Data burst transmission methods in wlan devices

TECHNICAL FIELD

The inventive issue is about wireless local area networks (WLAN) and, more particularly, about the transmission of data packets between a transmitter and a receiver in a WLAN.

BACKGROUND 5

Any Wireless Local Area Network (WLAN) device that supports an Institute of Electrical and Electronics Engineers (IEEE) 802.11 Standard (for example, IEEE Std 802.11-1997, 802.11a, 802.11e, etc.) includes two main parts: 1) a physical layer signaling control device (PHY); and 2) a media access control device (MAC). The function of the PHY device is to transfer data packets through the air interface. Among other things, the function of the MAC device is to control access to the shared 10-air interface equally.

The minimum MAC protocol consists of two frames: 1) a frame sent from a transmitter to a receiver; and 2) an acknowledgment (ACK) of the receiver that the frame was correctly received. If a transmitter has to send multiple packets to the receiver, some versions of the 802.11 standard require that the transmitter wait for an ACK after the transmission of each packet. In addition, the transmitter must wait for a particular time interval, called the Interframe Space (IFS), after receiving the ACK and before transmitting the next packet.

Other versions of the 802.11 standard (for example, IEEE Std 802.11e) support packet transmission with a selective acknowledgment. This feature is called "block ACK." The block ACK feature allows the transmitter to send the next packet to the same receiver without necessarily waiting for an ACK. On the other hand, after negotiating access to the air interface, the transmitter sends the first packet, waits for an IFS after the end of the first packet, and sends the next packet. After the transmitter has sent all its packets to the receiver, the transmitter asks the receiver for a response, which indicates an ACK for all previously transmitted packets.

Although the block ACK feature has provided some performance improvements, researchers 25 are still looking for ways to further increase performance. Consequently, what is needed are procedures and apparatus to further improve performance using burst mode transmissions.

EP 1 130 837 A discloses a method for adapting to a variety of link propagation conditions in a communication system that includes a burst of data packets that includes a header and an optional payload, the header being modulated using a default modulation model and being encoded using a default coding model.

WO 02/054805 A discloses a method for transferring data between different units of a radiocommunication system in which said data is placed together in a data packet containing header and channel control information for each channel that It indicates at least if at least the useful data has been transferred in each channel. 35

The present invention relates to the methods as defined by means of independent claims 1 and 7, the apparatus as defined by means of independent claims 12 and 15, and the computer-readable medium as defined by means of claim independent 17.

BRIEF DESCRIPTION OF THE DRAWINGS

The attached claims show different embodiments of the inventive matter with particularity. However, the detailed description presents a more complete understanding of the inventive issue when considered together with the figures, in which similar reference numbers refer to similar elements in all figures and:

Figure 1 is a simplified diagram of exemplary WLANs, according to an embodiment of the inventive issue;

Figure 2 is a simplified block diagram of a WLAN station, according to an embodiment of the inventive matter;

Figure 3 illustrates an example of a timing diagram for transmitting multiple frames of PHY protocol data units (PPDUs), each with a single service data unit (SDU);

Figure 4 illustrates an example of a timing diagram for transmitting a PPDU that can contain multiple SDUs and delimiters, according to an embodiment of the inventive subject; fifty

Figure 5 is a flow chart of a procedure for a transmitter to assemble and transmit a PPDU, such as that illustrated in Figure 4, according to an embodiment of the inventive matter;

Figure 6 is a flow chart of a procedure for a receiver to receive and divide a PPDU, such as that illustrated in Figure 4, according to an embodiment of the inventive matter;

Figure 7 illustrates an example of a timing diagram for transmitting a PPDU with multiple SDUs without intermediate data according to an embodiment of the inventive subject;

Figure 8 is a flow chart of a procedure for a transmitter to assemble and transmit a PPDU, such as that illustrated in Figure 7, according to an embodiment of the inventive matter;

Figure 9 is a flow chart of a procedure for a receiver to receive and divide a PPDU, such as that illustrated in Figure 7, according to an embodiment of the inventive matter;

Figure 10 illustrates an example of a timing diagram for transmitting a burst of multiple PPDUs according to an embodiment of the inventive subject; 10

Figure 11 is a flow chart of a procedure for a transmitter for transmitting a burst of multiple PPDUs, such as those illustrated in Figure 10, according to an embodiment of the inventive matter;

Figure 12 is a flow chart of a procedure for a receiver to receive a burst of multiple PPDUs, such as those illustrated in Figure 10, according to an embodiment of the inventive matter;

Figure 13 illustrates an example of a timing diagram for transmitting a burst of multiple PPDUs with 15 intermediate preambles shortened according to an embodiment of the inventive issue;

Figure 14 is a flow chart of a procedure for a transmitter to transmit a burst of multiple PPDUs, such as those illustrated in Figure 13, according to an embodiment of the inventive matter;

Figure 15 is a flow chart of a procedure for a receiver to receive a burst of multiple PPDUs, such as those illustrated in Figure 13, according to an embodiment of the inventive matter; twenty

Figure 16 illustrates an example of a timing diagram for transmitting a burst of multiple PPDUs without intermediate preambles, according to an embodiment of the inventive subject;

Figure 17 is a flow chart of a procedure for a transmitter to transmit a burst of multiple PPDUs, such as those illustrated in Figure 16, according to an embodiment of the inventive matter; and

Figure 18 is a flow chart of a procedure for a receiver to receive a burst of multiple PPDUs, such as those illustrated in Figure 16, according to an embodiment of the inventive matter.

DETAILED DESCRIPTION

In the following description of the various embodiments, reference has been made to the accompanying drawings, which form part of the present and show, by way of illustration, specific embodiments in which the inventive matter can be put into practice. 30

The embodiments of the inventive subject include ways of transmitting multiple packets in burst mode (ie, in succession). Various embodiments will be described in detail below, after a description of a wireless local area network (WLAN) system and a WLAN device, together with Figures 1 and 2. Various embodiments can be implemented in the systems and in the devices, such as the system and the device described together with Figures 1 and 2. Various embodiments can also be implemented in other systems and 35 devices, which have different configurations.

Figure 1 is a simplified diagram of exemplary WLANs according to an embodiment of the inventive issue. A WLAN may include multiple network stations 102 and zero or more access points 104 (AP).

In a WLAN, network stations 102 communicate through free space, usually referred to as the "air interface." In general, a station 102 may be called a network adapter or a network interface card (NIC). A station 102 can be mobile, portable or stationary. For example, a station 102 may be a portable computer, a portable radio, a desktop computer, or virtually any other unidirectional or bidirectional device with the ability to communicate with other devices 102 or AP 104 by wireless means.

A set of stations 102 can communicate directly with each other, as is the case in a Basic Service Set (BSS). An independent BSS (IBSS) 110 is a BSS in which there is no connection to a wired network.

An infrastructure BSS 112 is a BSS in which the BSS includes an AP 104. In an infrastructure BSS, all stations 102 communicate with an AP 104. The AP 104 provides the connection to the wired LAN, if any, and the local relay function for the BSS. Accordingly, if a first station 102 wants to communicate with a second station 102, the first station 102 sends the communication to AP 104, and AP 104

retransmits the communication to the second station 102.

An extended service set 114 (ESS) is a set of infrastructure BSS 112, in which the APs 104 communicate with each other to send traffic from one BSS 112 to another, and to facilitate the movement of the stations 102 of a BSS to another. The distribution system (DS) is a mechanism by which an AP 104 communicates with another to exchange frames from stations 102 in its BSS 112, send frames to follow 5 mobile stations 102 from one BSS 112 to another, and exchange frames with wired networks, if any.

