MXPA06004137A - High speed media access control with legacy system interoperability - Google Patents

Abstract

Techniques for MAC processing for efficient use of high throughput systems that is backward compatible with various types of legacy systems are disclosed. In one aspect a first signal is transmitted according to a legacy transmission format to reserve a portion of a shared medium, and communication according to a second transmission format transpires during the reserved portion. In another aspect, a communication device may contend for access on a legacy system, and then communicate according to a new class communication protocol with one or more remote communication devices during the access period. In another aspect, a device may request access to a shared medium according to a legacy protocol, and, upon grant of access, the device may communicate with or facilitate communication between one or more remote stations according to a new protocol.

Description

CONTROL OF HIGH-SPEED MEDIA ACCESS WITH INTEROPERABILITY OF LEGACY SYSTEM FIELD OF THE INVENTION The present invention generally relates to communications, and very specifically to media access control.

BACKGROUND OF THE INVENTION Wireless communication systems are widely deployed to provide various types of communication such as voice and data. A typical wireless data system, or network, provides multiple users with access to one or more shared resources. A system can use a variety of multiple access techniques such as Frequency Division Multiplexing (FDM), Time Division Multiplexing (TDM), Code Division Multiplexing (CDM), and others. Exemplary wireless networks include cell-based data systems. The following are several such examples: (1) the "Mobile Station Compatibility Standard-TIA / EIA-95-B Base Station for Dual-Mode Broadband Scattered Spectrum Cell System" (the IS-95 standard), (2) the standard offered by a consortium called "Third Generation Partnership Project" (3GPP) and incorporated into a set of documents that include Documents Number 3G TS 25.211, 3G TS 25.212, 3G TS 25.213, and 3G TS 25.214 (the W-CDMA standard), (3) the standard offered by the consortium named "Third Generation Society Project 2" (3GPP2) and incorporated into the "Physical Layer Standard TR-45.5 for Systems of Dispersed Spectrum cdma2000"(the IS-2000 standard), and (4) the high-speed data system (HDR) that conforms to the TIA / EIA / IS-856 standard (the IS-856 standard). Other examples of wireless systems include Wireless Local Area Networks (WLAN) such as the IEEE 802.11 standards (ie 802.11 (a), (b), or (g)). Improvements in these networks can be achieved by deploying a Multi-Input Multiple Output WLAN (MIMO) comprising Orthogonal Frequency Division Multiplexing (OFDM) modulation techniques. IEEE 802.11 (e) has been introduced to improve some of the deficiencies of previous 802.11 standards. As the designs of the wireless systems have advanced, higher data rates have become available. Higher data speeds have opened the possibility of advanced applications, among which are the rapid transfer of data, voice, video, and other applications. However, several applications may have different requirements for their respective data transfer. Many types of data may have latency and performance requirements, or may require a certain Quality of Service (QoS) guarantee. Without resource management, the capacity of a system can be reduced, and the system may not operate efficiently. The protocols of Control of Access to the Environment (MAC) are commonly used to assign a shared communication resource among a number of users. MAC protocols commonly interface higher layers with the physical layer used to transmit and receive data. To benefit from an increase in data rates, a MAC protocol must be designed to efficiently use the shared resource. Generally, it is also desirable to maintain interoperability with legacy or alternate communication standards. Therefore, there is a need in the art for MAC processing for the efficient use of high performance systems. In addition, there is a need in the art for such MAC processing that is backwards compatible with various types of legacy systems.

SUMMARY OF THE INVENTION The modalities described here focus on the need for MAC processing for the efficient use of high performance systems and that is backwards compatible with various types of lathe systems. In one aspect, a first signal is transmitted according to a legacy transmission format to reserve a portion of a shared medium, and communication according to a second transmission format results during the reserved portion. In another aspect, a communication device can fight for access in a legacy system, and then establish communication in accordance with a new class communication protocol with one or more remote devices during the access period. In another aspect, a device may request access to a shared medium in accordance with a legacy protocol, and, at the time of granting access, the device may establish communication with one or more remote stations (or facilitate communication between two or more remote stations) according to a new protocol. In another aspect, a new class access point assigns a contention-free period and a containment period, a portion of the contention-free period allocated to the communication according to a new class protocol, and a second portion of the free period containment optionally assigned to the communication according to a legacy communication protocol. The containment period can use any protocol, or a combination of both. Other aspects are also presented.

BRIEF DESCRIPTION OF THE FIGURES Figure 1 is an exemplary embodiment of a system that includes a high-speed LAN; Figure 2 shows an exemplary embodiment of a wireless communication device, which can be configured as an access point or user terminal; Figure 3 shows separation parameters between 802.11 frames; Figure 4 shows an exemplary physical layer transmission (PHY) segment illustrating the use of DIFS plus retrace for access according to the DCF; Figure 5 shows an exemplary physical layer transmission (PHY) segment illustrating the use of SIFS before an ACK, with a higher priority than a DIFS access; Figure 6 illustrates the segmentation of large packets into smaller fragments with associated SIFS; Figure 7 shows an exemplary physical layer transmission (PHY) segment illustrating a TXOP with per-frame recognition; Figure 8 illustrates a TXOP with block recognition; Figure 9 shows an exemplary physical layer transmission (PHY) segment illustrating a registered TXOP using HCCA; Figure 10 is an exemplary embodiment of a TXOP that includes multiple consecutive transmissions without any space; Figure 11 shows an exemplary embodiment of a TXOP illustrating the reduction of the required preamble transmission amount; Figure 12 shows an exemplary embodiment of a method for incorporating various aspects, including consolidation of preambles, removal of spaces such as SIFS, and insertion of GIF as appropriate; Figure 13 shows an exemplary physical layer transmission (PHY) segment illustrating consolidated records and their respective TXOPs; Figure 14 shows an exemplary embodiment of a method for the consolidation of shared line systems; Figure 15 illustrates an exemplary MAC frame; Figure 16 illustrates an exemplary MAC PDU; Figure 17 shows an example peer-to-peer communication; Figure 18 shows a physical layer burst of the prior art; Figure 19 shows an exemplary physical layer burst, which can be displayed for para-pair transmission; Figure 20 shows an exemplary embodiment of a MAC frame that includes an optional segment purposely for the case; Figure 21 shows an exemplary physical layer burst; Figure 22 shows an exemplary method for a peer-to-peer data transmission; Figure 23 shows an exemplary method for peer-to-peer communication; Figure 24 shows an exemplary method for providing speed feedback for use in a peer-to-peer connection; Figure 25 illustrates a peer-to-peer connection managed between two stations and an access point; Figure 26 illustrates a contention based on the peer-to-peer connection (or on purpose for that matter). Figure 27 shows an exemplary MAC frame illustrating peer-to-peer communication between stations; Figure 28 illustrates the support of both the legacy and new class stations in the same frequency assignment; Figure 29 illustrates the combination of access control to new class and legacy media; Figure 30 shows an exemplary method to gain a transmission opportunity; Figure 31 shows an exemplary method for sharing a single FA with multiple BSS; Figure 32 shows the overlap of the BSS using a single FA; Figure 33 shows an exemplary method for executing high-speed peer-to-peer communication while interoperating with a legacy BSS. Figure 34 illustrates peer-to-peer communication using MIMO techniques through competition for access in a legacy BSS; Figure 35 shows the encapsulation of one or more MAC frames (or fragments) within an aggregated frame; Figure 36 shows a legacy MAC frame; Figure 37 illustrates an exemplary uncompressed frame; Figure 38 illustrates an exemplary compressed frame; Figure 39 illustrates another exemplary compressed frame; Figure 40 illustrates an exemplary Aggregate Header; Figure 41 illustrates an exemplary mode of a Scheduled Access Period Frame (SCAP) for use in the ACF; Figure 42 illustrates how SCAP can be used in conjunction with HCCA and EDCA; Figure 43 illustrates beacon intervals comprising a number of SCAPs interspersed with contention-based access periods; Figure 44 illustrates the low latency operation with a large number of MIMO STA; Figure 45 illustrates an example of a SCHED message; Figure 46 shows an exemplary Energy Management field; Figure 47 shows an exemplary MAP field; Figure 48 illustrates exemplary SCHED control frames for TXOP assignment; Figure 49 shows a legacy 802.11 PPDU; Figure 50 shows an exemplary MIMO PPDU format for data transmissi Figure 51 shows an exemplary SCHED PPDU; Fig. 52 shows an exemplary FRACH PPDU; and Figure 53 illustrates an alternative embodiment of a method for interoperability with legacy systems.

DETAILED DESCRIPTION OF THE INVENTION In the present invention exemplary embodiments are described which support the highly efficient operation in conjunction with physical layers with a very high bit rate for a wireless LAN (or similar applications using transmission technologies that are emerging recently). The exemplary WLAN supports bit rates in excess of 100 Mbps (million bits per second) in 20 MHz bandwidths. Several exemplary modes retain the simplicity and robustness of the distributed coordination operation of legacy WLAN systems, examples of which are which are in 802.11 (ae). The advantages of the various modalities can be achieved at the same time that backwards compatibility with said legacy systems is maintained. (It can be appreciated that, in the description below, 802.11 systems are described as exemplary legacy systems, Those skilled in the art will recognize that improvements are also compatible with alternate systems and standards).

An exemplary WLAN may comprise a sub-network protocol stack. The sub-network protocol stack can support physical layer transport mechanisms of high bandwidth, high-speed data in general, including, but not limited to, those based on OFDM modulation, modulation techniques of a single carrier, systems that use multiple transmit antennas and multiple receive antennas (Multiple Inputs Multiple Outputs (MIMO) systems, including multiple input and single output systems (MISO)) for very high bandwidth efficiency operation , systems using multiple transmit and receive antennas in conjunction with spatial multiplexing techniques to transmit data to or from multiple user terminals during the same time interval, and systems using multiple code division (CDMA) access techniques to allow transmissions for multiple users simultaneously. Alternate examples include Single-Input Multiple Output (SIMO) and Single-Input Single Output (SISO) systems. One or more exemplary embodiments described herein are established in the context of a wireless data communication system. Although use within this context is convenient, different embodiments of the invention may be incorporated in different environments or configurations. In general, the various systems described herein can be formed using processors with controlled software, integrated circuits, or discrete logic. The data, instructions, commands, information, signals, symbols and chips (silicon wafers) that can be referenced in the application, are conveniently represented through voltages, currents, electromagnetic waves, fields or magnetic particles, optical fields or particles, or a combination thereof. In addition, the blocks shown in each block diagram can represent hardware or method steps. The steps of the method can be exchanged without departing from the scope of the present invention. The word "exemplary" is used in the present invention to mean "that it serves as an example, case, or illustration." Any modality described in the present invention as "exemplary" will not necessarily be construed as preferred or advantageous over other modalities. Figure 1 is an exemplary embodiment of system 100, comprising an Access Point (AP) 104 connected to one or more User Terminals (UT) 106A-N. According to the terminology of 802.11, in this document the AP and the UT are also referred to as stations or STAs. The AP and the UTs communicate through the Local Area Wireless Network (WLAN) 120. In the exemplary mode, WLAN 120 is a high speed MIMO OFDM system. Nevertheless, the WLAN 120 can be any wireless LAN. The access point 104 communicates with any number of external devices or processing through the network 102. The network 102 can be the Internet, an intranet (internal network), or any other wired, wireless or optical network. The connection 110 carries the physical layer signals of the network to the point of access point 104. The devices or processing can be connected to the network 102 or as UT (or through connections thereto) in WLAN 120. Examples of devices that can be connected to any network 102 or WLAN 120 includes telephones, Personal Digital Assistants (PDA), computers of various types (laptops, personal computers, workstations, terminals of any kind), video devices such as cameras, camcorders , network cameras and virtually any other type of data device. The procedures may include voice, video, data, etc. communications. Several data streams may have different transmission requirements, which can be accommodated through the use of different Quality of Service (QoS) techniques. The system 100 can be deployed with a centralized AP 104. All the UT 106 communicate with the AP in an exemplary mode. In an alternate modality, direct peer-to-peer communications between two UTs may be allowed, with modifications to the system, as will be apparent to those skilled in the art, examples of which are illustrated below. The access can be managed through an AP, or on purpose for the case (that is, based on contention), as detailed below. In one embodiment, the AP 104 provides Ethernet adaptation. In this case, an IP router can be deployed in addition to the AP to provide connection to the network 102 (the details are not shown). The Ethernet frames can be transferred between the router and the UT 106 over the WLAN sub-network (which is detailed below). Ethernet adaptation and connectivity are well known in the art. In an alternate modality, the AP 104 provides IP adaptation. In this case, the AP acts as a gateway router for the set of connected UTs (the details are not shown). In this case, the IP datagrams can be guided by the AP 104 a and from the UT 106. The adaptation and IP connectivity are well known in the art. Figure 2 shows an exemplary embodiment of a wireless communication device, which can be configured as an access point 104 or user terminal 106. Figure 2 shows the configuration of an access point 104. The transceiver 120 receives and transmits over connection 110 in accordance with the physical layer requirements of network 102. Data from, or directed to, devices or applications connected to network 102 are delivered to MAC processor 220. In the present invention, these data are referred to as flows 260. The flows may have different characteristics and may require different processing based on the type of application associated with the flow. For example, video or voice can be differentiated as low latency flows (video generally has higher performance requirements than voice). Many data applications are less sensitive to latency, but may have higher data integrity requirements (ie, speech may be tolerant of some packet loss, file transfer is generally intolerant of packet loss). The MAC 220 processor receives the flows 260 and processes them for transmission in the physical layer. The MAC 220 processor also receives the physical layer data and processes the data to form packets for issuing flows 260. Internal control and signaling are also communicated between the AP and the UTs. The MAC Protocol Data Units (MAC PDU), also referred to as Physical Data Protocol (PPDU) Units (PHY), or frames (in the 802.11 language) are delivered to and received from the wireless LAN transceiver 240 in connection 270. Exemplary techniques for converting flows and commands to MAC PDU, and vice versa, are detailed below. Alternate modes can employ any conversion technique. The feedback 280 corresponding to the various MAC IDs can be returned from the physical layer (PHY) 240 to the MAC 220 processor for various purposes. The feedback 280 may comprise any physical layer information, including bearable speeds for channels (including multicast channels as well as unicast channels), modulation format, and other parameters. In an exemplary mode, the Adaptation layer (ADAP) and the Data Link Control (DLC) layer are executed in the MAC 220 processor. The physical layer (PHY) is executed in the wireless LAN transceiver 240. Those skilled in the art will appreciate that the segmentation of the various Functions can be performed in any of a variety of configurations. The MAC 220 processor can execute some or all of the processing for the physical layer. A wireless LAN transceiver may include a processor for executing MAC processing, or sub-parts thereof. You can display any number of processors, special purpose hardware, or a combination thereof. The MAC 220 processor can be a general purpose microprocessor, a digital signal processor (DSP), or a special purpose processor. The MAC 220 processor can be connected with special purpose hardware to help with various tasks (the details are not shown). Various applications can be run on externally connected processors, such as an externally connected computer or on a network connection, can be run on an additional processor within access point 104 (not shown), or can be run on the processor MAC 220 same. The MAC 220 processor is shown connected to the memory 255, which can be used to store data as well as instructions for executing the various methods and methods described herein. Those skilled in the art will recognize that memory 255 may be composed of one or more memory components of various types, which may be incorporated in whole or in part within the MAC 220 processor. In addition to storing the instructions and data to execute the functions described in the present invention, the memory 255 may also be used to store data associated with several queues.

