associated). If desired, the access point may be programmed with information related to the performance of each terminal.

Referring to FIG. 7b, the queue 114 for a terminal capable of voice communication includes packet number 7 (UDP) and packet number 10 (UDP), both of which have a higher priority than the previously received packet number 3. Given. In queues 116 and 118, UDP has a lower priority than TCP because the access point has not determined that terminals T2 and T3 are capable of voice communication. In queues 116 and 118, the management packet (if any) has the highest priority, and all other packets have the second highest priority.

Queue 120 contains packets in the order in which they should be sent (ie, in the order they are sent). Packets can be transmitted in a round system such as one packet for each terminal, and the packet having the highest priority for each terminal is transmitted in each round. Such transmission techniques enable rapid delivery of voice communications without substantially increasing the complexity, cost, structure, or design of the network device.

The queues 114, 116, and 118 can be configured to be the same size. A queue of the same size can prevent a situation where many packets for one terminal occupy most of the access point's storage space. In such situations, insufficient storage space can interfere with the storage of new packets received by the access point. The size of the queue thus sized to the same size is determined based on system limits. For convenience of explanation, queues 114, 116, and 118 are shown as memorable for only four packets each.

FIG. 8a shows an exemplary step associated with prioritizing packets based on terminals that are ready for voice communication. In step 122, the terminal can send a packet containing the voice flag to the access point. The voice flag can be set to indicate that the terminal is capable of voice communication. In step 123, the access point can determine the state of the terminal by receiving the packet and reading the voice flag of the packet. In step 124, the access point can store information indicating a state in which the terminal can perform voice communication. In step 126, the access point can prioritize packets based on terminals that are ready for voice communication.

The queue 118 and packet flowchart 130 of FIG. 8b can be executed based on the exemplary steps of FIG. 8a. The flowchart 130 shows that the terminal T has transmitted a packet having a voice flag set to indicate the voice communication enable state of the terminal T to the access point. The terminal can send packets in the first communication exchange with the access point. The terminal T may be one of a plurality of terminals associated with the access point.

Packets in queue 128 may be received after the first interaction between the access point and terminal T. Packets in queue 128 are prioritized based on the voice communicable state of terminal T (for example, UDP packets have a higher priority than TCP packets). Within the access point, the application can assign a priority to each packet in queue 128. The packets are then transmitted based on the assigned priority, the receipt confirmation packet is transmitted by the terminal T, and is transmitted for each packet appropriately received by the terminal T. The received packets in the queue 128 are transmitted in the order of packet number 4 (MNGT), packet number 1 (UDP), packet number 3 (UDP), and packet number 2 (TCP).

In wireless local area networks that use Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA), greater access to communication bandwidth is provided to transmit voice communications than to transmit other communications. Figure 9a shows an exemplary step associated with the transmission of voice packets on a CSMA / CA. In step 132, the transmitter (such as an access point or terminal) can determine whether the packet to be transmitted is for voice communication. In step 136, the transmitter has a carrier channel T for a predetermined period of time.₀During that time, it can be determined whether or not it is idle (that is, the transport channel is available). This determination can be made using carrier sense means mounted on the transmitter. In step 134, if the transmitter determines that the packet to be transmitted is for voice communication, the transmitter will be in period T.₀Shorter period T_rIt can be determined whether the transport channel is idle during (ie, the period of actual use). In step 138, the transmitter has an appropriate period (eg, T).₀Or T_rIf the carrier channel is determined to be idle during), the transmitter sends a packet. The conflict window allows you to specify a period for the transmitter to detect the carrier channel frequency and determine if the channel is idle (eg, can be used to carry communications). FIG. 9b is a graph illustrating different conflict windows for audio and other data.

The transmitted packet is confirmed by each receiver when the designated receiver receives the transmitted packet and transmits a reception confirmation packet accordingly. The transmitter then discards the confirmed transmission packet and / or starts transmitting the untransmitted packet. Unconfirmed packets can be retransmitted (for example, transmitted packets remain in the queue). FIG. 10a shows exemplary steps associated with retransmitting packets for use in a wireless local area network (eg, wireless local area network 20 in FIG. 1). In step 140, a packet destined for a particular terminal can be sent. In step 142, the transmitter can determine whether or not the reception confirmation packet has been received. In step 144, after receiving the receipt confirmation for the transmitted packet, the transmitter transmits the next packet (eg, the packet with the next highest priority) to that terminal. In step 146, if no receipt confirmation for the transmitted packet has been received, the transmitter may continue to retransmit the packet until the packet is acknowledged or the number of times the packet has been transmitted reaches the retry threshold. .. Step 146 includes determining a retry threshold based on whether the packet is for voice communication. The retry threshold for voice packets can be preset to be smaller than the retry threshold for other packets.