Embodiments of the invention will now be described in more detail. Although various embodiments are described below in detail using terms that are similar to the terms used in the context of an IEEE 802.11 Standard (eg, IEEE Std 802.11-1997, 802.11a, 802.11e, etc.), it is not intended that The invention is limited to be used in a system that uses an IEEE 802.11 Standard. Instead, the embodiments of the invention could also be used in conjunction with other WLAN standards.

Figure 2 is a simplified block diagram of a WLAN station 200 (for example, stations 102, 104, Figure 1) according to an embodiment of the inventive subject. Any WLAN station 200 that supports an IEEE 802.11 Standard includes a physical layer signaling control device (PHY) 202 (PHY device), a media access control device (MAC) 204, and a client 206 of MAC. The WLAN station 200 supports 15 station services, which are provided by the PHY device 202 and the MAC device 204, and are used by the MAC client 206. These services may include authentication, de-authentication, privacy, and data delivery.

MAC client 206 creates and processes data, among other things. The purpose of PHY and MAC devices 202, 204 is to ensure that the two network stations communicate with the correct frame format and protocol. 20 An IEEE Std 802.11 defines the communication protocol between devices 202, 204 of PHY and MAC.

The function of the PHY device 202 is threefold: 1) to provide a frame exchange between MAC 204 and PHY 202 under the control of a physical layer convergence procedure sublayer (PLCP); 2) transmit data frames through the air interface under the control of the physical medium dependent sublayer (PMD); and 3) return an indication of the carrier's direction to MAC 204, so that MAC 204 can verify activity on the air interface.

PHY device 202 implements one of several physical layer specifications, such as an infrared baseband (IR), a frequency hopping propagation spectrum (FHSS), a direct sequence propagation spectrum (DSSS), or a multiplexing by orthogonal frequency division (OFDM). Other specifications can be implemented in other embodiments. 30

In general, the PHY device 202 includes a PLCP apparatus 210, and PMD 212, 214 transmitting and receiving devices. Each of these may or may not use part of the same physical circuitry, or all of it, (for example, processors, buses, clocks, storage, etc.). In addition, one or more antennas 216 may be interconnected with PMD 212, 214 devices. When an IR baseband specification is implemented, a light emitting diode (LED) (not shown) or other optical transmission device may be used instead of the antennas 216. 35

As mentioned above, a function of the PLCP apparatus 210 is to control the exchange of frames between the MAC device 204 and the PHY device 202. The function of PMD 212, 214 devices is to control the signal carrier and the modulation and demodulation of the propagation spectrum to transmit and receive data frames through the air interface.

The structures of the PMD 212, 214 devices depend on the particular specification of the physical layer (for example, the type of modulation) implemented in the station. For example, if a DSSS is used, the transmitting PMD 212 may include an encoder, an adder, a mask filter, and a DBPSK DQPSK modulator, and the receiving PMD 214 may include a narrowing correlator, a demodulator DBPSK DQPSK, a decoder, and a synchronization clock recovery device. If an FHSS is used, the transmission PMD 212 apparatus may include a data bleach, a symbol correlator, a Gaussian filter 45, and a modulator, and the PMD 214 reception apparatus may include a demodulator, a bleacher data, and a skip sync recovery device. If IR is used, the transmitting PMD 212 may include a symbol correlator, a modulator, and an LED driver, and the receiving PMD 214 may include a diode detector, a demodulator, and a symbol correlator. If an OFDM is used, the transmission device PMD 212 may include a convolutional encoder, a bit interleaving and interleaving device, a fast reverse Fourier transform (FFT), a symbol former, and an amplitude modulation modulator in quadrature (QAM), and the receiving PMD 214 apparatus may include a PSK QAM demodulator, an FFT, a deinterleaving device and bitmap resolution, a convolutional decoder, and a clock recovery device.

Among other things, the function of MAC device 204 is to control access to the shared air interface. The MAC device 204 provides an interface between the MAC client 206 and the PHY device 202. Further,

MAC device 204 may or may not carry out an encryption and a description. In one embodiment, the MAC device supports the MAC sublayer according to an IEEE Std 802.11. In other embodiments, the MAC device supports the MAC sublayer according to another standard.

Because the air interface is often very noisy and unreliable, an IEEE Std 802.11 MAC device 204 implements a frame exchange protocol to allow the origin of the data frame to determine 5 if the frame has been received. successfully or not at the destination. The minimum MAC protocol consists of two frames: 1) a frame sent that includes a frame sent from the transmitter to the receiver; and 2) a response frame that includes an acknowledgment (ACK) from the recipient that the frame sent was received correctly. In addition, a frame sent can be one of the following: an acknowledgment (ACK), a broadcast request (RTS), a broadcast ready (CTS), or an energy saving survey. The corresponding response frames would be, respectively: a fragment; a CTS; a data frame; and an ACK.

Figure 3 illustrates an example of a timing diagram for transmitting multiple frames of PHY protocol data units (PPDUs), each carrying a single service data unit (SDU). The frames 300, 310 of PPDU represent the format of a frame as transmitted by the air interface. In one embodiment, a PPDU frame includes a preamble 302, a header 304 of the PHY, and an SDU 306. 15

The preamble 302, the header 304 of the PHY, and the SDU 306 are each transmitted at the beginning of a limit of the symbol, as indicated by the chronometric marks on the time axis 320 of Figure 3. Each symbol can have a predetermined duration, or a duration that changes in different parts of the package. For example, the duration of the symbol can be 4 microseconds, although it can also be longer or shorter. twenty

Preamble 302 includes a bit pattern, which the receiver uses to synchronize itself. Specifically, the receiver can use preamble 302 to carry out the following tasks: 1) acquisition of the beginning of the package; 2) channel estimation; 3) diversity and antenna training; 4) automatic amplification control (AGC) of the receiver; 5) carrier displacement; and 6) symbol synchronization.

In one embodiment, within the header 304 of the PHY there is a transmission rate field and a length / size field. The transmission rate field indicates what type of modulation should be used to receive the incoming SDU 306. In an alternative embodiment, the transmission rate of the incoming SDU 306 is previously determined between a transmission station and a receiving station, and therefore, the transmission rate information may not be included in header 304 of the PHY.

The length / size field indicates the length of the SDU 306. In various embodiments, the 30 length / size field may include a number of microseconds necessary to transmit the SDU 306, a number of bytes in the SDU 306, or some other value indicating the length of the SDU 306. The header 304 of the PHY may also include a checksum or other field, which allow its contents to be validated. The head 304 of the PHY could have a fixed or variable length.

SDU 306 is a series of fields that is assembled by MAC 204 (Figure 2) and is passed to PHY 202 35 by means of a PLCP 210. As regards PHY 202, SDU 306 includes “data opaque ”, which means that PHY 202 does not know or care what data is included in SDU 306.

The SDU 306 can be of a variable length. The MAC device 204 may use an SDU frame to transport its MAC protocol data unit (MPDU), which may include an MPDU header, a frame body field, and a frame check sequence field (FCS). The body field of the frame 40 has a variable length, and its contents may be encrypted or not. This field can contain a whole MAC service data unit (MSDU) or a protocol service data unit (PSDU), or part thereof, from higher layer protocols.

Different modulation transmission rates can be used to transmit the preamble 302, the header 304 of the PHY, and the SDU 306. The preamble 302 and the header 304 of the PHY are transmitted at a first rate of transmission, referred to in the present document a “robust modulation rate”. The robust modulation rate can be in a range of about 6 megabits per second (Mbps) up to 12 Mbps, in one embodiment, although higher or lower transmission rates can be used in other embodiments. In one embodiment, the robust modulation rate does not change. When the robust modulation rate does not change, a receiver knows that he needs to look for a preamble 302 and a PHY header 304 at the known robust modulation rate 50. In another embodiment, the robust modulation rate may change. In yet another embodiment, the preamble 302 and the header 304 of the PHY are transmitted at different modulation rates.