The wireless LAN transceiver 240 can be any type of transceiver. In an exemplary embodiment, the wireless LAN transceiver 240 is an OFDM transceiver, which can be operated with a MIMO or MISO interface. Those skilled in the art know OFDM, MIMO and MISO. Several examples of OFDM, MIMO and MISO transceivers are detailed in the copending U.S. Patent Application serial number 10 / 650,295, entitled "SPACE PROCESSING OF INDEPENDENT FREQUENCY FOR MISO AND BROADBAND MIMO SYSTEMS", filed on August 27, 2003 , assigned to the assignee of the present invention. Alternate modes can include SIMO or SISO systems. The wireless LAN transceiver 240 is shown connected to the 250 A-N antennas. In various modalities, any number of antennas can be supported. The antennas 250 can be used to transmit and receive in WLAN 120. The wireless LAN transceiver 240 can comprise a spatial processor connected to each of the antennas 250. The spatial processor can independently process the data for transmission to each antenna or can process together the signals received on all the antennas. Examples of independent processing can be based on channel calculations, UT feedback, channel inversion, or a variety of other known techniques. The processing is executed using any of a variety of spatial processing techniques. Various transceivers of this type can use beamforming, beam conduction, self-conduction, or other spatial techniques to increase performance to and from a particular user terminal. In an exemplary embodiment, wherein the OFDM symbols are transmitted, the spatial processor may comprise sub-spatial processors for processing each of the OFDM sub-channels, or repositories. In an exemplary system, the AP can have N antennas, and an exemplary UT can have M antennas. There are then M x N trajectories between the antennas of the AP and the UT. A variety of spatial techniques are known in the art to improve performance using these multiple trajectories. In a Space-Time Transmission Diversity (STTD) system (also referred to herein as "diversity"), transmission data is formatted and encoded and sent across all antennas as a single data stream . With M transmitting antennas and N receiving antennas, MIN (M, N) independent channels can be formed. The spatial multiplexing exploits these independent trajectories and can transmit different data in each of the independent trajectories, to increase the transmission speed.

Several techniques are known to learn or adapt to the characteristics of the channel between the AP and a UT. Unique pilots can be transmitted from each transmit antenna. Pilots are received at each receiving antenna and measured. The feedback of the channel status information can then be returned to the transmission device for transmission use. The proper decomposition of the matrix of the measured channel can be done to determine the proper modes of the channel. An alternative technique, to avoid the proper decomposition of the channel matrix in the receiver, is to use the pilot's own conduction and data to simplify the spatial processing in the receiver. Therefore, depending on the current channel conditions, several data rates may be available for transmission to several user terminals in the system. In particular, the specific link between the AP and each UT may have a higher performance than a multicast or broadcast link, which may be shared from the AP to more than one UT. Below are examples of the above. The wireless LAN transceiver 240 can determine the bearable speed based on any spatial processing being used for the physical link between the AP and the UT. This information can be retro-loaded into connection 280 for use in MAC processing. The number of antennas can be displayed depending on the data needs of the UT as well as the size and form factor. For example, a high definition video screen can comprise, for example, four antennas, due to its high bandwidth requirements, while a PDA can be satisfied with two. An exemplary access point can have four antennas. A user terminal 106 may be deployed similarly to the access point 104 shown in Figure 2. Instead of having flows 260 connected to a LAN transceiver (although a UT may include said transceiver, either wired or wireless) , flows 260 are generally received from, or delivered to, one or more applications or processes operating in the UT or a device connected thereto. The upper levels connected to the AP 104 or UT 106 can be of any type. The layers described herein are illustrative only.

Legacy MAC 802.11 As mentioned above, various embodiments may be deployed in the present invention to be compatible with legacy systems. The IEEE 802.11 (e) feature set (which in turn is backwards compatible with previous 802.11 standards) includes several functions that will be summarized in this section, along with features introduced in previous standards. For a detailed description of these functions, consult the respective IEEE 802.11 standard. The basic 802.11 MAC consists of a Multiple Access with Carrier Detection / Collision Prevention (CSMA / CA) based on the Distributed Coordination Function (DCF), and a Point Coordination Function (PCF). DCF allows medium access without central control. The PCF is deployed in an AP to provide central control. The DCF and PCF use several spaces between consecutive transmissions to avoid collisions. Transmissions are referred to as frames, and a space between frames is referred to as an Interframe Separation (IFS). The frames can be user data frames, control frames or management frames. The durations in time of the separation between frames vary depending on the type of space inserted. Figure 3 shows the separation parameters between 802.11 frames: a Separation between Short Frames (SIFS), a Separation between Frames of Point (PIFS), and a Separation between Frames DCF (DIFS). It can be seen that SIFS < PIFS < DIFS. Therefore, a transmission after a shorter duration of time will have a higher priority than one that has to wait longer before attempting to access the channel. According to the carrier detection function (CSMA) of CSMA / CA, a station (STA) can gain access to the channel after detecting that the channel is inactive for at least a duration of DIFS. (As used in the present invention, the term STA may refer to any station that has access to a WLAN, and may include access points as well as user terminals). To avoid collision, each STA waits for a randomly selected retraction in addition to the DIFS before accessing the channel. STAs with a longer flashback will notice when a higher priority STA starts transmitting on the channel, and therefore will avoid colliding with that STA. (Each standby STA can reduce its respective recoil by the amount of time it waited before detecting an alternate transmission in the channel, thus maintaining its relative priority). Therefore, after the protocol collision prevention (CA) function, the STA retracts a random period of time between [0, CW] where CW is initially chosen to be CW in, but increases by a factor of two in each collision, up to a maximum value of CWmax. Figure 4 shows an exemplary physical layer transmission (PHY) 400 segment, which illustrates the use of DIFS plus backspace for access according to the DCF. An existing transmission 410 uses the channel. When the transmission 410 ends, in this example, higher priority accesses do not occur, and therefore a new transmission 420 starts after the DIFS and the associated backward period. In the analysis below, the STA performing the transmission 420 is said to have already gained this opportunity to transmit, in this case through contention. The SIFS is used during a frame sequence where only a specific STA is expected to respond to the current transmission. For example, when a Recognition (ACK) is transmitted in response to a received data frame, that ACK can be transmitted immediately after the received data plus the SIFS. Other streaming sequences can also use SIFS between frames. A Request To Send (RTS) frame may follow after SIFS with a Clear to Send (CTS) frame, then the data may be transmitted a SIFS after the CTS, after which an ACK can track the data after the SIFS. As noted, said frame sequences are interspersed with SIFS. The duration of SIFS can be used to (a) detect energy in the channel, and to determine if the power has gone (ie, the channel is clear), (b) time to decode the previous message and determine if an ACK frame will indicate that the transmission was received correctly, and (c) time for the STA transceivers to change from reception to transmission, and vice versa. Figure 5 shows an exemplary physical layer transmission (PHY) segment 500, which illustrates the use of SIFS before an ACK, with higher priority than a DIFS access. An existing transmission 510 uses the channel. When transmission 510 ends, in this example, ACK 520 follows the end of transmission 510 after a SIFS. It can be seen that an ACK 520 starts before the expiration of a DIFS, therefore, any other STA that is trying to win a transmission would not be successful. In this example, after the ACK 520 ends, no higher priority accesses occur, and therefore a new 530 transmission begins after the DIFS and the associated backward period, if any. The RTS / CTS frame sequence (in addition to providing flow control functions) can be used to improve protection for the transmission of data frames. The RTS and the CTS contain duration information for the subsequent data frame and ACK and any intervention SIFS. The STAs that listen to either the RST or the CTS mark the duration occupied in their Network Assignment Vector (NAV) and treat the medium as occupied by the duration.

Typically, frames longer than a specified length are protected with RTS / CTS, while shorter frames are transmitted without protection. The PCF can be used to allow an AP to provide centralized control of the channel. An AP can gain control of the medium after detecting that the medium is inactive for a duration of PIFS. The PIFS is shorter than the DIFS and therefore has a higher priority than the DIFS. Once the AP has gained access to the channel, it can provide contention-free access opportunities to other STAs and can therefore improve MAC efficiency compared to DCF. It can be seen that the SIFS has a higher priority than PIFS, so the PCF must wait until any of the SIFS sequences ends before taking control of the channel. Once the AP obtains access to the medium using the PIFS, it can establish a Containment-Free Period (CFP) during which the AP can provide registered access to the associated STAs. The free record of containment (CF-registration), or simply registration, is transmitted by the AP and is followed by a transmission from the STA registered to the AP. Again, the STA must wait for a duration of SIFS after the CF-registration, although the registered STA does not need to wait for the DIFS, or any backward movement. 802.11 (e) introduced several improvements, including improvements for registration, an example of which is detailed below with respect to Figure 9. The beacon transmitted by the AP establishes the duration of the CFP. This is similar to using RTS or CTS to avoid contention access. However, hidden terminal problems may still occur in terminals that can not hear the beacon, but whose transmissions may interfere with the transmissions programmed by the AP. Additional protection is possible through the use of a CTS-for-itself for each terminal that begins a transmission in the CFP. It allows the inclusion of ACK and CF-Registers in a frame, and can be included with data frames to improve MAC efficiency. It can be seen that the SIFS relationship < PIFS < DIFS provides a deterministic priority mechanism for channel access. The contention access between the STAs in the DCF is probabilistic based on the backward mechanism. Previous 802.11 standards also provided segmentation of large packets into small fragments. One benefit of such segmentation is that an error in a segment requires less retransmission than an error in a larger package. A disadvantage of the segmentation in these standards is, for the recognized transmission, the requirement to transmit an ACK for each segment, with the additional SIFS corresponding to the additional ACK transmissions and the fragment transmissions. This is illustrated in Figure 6. The exemplary physical layer transmission (PHY) segment 600 illustrates the transmission of N segments and their respective recognition. The existing 610 transmission is transmitted. At the end of the transmission 610, a first STA waits for the DIFS 620 and the retrace 630 to gain access to the channel. The first STA transmits N fragments 640A-640N to a second STA, after which N respective delays of the SIFS 650A-650N must occur. The second STA transmits N frames ACK 660A-660N. Between each fragment, the first STA must wait for the SIFS, in such a way that there is also N-l SIFS 670A-670N-1. Therefore, in contrast to the sending of a packet, an ACK and a SIFS, a segmented packet requires the same packet transmission time, with N ACK and 2N-1 SIFS. The 802.11 (e) standard adds extensions to improve the previous MAC of 802.11 (a), (b), and (g). 802.11 (g) and (a) are OFDM systems, which are very similar, but operate in different bands. Several lower-speed MAC protocol functions, such as 802.11 (b), were brought into systems with much higher bit rates, introducing inefficiencies, which are detailed below. In 802.11 (e), DCF is improved and is referred to as Enhanced Distributed Channel Access (EDCA). The primary Quality of Service (QoS) improvements of the EDCA are the introduction of a Separation between Arbitration Frames (AIFS). AIFS [i] is associated with a Traffic Class (TC) identified with the Index i. The AP may use AIFS [i] values different from the AIFS [i] values that are allowed to be used by the other STAs. Only the AP can use an AIFS value [i] that is equal to the PIFS. Otherwise, AIFS [i] is greater than or equal to DIFS. By default, the AIFS for "voice" and "video" traffic classes is chosen to be equal to DIFS. A larger AIFS involving lower priority is chosen for "best effort" and "bottom" traffic classes. The size of the containment window also performs a CT function. The highest priority class is allowed to set CW = 1, that is, without backspace. For other TCs, the different containment window sizes provide a relative probabilistic priority, but can not be used to achieve delay guarantees. 802.11 (e) introduced the Transmission Opportunity (TXOP). To improve the efficiency of the MAC, when an STA acquires the medium through the EDCA or through a registered access in HCCA, the STA can be allowed to transmit more than a single frame. The frame or frames are referred to as the TXOP. The maximum length of a TXOP in the middle depends on the traffic class and is established by the AP. Also, in the case of a registered TXOP, the AP indicates the allowed duration of the TXOP. During the TXOP, the STA can transmit a series of frames, interspersed with SIFS and destination ACK In addition to eliminating the need to wait for DIFS plus backspace for each frame, the STA that has won a TXOP is certain that it can keep The channel for subsequent transmissions During the TXOP, the ACKs coming from the destination can be per frame (as in the previous MAC 802.11), or they can use an immediate or delayed block ACK as discussed below. non-ACK for some traffic flows, eg, broadcast or multicast Figure 7 shows the exemplary physical layer transmission (PHY) segment 700, illustrating a TXOP with a through-acknowledgment An existing 710 transmission is transmitted. After the 710 transmission, and after waiting for the DIFS 720 and the 730 retrace, if any, an STA gains the TXOP 790. The TXOP 790 comprises N frames 740A-740N, each frame followed by N SIFS 750A-750N The reception STA responds with respective N ACK 760A-760N. The ACK 760s are followed by N-l SIFS 770A-770N-1. It can be seen that each frame 740 comprises a preamble 770 as well as a header and packet 780. Exemplary modes, which are detailed below, allow a large reduction in the amount of transmission time reserved for preambles. Figure 8 illustrates a TXOP 810 with block recognition. The TXOP 810 can be earned through contention or registration. The TXOP 810 comprises N frames 820A-820N, each frame followed by respective N SIFS 830A-830N. After transmission of the frames 820 and SIFS 830, an ACK request of block 840 is transmitted. The receiving STA responds to the block ACK request at a time in the future. The block ACK can be immediate after the completion of the transmission of a block of frames, or it can be delayed to allow processing of the receiver in software. Exemplary modes, which are detailed below, greatly reduce the amount of transmission time between frames (SIFS in this example). In some embodiments, there is no need for a delay between consecutive transmissions (ie, frames). It can be seen that, in 802.11 (a) and other standards, for some transmission formats, a signal extension is defined which adds additional delay at the end of each frame. Although it is not technically included in the definition of SIFS, several modalities, which are detailed below, also allow the removal of signal extensions. k ACK function provides improved efficiency. In one example, up to 64 MAC Service Data Units (SDU) (each possibly fragmented into 16 fragments) corresponding to 1024 frames can be transmitted by an STA, although the destination STA is allowed to provide a single response at the end of the session. k of frames indicating the ACK status of each of the 1024 frames. Typically, at high speeds, the MAC SDU will not fragment, and for low latency, less than 64 MAC SDUs can be transmitted before requiring a destination k ACK. In this case, to transmit M frames, the total time is reduced from M frames + M SIFS + M ACK + M-l SIFS, to M frames + M SIFS + ACK k. Modalities detailed below further improve the efficiency of the k ACK. The Direct Link Protocol (DLP), introduced by 802.11 (e) allows an STA to forward frames directly to another destination STA within a Basic Service Set (BSS) (controlled by the same AP). The AP may make a registered TXOP available for this frame direct transfer between STAs. Before the introduction of this function, during the registered access, the destination of the frames from the registered STA was always the AP, which in turn would forward the frames to the destination STA. By eliminating the frame re-routing of two jumps, the efficiency of the medium is improved. The modalities detailed below add substantial efficiency to DLP transfers. 802.11 (e) also introduces a PCF, called the Hybrid Coordination Function (HCF). In HCF Controlled Channel Access (HCCA), the AP is allowed to access the channel at any time, either to establish a Controlled Access Phase (CAP), which is like the CFP and is used to provide opportunities for transmission at any time during the containment phase, not just immediately after the beacon. The AP has access to the medium through waiting for a PIFS without recoil. Figure 9 shows the exemplary physical layer transmission (PHY) segment 800, which illustrates a registered TXOP using HCCA. In this example, the AP fights for the record. An existing transmission 910 is transmitted. After transmission 910, the AP waits for the PIFS, and then transmits the register 920, addressed to an STA. It can be appreciated that other STAs fighting over the channel would have to wait for at least DIFS, which does not occur due to the transmitted record 920, as shown. The registered STA transmits registered TXOP 940 after registration 920 and SIFS 930. The AP may continue to register, pending a PIFS between each registered TXOP 940 and register 920. In an alternate scenario, the AP may establish a CAP by waiting for a PIFS from a 910 transmission. The AP can transmit one or more records during the CAP.