The exemplary packet transmission rounds 148, 150, 152, and 162 of FIG. 10b can be performed based on the exemplary steps of FIG. 10a. In round 148 (first round), packet A is transmitted from access point 154 to terminal T2, but in response to this, reception confirmation is not transmitted from terminal T2. In round 150 (second round), packet A is retransmitted, but reception confirmation from terminal T2 is not received. Packet A continues to be transmitted in a total of n rounds thereafter, but no receipt confirmation for packet A is received in each round. The value of n is the retry threshold, which may be different for voice packets and other packets. After the nth round 152, the continuous transmission of packet A is interrupted, and in the subsequent round 162, another packet (for example, the packet having the next highest priority to the terminal T2) can be transmitted.

FIG. 11a retransmits unacknowledged packets for use in a wireless local area network configured to use frequency hopping spread spectrum modulation (eg, wireless local area network 20 in FIG. 1). An exemplary step of is shown. In step 104, the transmitter can send one packet to a particular terminal. In step 166, the transmitter can determine whether or not a receipt confirmation has been received in response to the transmitted packet. If the transmitter determines in step 168 that the receipt confirmation for the transmitted packet has been received, the transmitter can transmit the next packet to the terminal. If it is determined in step 170 that no receipt has been received, the packet is retransmitted until reception is confirmed or until the initial retry threshold is reached (eg, until the packet is transmitted k times). ). If desired, step 170 can include a step (step 170a) of determining how many times the transmission will be retried (eg, based on whether the packet is for voice communication). When the initial retry threshold is reached, further retry transmissions are interrupted until after the frequency hop for modulation (step 172). In step 174, the packet is further retransmitted until reception is confirmed or the total retry threshold is reached. If desired, step 174 can include determining how many times the packet is to be retried in total (eg, based on whether the packet is for voice communication or not).

The exemplary transmission rounds 176, 178, 180, and 182 of FIG. 11b can be performed based on the exemplary steps of FIG. 11a. In round 176, access point 184 can send packet A to terminal T2. In round 178, access point 184 can retransmit packet A to terminal T2 if no receipt confirmation for packet A has been received in the previous round. In subsequent rounds, access point 184 continues to transmit packet A until a confirmation of receipt of the response is received and packet A is transmitted a certain number of times k. If packet A is transmitted k times, further retransmissions are interrupted up to the hop at the frequency used for spread spectrum communication. In round 182 after the frequency hop, access point 182 resumes packet transmission to terminal T2.

Retransmission of unacknowledged packets can be replaced by reception of packets with a higher priority than unacknowledged packets. FIG. 12a shows an exemplary step associated with the transmission of the highest priority packet for each terminal of a wireless local area network (eg, the wireless LAN of FIG. 1). At step 190, the received packets can be prioritized. At step 192, the highest priority packet for each terminal can be selected. In step 194, one round of the packet (eg, the selected packet) is transmitted. In step 196, the transmitter determines whether a receipt confirmation for each packet has been received. In step 198, a new transmit packet is received. In step 200, packets to be transmitted (ie, received packets and unacknowledged packets) are prioritized. In step 202, the highest priority packet for each terminal is selected. At step 204, another round of the packet is transmitted.

The exemplary queues 206, 208, 210, 212, and 214 of FIG. 12b can be performed based on the exemplary steps of FIG. 12a. The queues 206 and 208 may be queues containing prioritized packets that the access point 216 is now sending to terminals T1 and T2, respectively. In the first round, if a half-duplex communication channel (eg, a predetermined frequency bandwidth that the multiplexing device communicates with using carrier-sense multiplex access and spread spectrum modulation) is determined to be idle, then the access point. Can transmit packet numbers 1 and 6, which are the highest priority packets for terminals T1 and T2, respectively. In the first round, packet number 6 (UDP) transmitted to terminal T2 capable of voice communication has not been confirmed to be received by terminal T2. At the next round, packet number 6 is re-added into queue 206 for terminal T2. Additional transmitted packets 210 to terminals T1 and T2 may be received by access point 216 before the next round of packets are transmitted. Once the additional packets are prioritized, the queues 206a and 206b can be executed.