Instead, SDU 306 is transmitted at a second transmission rate, referred to herein as "data modulation rate." For illustrative purposes, SDU 306 is networked, indicating that it is transmitted at the data modulation rate, as opposed to the robust modulation rate. 55

The data modulation rate may vary from frame to frame. In one embodiment, the transmission rate varies in a range between about 6 to 240 Mbps. In one embodiment, a receiver determines the data modulation rate for a particular SDU by evaluating the transmission rate field of header 304 of PHY, as described above.

Lower modulation rates may be more robust, which means that data can tolerate 5 worse channel conditions. The preamble 302 and the header 304 of the PHY are sent at the lower modulation rate, so that the data within the header 304 of the PHY is less likely to be corrupted, although corruption is possible given sufficient signal strength of interference If the data were corrupted within the transmission rate field of the PHY header 304, for example, the receiver could not demodulate the SDU 306. If the data were corrupted within the header size field 304 of the 10 PHY , the receiver would either truncate the SDU 306 or extend the SDU 306, causing the receiver to demolish invalid data after the termination of the SDU 306.

The data modulation rate for SDU 306 can be chosen based on an estimate of the channel conditions. If the channel is excellent, then a high transmission rate (for example, approximately 240 Mbps) can be selected, thereby increasing system performance. If the channel is very noisy, then a relatively low transmission rate (for example, approximately 6 Mbps) can be selected, so that data integrity can be maintained as well as possible.

Each packet is completely “self-descriptive”, which means that the receiver does not need a priori information about the structure (that is, the size and / or the data rate) of the next packet. Each package is completely self-descriptive, which means that each package includes both the modulation rate of 20 data, in the 304 header of the PHY, as well as the length / size information. Length / size information is included in the SDU itself.

In another embodiment, which is not part of the invention, each packet is partially self-descriptive, which means that each packet includes length / size information, but the data modulation rate can be defined between the transmitting station and the station. of reception in a previous training exchange. 25 Consequently, the data modulation rate is not necessarily included in header 304 of the PHY.

This "self-descriptive" feature differentiates the embodiments of the invention from other protocols, such as the Hiperlan 2 protocol, for example. When using the Hiperlan 2 protocol, the transmitter emits a known block of data every 2 milliseconds. The data block includes a complete correspondence of everything that the transmitter will transmit during the rest of the next 2 millisecond time period. This means that all receivers 30 have a priori information about the modulation rates and lengths of the packets that the transmitter will send. Modulation and length information is not included in each package, using Hiperlan 2, and therefore, the packages are not "self-descriptive".

As mentioned above, prior art systems support a "burst mode" transmission of PPDU frames with a selective acknowledgment using the "block ACK" feature. The block ACK feature allows the transmitter to send the next PPDU frame to the same receiver without necessarily waiting for an ACK. Instead, after negotiating access to the air interface, the transmitter sends the same PPDU frame, expects a Frame Between Frames (IFS) after the end of the first packet, and sends the next PPDU frame.

It is intended that the term "IFS", as used herein, include various related periods of time, including but not limited to the IFS, a short IFS (SIFS), a priority IFS (PIFS), a distributed IFS (DIFS), and an extended IFS (EIFS), as defined in an IEEE 802.11 Standard, although the term IFS is not intended to be limited to periods of time defined only in that standard. The IFS can consume multiple symbol limits. Figure 3 illustrates a second PPDU 310 that is transmitted after a gap 312 of symbols of four or more symbols, which may represent an IFS. An IFS can be an integer or non-integer number of symbol widths. In addition, the duration of the IFS can be greater or less than four symbols.

Using the block ACK feature, after the transmitter has sent all its PPDU frames to the receiver, the transmitter requests a response from the receiver, which indicates an ACK for all previously transmitted frames. Using prior art procedures, each PPDU frame includes a single SDU, and essentially each PPDU frame is formatted as described in conjunction with Figure 3.

According to various embodiments of the inventive matter, a single PPDU frame includes one or more concatenated opaque SDUs, in which the SDU (s) in this document is referred to as the "payload." In one embodiment, each SDU includes a "delimiter", which indicates the size of the SDU, and the header of the PHY may include a length field that includes the full length of the concatenated SDUs. In another embodiment that is not part of the invention, the PHY header contains length information for each SDU, allowing the

receiver assemble and re-divide the payload into different SDUs.

In yet another embodiment, each PPDU frame includes a single SDU. However, during burst mode, multiple PPDU frames concatenate each other, instead of waiting for the IFS between each frame. In yet another embodiment, multiple PPDU frames are concatenated with each other, but a shortened preamble is included with each PPDU frame after the first frame. In yet another embodiment, multiple PPDU frames are concatenated, 5 but the preamble for each PPDU frame after the first frame is removed. Various embodiments will now be described together with Figures 4-18.

Figure 4 illustrates an example of a timing diagram for transmitting a PPDU that can contain multiple SDUs and delimiters, according to an embodiment of the inventive subject. The PPDU 400 includes a preamble 402, a header 404 of the PHY, and a consolidated payload 406 with at least one SDU 420, 422, 424. In the illustrated example 10, the consolidated payload 406 includes three SDUs. More or less SDUs can be included in a single payload.

Preamble 402 includes a bit pattern, which is used by the receiver to synchronize itself, as described above. The 404 header of the PHY includes a transmission rate field that indicates which data modulation rate is used for the consolidated payload 406. In one embodiment, the header 404 of the 15 PHY also includes a length / size field that may include a number of microseconds necessary to transmit the consolidated payload 406, a number of bytes in the consolidated payload 406, or some other value indicating the length of the consolidated payload 406. In another embodiment, the header 404 of the PHY does not include the total length information. The 404 header of the PHY could have a fixed or variable length.

The PHY in the receiver must separate and supply intact each SDU 420, 422, 424. To facilitate the decomposition of the consolidated payload 406 into individual SDUs, the consolidated payload also includes information indicating the lengths of each of the multiple SDU The information includes multiple "delimiters" 408, 410, 412, each SDU being preceded by a delimiter.

Each delimiter includes a length field, which indicates the variable length 430, 432, 434 of the SDU 420, 422, 424, respectively, which follows. If the next SDU is not the last SDU in consolidated payload 406, the delimiter information also allows a receiver to determine where the delimiter of the next SDU should be located.

In one embodiment, each delimiter 408, 410, 412 also includes a length validation field, which allows a receiver to determine whether or not the length field has been corrupted, as described in more detail below. In one embodiment, the length validation field includes a checksum 30 or CRC, although other validation information may be used in other embodiments. The length validation field allows robust error detection, as will be described in detail together with Figures 5 and 6.

In addition, in one embodiment, each delimiter 408, 410, 412 may also include a sequence field, indicating that the SDU 420, 422, 424, respectively, that follows is either the last SDU or not the last SDU. In other embodiments, the delimiter may not include the sequence field. 35

In an embodiment described above, there is a one-to-one correlation between delimiters and SDUs. In another embodiment, there may be no one-to-one correlation between delimiters and SDUs. Instead, a smaller number of delimiters can be transmitted than the SDU number. For example, a single delimiter can be transmitted, which indicates the lengths of all SDUs.

Figure 5 is a flow chart of a procedure for a transmitter to assemble and transmit a PPDU, such as that illustrated in Figure 4, according to an embodiment of the inventive matter. The procedure begins, in block 502, when the PHY device obtains at least one SDU. In one embodiment, the SDUs have the same intermediate or final destination as the same receiver, although it is possible that the SDUs have different destinations.