MAC Improvements As described above, several previous inefficient MAC functions were taken to later versions. For example, very long preambles, designed for 11 Mbps versus 64 Mbps, introduce inefficiency. According to the MAC Protocol Data Unit (MPDU) continues to decrease as speeds increase, maintaining the various separations between frames and / or constant preambles means a corresponding reduction in channel utilization. For example, a high-speed data MIMO MPDU transmission may have a few microseconds in length, compared to 902.11 (g) having a preamble of 72 μs. The elimination or reduction of delays, such as SIFS, signal extensions, and / or preambles will increase the performance and utilization of the channel. Figure 10 is an exemplary embodiment of a TXOP 1010 that includes multiple consecutive transmissions without any space. The TXOP 1010 comprises N frames 1020A-1020N which are transmitted in sequence without any space (compare this with the SIFS required in the TXOP 810, which is shown in Figure 8). The number of frames in the TXOP is limited only by the buffer and the decoding capability of the receiver. When an STA is transmitting consecutive frames with a block ACK in a TXOP 1010, it is unnecessary to interleave the durations of the SIFS because no other STA needs to gain access to the medium between consecutive frames. An optional block ACK request 1030 is appended to the N frames. Some kinds of traffic may not require recognition. You can respond to a block ACK request immediately after the TXOP, or it can be transmitted at a later time. The 1020 frames do not require signal extensions. The TXOP 1010 can be displayed in any of the modalities detailed here where a TXOP is used. As shown in Figure 10, the transmission of SIFS between consecutive frames in a TXOP can be eliminated when all the frames are transmitted by the same STA. In 802.11 (e), these spaces were conserved to limit the requirement of complexity in the receiver. In the 802.11 (e) standard, the SIFS period of 10 μs and the OFDM signal extension of 6 μs provide the receiver with a total of 16 μs for the processing of the received frame (including demodulation and decoding). However, at large PHY speeds, these 16 μs result in significant inefficiency. In some modalities, with the introduction of MIMO processing, even 16 μs may be insufficient to complete the processing. Rather, in this exemplary embodiment, the SIFS and the OFDM signal extension between consecutive transmissions from an STA to the AP or to another STA (using the Direct Link Protocol) are eliminated. Therefore, a receiver that requires an additional period after the completion of transmission, for MIMO receiver processing and channel decoding (eg, turbo / convolutional decoding / LDPC) can perform these functions while the medium is used for additional transmission. An acknowledgment can be transmitted at a later time, as described above (using the block ACK, for example). Due to the different propagation delays between the STAs, transmissions between different STA pairs can be separated by guard periods to avoid collisions in a receiver between consecutive transmissions in the medium from different STAs (not shown in Figure 10). , but which are detailed below). In an exemplary embodiment, a guard period of an OFDM symbol (4 μs) is sufficient for all operating environments for 802.11. Transmissions from the same STA to different destination STAs do not need to be separated by guard periods (as shown in figure 10). Detailed below, these guard periods can be referred to as Separations Between Guardband (GIFS). Instead of using SIFS and / or signal extension, the required processing time of the receiver (for MIMO processing and decoding, for example) can be provided through the use of a window-based ARQ scheme (eg, return to N or selective repetition), techniques known to those skilled in the art. The legacy 802.11 stop-and-expect MAC layer ACK has been enhanced in 802.11 (e) to a window-like mechanism with 1024 frames and block ACKs, in this example. It might be preferable to introduce an ARQ mechanism based on standard window instead of the block ACK scheme on purpose for the case designed in 802.11 (e). The maximum allowed window can be determined through the processing, complexity and buffer of the receiver. The transmitter can be allowed to transmit enough data to fill the receiver window at the peak PHY rate achievable between the transmitter-receiver pair. For example, because the processing of the receiver may not be able to maintain the PHY speed, the receiver may need to store soft outputs of the demodulator until they can be decoded. Therefore, the buffer requirements for processing the physical layer at the peak PHY rate can be used to determine the maximum window allowed. In an exemplary embodiment, the receiver can announce the maximum allowed PHY block size that it can process at a given PHY rate without overflowing its physical layer buffers. Alternatively, the receiver can announce the maximum allowed PHY block size that it can process at maximum PHY speed without overflowing its physical layer buffers. At lower PHY speeds, larger block sizes can be processed without overflowing the buffers. Transmitters can use a known formula to calculate the maximum PHY block size allowed for a given PHY rate, from the maximum allowed PHY block size advertised at the maximum PHY rate. If the maximum announced PHY block size is a static parameter, then the amount of time before the physical layer buffers can be processed and the receiver is ready for the next PHY burst is another receiver parameter that can be known in the transmitter and also in the programmer. Alternatively, the maximum announced PHY block size may vary dynamically according to the occupation of the buffers of the physical layer. The processing delay of the receiver can be used to determine the round trip delay for the ARQ, which in turn can be used to determine the delays observed by the applications. Therefore, to enable low latency services, the allowed PHY block size can be limited. Figure 11 shows an exemplary embodiment of a TXOP 1110 illustrating the reduction of the required preamble transmission amount. The TXOP 1110 comprises the preamble 1120 followed by N consecutive transmissions 1130A-1130N. An optional block ACK request 1140 may be appended. In this example, a transmission 1130 comprises a header and a packet. Contrast the TXOP 1110 with the TXOP 790 of Figure 7, wherein each frame 740 comprises a preamble, in addition to the header and the packet. When sending a single preamble, the required preamble transmission is a preamble instead of N preambles, for the same amount of data transmitted.

Therefore, preamble 1120 can be eliminated from successive transmissions. The initial preamble 1120 can be used by the receiver to acquire the signal, as well as for the acquisition of fine frequency for OFDM. For MIMO transmissions, the initial preamble 1120 may be extended compared to the current OFDM preamble to allow the receiver to calculate the spatial channels. However, subsequent frames within the same TXOP may not require additional preambles. The pilot tones within the OFDM symbols are generally sufficient for signal tracking. In an alternate mode, additional symbols (preamble type) may be interleaved periodically during the TXOP 1110. However, the overall overload of the preamble can be significantly reduced. The preamble may be sent only as necessary, and may be sent differently based on the amount of time elapsed from a previously transmitted preamble. It can be seen that the TXOP 1110 can also incorporate functions of legacy systems. For example, the block ACK is optional. More frequent ACKs can be supported. Despite this, a smaller space, such as GIFS, can be replaced by the longer SIFS (plus the signal extension, if used). Consecutive transmissions 1130 may also include segments of a larger packet, as described above. It can further be appreciated that the header for consecutive transmissions 1130 to the same receive STA can be compressed. An example of compressed headers is detailed below. Figure 12 shows an exemplary embodiment of a method 1200 to incorporate various aspects described above, including consolidation of preambles, removal of spaces such as SIFS, and insertion of GIFS as appropriate. The procedure begins at block 1210, where an STA obtains a TXOP using any of the techniques detailed in the present invention. In block 1220 a preamble is transmitted as necessary. Again, the preamble may be longer or shorter than a legacy preamble, and may vary depending on various parameters such as the time elapsed since the last transmitted preamble, as necessary to allow the receiving STA to calculate the MIMO spatial channel . In block 1230, the STA transmits one or more packets (or, more generally, consecutive transmissions of any type), to a destination. It can be seen that there is no need to transmit additional preambles. In an alternate embodiment, one or more additional preambles may optionally be transmitted, or a preamble symbol may be interleaved as desired.

In block 1240, the STA may optionally transmit to an additional receiving STA. In this case, a GIFS is inserted as necessary, and one or more consecutive transmissions can be transmitted to the additional receiving STA. Then the procedure stops. In various modalities, the STA may continue transmitting to more than two STAs, inserting GIFS and / or preambles as required for the desired performance level. Therefore, as described above, MAC efficiency can be further enhanced by consolidating transmissions from one STA to multiple destination STAs in consecutive transmissions, thus eliminating many or all guard periods and reducing overload. of the preamble. A single preamble (or pilot transmission) can be used for multiple consecutive transmissions from the same STA to different destination STAs. Additional efficiency can be obtained through the consolidation recorded. In an exemplary embodiment, several registers can be consolidated in a control channel, examples of which are detailed below. In one example, the AP may transmit to multiple destination STAs a signal that includes registration messages to assign TXOP. In contrast, in 802.11 (e), each TXOP is preceded by a CF-Register from the AP followed by a SIFS.

An increased efficiency is obtained when several of said CF-Register messages are consolidated into a single control channel message (referred to as a SCHED message in an exemplary mode, which is detailed below) used to assign several TXOPs. In a general modality, any period of time can be assigned to consolidated records and their respective TXOPs. An exemplary embodiment with respect to Figure 15 is detailed below, and additional examples are also included. A control channel message (i.e., SCHED) can be encoded with a stepped speed structure to further improve efficiency. Accordingly, a registration message to any STA can be encoded according to the quality of the channel between the AP and the STA. The order of the transmission of the registration messages does not have to be the order of the assigned TXOPs, but they can be ordered according to the robustness of the coding. Figure 13 shows the physical layer transmission (PHY) segment 1300, which illustrates the consolidated registers and their respective TXOPs. The consolidated registers 1310 are transmitted. The registers can be transmitted using a control channel structure, examples of which are detailed in the present invention, or can be transmitted using thousands of alternate techniques, which will be readily apparent to those skilled in the art. The technique. In this example, to eliminate the need for an inter-frame spacing between the registers and any of the forward link TXOPs, the forward link TXOPs 1320 are transmitted directly after the consolidated registers 1310. Subsequent to forward link TXOPs 1320, several reverse link TXOPs 1330A-1330N are transmitted, with GIFS 1340 inserted as appropriate. It can be seen that GIFS do not need to be included when performing transmissions in sequence from an STA (similar to the lack of GIFS requirement for forward link transmissions that emanate from the AP to several STAs). In this example, reverse link TXOPs include TXOP (using DLP, for example) from STA to STA (that is, peer-to-peer). It can be seen that the order of transmission shown is for illustration only.

The forward link and reverse link TXOPs (including peer-to-peer transmission) can be interchanged or interleaved. Some configurations may not result in the elimination of as many spaces as other configurations. Those skilled in the art will readily adapt thousands of alternative embodiments by virtue of the teachings of the present invention.

Figure 14 shows an exemplary embodiment of a method 1400 for consolidating records. The procedure begins in block 1410, where the channel resources are allocated in one or more TXOP. You can display any programming function to perform the TXOP assignment determination. In block 1420, the records are consolidated to assign the TXOPs according to the assignment. In block 1430, the consolidated registers are transmitted to one or more STAs in one or more control channels (ie, the CTRLJ segments of the SCHED message, in an exemplary embodiment that is detailed below). In an alternate modality, any message sending technique can be displayed to transmit the consolidated records. In block 1440, the STAs transmit TXOP according to the assignments recorded in the consolidated registers. Then the process stops. This method can be deployed along with consolidated logging intervals of any length, which can comprise all or part of the beacon interval of the system. The consolidated record can be used intermittently with access based on contention, or legacy record, as described above. In an exemplary mode, the 1400 method can be repeated periodically, or according to other parameters, such as the system load or the data transmission demand. An exemplary embodiment of a MAC protocol illustrating various aspects is detailed with respect to FIGS. 15 and 16. This MAC protocol is further detailed in copending U.S. Patent Applications with Serial Numbers XX / XXX, XXX, XX / XXX, XXX and XX / XXX, XXX (cases number 030428, 030433, 030436) entitled "PILA DE PROTOCOLO DE LAN INAL MBRICA", filed simultaneously with the present, assigned to the assignee of the present invention. A MAC TDD 1500 frame interval is illustrated in FIG. 15. The use of the term TDD MAC frame interval in this context refers to the period of time in which the various transmission segments are defined which are detailed below. The TDD 1500 MAC frame interval is distinguished from the generic use of the term frame to describe a transmission in an 802.11 system. In terms of 802.11, the MAC TDD 1500 frame interval may be analogous to the radio beacon interval or a fraction of the beacon interval. The detailed parameters with respect to Figures 15 and 16 are illustrative only. Those skilled in the art will readily adapt this example to thousands of alternate embodiments, using some or all of the described components, and with various parameter values. The MAC 1500 function is assigned among the following transport channel segments: broadcast, control, forward and reverse traffic (referred to as the downlink phase and the uplink phase, respectively), and random access. In the exemplary mode, a frame interval MAC TDD 1500 is Duplexed by Time Division (TDD) in a time interval of 2 ms, divided by five segments of transport channel 1510-1550 as shown. In alternate modes, alternate orders and different frame sizes can be displayed. The durations of the assignments in the TDD 1500 MAC frame interval can be quantized at a certain small common time interval. The five exemplary transport channels within the MAC TDD 1500 frame interval include: (a) the Broadcast Channel (BCH) 1510, which carries the Broadcast Control Channel (BCCH); (b) the Control Channel (CCH) 1520, which carries the Frame Control Channel (FCCH) and the Random Access Feedback Channel (RFCH) in the forward link; (c) the Traffic Channel (TCH), which carries the data and user control information, and is subdivided into (i) the Advance Traffic Channel (F-TCH) 1530 on the forward link and ( ii) the Reverse Traffic Channel (R-TCH) 1540 in the reverse link; and (d) the Random Access Channel (RCH) 1550, which carries the Access Request Channel (ARCH) (for UT access requests). A pilot beacon is also transmitted in segment 1510. The downlink phase of frame 1500 comprises segments 1510-1530. The uplink phase comprises segments 1540-1550. Segment 1560 indicates the start of a TDD MAC frame interval. The following illustrates an alternate modality that encompasses peer-to-peer transmission. The Broadcast Channel (BCH) and the 1510 beacon are transmitted by the AP. The first portion of the BCH 510 contains common physical layer overload, such as pilot signals, including frequency acquisition and timing pilot. In an exemplary embodiment, the beacon consists of 2 short OFDM symbols used for timing and frequency acquisition by the UTs followed by 8 short OFDM common MIMO pilot symbols used by the UTs to calculate the channel. The second portion of the BCH 1510 is the data portion. The data portion BCH defines the mapping of the TDD MAC frame interval with respect to the segments of the transport channel: CCH 1520, F-TCH 1530, R-TCH 1540 and RCH 1550, and also defines the composition of the CCH with respect to the sub-channels. In this example, the BCH 1510 defines the coverage of the wireless LAN 120, and is therefore transmitted in the most robust data transmission mode available. The length of the entire BCH is fixed. In an exemplary embodiment, the BCH defines the coverage of a MIMO WLAN, and is transmitted in the Space-Time Transmission Diversity (STTD) mode using the Binary Phase Displacement Transmission (BPSK) encoded at 1/4 of speed. In this example, the length of the BCH is fixed to 10 short OFDM symbols. In alternative modalities, other signaling techniques can be displayed. The control channel (CCH) 1520, transmitted by the AP, defines the composition of the remainder of the TDD MAC frame interval, and illustrates the use of the consolidated registers. The CCH 1520 is transmitted using highly robust transmission modes in multiple sub-channels, each sub-channel with a different data rate. The first sub-channel is the most robust and it is expected that it can be decoded by all the UT. In an exemplary embodiment, the BPSK encoded at 1/4 speed is used for the first CCH sub-channel. Other sub-channels with less robustness (and greater efficiency) are also available. In an exemplary mode, up to three additional sub-channels are used. Each UT tries to decode all the sub-channels in order until the decoding fails. The segment of the transport channel CCH in each frame is of variable length, the length depends on the number of messages of the CCH in each sub-channel. The acknowledgments for the reverse link random access bursts are carried in the (first) most robust sub-channel of the CCH. The CCH contains assignments of physical layer bursts in forward and reverse links, (analogous to consolidated records for TXOP). Assignments can be for the transfer in the forward or reverse link. In general, a physical layer burst assignment comprises (a) a MAC ID; (b) a value indicating the start time of the assignment within the frame (in the F-TCH or the R-TCH); (c) the length of the assignment; (d) the length of the overload of the dedicated physical layer; (e) the mode of transmission; and (f) the coding and modulation scheme to be used for the physical layer burst. Other types of assignment examples in the CCH include: an assignment in the reverse link for the transmission of a dedicated pilot from a UT, or an assignment in the reverse link for the transmission of link state and buffer information from a UT. The CCH can also define portions of the frame that are to be left unused. These unused portions of the frame can be used by UTs to make noise threshold calculations (and interference) as well as to measure radio beacons from neighboring systems. The Random Access Channel (RCH) 1550 is a reverse link channel over which a UT can transmit a random access burst. The variable length of the RCH is specified for each frame in the BCH The Advance Traffic Channel (F-TCH) 1530 comprises one or more bursts of physical layer transmitted from the AP 104. Each burst is directed to a particular MAC ID, as indicated in the CCH assignment. Each burst comprises dedicated physical layer overload, such as a pilot signal (if any) and a MAC PDU transmitted according to the transmission mode and the coding and modulation scheme indicated in the CCH mapping. The F-TCH is of variable length. In an exemplary embodiment, the dedicated physical layer overload may include a dedicated MIMO pilot. An exemplary MAC PDU is detailed with respect to Figure 16. The Reverse Traffic Channel (R-TCH) 1540 comprises the physical layer burst transmissions from one or more UT 106. Each burst is transmitted by a particular UT such as it is indicated in the CCH assignment. Each burst may comprise a dedicated pilot preamble (if any) and a MAC PDU transmitted in accordance with the transmission mode and the coding and modulation scheme indicated in the CCH assignment. The R-TCH is of variable length. In the exemplary embodiment, the F-TCH 530, the R-TCH 540, or both, may use multiple code division or spatial multiplexing access techniques to allow simultaneous transmission of MAC PDUs associated with different UTs. A field containing the MAC ID with which the MAC PDU is associated (ie, the sender in the uplink, or the intended recipient in the downlink) can be included in the header of the MAC PDU. This can be used to resolve any addressing ambiguities that might arise when using spatial multiplexing or CDMA. In alternate modes, when multiplexing is strictly based on time division techniques, the MAC ID in the MAC PDU header is not required, because the addressing information is included in the CCH message that assigns a period of time. of time determined in the MAC TDD frame interval to a specified MAC ID. Any combination of spatial multiplexing, code division multiplexing, time division multiplexing, and any other known technique can be displayed. Figure 16 shows the formation of an exemplary MAC 1660 PDU from a pack 1610, which may be an IP datagram or an Ethernet segment, in this example. Sizes and exemplary types of fields are described in this illustration. Those skilled in the art will recognize that other sizes, types and configurations are contemplated within the scope of the present invention. As shown, the data packet 1610 is segmented into an adaptation layer. Each adaptation sub-layer PDU 1630 carries one of these segments 1620. In this example, the data packet 1610 is segmented into N segments 1620A-N. An adaptation sub-layer PDU 1630 comprises a payload 1634 containing the respective segment 1620. A field of type 1632 (one byte in this example) is appended to the adaptation sub-layer PDU 1630. A Link header Logic (LL) 1642 (4 bytes in this example) is appended to payload 1644, which comprises the adaptation layer PDU 1630. Exemplary information for the LL 1642 header includes a stream identifier, control information, and numbers of sequence. A CRC 1646 is calculated on the header 1642 and payload 1644, and appended to form a logical link sub-layer PDU (LL PDU) 1640. The Logical Link Control (LLC) PDUs and the Link Control Radio (RLC) can be formed in a similar manner.