The queues 206a and 206b contain prioritized packets sent to terminals T1 and T2, respectively. In the previous round, packet number 6 to terminal T2 is not confirmed to be received and is re-added to queue 208a. New management packets for terminal T2 are received after the first round and are prioritized to have a higher priority than packet number 6. When the access point 216 transmits the highest priority packet for the terminal T2, the packet number 13 is transmitted after terminating the packet number 6 which has not been confirmed to be received. That is, the retransmission of packet number 6 is replaced by the transmission of packet number 13, which has a higher priority. If packet number 6 is the highest priority packet pending transmission to terminal T2, retransmission is initiated in subsequent rounds.

Therefore, it can be understood that a wireless local area network system and method for effectively transporting mixed traffic communication are provided. While giving a higher priority to a packet for voice communication than a packet for data communication, it prevents the transmission of data communication from being substantially disturbed. Moreover, this system and method meets the complex requirements of a mixed communication traffic environment without substantially increasing the structure, complexity, cost, processing delay, etc. of known wireless local area network systems and methods. Can be executed. The above description merely illustrates the principles of the present invention, and those skilled in the art can make various modifications without departing from the scope and spirit of the present invention.

<figref num="1">An exemplary communication network including an exemplary wireless local area network according to the present invention is shown.</figref><figref num="2a">FIG. 6 is a flow chart of exemplary steps related to packet traffic management for use in a transmitter according to the present invention.</figref><figref num="2b">Shown is an exemplary queue performed based on the exemplary steps of FIG. 2a according to the present invention.</figref><figref num="3a">FIG. 3 is a flow chart of exemplary steps related to packet transmission according to the present invention.</figref><figref num="3b">Shown is an exemplary queue performed based on the exemplary steps of FIG. 3a according to the present invention.</figref><figref num="4a">It is a flowchart of an exemplary step related to packet traffic management based on which packet is for voice communication according to the present invention.</figref><figref num="4b">Shown is an exemplary queue performed based on the exemplary steps of FIG. 4a according to the present invention.</figref><figref num="5a">It is a flowchart of an exemplary step related to packet traffic management based on which packet is for network management according to the present invention.</figref><figref num="5b">Shown is an exemplary queue performed based on the exemplary steps of FIG. 5a according to the present invention.</figref><figref num="6a">It is a flowchart of an exemplary step relating to packet traffic management having a plurality of levels of priority according to the present invention.</figref><figref num="6b">Shown is an exemplary queue performed based on the exemplary steps of FIG. 6a according to the present invention.</figref><figref num="7a">It is a flowchart of an exemplary step related to packet traffic management based on which terminal is capable of voice communication according to the present invention.</figref><figref num="7b">Shown is an exemplary queue performed based on the exemplary steps of FIG. 7a according to the present invention.</figref><figref num="8a">It is a flowchart of an exemplary step related to traffic management based on the determination of which terminal is capable of voice communication according to the present invention.</figref><figref num="8b">Shown is an exemplary queue performed based on the exemplary steps of FIG. 8a according to the present invention.</figref><figref num="9a">It is a flowchart of an exemplary step relating to the use of a variable conflict window according to the present invention.</figref><figref num="9b">An exemplary duration for a variable competition window according to the present invention is shown.</figref><figref num="10a">FIG. 3 is a flow chart of exemplary steps related to packet transmission according to the present invention.</figref><figref num="10b">FIG. 5 is a flowchart of an exemplary packet communication according to the exemplary step of FIG. 10a according to the present invention.</figref><figref num="11a">FIG. 3 is a flowchart of exemplary steps related to packet-based communication using the frequency hopping scheme according to the present invention.</figref><figref num="11b">FIG. 6 is a flowchart of an exemplary packet communication according to the exemplary step of FIG. 11a according to the present invention.</figref><figref num="12a">FIG. 6 is a flow chart of exemplary steps related to incrementally transmitting packets according to the present invention.</figref><figref num="12b">Shown is an exemplary queue performed based on the exemplary steps of FIG. 12a according to the present invention.</figref>

Code description

20 LAN24 Access Point 26 Terminals 44, 46, 48, 50, 52, 58, 60, 62, 64, 66, 72, 74, 76, 82, 84, 86, 96, 98, 100, 102, 112, 114, 116, 118, 120, 206, 208, 210, 212, 214 Queue