In block 504, the lengths of each SDU and the length validation data are determined. For example, in one embodiment, the length of the SDU is represented by two bytes, and the length validation field 45 includes a checksum or CRC for the two byte length field. Consequently, the length validation field can also be two bytes. In other embodiments, the length and / or length validation fields may be greater or less.

The delimiters for each SDU are assembled, in one embodiment, in block 506. Each delimiter includes the length field, the length validation field, and a sequence field, indicating whether the 50 SDU is the last or no. In other embodiments, the length validation field, the sequence field, or both can be excluded from the delimiter.

In one embodiment, the total length of the consolidated payload, in block 508, is determined to be included in the PHY header. The total length includes the lengths of each of the delimiters, in addition to the lengths of each of the SDUs. The total length allows the receiver to determine when the 55 should occur

end of consolidated payload. In another embodiment, the total length is not included in the PHY header. For example, in another embodiment, the receiver may instead depend on the delimiter sequence field to predict the end of the consolidated payload. As will be explained in more detail below, if a delimiter is corrupted, the receiver can measure the energy of the symbol to determine if the end of the consolidated payload has been reached. 5

After negotiating access to the air interface, the transmitter transmits the preamble and the PHY header over the air at the robust modulation rate, in block 510. In one embodiment, the transmitter begins transmitting each of the preamble and from the PHY header at the beginning of a symbol boundary. In one embodiment, the preamble for two symbols is transmitted, and the PHY header for a symbol is transmitted. In other embodiments, either the preamble or the PHY header may be transmitted for longer periods or short periods of time.

When the transmission of the PHY header is completed, the transmitter goes to the data modulation rate, in block 512, which will be used to transmit the consolidated payload. The transmitter begins transmitting the first delimiter, in block 514. In one embodiment, the transmitter begins transmitting the first delimiter at the beginning of the next limit of the symbol after the termination of the PHY header. Alternatively, the first delimiter can start at a time other than a symbol limit. In other words, transmission can begin before or after a limit of the symbol. In one embodiment, the transmitter begins transmitting the consolidated payload within a symbol width of the end of the PHY header. An internal block fill can be included at the end of each SDU.

In one embodiment, the delimiter may take less than one symbol to complete, and the transmitter may begin transmitting the SDU in the last part of the same symbol as the delimiter. In another embodiment, the transmitter begins transmitting the SDU at the next limit of the symbol after the termination of the delimiter transmission. An internal block fill can be included at the end of each SDU.

In block 516, a determination is made as to whether more delimiters and SDUs remain to be transmitted. In another embodiment, this determination can be excluded. If more delimiters and SDU remain to be transmitted, the transmitter begins transmitting the next delimiter and its associated SDU, in block 514.

In one embodiment, the transmitter begins transmitting the next delimiter immediately after the termination of the transmission of the previous SDU, whether or not that moment occurs within a limit of the symbol. In addition, the transmitter begins transmitting the associated SDU immediately upon termination of the delimiter transmission. Consequently, in this embodiment, all the data in the consolidated payload 30 is effectively concatenated to each other. In other embodiments, there may be gaps or fill data between subsequent delimiters and / or SDUs. After transmitting the last SDU, the procedure ends.

Figure 6 is a flow chart of a procedure for a receiver to receive and divide a PPDU, such as that illustrated in Figure 4, according to an embodiment of the inventive matter. The procedure begins, in block 602, when the receiver detects an incoming preamble at the robust modulation rate. The receiver uses the preamble to synchronize with the incoming PPDU frame, in block 604.

In one embodiment, the receiver determines the modulation rate of the consolidated payload of the PPDUs from the header of the PHY, in block 606. In an alternative embodiment, the data modulation rate during an exchange can be determined. previous training.

In one embodiment, the receiver also determines the full length of the consolidated payload from the head of the PHY. This allows the receiver to know for how long it should demodulate incoming data at the data modulation rate. In another embodiment, the receiver uses the length and sequence fields in the delimiters to carry out this determination, and the total length is not necessarily provided in the PHY header. Once the PHY header has been completed, the receiver will demodulate the data modulation rate, in block 608, to receive and demodulate the consolidated payload. Four. Five

In one embodiment, the first thing that occurs in the consolidated payload is a delimiter. Therefore, in block 610, the receiver receives and attempts to validate a segment of data that is the size of a delimiter. In one embodiment, if included, the size of the delimiter is the size of the length field (for example, two bytes), in addition to the size of the length validation field (for example, two bytes), in addition to the size of the length sequence field (for example, one byte). In other embodiments, the absolute or relative sizes of the various 50 fields of the delimiters may be different.

The validation is carried out by determining if the length validation field correlates with the data in the length field. In one embodiment, the length validation field includes a checksum or CRC, which allows the receiver to determine whether the length data is corrupted or uncorrupted. 55

A determination is made, in block 612, of whether the delimiter size data segment includes what appears to be a valid delimiter. If so, then, in block 614, the receiver receives and stores an amount of SDU data with a length as indicated in the delimiter length field, and the procedure proceeds to block 622, which will be described below.

If the delimiter size segment does not include what appears to be a valid delimiter, then receiver 5 goes into a delimiter search mode, indicated by blocks 616, 618 and 620. In this mode, the receiver determines if it can having reached the end of the payload, in block 616. In various embodiments, the end of the payload can be determined if a delimiter is not detected in an amount of time, or if a known endpoint has been reached, or if the energy of the symbol falls below a threshold. If the end of the payload has been reached, the procedure ends. 10

If the end of the payload has not been reached, then the receiver receives and evaluates each subsequent segment of delimiter size data, in block 618. Subsequent segments may be overlapping or sequential.

In block 620, a determination is made as to whether the next segment of delimiter size data appears to be a possible delimiter by validating what the length field may be with what may be the validation field of the length. If the delimiter size data segment does not appear to be a possible delimiter, then the procedure is repeated, while storing the received data as a potential SDU. When a possible delimiter is detected, the receiver suspends the delimiter search mode.

In block 622, a determination is made as to whether or not the end of the consolidated payload has been reached. In one embodiment, the receiver knows that it has reached the end of the consolidated payload if it has received an amount of data that corresponds to the field of the total length provided in the PHY header. In another embodiment, the receiver knows that it has reached the end of the consolidated payload if it has received an amount of data indicated in the last delimiter as the length of the last SDU. In one embodiment, the receiver knows whether an SDU is the last SDU or not of the consolidated payload when evaluating the delimiter sequence field of the last SDU. In other embodiments, the field of the total length in the header of the PHY, the sequence field in the delimiter, or both can be excluded, and another way of determining the end of the consolidated payload can be used. For example, the receiver can measure the energy of the symbol to determine if the end of the consolidated payload has been reached.

If the end of the consolidated payload has not yet been reached, the procedure is repeated as shown. Specifically, the receiver evaluates the next segment of delimiter size data, in block 610, and the procedure is repeated.

If the end of the consolidated payload has been reached, the receiver supplies the various SDUs that it has analyzed in the consolidated payload, in block 624, and the procedure ends. In another embodiment, the receiver can supply each SDU while receiving the SDU, or in parallel with the reception of other SDUs.

The embodiments described above in conjunction with Figures 4-6 provide a high throughput method in burst mode with robust error detection and recovery. The performance of prior art procedures is improved by eliminating the IFS between SDUs, as well as eliminating intermediate preambles and PHY headers associated with SDUs that occur after the first SDU.

The length validation field allows robust error detection and recovery.

First, the length validation field allows the receiver to determine if the length field 40 is corrupted in the delimiter. If the receiver determines that the length field is corrupted, the receiver can consider each byte that follows, to try to find a segment of data that appears to be a delimiter. If the receiver finds a segment of data that appears to be a delimiter, the receiver assumes that the data represents a delimiter, and the receiver is synchronized again to receive the next SDU.