The LL 1640 PDUs, as well as the LLC PDUs and RLC PDUs are placed in queues (for example, a high QoS queue, a best effort queue, or control message queue) for service by a MUX function. A MUX header 1652 is appended to each LL PDU 1640. An exemplary MUX header 1652 may comprise a length and a type (the 1652 header has two bytes in this example). A similar header can be formed for each control PDU (ie, LLC PDU and RLC). The LL 1640 PDU (or LLC or RLC PDU) forms the payload 1654. The header 1652 and the payload 1654 form the MUX sub-layer PDU (MPDU) 1650 (the MUX sub-layer PDUs are also referred to as the PDU MUX in the present invention). The communication resources in the shared medium are assigned by the MAC protocol in a series of TDD MAC frame intervals, in this example. In alternate modes, examples of which are detailed below, these types of TDD MAC frame ranges can be interleaved with other MAC functions, including those based on contention or registered, and including interface connection with legacy systems using other types of access protocols. As described above, a programmer can determine the size of physical layer bursts allocated for one or more MAC IDs in each TDD MAC frame interval (analogous to consolidated registered TXOPs). It can be seen that not all MAC IDs with data to be transmitted will necessarily be allocated space in some particular TDD MAC frame interval. Any programming scheme or access control can be displayed within the scope of the present invention. When an assignment is made for a MAC ID, a respective MUX function for that MAC ID will form a MAC PDU 1660, including one or more MUX PDU 1650 for inclusion in the TDD MAC frame interval. One or more MUX PDUs 1660, for one or more assigned MAC IDs, will be included in a TDD MAC frame interval (ie, TDD 1500 MAC frame interval, which was detailed above with respect to FIG. 15). In an exemplary embodiment, one aspect allows the transmission of a partial 1650 MPDU, enabling efficient packing on a 1660 MAC PDU. In this example, the non-transmitted bytes of any partial 1650 MPDUs that remained from a previous transmission can be included, identified by the partial MPDU 1664. These 1664 bytes will be transmitted before any new 1666 PDU (ie, LL PDU or control PDU) in the current frame. Heading 1662 (two bytes in this example) includes a MUX flag, which indicates the start of the first new MPDU (MPDU 1666A in this example) to be transmitted in the current frame. The header 1662 may also include a MAC address. The MAC PDU 1660 comprises the MUX indicator 1662, a possible partial MUX PDU 1664 at the start (remaining from a previous assignment), followed by zero or more complete MUX PDUs 1666A-N, and a possible partial MUX PDU 1668 (from the current assignment) or other compensation, to fill the allocated portion of the physical layer burst. The MAC 1660 PDU is carried in the physical layer burst assigned to the MAC ID. Therefore, the exemplary MAC PDU 1660 illustrates a transmission (or frame, in 802.11 terminology), which can be transmitted from one STA to another, including data portions of one or more streams directed to that destination STA. Efficient packaging is achieved with the optional use of partial MUX PDUs. Each MAC PDU can be transmitted in a TXOP (using 802.11 terminology), at a time indicated in the consolidated record included in the CCH. The exemplary embodiment detailed in Figures 15-16 illustrates various aspects, including consolidated records, reduced preamble transmission, and elimination of spaces by bursts of physical layer that are transmitted in sequence from each STA (including the AP). These aspects can be applied to any MAC protocol, including 802.11 systems. Below are alternative modalities that illustrate other techniques to achieve MAC efficiency, and that also support peer-to-peer transmission and integration with and / or cooperation with legacy protocols or existing systems. As described above, various embodiments detailed in the present invention may employ channel calculation and adjusted speed control. Improved MAC efficiency can be obtained by minimizing unnecessary transmission in the medium, but inadequate speed control feedback can, in some cases, reduce overall throughput. Therefore, sufficient opportunities can be provided for channel calculation and feedback to maximize the transmitted speed in all MIMO modes, to avoid loss of performance due to inadequate channel calculation, which can compensate for any MAC efficiency gains. Therefore, as described above, and as detailed below, exemplary MAC modalities can be designed to provide sufficient preamble transmission opportunities, as well as opportunities for receivers to provide speed control feedback to the transmitter. In one example, the AP periodically intersperses the MIMO pilot in its transmissions (at least every TP ms, where TP can be a fixed or variable parameter). Each STA can also start its registered TXOP with a MIMO pilot that can be used by other STAs and the AP to calculate the channel. In the case of a transmission to the AP or other STA using the Direct Link Protocol (detailed below), the MIMO pilot can be a reference oriented to help simplify the processing of the receiver in the destination STA. The AP can also provide opportunities for the destination STA to provide ACK feedback. The destination STA can also use these feedback opportunities to provide speed control feedback for the MIMO modes available for the transmission STA. Said speed control feedback is not defined in legacy 802.11 systems, including 802.11 (e). The introduction of MIMO can increase the total amount of speed control information (per MIMO mode). In some cases, to maximize the benefit of improvements in MAC efficiency, these can be supplemented by adjusted speed control feedback. Another aspect introduced here, and that is detailed below, is the information of pending orders and programming for STA. Each STA can start its TXOP with a preamble followed by a requested duration of the next TXOP. This information is intended for the AP. The AP collects the information in the next requested TXOP from several different STAs and determines the duration allocation in the middle of the TXOPs for a subsequent TDD MAC frame interval. The AP can use different priority or QoS rules to determine how to share the medium, or it can use very simple rules to proportionally share the medium according to the requests of the STAs. You can also deploy any other programming technique. The assignments for the TXOPs for the next TDD MAC frame interval are assigned in the subsequent control channel message from the AP.

Designated access point In embodiments that are detailed in the present invention, a network can support the operation with or without a true access point. When a true AP is present, it may be connected, for example, to a wired thick pipe connection (i.e., cable, fiber, DSL, or T1 / T3, Ethernet) or a local entertainment server. In this case, the real AP can be the source and collector for most of the data that flows between devices in the network. When there is no true AP, the stations can still communicate with each other using techniques such as Distributed Coordination Function (DCF) or 802.11b / g / a or Enhanced Distributed Channel Access from 802. lie, as described above. As detailed below, when additional resources are required, a more efficient use of the medium can be achieved with a centralized programming scheme. This network architecture could arise, for example, in a house where many different devices need to communicate with each other (ie, DVD-TV, CD-Amplifier-Speakers, etc.). In this case, network stations automatically designate a station to become the AP. It can be seen that, as detailed below, an Adaptive Coordination Function (ACF) can be used with a designated access point, and can be deployed with centralized programming, random access, communications on purpose for the case, or any combination of them. Some, but not necessarily all, non-AP devices may have improved MAC capability and are convenient for operation as a designated AP. It should be noted that not all devices need to be designed to support a designated MAC AP capability. When QoS (for example, guaranteed latency), high performance, and / or efficiency are critical, it may be necessary for one of the devices in the network to have the capacity for a designated AP operation. This means that the designated AP capacity will generally be associated with devices with higher capacity, for example, with one or more attributes such as one power per line, a large number of antennas and / or transmission / reception chains, or a performance requirement high. (Additional factors for the selection of a designated PA are listed below). Therefore, a low quality device such as a camera or low quality phone needs not to be charged with designated AP capacity, while a high quality device such as a high quality video source or a high video screen definition can be equipped with designated AP capability. In a network without AP, the designated AP assumes the function of the true AP and may or may not have reduced functionality. In several modalities, a designated AP may execute the following: (a) establish the ID of the Basic Network Services Set (BSS); (b) setting the network timing by transmitting network configuration information of a broadcast channel (BCH) and radio beacon (the BCH can define the composition of the medium to the next BCH); (c) manage the connections by programming network transmissions in the network using the Advance Control Channel (FCCH); (d) manage the association; (e) provide admission control for QoS flows; and / or (f) other functions. The designated AP can run a sophisticated scheduler, or any type of programming algorithm. A simple programmer can be displayed, an example of which is detailed below. The following is a modified header of the Physical Capability Convergence Protocol (PLCP) with respect to peer-to-peer communications, which can also be applied to designated APs. In one embodiment, the PLCP header of all transmissions is transmitted at the basic data rate that can be decoded by all stations (including the designated AP). The PLCP header of transmissions from stations contains pending data orders at the station associated with a given flow priority. Alternatively, this contains a request for duration of a subsequent transmission opportunity for a given priority or flow. The designated AP can determine the pending orders or the durations of the transmission opportunities requested by the "sniffing" stations in the PLCP Headers of all station transmissions. The designated AP can determine the fraction of time to be allocated to access based on EDCA (distributed access) and the fraction of time allocated to registered (centralized) access free of contention based on load, collisions or other measures of congestion. The designated AP may run a rudimentary programmer that allocates bandwidth in proportion to the requests and the programs in the contention-free period. Improved programmers are allowed but are not required. Scheduled transmissions can be announced by the designated AP on the CCH (control channel). An AP designated to echo the transmission from one station to another station (ie, serve as a jump point) may not be required, although this is functionally allowed. A true AP has the ability to echo. When a designated access point is selected, a hierarchy can be created to determine which device should serve as the access point. Exemplary factors that may be incorporated in the selection of a designated access point include the following: (a) user cancellation; (b) higher preference level; (c) security level; (d) capacity: energy per line; (e) capacity: number of antennas; (f) capacity: maximum transmission power; (g) breaking a link based on other factors: Control of Medium Access Control (MAC); (h) ignition of the first device; (i) any other factors. In practice, it may be desirable for the designated AP to be centrally located and have the best added SNR Rx CDF (ie, that it can receive all stations with a good SNR). In general, the more antennas a station has, the better reception sensitivity will be. In addition, the designated AP may have a higher transmission power so that the designated AP can be heard by a large number of stations. These attributes can be evaluated and exploited to allow the network to dynamically reconfigure as stations are added and / or moved. Peer-to-peer connections can be supported in cases where the network is configured with a true AP or a designated AP. The peer-to-peer connections, in general, are detailed in the next section. In one modality, two types of peer-to-peer connections can be supported: (a) managed para-pair, where the AP programs the transmissions for each station involved; and (b) purposely for the case, where the AP is not involved in the management or programming of the transmissions of the stations. The designated AP can configure the MAC frame interval and transmit a beacon at the beginning of the frame. The control and broadcast channels can specify the durations assigned in the frame for the stations to transmit. For stations that have requested assignments for peer-to-peer transmissions (and these requests are known as the AP), the AP can provide scheduled assignments. The AP can announce these assignments in the control channel, such as, for example, with each MAC frame. Optionally, the AP may also include an A-TCH segment (incidentally for that matter) in the MAC frame (which is detailed below). The presence of the A-TCH in the MAC frame can be indicated in the BCH and FCCH. During the A-TCH, stations can engage par-apar communication using CSMA / CA procedures. The CSMA / CA procedures of the IEEE 802.11 Wireless LAN Standard can be modified to exclude the requirement for the immediate ACK. A station can transmit a PDU-MAC (Protocol Data Unit) consisting of multiple LLC-PDUs when the station takes the channel. The maximum duration that can be occupied by a station in the A-TCH can be indicated in the BCH. For the recognized LLC, the window size and the maximum recognition delay can be negotiated according to the required application delay. A modified MAC frame with an A-TCH segment, for use with both true APs and designated APs, is detailed below with respect to FIG. 20. In one embodiment, the non-oriented MIMO pilot may allow all stations to know the channel between themselves and the transmission station. This can be useful in some scenarios. In addition, the designated AP can use the non-oriented MIMO pilot to allow the calculation of the channel and facilitate the demodulation of the PCCH from which the assignments can be derived. Once the designated AP receives all the requested assignments in a given MAC frame, it can schedule the assignments for the subsequent MAC frame. It can be seen that the speed control information does not have to be included in the FCCH. In a modality, the programmed one can execute the following operations: First, the programmer collects all the requested assignments for the next MAC frame and calculates the requested requested aggregate (Total Requested). Second, the programmer calculates the total available resource for allocation to F-TCH and R-TCH (Total Available). Third, if the Requested Total exceeds the Available Total, all requested allocations are scaled by the ratio defined by Total Available / Total Requested. Fourth, for any escalated assignments that are less than 12 OFDM symbols, these assignments are increased to 12 OFDM symbols (in the exemplary mode, alternative modalities with alternate parameters can be displayed).

Fifth, to accommodate the resulting assignments in the F-TCH + R-TCH, any excess OFDM symbols and / or guard times can be accommodated by reducing all assignments that are greater than 12 OFDM symbols, one symbol at a time in form circular starting with the largest. An example illustrates the modality just described. Consider assignment requests in the following way: 20, 40, 12, 48. Therefore, Total Requested = 120. Assume that the Available Total = 90. Also assume that the required guard time is 0.2 OFDM symbols. Then, as detailed in the third previous operation, the scaled assignments are: 15, 30, 9, 36. As detailed in the fourth operation above, an allocation of 9 is increased to 12. According to the fifth operation, the sum of the revised assignments and the guard time produces a total allocation of 93.8. This means that the assignments will be reduced by 4 symbols. When starting with the largest one, and removing one symbol at a time, a final assignment of 14, 29, 12, 34 (that is, a total of 89 symbols and 0.8 symbols for guard times) is determined. In an exemplary mode, when the designated AP is present, it can establish the beacon for the BSS and set the network timing. The devices are associated with the designated AP. When two devices associated with a designated AP require a QoS connection, for example, an HDTV link with a requirement of low latency and high performance, they provide the traffic specification to the AP designated for admission control. The designated AP can support or deny the connection request. If the use of the medium is low enough, the entire duration of the medium between radio beacons can be reserved for the EDCA operation using CSMA / CA. If the EDCA operation is running smoothly, for example, there are no excessive collisions, setbacks and delays, the designated AP does not need to provide a coordination function. The designated AP can continue to monitor the use of the medium by listening to the PLCP headers of station transmissions. Based on the observation of the environment, as well as pending orders or transmission opportunity length requests, the designated AP may determine the time when the EDCA operation is not satisfying the QoS required of the admitted flows. For example, it can observe the trends in pending orders reported or durations requested, and compare them against the expected values based on the admitted flows.

When the designated AP determines that the required QoS is not being met under distributed access, it may change the operation in the middle to the operation with registration and programming. The latter provides more deterministic latency and greater efficiency of performance. Examples of such operation are detailed below. Therefore the adaptive transition from EDCA (distributed access scheme) to programmed (centralized) operation can be deployed as a function of observing the use of the medium, collisions, congestion, as well as the observation of opportunity requests of transmission from the transmission stations and the comparison of the requests against the admitted QoS flows. As mentioned above, in any embodiment detailed in the present invention, where the access point is described, those skilled in the art will recognize that the mode may be adapted to operate with a true access point or designated access point. A designated access point may also be displayed and / or selected as detailed herein, and may operate in accordance with any protocol, including protocols not described in this description, or any combination of protocols.

Pair-to-pair transmission and direct link protocol (DLP) As described above, peer-to-peer (or simply called "parpar") transmissions allow an STA to transmit data directly to another STA, without first sending the data to an AP. In the present invention, various aspects that can be adopted for use with peer-to-peer transmission are detailed. In one modality, the Direct Link Protocol (DLP) can be adapted as detailed below. Figure 17 shows an example of peer-to-peer communication within a system 100. In this example, the system 100, which may be similar to the system 100 shown in Figure 1, is adapted to allow direct transmission of one UT to another (in this example the transmission between UT 106A and UT 106B is illustrated). The UT 106 may execute any combination directly with an AP 104 on the WLAN 120, as described in the present invention. In several exemplary embodiments, two types of pair-pair connections can be supported: (a) managed peer-pair, wherein the AP schedules the transmissions for each STA involved, and (b) purposely for the case, wherein the AP is not involved in the management or programming of STA transmissions. One modality can include either or both types of connections. In an exemplary embodiment, a transmitted signal may comprise a portion that includes common information that can be received by one or more stations, possibly including an access point, as well as information specifically formatted for reception by a peer-to-peer receiving station. . The common information can be used for programming (as shown in figure 25, for example) or for contention backspace through several neighboring stations (shown in figure 26, for example). Several exemplary embodiments, which are detailed below, illustrate closed-loop velocity control for pair-pair connections. Said speed control can be deployed to take advantage of the high data rates available. For clarity of the analysis, several functions (ie, recognition) are not necessarily detailed in the exemplary modalities. Those skilled in the art will recognize that the functions described herein can be combined to form any number of sets or subsets in various modalities. Figure 18 shows a physical layer burst 1800 of the prior art. A preamble 1810 can be transmitted, followed by a Physical Layer Convergence Protocol Header (PLCP) protocol 1820. The 802.11 legacy systems define a PLCP header to include the rate type and the modulation format for data transmitted as data symbols 1830. Figure 19 shows an exemplary physical layer burst 1900, which can be deployed for a peer-to-peer transmission. As shown in Figure 18, preamble 1810 and PLCP header 1820 may be included, followed by a peer-to-peer transmission, labeled P2P 1940. P2P 1940 may comprise a MIMO pilot 1910 for use by the receiving UT. The MIMO 1920 speed feedback may be included for use by the receiving UT in future transmissions back to the UT that it sends. The speed feedback may be generated in response to a previous transmission from the receiving station to the transmitting station. The data symbols 1930 can be transmitted according to the selected speed and the modulation format for the peer-to-peer connection. It can be seen that a burst of physical layer, such as the PHY 1900 burst, can be used with a pair-pair connection managed by the AP, as well as with a pair-to-pair transmission on purpose for that matter. Exemplary velocity feedback modalities are described below. Alternative modes of physical layer transmission bursts including these aspects are also included below. In an exemplary embodiment, an AP sets the TDD MAC frame interval. The control and broadcast channels can be displayed to specify the assigned durations in the TDD MAC frame interval. For STAs that have requested assignments for peer-to-peer transmissions (and known as the AP), the AP can provide scheduled assignments and announce them on the control channel every MAC TDD frame interval. An exemplary system is described in Figure 15. Figure 20 shows an exemplary modality of a TDD 2000 MAC frame interval that includes a segment on purpose for the optional case, identified as A-TCH 2010. Sections with equal numbering of the TDD 2000 MAC frame range can be included as operational , substantially as described above with respect to Figure 15. The presence of the A-TCH 2010 in the TDD 2000 MAC frame interval can be indicated in the BCH 510 and / or CCH 520. During the A-TCH 2010, the STAs they can establish peer-to-peer communication using any containment procedure. For example, 802.11 techniques such as SIFS, DIFS, backspace, etc., can be displayed, as detailed above. QoS techniques, such as those introduced in 802.11 (e) (ie, AIFS), can optionally be deployed. Other schemes based on containment can also be displayed. In an exemplary embodiment, the CSMA / CA procedures for containment, such as those defined in 802.11, can be modified in the following manner. An immediate ACK is not required. An STA can transmit a MAC Protocol Data Unit (PDU-MAC) consisting of multiple PDUs (ie PDU-LLC) when it takes the channel. In the BCH, a maximum duration occupied by an STA in the A-TCH can be indicated. When the recognized transmission is desired, a maximum recognition delay and window size can be negotiated according to the required application delay. In this example, the F-TCH 530 is the portion of the MAC TDD frame interval for transmissions from the AP to the STAs. Peer-to-peer communications between STAs that use containment techniques can be performed on the 2010 A-TCH. Peer-to-peer communications scheduled between the STAs can be performed on the R-TCH 540. Any of these three segments can be set to null. Figure 21 shows an exemplary physical layer burst 2100, also referred to as a "PHY burst". The PHY 2100 burst can be deployed with programmed peer-to-peer connections, such as during R-TCH 540, or during purposeful connections for the case such as A-TCH 2010, as detailed above with respect to FIG. 20. PHY burst 2100 comprises a non-oriented MIMO pilot 2110, Common Pair Control Channel (PCCH) 2120, and one or more data symbols 2130. The non-oriented MIMO pilot 2110 may be received at one or more stations, and can be used as a reference by a receiving station to calculate the respective channel between the transmitting station and the receiving station. This exemplary PCCH comprises the following fields: (a) a destination MAC-ID, (b) an allocation request for the desired transmission duration for the nTDD MAC frame interval, (c) a transmission rate indicator for indicate the transmission format for the current data packet, (d) a control channel sub-channel (ie, CCH) to receive any assignment from the AP, and (e) a CRC. The PCCH 2120, together with the non-oriented MIMO pilot 2110, is a common segment that can be received by several listening stations, including the access point. A request for assignment can be inserted into the PCCH to allow a peer-to-peer connection in a future TDD MAC frame interval. Said burst PHY may be included in a connection purposely for the case, and may continue to request a peer-to-peer mapping programmed in a future TDD MAC frame interval. In exemplary mode, the non-oriented MIMO pilot is eight OFDM symbols (in alternate modes, which are detailed below, fewer symbols may be sufficient for the channel calculation) and the PCCH is two OFDM symbols. Following the common segment, comprising the non-oriented MIMO pilot 2110 and the PCCH 2120, one or more data symbols 2130 are transmitted using spatial multiplexing and / or higher modulation formats, as determined by each STA in the peer-to-peer connection. . This portion of the transmission is coded according to speed control information incorporated in the transmission data portion. Therefore, a portion of the PHY 2100 burst can be received by multiple surrounding stations, while the actual data transmission is adapted for efficient transmission to one or more specific peer-to-peer stations or to the AP. The data at 2130 can be transmitted as assigned by an access point, or it can be transmitted according to a connection on purpose for the case (ie, procedures based on CSMA / CA containment). An exemplary embodiment of a PHY burst comprises a preamble consisting of 8 OFDM symbols of a non-oriented MIMO reference. A PDU-MAC header of the Common Pair Control Channel (PCCH) is included in the following 2 OFDM symbols, using the STTD mode, coded with R = l / 2 BPSK. The MAC-ID is 12 bits. An 8-bit allocation request is included for reception by the AP for a desired duration in the nTDD MAC frame interval (therefore, the maximum request is 256 short OFDM symbols). The TX speed is 16 bits to indicate the speed that is being used in the current packet. The FCCH sub-channel preference is two bits, which corresponds to a preference between up to four sub-channels, where the AP should make any applicable allocation. The CRC is 10 bits. Any number of other fields and / or field sizes can be included in an alternate PHY burst mode. In this example, the rest of the PDU-MAC transmission uses spatial multiplexing and higher modulations as determined by each STA in the peer-to-peer connection. This portion of the transmission is coded according to the speed control information incorporated in the data portion of the transmission. Figure 22 shows the exemplary method 2200 for pair-pair data transmission. The procedure begins at block 2210 where a station transmits a non-oriented MIMO pilot. In block 2220, the station commonly transmits information that can be decoded. For example, the non-oriented MIMO pilot 2110 and the PCCH 2120 serve as an example of a mechanism for requesting assignment in a managed connection, for which the AP, and another programming station, would need to be able to decode the portion of the signal comprising application. Those skilled in the art will recognize thousands of alternative request mechanisms for programming peer-to-peer connections on a shared channel. In block 2230, the data is transmitted from one station to another according to negotiated transmission formats. In this example, the oriented data is transmitted using velocities and parameters as determined in accordance with the non-oriented MIMO pilot measurements 2110. Those skilled in the art will recognize several alternate means for transmitting data adapted for a specific even-par channel. Figure 23 shows the exemplary method 2300 for peer-to-peer communication. This exemplary method 2300 illustrates various aspects, subsets of which can be displayed in any given mode. The procedure begins in decision block 2310. In decision block 2310, if there is data for STA-STA transfer, it is continued with decision block 2320. If not, continue with block 2370 and execute any another type of communication, including other types of access, if any. Continue with decision block 2360 where the procedure can be repeated by returning to decision block 2310, or the procedure can be stopped. In decision block 2320, if there is data for STA-STA transmission, determine if the parpar connection is to be programmed or purposely for the case. If the transmission is to be scheduled, continue with block 2320 and request an assignment to earn a TXOP. It can be appreciated that an allocation request may be made during a random access portion of a TDD MAC frame interval, as described above, or it may be included in a purposeful transmission for the case. Once the transmission is done, a STA-STA physical burst can be transmitted in block 2350. In an exemplary embodiment, method 2200 can serve as a burst type PHY STA-STA. In decision block 2320, if the programmed torque-pair connection is not desired, continue with block 2340 to fight for access. For example, the segment A-TCH 2010 of the TDD 2000 MAC frame interval can be used. When a successful access through contention has been successfully gained, continue with block 2350 and transmit a PHY STA-STA burst, as shown in FIG. described earlier. From block 2350, continue with decision block 2360 where the procedure can be repeated, as described above, or it can be stopped. Figure 24 shows the exemplary method 2400 for providing speed feedback for use in peer-to-peer connection. This figure illustrates several transmissions and other steps that can be executed by two stations, STA 1 and STA 2. STA 1 transmits a non-oriented pilot 2410 to STA 2. STA 2 measures channel 2420 while receiving non-oriented pilot 2410 In an exemplary embodiment, STA 2 determines a bearable speed for transmission in the channel as measured. This speed determination is transmitted as speed feedback 2430 to STA 1. In several alternate modes, alternate parameters can be delivered to allow a speed feedback decision to be made in STA 1. In 2440, STA 1 receives a programmed assignment or contends for a transmission opportunity, for example, during A-TCH. Once an opportunity to transmit has been gained, at 2450, STA 1 transmits STA 2 data at a speed and modulation format determined in response to the 2430 speed feedback. The method illustrated in Figure 24 can be generalized and applying to various modalities, as will be readily apparent to those skilled in the art. Below are some examples that incorporate torque-pair speed feedback, as well as other aspects. Figure 25 shows the method 2500 illustrating the managed peer-to-peer connection between two stations, STA 1 and STA 2, and an access point (AP). In 2505, STA 1 transmits an unoriented pilot as well as a request for an assignment. Data can also be transmitted according to an early assignment and pre-speed feedback, as will be illustrated below. In addition, any of said data may be transmitted in accordance with the speed feedback of a previous managed pair-pair connection or of a purposeful communication for the case originated either by STA 1 or STA 2. The unoriented pilot and the request Transmission is received by both STA 2 and the access point (and can be received by other stations in the area). The access point receives the transmission request and, according to one of any number of programming algorithms, it makes a determination as to when to make an assignment and whether it should be done for peer-to-peer communication. STA 2 measures the channel while the pilot not oriented on 2505 is transmitted and can make a determination regarding the bearable speed for peer-to-peer communication with STA 1. Optionally, STA 2 can also receive speed feedback and / or data of STA 1 according to a previous transmission. In this example, the access point has determined that an allocation will be made for the requested transmission. At 2515 an assignment is transmitted from the access point to STA 1. In this example, the assignments in the R-TCH 540 are transmitted during the control channel, such as CCH 520, which are illustrated above. Similarly, in 2520 an assignment is made in the R-TCH for STA 2. In 2525, STA 1 receives the access point assignment. At 2530, STA 2 receives the access point assignment. STA 2 transmits speed feedback at 2535, in accordance with assignment 2520. Optionally, a scheduled transmission request may be included, as described above, as well as any data to be transmitted according to a prior request. The transmitted velocity feedback is selected according to the channel measurement 2510, as described above. The PHY burst of 2535 may also include an unoriented pilot. At 2540, STA 1 measures the STA 2 channel, receives the speed feedback, and can also receive optional data. At 2545, according to assignment 2515, STA 1 transmits data in accordance with the received velocity feedback information. In addition, a request can be made for a future assignment as well as for speed feedback according to the channel measurement at 2540. The data is transmitted according to the measurement of the specific channel for peer-to-peer communication. At 2550, STA 2 receives the data as well as any optionally transmitted speed feedback. STA 2 can also measure the channel to provide speed feedback for future transmissions. It can be seen that both 2535 transmissions and 2545 can be received by the access point, at least the non-oriented portion, as described above. Therefore, for any included request, the access point may make additional allocations for future transmissions as indicated by assignments 2555 and 2560 for STA 1 and STA 2, respectively. In 2565 and 2670, STA 1 and STA 2 receive their respective assignments. The procedure can then be repeated indefinitely with the access point managing the access in the shared medium and STA 1 and STA 2 transmitting peer-to-peer communication directly to each other at speeds and modulation formats selected as bearable in the peer-peer channel. It can be seen that, in an alternate modality, a peer-to-peer communication can also be established for the case along with the managed peer-to-peer communication illustrated in Figure 25. Figure 26 illustrates a peer-to-peer connection in containment (or on purpose for that matter). STA 1 and STA 2 will communicate with each other. Other STAs may also be in the reception range and may have access to the shared channel. In 2610, STA 1, which has data to transmit to STA 2, monitors the shared channel and fights for access. Once an opportunity to transmit has been gained, the par-pair 2615 PHY burst is transmitted to STA 2, which can also be received by other STAs. In 2620, other STAs, which monitor the shared channel, can receive the transmission of STA 1 and know how to avoid access to the channel. For example, a PCCH, described above, can be included in transmission 2615. In 2630, STA 2 measures the channel according to an unoriented pilot, and fights for the return access in the shared channel. STA 2 can also transmit data, as necessary. It can be seen that the time of contention can vary. For example, an ACK can be returned after SIFS in a legacy 802.11 system. Because SIFS is of higher priority, STA 2 can respond without losing the channel. Several modalities may allow for less delay, and may provide for the return of data with high priority. In 2635, STA 2 transmits speed feedback along with optional data to STA 1. In 2640, STA 1 receives the speed feedback, fights once again for access to the shared medium, and transmits in 2645 to STA 2 according to the speed feedback received. In 2640, STA 1 can also measure the channel to provide the speed feedback to STA 2 for future transmission, and can receive any optional data transmitted by STA 2. In 2650, STA 2 receives the 2645 data transmission according to the format of modulation and speed determined by the measured channel conditions. STA 2 can also receive speed feedback for use in the return of a transmission to STA 1. STA 2 can also measure the channel to provide future speed feedback. Therefore, the procedure can be repeated by returning to 2635 for STA 2 to return speed feedback as well as data. Therefore, two stations can execute communication purposely for the case in both directions by means of a fight for access. The even-par connection becomes efficient through the use of speed feedback and adaptation of the transmission to the receiving station. When a commonly admissible portion of the PHY burst is deployed, such as the PCCH, then, as illustrated in 2620, other STAs may have access to the information and may avoid interference to it on the occasions when it is known to be busy. , as indicated in the PCCH. With regard to Figure 25, either the managed communication or the purposeful communication for the case can initiate the data transfer before the steps illustrated in Figure 26, and can be used to continue the direct communication. pair later. Thus, any combination of scheduled communication can be displayed on purpose for the even-par case. Figure 27 shows the TDD 2700 MAC frame interval, which illustrates the peer-to-peer communication between stations. In this example, both the duration of the F-TCH and the duration of the A-TCH have been set to zero. Radio beacon / BCH 510 and CCH 520 are transmitted as mentioned above. Radiobaliza / BCH 560 indicates the beginning of the next frame. CCH 520 indicates the assignments for peer-to-peer communications. According to these assignments, STA 1 transmits to STA 2 in assigned burst 2710. It can be seen that, in the same MAC TDD frame interval, STA 2 is assigned segment 2730 to respond to STA 1. Any of the various components, which were detailed above, such as speed feedback, requests, oriented and / or unoriented pilots, and oriented and / or unoriented data may be included in any given par-pair PHY layer burst. STA 3 transmits to STA 4 in assignment 2720. STA 4 transmits to STA 3 in assignment 2740 in a similar way. Other reverse link transmissions can be included in the R-TCH, including connections that are not even-par. Below are additional exemplary modalities that illustrate these and other aspects. It can be seen that, in figure 27, guard intervals can be programmed between segments, as necessary. A key issue with peer-to-peer communications is that the path delay between the two STAs is generally unknown. One method to handle this is to have each STA keep its fixed transmission times so that they reach the AP in synchronization with the AP timer. In this case, the AP can provide guard time on either side of each para-pair assignment to compensate for unknown path delays between the two STAs in communication. In many cases, a cyclic prefix will be adequate and no adjustments will be needed in the STA receivers. The STAs must then determine their respective time offsets to know when to receive the transmission of the other STAs. The STA receivers may need to maintain two reception timers: one for the AP frame timing and another for the peer-to-peer connection. As illustrated in several previous modalities, recognitions and channel feedback can be derived through a receiver during its allocation and feedback to a transmitter. Even if the general traffic flow is unidirectional, the receiver sends reference and requests to obtain assignments. The AP programmer ensures that adequate resources are provided for feedback.