In one embodiment, the probability is very remote that the receiver finds a segment of data that appears to be a delimiter, but is not. In one embodiment that includes a 2-byte CRC, the probability of incorrectly detecting a delimiter is approximately 1 in 65,000. Even if this happens, the receiver will detect an error again when it does not find a valid delimiter at the end of the supposed SDU. And again, the receiver will look for a segment of data that appears to be a delimiter. Therefore, even if one delimiter is corrupted, and another segment of data coincidentally resembles a delimiter, the receiver will end up recovering when it finds a valid delimiter. Consequently, this embodiment provides a robust error detection and recovery procedure.

In another embodiment, which is not part of the invention, the delimiter includes only one length field, and the length validation field is excluded. This embodiment works well when the channel is robust, and it is very unlikely that the field of the delimiter length is corrupted. If the data is more likely in 55

Length field are corrupted, so the absence of a length validation field can make it more difficult for the receiver to recover from an error in the length validation field. The receiver can search for a next delimiter based on the corrupted length, and would probably only find random data there, which would make it even more difficult for the receiver to recover from erroneous data.

In an embodiment described in conjunction with Figures 6-8, the delimiter is transmitted at the modulation rate of 5 data. Although this may increase the likelihood of the field of the delimiter length being corrupted, the field of validation of the length of the delimiter allows robust error detection and recovery.

In another embodiment, which is not part of the invention, described in conjunction with Figures 7-9, the PPDU frame may include multiple SDUs, but the length of each SDU is included in the header of the PHY, and therefore , is transmitted at the robust modulation rate. In this embodiment, the probability that the SDU 10 length fields are corrupted is less than it would be if the lengths were transmitted at the data modulation rate.

Figure 7 illustrates an example of a timing diagram for transmitting a PPDU with multiple SDUs without intermediate data according to an embodiment of the inventive subject. The PPDU 700 includes a preamble 702, a header 704 of the PHY, and a consolidated payload with at least one SDU 706, 716, 726. In the illustrated example, the consolidated payload includes three SDUs. More or less SDUs can be included in a single consolidated payload. fifteen

Preamble 702 includes a bit pattern, which the receiver uses to synchronize, as described above. Header 704 of the PHY includes a transmission rate field, which indicates what data modulation rate is used for the consolidated payload. The header 704 of the PHY could have a fixed or variable length.

The PHY at the receiver must separate and supply intact each SDU 706, 716, 726. In one embodiment, to facilitate the decomposition of the consolidated payload into individual SDUs, the header 704 of the PHY also includes a length / size field associated with each SDU 706, 716, 726 included in the consolidated payload.

In one embodiment, each length / size field indicates the length of its associated SDUs. In another embodiment, the length / size field defines the aggregate length of the associated SDU and any preceding SDU within the consolidated payload. Therefore, the length of SDU 706 would be represented as the length 730 of SDU 25 706. The length of SDU 716 would be represented as the aggregate length 732 of SDU 706 and 716. Finally, the length of SDU 726 would be represented as the aggregate length 734 of SDU 706, 716, and 726. In various embodiments, the length / size field may include a number of microseconds, a number of bytes, or some other value indicating the length.

The values ​​in the length / size fields allow the receiver to determine where one SDU ends, and another begins. Consequently, in yet another embodiment, the length / size field may include, instead, a "shift" value, which indicates the magnitude of a shift in the consolidated payload when the next SDU begins. (or when the end of a previous SDU occurs).

Figure 8 is a flow chart of a procedure for a transmitter to assemble and transmit a PPDU, such as that illustrated in Figure 7, according to an embodiment of the inventive subject. The procedure begins, in block 802 when the PHY device obtains at least one SDU. In one embodiment, the SDUs have the same intermediate or final destination as the same receiver, although it is possible that the SDUs have different destinations.

In block 804, the lengths (or displacements) associated with each SDU are determined. The lengths can be the individual length of each SDU, or the aggregate length of each SDU within the consolidated payload. For example, in one embodiment, the length of the SDU is represented by two bytes. In another 40 embodiments, the length field may be greater or less. In other additional embodiments, a offset value can be used to allow a determination of the end of an SDU and the beginning of a next SDU, instead of using a length value.

Each of the lengths or displacements is included in the PHY header. Consequently, if the consolidated payload includes three SDUs, the PHY header would include at least three length fields. In one embodiment, the PHY header has a fixed size, which limits the number of SDUs that can be described by the PHY header. In another embodiment, the PHY header has a variable size. In such an embodiment, the PHY header may include information that allows a determination of how many SDUs the PHY header describes and / or the length of the PHY header.

After negotiating access to the air interface, the transmitter transmits the preamble and the head of the PHY 50 over the air at the robust modulation rate, in block 806. In one embodiment, the transmitter begins transmitting each of the Preamble and header of the PHY at the beginning of a limit of the symbol. In one embodiment, the preamble for two symbols is transmitted, and the PHY header for a symbol is transmitted. In other embodiments, either the preamble or the PHY header may be transmitted for longer or shorter periods of time. 55

When the transmission of the PHY header has been completed, the transmitter goes to the data modulation rate, in block 808. The transmitter begins transmitting the first SDU, in block 810. In one embodiment, the transmitter begins to transmit the first SDU at the beginning of the next limit of the symbol after the termination of the PHY header. Alternatively, the first SDU may start at a time other than a symbol limit. In other words, the transmission can begin before or after a limit of the 5 symbol. In one embodiment, the transmitter begins transmitting the consolidated payload within a symbol width of the end of the PHY header. An internal block fill can be included at the end of each SDU.

In block 812, a determination is made as to whether more SDUs remain to be transmitted or not. If more SDUs remain to be transmitted, the transmitter begins transmitting the next SDU, in block 810. In one embodiment, the transmitter begins transmitting the next SDU immediately upon termination of the transmission of the previous 10 SDU, whether or not such occurs. position within the payload at a limit of the symbol. Consequently, in this embodiment, all the data within the consolidated payload is effectively concatenated to each other. In other embodiments, gaps or fill data may exist between subsequent SDUs. After transmitting the last SDU, the procedure ends.

Figure 9 is a flow chart of a procedure for a receiver to receive and divide a PPDU, such as that illustrated in Figure 7, according to an embodiment of the inventive matter. The procedure begins, in block 902, when the receiver detects an incoming preamble at the robust modulation rate. The receiver uses the preamble to synchronize with the incoming PPDU frame, in block 904.

The receiver determines the modulation rate of the consolidated payload of the PPDU from the head of the PHY, in block 906. In an alternative embodiment, which is not part of the invention, the modulation rate 20 can be determined of data in a previous training exchange.

In one embodiment, which is not part of the invention, the receiver also determines the lengths or displacements associated with each SDU in the consolidated payload from the PHY header. This allows the receiver to know where SDU limits occur, and for how long it should demodulate incoming data at the data modulation rate. Once the reception of the PHY header has been completed, the receiver starts demodulating the data modulation rate, in block 908.

In block 910, the receiver receives and stores an amount of SDU data with a length as indicated in the associated length field for the SDU in the PHY header. In block 912, a determination is made as to whether the end of the consolidated payload has been reached. In one embodiment, the receiver knows that it has reached the end of the consolidated payload if it has received an amount of data that corresponds to field 30 of the length for the last SDU provided in the PHY header, indicate that field of length the length of the last SDU separately, or indicate that length field the aggregate length. In an alternative embodiment, the receiver can determine that the end of the payload has been reached using a measurement of the symbol's energy.

If the end of the consolidated payload has not yet been reached, the procedure is repeated as shown. Specifically, the receiver receives and stores the following SDU, in block 910, and the procedure is repeated.