Interoperability with legacy stations and access points As detailed in the present invention, several described modalities provide improvements on legacy systems. However, given the extensive deployment of existing legacy systems, it may be desirable for a system to retain backward compatibility with either an existing legacy system and / or legacy user terminals. As used in the present invention, the term "new class" will be used to make a difference with respect to legacy systems. A new class system may incorporate one or more of the aspects or functions described herein. An example of a new class system is the MIMO OFDM system described below with respect to Figures 35-52. In addition, the aspects detailed below for interoperating a new class system with a legacy system can also be applied to other systems, which are to be developed, whether or not any particular improvement detailed here is included in said system. In an exemplary embodiment, backwards compatibility with alternate systems can be improved by using separate Frequency Assignments (FA) to allow the operation of a new class system in a separate FA of legacy users. Therefore, a new class system can look for an available FA in which to operate. A Dynamic Frequency Selection (DFS) algorithm can be executed on the new class WLAN to accommodate it. It may be desirable to deploy an AP to be multiple carriers. Legacy STAs that try to access a WLAN can use two scanning methods: passive and active. With passive scanning, an STA develops a list of viable Basic Service Sets (BSS) in its vicinity with scarce operating bands. With the active scan, an STA transmits a question to request a response from other STAs in the BSS. The legacy standards are silent with regard to how an STA decides which BSS to join, but, once the decision is made, the association can be attempted. If it is not successful, the STA will move through its BSS list until it succeeds. A legacy STA may not attempt to associate with a new class WLAN when the beacon information transmitted would not be understood by that STA. However, a new class AP (as well as UT) can ignore requests for legacy STAs as a method to maintain a single WLAN class in a single FA. An alternate technique is for new-class APs or new-class STAs to reject any legacy STA request using the valid legacy message (ie, 802.11) message. If a legacy system supports such sending of messages, the legacy STA may be provided with a redirect message. An obvious compensation associated with the operation in separate FAs is the additional spectrum required to support both classes of STA. A benefit is to facilitate the management of the different WLANs by keeping the functions such as QoS and the like. However, as detailed in this description, legacy MAC CSMA protocols (such as those detailed in legacy 802.11 standards) are generally inefficient for high data rates supported for new class systems, such as the legacy mode. MIMO system that is detailed in the present invention. Therefore, it is desirable to deploy backward compatible operation modes that allow a new class MAC to coexist with a legacy MAC in the same FA. The following describes several exemplary modalities in which the legacy and new class systems can share the same FA. Figure 28 shows method 2800 to support both legacy stations and new class stations in the same frequency assignment. In this example, for clarity, it is assumed that the BSS is operating in isolation (ie, there is no coordination between multiple overlapping BSs). The procedure starts in block 2810, where the legacy signaling is used to establish a period free of containment. Below are several illustrative examples, for use with legacy 802.11 systems, where the new class WLAN AP can use the hooks constructed in the legacy 802.11 standard to reserve time for exclusive use by new class stations . Any number of additional signaling techniques may be used, in addition to these, to establish a containment-free period for various types of legacy systems. One technique is to set the containment-free periods (CFP) in PCF / HCF mode. The AP can establish a beacon interval and announce a contention-free period within the beacon interval where it can serve both new class STA and legacy STA in registered mode. This causes all legacy STAs to configure their Network Assignment Vectors (NAV), which are counters used to track the CFP, to the duration of the announced CFP. As a result, the legacy STAs receiving the beacon are prevented from using the channel during the CFP, unless it is registered by the AP. Another technique is to establish a CFP, and configure the NAV, through an RTS / CTS field and duration / ID. In this case, the new class AP can send a special RTS that has a Reserved Address (RA) that tells all new class STAs that the AP is reserving the channel. Legacy STA interprets the RA field as directed to a specific STA and does not respond. The new class STAs respond with a special CTS to clear the BSS for the period of time specified in the duration / ID field in the CTS / RTS message pair. At this point, new class stations are free to use the channel without conflict for the reserved duration. In block 2820, the legacy class STAs, which have received the signal to establish the containment-free period, wait until they are registered or until the containment-free period ends. Therefore, the access point has successfully assigned the shared media for use with the new class MAC protocol. In block 2830, new STAs can have access according to this protocol. Any set or sub-set of the aspects detailed here can be displayed in said new class MAC protocol. For example, programmed forward link and reverse link transmissions, as well as peer-to-peer transmissions, contention-based or purposeful communication (including peer-to-peer), or any combination thereof may be displayed. previous In block 2840, the new class access period ends, using any of a variety of signal types, which may vary according to the legacy system deployed. In exemplary mode, a containment-free end-of-period signal is transmitted. In an alternate mode, legacy STAs can also be registered during a contention-free period. These accesses can be subsequent to the new class accesses, or they can be interspersed within them. In block 2850, all STAs can fight for access, if a containment period is defined for the legacy system. This allows legacy systems, which can not establish communication during the contention-free period, make requests and / or attempt to transmit. In decision block 2860, the procedure may continue to return to block 2810, or it may be stopped. Figure 29 illustrates the combination of new class and legacy media access control. A legacy MAC protocol 2910 is shown above a new class protocol 2930, which, when combined, forms a MAC protocol such as the combined MAC protocol 2950. In this example, 802.11 legacy signaling is used for of illustration. Those skilled in the art will appreciate that the techniques described herein can be applied to any of a variety of legacy systems, and any new class MAC protocol, including any combination of the functions described here. The legacy MAC protocol 2910 comprises radio beacons 2902, which identifies the beacon interval. The legacy beacon interval comprises containment-free period 2904 followed by containment period 2906. A number of containment-free records 2908A-N can be generated during contention-free period 2904. The contention-free period 2904 is terminated by the end of containment-free period 2910. Each beacon 2902 is transmitted on the Target Broadcast Transmission Time (TBTT) in exemplary modes 802.11. The new class MAC protocol 2930 comprises MAC frames 2932A-N. The combined beacon interval 2950 illustrates the interoperability of new class and legacy MAC protocols during contention-free period 2904. The new class TD32 MAC frame intervals are included followed by the CF legacy registers, register 2908A-N . The contention-free period ends with CFPEND 2910, followed by a contention period 2906. The new class TD32 MAC frame intervals 2932 can be of any type, optionally including several aspects detailed herein. In an exemplary embodiment, the new class TDD MAC frame interval 2932 comprises several segments, such as those illustrated with respect to Figure 20 above. Therefore, a new new class TDD MAC frame interval, in this example, comprises the pilot 510, a control channel 520, a forward transmission channel 530, and a peer-to-peer section for the case ( A-TCH) 2010, a reverse link transmission channel 540, and a random access channel 550. It can be seen that, during CFP 2904, legacy STAs should not interfere with any new class WLAN transmission. The AP can register any legacy STAs during the CFP, allowing mixed-mode operation in the segment. In addition, the AP can reserve all of CFP 2904 for new class use and push all legacy traffic to containment period (CP) 2906 near the end of the beacon interval. The exemplary 802.11 legacy standard requires that the CP 2906 be long enough to support an exchange between two legacy terminals. Therefore, the beacon can be delayed, resulting in an instability of the time base in the system. If desired, to mitigate the instability of the time base, the CFP interval can be shortened to maintain a fixed beacon interval. The timers used to stabilize the CFP and the CP can be configured so that the CFP is extended (ie, around 1024 seconds) in relation to the CP (ie, less than 10 msec). However, if during the CFP, the AP registers legacy terminals, the duration of its transmission may be unknown and may cause instability of the additional time base. As a result, care must be taken to maintain the QoS for new class STAs when legacy STAs are accommodated in the same FA. The legacy 802.11 standard synchronizes with the Time Units (TU) of 1,024 msec. The new class MAC can be designed to be synchronous with a legacy system, using a MAC frame length of 2 TU or 2,048 msec, in this example. In some embodiments, it may be desirable to ensure that the new class MAC frame is synchronous. That is, the timer of the MAC frame for the system can be continuous and the limits of the MAC frame, when transmitted, start at multiples of the frame interval of 2048 msec. In this way, sleep mode can easily be maintained for STAs. New class transmissions do not need to be compatible with legacy transmissions. The headings, preambles, etc. may be unique to the new class system, examples of which are detailed in this description. Legacy STAs can try to demodulate the same, but they will not be able to decode properly. Legacy STAs in sleep mode will generally not be affected. Figure 30 shows the 3000 method to gain a transmission opportunity. Method 3000 can be displayed as block 2830 in an exemplary embodiment of method 2800, which was illustrated above. The procedure begins with decision block 3010, where you can program or not schedule an access. Those skilled in the art will appreciate that, although this example illustrates two types of access, in either particular mode one or both of these types of access can be supported. In decision block 3010, if unscheduled access is desired, continue with block 3040 to fight for access. You can display any number of access techniques based on containment. Once a transmission opportunity (TXOP) has been earned, transmit according to the transmission opportunity in block 3050. Then the procedure can be stopped. In block 3010, if a scheduled access is desired, continue with block 3020 to request access. This access request can be made in a random access channel, during containment on purpose for the case, or any of the other techniques described here. In block 3030, when the access request is granted, an assignment will be received. Continue with block 3050 to transmit the TXOP according to the received assignment. In some cases, it may be desirable to accommodate the interoperation between a new class AP, and its associated BSS, with an overlapping legacy BSS, in the same frequency assignment. The legacy BSS may be operating in DCF or PCF / HCF mode, and therefore, synchronization between the new class BSS and the legacy BSS can not always be achieved. If the legacy BSS is operating in PCF or HCF mode, the new class AP may attempt to synchronize with the TBTT. If this is possible, the new class AP may take over the channel during the contention period, using any of several mechanisms, examples of which were described above, to operate within the overlapping BSS area. If the legacy BSS is operating under DCF, the new class AP may also try to seize the channel and announce a CFP to release the channel. There may be situations where some or all of the STAs in the legacy BSS do not receive the transmissions from the new class AP. In this case, those legacy STAs may interfere with the operation of the new class WLAN. To avoid this interference, new class stations can disregard the CSMA-based operation and rely on peer-to-peer transmissions (this is further detailed below with respect to Figures 33-34). Figure 31 shows the exemplary method 3100 for sharing a single FA with multiple BSS. In block 3110, a legacy access point transmits a beacon. A new class access point, which shares the same frequency assignment, can be synchronized with the TBTT associated with the radio beacon (optional). In block 3120, its a period of free legacy containment has been recommended according to the beacon, this is carried out. Once the free containment period is completed, if any, all STAs can fight for access during a prescribed containment period. In block 3130, the new class access point fights for access during the contention period. In block 3140, new class STAs can access the shared media during the period for which the new class access point has fought for access. The types of access during this new class access may include any of the aspects detailed in the present invention. A variety of techniques, such as those detailed above, can be used to indicate to legacy STAs the amount of time by which the access point is reserving the channel. Once this period has been completed, then the legacy STAs can fight in block 3150. In decision block 3160, the procedure can continue to return to block 3110 or it can be stopped. Figure 32 illustrates the overlapping BSS using a single FA. The legacy system 3210 transmits beacons 3205 (3205A and 3205B are shown illustrating the TBTT and the general beacon interval of the legacy system). Beacon 3205A identifies free containment period 3210 and containment period 3215. During free containment period 3210, free legacy containment records 3220A-N can be carried out followed by the free period end indicator. containment 3225. The stations in the new class 3240 WLAN monitor the channel, the reception beacon 3205, and refrain from accessing the media until it receives an opportunity to fight for access. In this example, the earliest opportunity is during the free containment period. After PIFS 3230, the new class access point transmits a legacy signal 3245 to indicate to the legacy stations the amount of time the channel will be occupied. A variety of symbols can be used to perform this function, examples of which were detailed above. Other signals can be displayed, depending on the legacy system with which interoperability is desired. Legacy STAs within the range of reception of legacy signal 3245 may prevent access to a channel until the end of the new class access period 3250. Period 3250 comprises one or more TDD 3260 MAC frame ranges (3260A- N, in this example). The TDD 3260 MAC frame ranges can be of any type, examples of which include one or more of the aspects detailed in the present invention. In an exemplary mode, the new class AP seizes the channel at synchronized intervals (ie, every 40 msec the new class AP seizes the channel by 20 msec). The new class AP can maintain a timer to ensure that it is only retaining the channel for a desired time, thus ensuring the fair distribution of the channel. By seizing the channel, the new class AP can use various signaling techniques. For example, a CTS / RTS or a legacy beacon announcing a new CFP can be transmitted. During the new class 3250 interval, a first exemplary TDD MAC frame interval can be defined as follows: First, send a beacon plus the F-CCH indicating the UTs in the list to be registered in the current MAC frame . After the F-CCH, transmit a section of the MIMO pilot to allow the STAs to acquire and form an accurate measurement of the MIMO channel. In an exemplary embodiment, excellent performance can be achieved with 2 short OFDM symbols per antenna. This implies that the F-TCH in the initial MAC frame can be composed of approximately 8 MIMO pilot symbols. The portion of the R-TCH of the first MAC frame can be structured so that the STAs in the registration list transmit oriented MIMO pilot and a speed indicator (for the downlink) with acknowledgment back to the AP. At this point, in this example, all terminals in the registration list are ready to operate in a normal programmed manner in the next TDD MAC frame interval. The TDD MAC frame intervals following the first TDD MAC frame interval can then be used to exchange data, coordinated by the AP, using any of the techniques described in the present invention. As mentioned above, new class stations may disregard the CSMA-based operation and rely on peer-to-peer transmissions in some situations (for example, situations when some or all of the STAs in the legacy BSS do not receive the AP transmissions). of new class). In such cases, the on / off cycle described above may not be favorable, or it might even be impossible. In these cases, new class stations may neglect the peer-to-peer operation. Figure 33 shows the exemplary method 3300 for executing high-speed peer-peer communication, using various techniques described in the present invention, while there is an interoperation with a legacy BSS. The procedure begins at block 3310, where a first STA having data to send to a second STA fights for access. In block 3320, having successfully fought for access, the station releases the medium using a legacy signal, such as those described above. In block 3330, the first STA transmits a request (together with a pilot) to a second STA. The second STA can measure the channel according to the transmitted pilot. The second STA transmits the channel feedback to the first STA. Therefore, in block 3340, the first station receives a response with channel feedback (speed feedback, for example). In block 3350, the first STA transmits the pilot and the data oriented to the second station, according to the feedback. In block 3360, the second STA can transmit recognition to the first STA, and can transmit continuous velocity feedback for use in additional transmissions. The legacy signal used to release the medium allows the blocks 3330 to 3360 to be carried out using any of the high speed techniques and improvements for the legacy systems, such as those described in the present invention. Once an STA has released the medium, any peer-to-peer MAC protocol can be deployed within the scope of the present invention. The procedure may continue as shown in decision block 3370 returning to block 3310, or the procedure may be stopped. In an exemplary mode, with peer-to-peer mode, the channel capture works in accordance with the legacy rules for CSMA. In this example, PCF and HCF are not used, and do not necessarily have to be a centralized network architecture. When a new class STA wants to communicate with another new class STA (or AP), the STA seizes the channel. The first transmission consists of a sufficient MIMO pilot plus a certain message requesting the establishment of a connection. CTS and RTS can be used to clear the area and reserve time. The message of the requesting STAs must contain the BSS ID of the STAs, the MAC ID of the STAs, and the MAC ID of the target STAs (if known). The response should contain the BSS ID of the responding STA. This allows the STAs to determine if they need to execute receiver correction of the transmission orientation vectors, if the orientation is being used. It can be seen that, in this case, the transmission orientation does not have to be used, although it may be advisable to do so if the STAs have been calibrated with a designated AP that coordinates the BSS. As described with respect to the figure 33, a response may contain MIMO pilot (oriented, if used) plus some indication of speed. Once this exchange has occurred, orientation is possible in each link. However, if the STA belong to different BSS, the first transmission oriented between the STA that initiated the connection may contain MIMO pilot oriented to allow the receiver of the responding STA to correct the phase differential between the different BSS. In this exemplary mode, once the initial exchanges have occurred, orientation is possible. Exchanges should adhere to the SIFS interval between downlink and uplink transmissions. Due to the potential processing delays in calculating the eigenvectors for orientation, this may require that the STAs use the least Mean Square Error (MMSE) processing instead of the eigenvector processing. Once the orientation vectors are calculated, the STAs can start to use the eigenvectors on the transmission side and the reception side can continue to employ the MMSE processing, adapting to the spatially adjusted optical filter solution. Tracking and speed control can be facilitated through periodic feedback between the two STAs. The SIFS interval can be adhered to so that the STAs maintain control over the channel. Figure 34 illustrates peer-to-peer communication using MIMO techniques through the fight over access (that is, not managed) in a legacy BSS. In this example, the start station 106A fights for access in the channel. When it has successfully taken over the channel, the MIMO 3405 pilot is transmitted, followed by the 3410 request. The message can contain the BSS ID, the MAC ID of the start STA and a MAC ID of the target STA, if known . Other signaling may be employed to further clear the channel, such as CTS and RTS. Response STA 106B transmits steered pilot 3420 followed by speed recognition and feedback 3425. Steered pilot 3420 transmits SIFS 3415 followed by request 3410. In exemplary mode, where the legacy access point is an 802.11 access point , calling that SIFS is the highest priority and, therefore, the station that answers 106B will retain control of the channel. The various transmissions that are detailed in Figure 34 can be SIFS transmitted rately from each other to maintain control of the channel until peer-to-peer communication is completed. In an exemplary embodiment, a maximum duration can be determined per channel occupation. The oriented pilot 3430, subsequent to the speed feedback 3425, and the data 3435 are transmitted from the starting STA 106A to the response STA 106B in accordance with the speed feedback. After the data 3435, the response STA 106B transmits oriented pilot 3440 and speed recognition and control 3445. In response, the start station 106A transmits oriented pilot 3450 followed by the data 3455. The procedure may continue indefinitely or until time maximum allowed for channel access, depending on the deployment period. It is not shown in Figure 34 but the response STA can also transmit data and the start station can also transmit speed control. These data segments can be combined with those shown in Figure 34 to maximize efficiency (ie, there is no need to add SIFS between these transmissions). When two or more BSS overlap, it may be desirable to deploy mechanisms that allow the channel to be shared in a coordinated manner. Following are several exemplary mechanisms, along with exemplary operating procedures associated with each. These mechanisms can be deployed in combination. A first exemplary mechanism is Dynamic Frequency Selection (DFS). Before establishing a BSS, WLANs may be required to search for the wireless medium to determine the best Frequency Assignment (FA) to establish operations for the BSS. In the search procedure of the candidate FA, an AP can also create a list of neighbors to facilitate redirection and transfer between APs. In addition, the WLAN can synchronize the MAC frame timing with neighboring BSS (described below). The DFS can be used to distribute the BSS to minimize the need for synchronization between the BSS. A second exemplary mechanism is the synchronization between BSS. During a DFS procedure, an AP can acquire the timing of the neighboring BSS. In general, it may be desirable to synchronize all BSS (in a single FA in one mode, or across multiple FAs in an alternate mode) to facilitate transfer between BSS. However, with this mechanism, at least those BSS operating in the same FA in close proximity to each other synchronize their MAC frames. In addition, if the co-channel BSS are overlapping (that is, the APs can listen to each other), the AP that is just arriving can alert the established AP of its presence and institute a resource allocation protocol, of the following shape. A third exemplary mechanism is a resource allocation protocol. Overlapping BSS in the same FA can share the channel equally. This can be done by altering the MAC frames between the BSSs in some defined way. This allows traffic in any BSS to use the channel without there being any risk of interference from neighboring BSS. The cast can be made between all the overlapping BSSs. For example, with 2 BSSs in overlap, one AP uses MAC frames with even numbering and the other AP uses MAC frames with odd numbering. With 3 BSS in overlap, the cast can be run modulo-3, etc. Alternate modes can display any type of distribution scheme. The control fields in the BCH overload message can indicate whether the resource allocation is enabled and the type of distribution cycles. In this example, the timing for all STAs in the BSS is adjusted to the appropriate partitioning cycle. In this example, the latency will increase with overlapping BSS. A fourth exemplary mechanism is STA-assisted resynchronization. It is possible that two BSS do not listen to each other, but that a new STA in the overlapped area can both. The STA can determine the timing of both BSS and report this to both. In addition, the STA can determine the time offset and indicate which AP should slide its frame timing or by how much. This information has to be propagated to all BSSs connected to the AP and all of them have to reset the frame timing to achieve synchronization. The frame re-synchronization can be announced in the BCH. The algorithm can be generalized to handle more overlapping BSs ignored. Exemplary procedures are detailed below, which can be deployed in one or more of the mechanisms just described. The synchronization can be executed by APs turned on, or at other designated times. The system timing can be determined through the search in all FAs for nearby systems. To facilitate synchronization, a set of orthogonal codes can be used to assist in the discrimination of different APs. For example, APs have known beacons repeated every MAC frame. These radio beacons can be covered with Walsh sequences (for example, of length 16). Therefore, a device, such as an AP or STA, can perform Pilot Intensity Measurements (PSM) of the local APs to determine the overlapping BSSs. As detailed below, active STAs, associated with an AP, can transmit echoes to aid in synchronization. Echoes can use the corresponding timing and coverage for AP coverage. Thus, when the BSS overlap, but the respective APs for these BSS can not detect signals from each other, the echo of an STA can be received by a neighboring AP, thus providing information related to its AP, and a signal with which it can be synchronize the next AP. It can be seen that orthogonal coverage codes can be reused in different FAs. The selection of a Walsh code can be performed deterministically based on a set of undetected Walsh codes (ie, selecting a Walsh code that is not detected in a neighboring AP). If all codes are present, the code corresponding to the weakest Received Signal Level (RSL) can be reused by the new AP. Otherwise, in one modality, the code can be selected in such a way as to maximize the operational point for the AP (see the retraction of operative power for adaptive re-use, which is detailed below). In this example, the frame counters transmitted by each AP are alternated with each other. The alternation used corresponds to the Walsh Code Index. Therefore APO uses the Walsh code 0. APj uses the Walsh j code, and has its frame counter equal to 0 as long as the APO = frame counter. At the time of power-up, or at any time when synchronization is performed, an AP listens to the neighboring AP radio beacons and / or STA echoes. When not detecting neighboring systems, the AP establishes its own time reference. This can be arbitrary, or related to GPS, or any other local time reference. When detecting a single system, local timing is established accordingly. If the AP detects two or more systems that operate with different timelines, the AP can be synchronized with the system with the strongest signal. If the systems are operating in the same frequency assignment (FA), the AP may attempt to associate with the weaker AP to inform it about another nearby AP that is operating in a separate clock. The new AP attempts to inform the weaker AP about the timing bias that is required to synchronize both AP zones. The weakest area AP can then divert its timing. This can be repeated for multiple neighboring APs. The new AP can set its timing with the synchronized timing of the two or more systems. In a situation where all neighboring APs can not, for any reason, be synchronized with a single timing, the new AP can be synchronized with any of the neighboring APs. The dynamic frequency selection can be executed by AP at power-up. As mentioned above, it is typically desirable to minimize the overlap of the BSS with the DFS selection, to minimize the number of BSS requiring synchronization, and any delay or performance reduction that could be associated with the synchronization (i.e. a BSS with access to the entire medium in an FA can be more efficient than a BSS that must share the medium with one or more neighboring BSS). After synchronization, the new AP can select the FA that has the minimum RSL associated with it (that is, when neighboring APs are measured, or during the echo period). Periodically, the AP may ask the STAs for pilot measurements of the AP. Similarly, the AP can schedule periods of silence to allow the assessment of interference levels in the AP caused by STAs in other zones (ie, neighboring BSS). If the RSL levels are excessive, the AP may attempt to find another FA during unscheduled periods, and / or institute a power backout policy, as described below. As described above, APs can be organized according to a pilot cover code. Each AP can use a Walsh sequence cover of length 16, in this example. You can display any number of codes of various lengths. The pilot deck is used to modulate the signal of the beacon during a super-frame period. In this example, the super-frame period is equivalent to 32 ms (ie 16 consecutive MAC frame beacons). The STAs can then be integrated consistently over the superframe range to determine the pilot power associated with a given AP. As mentioned before, an AP can select its Walsh code from the pool of undetected Walsh codes available. If all the codes are detected (in the same FA), then the AP can align these in order from the most intense to the weakest. The AP can reuse the Walsh code that corresponds to the weakest Walsh code detected. To facilitate identification of neighboring APs, STAs can be used to transmit an echo to identify their respective AP. Therefore, as described above, an AP that does not detect a neighboring AP can detect a corresponding STA echo, thus identifying the AP and its timing. Each AP can transmit configuration information on its beacon, and each STA can operate as a relay to retransmit AP configuration information, as well as timing, to any receiving APs. Active STAs may be required to transmit, upon receiving an order from the AP, a predefined pattern that allows neighboring APs to operate on the same FA to detect the presence of the neighboring system. A simple way to facilitate this is to define an observation interval in the MAC frame (for example, between the FCH and RCH segments) that is not used by the AP for any traffic. The duration of the observation interval can be defined to be long enough to handle the maximum differential propagation delay between STAs associated with the AP and STA associated with a neighboring AP (e.g., 160 chips or 2 OFDM symbols). For example, the STAs associated with the AP using the Walsh cover code j can transmit the echo provided their Mac frame counter = 0. The echo is encoded with necessary information to allow neighboring APs to detect presence and coexist efficiently. with STAs in the adjacent AP zone. The structured power retrace can be displayed for adaptive reuse. When a system is congested to the point where each FA must be reused in the vicinity of another AP, it may be desirable to impose a structured power backward scheme to allow terminals in both zones to operate at maximum efficiency. When congestion is detected, power control can be used to improve the efficiency of the system. That is, instead of transmitting at full power all the time, APs can use a structured power backward scheme that is synchronized with their MAC frame counter. As an example, assume that two APs are operating in the same FA. Once APs detect this condition, they can institute a known power backward policy. For example, both APs use a backward scheme that allows full power, Ptot, in the MAC 0 frame, Ptot (15/16) in the MAC 1 frame, ... Ptot / 16 in the MAC 15 frame. that the APs are synchronized, and their frame counters are alternated, no AP zone is using all the power simultaneously. The objective is to select the backward pattern that allows STAs in each AP zone to operate at the highest possible performance. The regression pattern used by a given AP can be a function of the degree of interference detected. In this example, up to 16 known backward patterns can be used by a given AP. The retrace pattern used can be transmitted by the APs in the BCH and in the echoes transmitted by the STAs associated with an AP. An exemplary regression scheme is detailed in U.S. Patent No. 6,493,331, entitled "Method and apparatus for controlling transmissions of a communications system" by Walton et. al, assigned to the assignee of the present invention. In Fig. 53 another exemplary embodiment of a technique for interoperability with legacy systems is shown. An exemplary 1500 MAC frame is shown, as detailed above with respect to FIG. 15. A slotted mode is entered wherein the slot intervals 5310 are defined. A slot slot 5310 comprises a MIMO pilot slot 5315 and a slot slot 5320. The pilots 5315 are inserted, as shown, to reserve the channel against interference from other stations (including APs) that operate in accordance with the rules, such as EDCA. The modified MAC frame 5330 substantially comprises the MAC 1500 frame with inserted 5315 pilots to retain control of the medium. Figure 53 is illustrative only, as will be apparent to those skilled in the art. A slotted mode can be incorporated with any type of MAC frame, several examples of which are detailed in the present invention. In this example, for illustration purposes, assume a legacy 802.11 system that uses MAC frames that are multiples of 1,204 ms. The MAC frame can be configured to be 2,048 ms to be synchronous. In the Target Broadcast Transmission Time (TBTT), a CFP duration is announced for the STAs to configure their NAV. During the CFP, the STAs in the BSS should not transmit unless they were registered. Optionally, as described above, an AP can send an RTS and have the STAs echo an identical CTS to further clear the BSS. This CTS can be a synchronized transmission of all STAs. In this example, the instability of the time base can be eliminated by ensuring that the MAC frames always start in limits of 2,048 ms. This maintains time synchronization between adjacent / overlapping BSS even with reduced TBTT. Other techniques, such as those described above, can be combined with the technique described above. Once the medium is reserved for the modified 5330 MAC frame, using any available technique, the slotted mode can be displayed to maintain the possession of the medium, to prevent a legacy STA from interfering with the scheduled transmissions, thus potentially reducing the gains. of performance of a new class system (ie, one using a scheme such as that shown in Figure 15 or Figure 53, or several others detailed in the present invention). In this example, the new class AP is subject to the CSMA rules to seize the channel. However, before this, he should try to determine the presence of another BSS, either by listening to the beacon, or other STAs. However, synchronization is not required to allow the fair distribution of resources. Once neighboring BSS have been detected, the new class AP can seize the channel by transmitting its beacon. To block other users, the new class AP transmits a pilot with a frequency that prevents other STAs from using the channel (that is, there are no inactive periods longer than PIFS = 25 useg). The new class AP can configure a timer that allows it to occupy the channel for a fixed duration determined to be just. This may be approximately synchronized with the beacon period of the legacy or asynchronous AP (ie, 100 msec every 200 msec). The new class AP can seize the channel at any point during its allowed interval, which can be delayed by the legacy BSS users. The new class AP can drop the channel before its time has expired if there is no traffic to serve. When the new class AP seizes the channel, it has its limited use for a fair period of time. In addition, the timing established by the new class AP may be consistent with the established MAC frame timing. That is, new class radio beacons occur within 2,048 ms of the new class AP clock. In this way, new class STAs can be kept in sync by locking to these specific ranges to determine if the AP HT has taken over the channel. The new class AP can announce its frame parameters in a beacon. Part of the frame parameters may include the separation of the pilot interval indicating the frequency of the pilot transmission through the MAC frame. It can be appreciated that the new class AP can program the STAs so that their transmission overlaps the periodic burst pilot. In this case, the STA whose assignment overlaps, knows this and ignores the pilot during that period. Other STAs do not know this and therefore use a threshold detector to validate if the pilot was transmitted during the prescribed interval. It is possible for an STA to transmit a pilot at the instant in which the AP is supposed to transmit, or that the AP is transmitting pilot oriented to an STA during this interval. To prevent other STAs from using this pilot, thus corrupting their channel calculations, the AP pilot may use Walsh decks that are orthogonal to the common pilot Walsh decks. A structure can be displayed to assign the Walsh decks. For example, when STAs and APs use different Walsh decks, the Walsh space may include 2N decks, with N decks reserved for APs, and the remainder for STAs associated with a given AP using a deck that is docked in a known form with the Walsh cover of the respective AP. When the new class AP transmits an assignment to an STA, the STA is expected to transmit it during the prescribed interval. The STA may fail to receive the assignment, in which case the channel may not be used for a longer interval than PIFS. To prevent this from happening, the AP can detect the channel for t <; SIFS and determine if it is busy. If not, the AP can immediately seize the channel by transmitting the pilot, staggered accordingly. New class channel assignments can be slotted at SIFS intervals (16 useg). In this way, it can be guaranteed that the occupation of the channel will prohibit the passage to legacy users during the exclusive use period of a new class. The RCH should be designed to allow interoperability because the duration of the RCH could exceed 16 useg. If the RCH can not be easily accommodated in a particular mode, the RCH can be assigned to work in the legacy modes when the new class MAC does not have control of the channel (ie coexist in the legacy mode). The F-RCH can be accommodated by allowing STAs to transmit access requests at any time after a pilot transmission (ie, wait 4 useg and transmit during 8 useg), as illustrated in Figure 53.

Exemplary mode: Enhanced 802.11 MIMO WLAN The following is an example mode illustrating several aspects mentioned above, as well as additional aspects. In this example, an enhanced 802.11 WLAN using MIMO is illustrated. Several MAC enhancements are detailed, as well as structures for sending messages and corresponding data for use in the MAC layer and the physical layer. Those skilled in the art will recognize that only an illustrative subset of features of a WLAN is described, and will readily adapt the teaching of the present invention for the interoperability of the 802.11 legacy system, as well as interoperability with other systems. The exemplary mode, which is detailed below, includes interoperability with legacy STA 802.11a, 802. llg as well as with sketch 802. lie and anticipated final standard. The exemplary embodiment comprises a MIMO OFDM AP, so named to be distinguished from the legacy APs. Due to backward compatibility, as detailed below, legacy STAs can be associated with a MIMO OFDM AP. However, the AP OFDM MIMO can explicitly reject an association request from a legacy STA, if desired. The DFS procedures can direct the rejected STA to another AP that supports the legacy operation (which can be a legacy AP or another MIMO OFDM AP). The MIMO OFDM STAs can be associated with a BSS 802.11a or 802. llg or Independent BSS (IBSS) where an AP is not present. Therefore, for said operation, said STA will execute all the obligatory functions of 802.11a, 802. llg as well as the anticipated final draft of 802. lie. When the MIMO and legacy OFDM STAs share the same RF channel, either in a BSS or an IBSS, several functions are supported: the proposed PHY OFDM MIMO spectral mask is compatible with the existing 802.11a, 802. llg spectral mask. that no additional adjacent channel interference is introduced to the legacy STAs. The SIGNAL field extended in the PLCP Header (detailed below) is backwards compatible with the legacy 802.11 SIGNAL field. SPEED values not used in the field of legacy SIGNAL are configured to define new types of PPDUs (which are detailed below). The Adaptive Coordination Function (ACF) (which is detailed below) allows the arbitrary distribution of the medium between the MIMO OFDM and legacy STAs. Periods of EDCA 802. lie, CAP 802. lie and SCAP (which is introduced below) can be arbitrarily interleaved at any beacon interval, as determined by the AP programmer. As described above, a high performance MAC is required to effectively leverage the high data rates allowed by the WIM MIMO physical layer. Below are several attributes of this exemplary MAC mode. Several exemplary attributes are shown below: The adaptation of the transmission modes and PHY speeds effectively exploits the capacity of the MIMO channel. The low-latency service of the PHY provides low end-to-end delays to address the requirements of high-performance applications (eg, multimedia). The low latency operation can be achieved with MAC techniques based on containment at low loads, or using centralized or distributed programming in heavily loaded systems. Low latency provides many benefits. For example, low latency allows a fast speed adaptation to maximize the physical layer data rate. Low latency allows inexpensive MAC execution with small buffers, without binding ARQ. Low latency also minimizes end-to-end delay for multimedia and high-performance applications. Another attribute is the high efficiency of the MAC and the low containment overload. In MACs based on containment, at high data rates, the time occupied by useful transmissions is reduced while an increasing fraction of time is wasted in overloads, collisions and periods of inactivity. Wasted time in the medium can be reduced through programming, as well as through the aggregation of multiple upper layer packages (eg, IP datagrams) into a single MAC frame. Aggregated frames can also be formed to minimize training overload and preamble. The high data rates allowed by the PHY allow for simplified QoS management. The exemplary MAC enhancements, which are detailed below, are designed to address the above performance criteria in a way that is backwards compatible with 802. llg and 802.11a. In addition, support for and improvements to the functions included in the draft standard 802. lie, described above, include functions such as TXOP and the Direct Link Protocol (DLP), as well as the optional Block Recognition mechanism. . In describing the exemplary modalities below, new terminology is used for some concepts introduced earlier. Table 1 details a mapping for the new terminology.