If the end of the consolidated payload has been reached, in block 914, the receiver supplies the various SDUs that it has analyzed in the consolidated payload, and the procedure ends. In another embodiment, the receiver can supply each SDU while receiving the SDU, or in parallel with the reception of other SDUs.

In the embodiments described in conjunction with Figures 7-9, no preamble or any PHY header 40 is transmitted between SDUs. Consequently, it is not necessary for the receiver to pass in one way or another between the data modulation rate and the robust modulation rate while the receiver receives the consolidated payload. In another embodiment, illustrated in conjunction with Figures 10-12, a preamble and a PHY header are transmitted for each SDU. However, the transmitter does not wait for the IFS before transmitting subsequent PPDU frames whose intermediate or final destination is the same receiver. Instead, the transmitter starts transmitting the next PPDU frame at the next symbol limit after the termination of an earlier frame.

Figure 10 illustrates an example of a timing diagram for transmitting multiple PPDUs according to an embodiment of the inventive issue. Each PPDU 1000, 1010, 1020 includes a preamble 1002, 1012, 1022, a header 1004, 1014, 1024 of the PHY, and an SDU 1006, 1016, 1026. In the illustrated example, three concatenated PPDUs are shown. More or less PPDUs can be sent according to the embodiments described together with Figures 10-12. fifty

Each preamble 1002, 1012, 1022 includes a bit pattern, which is used by the receiver to synchronize, as described above. Each header 1004, 1014, 1024 of the PHY includes a transmission rate field, which indicates which modulation rate is used for the payload. The data modulation rate may or may not be the same for each payload. In addition, each header 1004, 1014, 1024 of the PHY includes a length / size field for the SDU 1006, 1016, 1026 that follows. The lengths of the payloads may be the same 55 or not. In one embodiment, each length / size field indicates the length of its associated SDU. In various

embodiments, the length / size field may include a number of microseconds, a number of bytes, or some other value indicating the length. The header 1004 of the PHY could have a fixed or variable length.

Figure 11 is a flow chart of a procedure for a transmitter for transmitting a burst of multiple PPDUs, such as those illustrated in Figure 10, according to an embodiment of the inventive subject. The procedure begins, in block 1102 when the PHY device obtains at least one SDU. In one embodiment, the SDUs have the same receiver as intermediate or final destination, although it is possible that the SDUs have different destinations.

In block 1104, the length associated with the next SDU to be transmitted is determined. For example, in one embodiment, the length of the SDU is represented by two bytes. In other embodiments, the length field may be greater or less. The length is included in the PHY header for that SDU. 10

After negotiating access to the air interface, the transmitter transmits the preamble and header of the PHY to the SDU over the air at the robust modulation rate, in block 1106. In one embodiment, the transmitter begins transmitting each one of the preamble and the header of the PHY at the beginning of a limit of the symbol. In one embodiment, the preamble for two symbols is transmitted, and the PHY header for a symbol is transmitted. In other embodiments, either the preamble or the PHY header may be transmitted for longer or shorter periods of time.

When the transmission of the PHY header is completed, the transmitter goes to the data modulation rate, in block 1108. In block 1110, the transmitter starts transmitting the first SDU. In one embodiment, the transmitter begins transmitting the first SDU at the beginning of the next limit of the symbol after the termination of the PHY header. Alternatively, the first SDU may start at a time 20 other than a symbol limit. In other words, transmission can begin before or after a limit of the symbol. Although not illustrated in Figure 11, only the last symbol in which an SDU is transmitted can only be partially used. In such a case, there may be a gap between the end of the SDU and the beginning of the next limit of the symbol. In addition, a padding of the internal block can be included at the end of each SDU.

In block 1112, a determination is made as to whether more SDUs remain to be transmitted. If there are still 25 more SDUs transmitted, then the procedure is repeated as shown. Specifically, the transmitter prepares and transmits the preamble, the PHY header, and the following SDU.

In one embodiment, the transmitter begins transmitting the preamble for the next PPDU at the beginning of the next symbol limit after the termination of the previous SDU. Alternatively, the following PPDU may start at a time other than a symbol limit. In other words, the transmission can begin 30 before or after a symbol limit. After transmitting the last SDU, the procedure ends.

Figure 12 is a flow chart of a procedure for a receiver to receive a burst of multiple PPDUs, such as those illustrated in Figure 10, according to an embodiment of the inventive matter. The procedure begins, in block 1202, when the receiver detects an incoming preamble at the robust modulation rate. The receiver uses the preamble to synchronize with the incoming PPDU frame, in block 1204. 35

In one embodiment, the receiver determines the modulation rate of the PPDU payload from the PHY header, in block 1206. In another embodiment, the data modulation rate can be determined during a previous exchange of training.

In one embodiment, the receiver also determines the length of the associated SDU from the PHY header. Once the reception of the PHY header has been completed, the receiver starts demodulating at the rate of 40 data modulation, in block 1208.

In block 1210, the receiver receives and stores an amount of SDU data with a length as indicated in the associated length field for the SDU in the PHY header. In an alternative embodiment, the receiver can determine that the end of the payload has been reached using a measurement of the symbol's energy.

When the end of the SDU has been reached, in block 1212, the receiver supplies the SDU. In another embodiment, the receiver can begin supplying the SDU while the SDU is being received. Then, the procedure is repeated as shown, when the receiver tries to detect a preamble at the robust modulation rate, in block 1202.

In the embodiments described together with Figures 10-12, a full-length preamble and a PHY header are transmitted between SDUs. In another embodiment, illustrated in conjunction with Figures 13-15, a full-length preamble is transmitted for the first PPDU frame, and partial preambles are transmitted for subsequent PPDU frames.

Figure 13 illustrates an example of a timing diagram for transmitting a burst of multiple PPDUs with shortened intermediate preambles according to an embodiment of the inventive issue. In one embodiment, the first PPDU

1300 includes a full length preamble 1302, and subsequent PPDUs 1310, 1320 in the burst include partial preambles 1312, 1322.

The full length preamble 1302 includes a bit pattern, which is used by the receiver to synchronize. Specifically, the receiver can use preamble 1302 to carry out the following tasks: 1) acquisition of the beginning of the package; 2) channel estimation; 3) diversity and antenna training; 4) 5 automatic amplification control (AGC) of the receiver; 5) carrier displacement; and 6) symbol synchronization. In one embodiment, all these tasks can be carried out once at the beginning of the burst, except in the acquisition of the beginning of the package. For subsequent PPDUs after the first PPDU of the burst, a partial preamble 1312, 1322 is transmitted. The receiver can use partial preamble 1312, 1322 to carry out a task of acquiring the start of the packet. 10

In one embodiment, each PPDU 1300, 1310, 1320 also includes a header 1304, 1314, 1324 of the PHY, and an SDU 1306, 1316, 1326. Each header 1304, 1314, 1324 of the PHY includes a transmission rate field , in one embodiment, which indicates what data modulation rate is used for the payload. In another embodiment, the data modulation rate could be determined during a training exchange.

In addition, each header 1304, 1314, 1324 of the PHY includes a length / size field for SDU 1306, 15 1316, 1326 that follows. In one embodiment, each length / size field indicates the length of its associated SDU. In various embodiments, the length / size field may include a number of microseconds, a number of bytes, or some other value indicating the length. In the illustrated example, three concatenated PPDUs are shown. More or less PPDUs can be sent according to the embodiments described together with Figures 13-15. The head 1304 of the PHY could have a fixed or variable length. twenty

Figure 14 is a flow chart of a procedure for a transmitter for transmitting a burst of multiple PPDUs, such as those illustrated in Figure 13, according to an embodiment of the inventive subject. The procedure begins, in block 1402 when the PHY device obtains at least one SDU. In one embodiment, the SDUs have the same intermediate or final destination as the same receiver, although it is possible that the SDUs have different destinations. 25

In block 1404, the length associated with the next SDU to be transmitted is determined. For example, in one embodiment, the length of the SDU is represented by two bytes. In other embodiments, the length field may be greater or less. The length is included in the PHY header for that SDU.

After negotiating access to the air interface, the transmitter transmits a full length preamble and the PHY header for the SDU over the air at the robust modulation rate, in block 1406. In one embodiment, the transmitter starts transmitting each of the full length preamble and the PHY header at the beginning of a symbol boundary. In one embodiment, the full length preamble is transmitted for two symbols, and the PHY header for a symbol is transmitted. In other embodiments, either the full length preamble or the PHY header may be transmitted for longer or shorter periods of time. 35

When the transmission of the PHY header has been completed, the transmitter goes to the data modulation rate, in block 1408. In block 1410, the transmitter starts transmitting the first SDU. In one embodiment, the transmitter begins transmitting the first SDU at the beginning of the next limit of the symbol after the termination of the PHY header. Alternatively, the first SDU may start at a time other than a symbol limit. In other words, the transmission can begin before or after a limit of 40 symbol. Although not illustrated in Figure 14, only the last symbol in which an SDU is transmitted can only be partially used. In such a case, there may be a gap between the end of the SDU and the beginning of the next limit of the symbol. In addition, a padding of the internal block can be included at the end of each SDU.

In block 1412, the transmitter returns to the robust modulation rate, so that it will be ready to transmit the next preamble. In block 1414, a determination is made as to whether or not more SDUs remain to be transmitted. In another embodiment, this determination can be excluded. If more SDUs remain to be transmitted, the transmitter determines the length of the next SDU to be transmitted, in block 1416.

The transmitter begins transmitting a partial preamble and the PHY header for the SDU over the air at the robust modulation rate, in block 1418. In one embodiment, the partial preamble for a symbol is transmitted, and the header is transmitted of the PHY for a symbol. In other embodiments, either the partial preamble or the PHY header may be transmitted for longer or shorter periods of time. In one embodiment, the transmitter begins transmitting the partial preamble to the next PPDU at the beginning of the next symbol limit after the termination of the previous SDU. Alternatively, the following PPDU may start at a time other than a symbol limit. In other words, transmission can begin before or after a limit of the symbol. 55

After transmitting the partial preamble and the PHY header, the procedure is repeated as shown.

Specifically, the transmitter returns to the data modulation rate and transmits the following SDU. The procedure ends after all SDUs have been transmitted in the burst.

Figure 15 is a flow chart of a procedure for a receiver to receive a burst of multiple PPDUs, such as those illustrated in Figure 13, according to an embodiment of the inventive matter. The procedure begins, in block 1502, when the receiver detects a full length incoming preamble at the robust 5 modulation rate. The receiver uses the preamble to fully synchronize with the incoming PPDU frame, in block 1504. As described above, full synchronization includes the tasks of: 1) acquisition of the start of the package; 2) channel estimation; 3) diversity and antenna training; 4) automatic amplification control (AGC) of the receiver; 5) carrier displacement; and 6) symbol synchronization. In other embodiments, more, less or different tasks may be performed during a full synchronization. 10

In one embodiment, the receiver determines the modulation rate of the PPDU payload from the head of the PHY, in block 1506. In another embodiment, which is not part of the invention, the rate of data modulation during a previous training exchange.

In one embodiment, the receiver also determines the length of the associated SDU from the PHY header. Once the reception of the PHY header has been completed, the receiver starts demodulating at the rate of data modulation, in block 1508.

In block 1510, the receiver receives and stores an amount of SDU data with a length as indicated in the associated length field for the SDU in the PHY header. In an alternative embodiment, the receiver can determine that the end of the payload has been reached using a measurement of the symbol's energy.

When the end of the SDU has been reached, the receiver returns to the robust modulation rate, in block 1512, so that it will be ready to receive the next incoming preamble. In addition, in block 1514, the receiver supplies the SDU. In another embodiment, the receiver can begin supplying the SDU while the SDU is being received.

After the reception of the first SDU has been completed, the receiver determines whether a partial preamble is detected, in block 1516. If no partial preamble is detected in an amount of time, the receiver may assume that it has been completed. the blast, and the procedure ends.

If a partial preamble is detected, the receiver uses the partial preamble to carry out a partial synchronization procedure, in block 1518. In one embodiment, this involves carrying out at least the task of acquiring the start of the package. Because it is not necessary to repeat at least one of the synchronization tasks performed above, it will take significantly less time for the receiver to synchronize with the incoming PPDU, and the partial preamble may be significantly shorter than the full length preamble. In other embodiments, the receiver may use the partial preamble to perform more or different tasks. After partially synchronizing itself, in block 1518, the procedure is repeated as shown. Specifically, the receiver receives and processes the PHY header and SDU for the PPDU associated with the partial preamble. 35

In the embodiments described together with Figures 13-15, a partial preamble and a PHY header are transmitted between SDUs. In another embodiment, illustrated in conjunction with Figures 16-18, only one PHY header is transmitted between SDUs, and intermediate preambles are excluded. Although a preamble is useful for carrying out the task of acquiring the beginning of the package, it is possible to acquire the beginning of a package even after the loss of structural information when entering a PHY header search mode, which will be described. in more detail along with Figure 18, in one embodiment. Consequently, synchronization, error detection, and acceptable error recovery may be possible even without intermediate preambles between SDUs.

Figure 16 illustrates an example of a timing diagram for transmitting a burst of multiple PPDUs without intermediate preambles, according to an embodiment of the inventive issue. The first PPDU 1600 includes a preamble 1602. The preamble 1602 includes a bit pattern, which is used by the receiver to synchronize itself. In one embodiment, subsequent PPDUs 1610, 1620 in the burst do not include preambles.

In one embodiment, each PPDU 1600, 1610, 1620 includes a header of the PHY 1604, 1614, 1624, and an SDU 1606, 1616, 1626. Each header 1604, 1614, 1624 of the PHY includes a transmission rate field, In one embodiment, it indicates what data modulation rate is used for the payload. In another embodiment, the data modulation rate can be determined during a training exchange. fifty

In addition, each header 1604, 1614, 1624 of the PHY includes a length / size field for the SDU 1606, 1616, 1626 that follows. In one embodiment, each length / size field indicates the length of its associated SDU. Consequently, the length / size field allows the receiver to determine when the end of the SDU will occur, and to predict when the next PHY header should start in the burst. In various embodiments, the length / size field may include a number of microseconds, a number of 55

bytes, or some other value that indicates the length. In the illustrated example, three concatenated PPDUs are shown. More or less PPDUs can be sent according to the embodiments described together with Figures 16-18. The header 1604 of the PHY could have a fixed or variable length.

Figure 17 is a flow chart of a procedure for a transmitter to transmit a burst of multiple PPDUs, such as those illustrated in Figure 16, according to an embodiment of the inventive subject. The procedure begins, in block 1702, when the PHY device obtains at least one SDU. In one embodiment, the SDUs have the same intermediate or final destination as the same receiver, although it is possible that the SDUs have different destinations.

In block 1704, the length associated with the first SDU to be transmitted is determined. For example, in one embodiment, the length of the SDU is represented by two bytes. In other embodiments, the length field may be greater or lesser. The length is included in the PHY header for that SDU.

After negotiating access to the air interface, the transmitter transmits a preamble and the PHY header for the SDU over the air at the robust modulation rate, in block 1706. In one embodiment, the transmitter starts transmitting each one of the preamble and the header of the PHY at the beginning of a limit of the symbol. In one embodiment, the preamble for two symbols is transmitted, and the PHY header for a symbol is transmitted. In other embodiments, either the preamble or the PHY header may be transmitted for longer or shorter periods of time.

When the transmission of the PHY header has been completed, the transmitter goes to the data modulation rate, in block 1708. The transmitter begins transmitting the first SDU, in block 1710. In one embodiment, the transmitter begins to transmit the first SDU at the beginning of the next limit of the symbol after 20 of the termination of the PHY header. Alternatively, the first SDU may start at a time other than a symbol limit. In other words, transmission can begin before or after a limit of the symbol. Although not illustrated in Figure 17, only the last symbol in which an SDU is transmitted can only be partially used. In such a case, there may be a gap between the end of the SDU and the beginning of the next limit of the symbol. In addition, a padding of the internal block can be included at the end of each SDU. 25

In block 1712, the transmitter returns to the robust modulation rate, so that it will be ready to transmit the next PHY header. In block 1714, a determination is made as to whether more SDUs remain to be transmitted. In another embodiment, this determination can be excluded. If more SDUs remain to be transmitted, the transmitter determines the length of the next SDU to be transmitted, in block 1716.

The transmitter begins transmitting the PHY header for the SDU over the air at the robust modulation rate 30, in block 1718. In one embodiment, the PHY header for a symbol is transmitted. In other embodiments, the PHY header may be transmitted for longer or shorter periods of time. In one embodiment, the transmitter begins transmitting the PHY header for the next PPDU at the beginning of the next symbol limit after the termination of the previous SDU. Alternatively, the following PPDU may start at a time other than a symbol limit. In other words, the transmission may begin before or after a limit of the symbol.

After transmitting the PHY header, the procedure is repeated as shown. Specifically, the transmitter returns to the data modulation rate, and transmits the following SDU. The procedure ends after all SDUs have been transmitted in the burst.

Figure 18 is a flow chart of a procedure for a receiver to receive a burst of multiple 40 PPDUs, such as those illustrated in Figure 16, according to an embodiment of the inventive matter. The procedure begins, in block 1802, when the receiver detects an incoming preamble at the robust modulation rate. The receiver uses the preamble to synchronize with the incoming PPDU frame, in block 1804.

At the next limit of the symbol after the end of the preamble, the receiver should start receiving a PHY header. Therefore, the receiver receives and attempts to validate a segment of data that is 45 in size at a PHY header. In one embodiment, the size of the PHY header is a symbol width.

Validation is carried out by determining if a data integrity field within the PHY header correlates with the data in the PHY header. In one embodiment, the data integrity field includes a checksum or CRC, which allows the receiver to determine whether the data is corrupted or uncorrupted. fifty

A determination is made, in block 1806, of whether or not the segment of data of the size of the PHY header includes what appears to be a valid PHY header. If not, then the receiver enters a PHY header search mode, indicated by blocks 1808, 1810, and 1812. In this mode, the receiver determines whether the end of the burst may have been reached, in the block 1808. In various embodiments, the end of the burst can be determined if no PHY header is detected in an amount of time, or

if a known endpoint has been reached, or if the energy of the symbol falls below threshold. The procedure ends if the end of the burst has been reached.

If the end of the burst has not been reached, then the receiver receives and evaluates each subsequent segment of data of the size of the PHY header, in block 1810. Subsequent segments may be overlapping or sequential. 5

A determination is made, in block 1812, of whether the next segment of data of the size of the PHY header appears to be a possible PHY header by validating what the header data can be with what it can Be the header integrity field. If the header size data segment of the PHY does not appear to be a possible header of the PHY, then the procedure is repeated. When a possible PHY header is detected, the receiver suspends the PHY header search mode. 10

When the PHY header search mode is exited, or when the next PHY header has been validated, the receiver determines the modulation rate of the PPDU payload from the PHY header, in the PHY header. block 1814, in one embodiment. In another embodiment, the data modulation rate can be determined during a previous training exchange.

The receiver also determines the length of the associated SDU from the header of the PHY, in one embodiment. Once the reception of the PHY header has been completed, the receiver starts demodulating the data modulation rate, in block 1816.

In block 1818, the receiver receives and stores an amount of SDU data with a length as indicated in the associated length field for the SDU in the PHY header. In an alternative embodiment, the receiver can determine that the end of the payload has been reached using a measurement of the energy of the symbol.

When the end of the SDU has been reached, the receiver returns to the robust modulation rate, in block 1820, so that it will be ready to receive the next incoming PHY header. In addition, in block 1822, the receiver supplies the SDU. In another embodiment, the receiver can begin supplying the SDU while the SDU is being received. 25

After the reception of the first SDU has been completed, the receiver determines whether the end of the burst has occurred, in block 1824. If no PHY header is detected in an amount of time, or if it has been reached a known endpoint, or if the energy of the symbol falls below a threshold, the receiver may assume that the burst has been completed, and the procedure ends. If a PHY header is detected, the procedure is repeated as shown. Specifically, the receiver receives and processes the header of the PHY and the 30 SDU for the next PPDU.

An embodiment described above in conjunction with Figures 16-18 provides a high throughput method in burst mode with robust error detection and recovery. The performance of prior art procedures is improved by eliminating the IFS and preambles between SDUs.

The header integrity field of the PHY header allows robust error detection and recovery. If the receiver determines that the PHY data is corrupted, which may indicate a condition of lack of synchrony, the receiver may consider each byte that follows, to try to find a segment of data that appears to be a PHY header. If the receiver finds a segment of data that appears to be a PHY header, the receiver assumes that the data represents a PHY header, and the receiver is synchronized again to receive the next SDU. 40

Therefore, various embodiments of a method, of an apparatus, and of a system that allow higher performance data burst transmissions have been described. The above description of the specific embodiments sufficiently reveals the general nature of the inventive matter, so that others can, by applying current knowledge, modify and / or adapt them easily for various applications without departing from the generic concept. Therefore, such adaptations and modifications fall within the meaning and range of the 45 equivalents of the disclosed embodiments. The wording or terminology used in this document is for the purpose of description and not limitation.

In addition, it will be understood that, although some procedures are described as having a "termination", they can be carried out continuously.

Although the above embodiments have been described in conjunction with an 802.11 Standard, the embodiments may be implemented in conjunction with other standards that have completely or partially "self-describing" frames. In other words, the embodiments are not intended to be limited to procedures, systems and devices that implement an 802.11 Standard.

The various procedures described in this document can be implemented in hardware, firmware or

software. A software implementation can use microcode, assembly language code, or a high level language code. The code can be stored in one or more volatile or non-volatile computer-readable media during execution or at other times. These computer-readable media may include hard drives, removable magnetic discs, removable optical discs, cassette magnetic tapes, flash memory cards, digital video discs, Bernoulli cartridges, random access memories (RAM), read-only memories 5 ( ROM), and the like.

The embodiments of the inventive matter may concern any of a variety of types of PHY layers that support an IEEE Std 802.11 and other WLAN standards, including, without limitation, infrared baseband (IR) PHY, skip propagation spectrum radios frequency (FHSS) (for example, in the 2.4 GHz band), direct sequence propagation spectrum (DSSS) radios (for example, in the 2.4 GHz band), 10 orthogonal frequency division multiplexing (OFDM) radios (for example, in UNII bands), and other types of PHY layers to which IEEE Std 802.11 and other WLAN standards are being extended now and in the future. In addition, embodiments of the inventive subject may be used in conjunction with any IEEE Std 802.11, including IEEE Std. 802.11-1997, 802.11 a, 802.11b, 802.11e, other variants of the IEEE Std 802.11 existing or currently being developed or in the future, and other WLAN standards in addition to the IEEE Std. 802.11. fifteen

In the claims, the terms "first modulation rate" and "second modulation rate" are used. It should be understood that these modulation rates may be the same or may be different from each other.