TABLE 1 Flexible Frame Aggregation In this exemplary mode, flexible frame aggregation is facilitated. Figure 35 shows the encapsulation of one or more MAC frames (or fragments) within an aggregated frame. Frame aggregation allows the encapsulation of one or more MAC frames (or fragments) 3510 within an aggregate frame 3520, which may incorporate the compression of the header, which is detailed below. The added MAC frame 3520 forms the PSDU 3530, which can be transmitted as a single PPDU. The aggregate frame 3520 may contain encapsulated frames (or fragments) 3510 of the data type, management or control. When privacy is enabled, the payload of the frame can be encrypted. The header of the MAC frame of an encrypted frame is transmitted "in the clear". This frame aggregation of the MAC level, as just described, allows the transmission of frames with zero IFS or BIFS (Separation Between Burst Frames, which is detailed below) to the same receiving STA. In some applications, it is desirable to allow the AP to transmit frames with zero IFS, or aggregate frames, to multiple receive STAs. This is allowed through the use of the SCHED frame, which is discussed below. The SCHED frame defines the start time of multiple TXOPs. Preambles and IFS can be deleted when the AP makes transmissions backed up to multiple receiving STAs. This is called a PPDU aggregation to be distinguished from the MAC-level frame aggregation. An exemplary aggregate MAC frame transmission (ie, a PPDU) starts with a preamble followed by the PLCM OFDM MIMO HEADER (including a SIGNAL field, which may comprise two SIGNAL 1 and SIGNAL 2 fields), followed by training symbols OFDM MIMO (if any). Exemplary PPDU formats are detailed below with respect to Figures 49-52. The aggregatively added MAC frame adds one or more encapsulated frames or fragments to be transmitted to the same receiving STA. (The SCHED message, which is detailed below, allows the aggregation of TXOP from the AP to multiple receiving STAs). There is no restriction on the number of frames and fragments that can be added. There may be a limit to the maximum size of an aggregate frame that is established through negotiation. Typically, the first and last frames in the aggregate frame can be fragments that are created for efficient packaging. When several encapsulated data frames are included within an aggregated frame, the MAC headers of the data and the QoS data frames can be compressed, as detailed below. The transmission MAC can try to minimize the overloads of PHY and PLCP and the periods of inactivity through the use of the aggregation of flexible frames. This can be achieved by adding frames to eliminate the separation between frames and PLCP headers, as well as the fragmentation of flexible frames, to completely occupy the space available in a TXOP. In an exemplary technique, the MAC first calculates the number of octets to be provided to the PHY based on the current data rate and the duration of the allocated TXOP or based on contention. The fragmented and complete MAC frames can then be packed to occupy the entire TXOP. If a complete frame can not be accommodated in the remaining space in a TXOP, the MAC can fragment the next frame to occupy as many of the remaining octets as possible in the TXOP. Frames can be fragmented arbitrarily for efficient packaging. In an exemplary embodiment, this arbitrary fragmentation is subject to the restriction of a maximum of 16 fragments per frame. In alternate modalities, this limitation may not be required. The remaining fragments of the MAC frame can be transmitted in a later TXOP. In the subsequent TXOP, the MAC can give higher priority to fragments of an incompletely transmitted frame, if desired. An Aggregation Header (2 octets, in this example), which are described below, is inserted into the MAC Header of each encapsulated frame (or fragment) that is inserted into the aggregated frame. A Length field in the Aggregation Header indicates the length (in octets) of the encapsulated MAC frame, and is used by the receiver to extract frames (and fragments) from the aggregated frame. The PPDU Size field in the proposed SIGNAL field provides the size of the MIMO OFDM PPDU transmission (number of OFDM symbols) while the length of each encapsulated MAC frame (in octets) is indicated by the Aggregation Header.

Header Compression of Encapsulated Frames Figure 36 shows a legacy MAC frame 3600, comprising the MAC Header 3660, followed by a frame body 3650 (which may include a variable number of octets, N) and a Verification Symbol of Frame (FCS) 3655 (4 octets, in this example). The MAC frame format of the prior art is detailed at 802. lie. The MAC Header 3660 comprises a frame control field 3610 (2 octets), a duration field / ID 3615 (2 bytes), a sequence control field 3635 (2 bytes), and a QoS 3645 control field (2) bytes). Also included are four address fields, Address 1 3620, Address 2 3625, Address 3 3630, and Address 4 3640 (6 octets each). These addresses can also be referred to as TA, RA, SA and DA, respectively. The TA is the address of the transmission station. The RA is the address of the reception station. The SA is the address of the source station. The DA is the address of the destination station. When several encapsulated data frames are included within an aggregated frame, the MAC headers of the data and the QoS data frames can be compressed. Exemplary compressed MAC headers for QoS data frames are shown in Figures 37-39. It can be seen that the FCS is calculated in the compressed MAC header and the payload (encrypted or unencrypted). As shown in Figure 37-39, when the frames are transmitted using a MIMO Data PPDU (Type 0000), an aggregation header field is entered into the MAC Header 3660 of the MAC 3600 frame to create an encapsulated MAC frame , that is, 3705, 3805 or 3905, respectively. The MAC Header, including the Aggregate Header field, is called the Extended MAC Header (that is, 3700, 3800, or 3900). One or more encapsulated management, control and / or data frames (including QoS data) can be added in an aggregated MAC frame. When data privacy is in use, the payload of the data or the QoS data frames can be encrypted. Aggregation Header 3710 is inserted for each frame (or fragment) inserted in the aggregate frame (3705, 3805, or 3905, respectively). The compression of the header is indicated by the Aggregate Header type field, which is detailed below. The data frame headers and QoS data frames can be compressed to eliminate redundant fields. The aggregate frame 3705, shown in Figure 37, illustrates an uncompressed frame, which includes the four directions and the Duration / ID field. After an aggregated non-compressed frame is transmitted, additional aggregate frames do not need to identify the addresses of the transmit and receive stations, since they are identical. Therefore, Address 1 3620 and Address 2 3625 can be omitted. The Duration / ID field 3615 does not need to be included for subsequent frames in the aggregated frame. The duration can be used to configure the NAV. The Duration / ID field is overloaded based on the context. In Log messages, it contains the Access ID (AID). In other messages, the same field specifies the duration to configure the NAV. The corresponding frame 3805 is illustrated in Figure 38. Additional compression is available when the source address and addresses of the destination station contain duplicate information. In this case, Address 3 3630 and Address 4 3640 can also be deleted, resulting in frame 3905 which is illustrated in Figure 39. When fields are deleted, for decompression, the receiver can insert the corresponding field of the previous heading (after decompression) in the frame. In this example, the first frame in an aggregated frame always uses the uncompressed header. The descriptografla of the payload may require some fields of the MAC Header that could have been removed for the compression of the header. After the decompression of the frame header, these fields may be available for the decryption engine. The Length field is used by the receiver to extract frames (and fragments) from the added frame. The Length field indicates the length of the frame with the compressed header (in octets). After extraction, the field in the Aggregation header is removed. The decompressed frame is then passed to the decryption engine. Fields in MAC headers (unzipped) may be required for verification of message integrity during decryption. Figure 40 illustrates an exemplary Aggregation Header 3710. The Aggregation Header field is added to each frame header (or fragment) for one or more frames (encrypted or unencrypted) that are transmitted in a MIMO Data PPDU. The Aggregation Header comprises a 2-bit Aggregation Header Type field 4010 (to indicate whether header compression is used or not, and what type) and a 12-bit Length field 4030. Type 00 frames do not use compression of heading. Type 01 frames have the Duration / ID, Address 1 and Direction 2 fields removed. Type 10 frames have the same fields removed as type 01 frames, with the Address 3 and Direction 4 fields also removed. The field of Length 4030 in the Aggregation Header indicates the length of the frame in octets with the compressed header. 2 bits are reserved 4020. The types of Aggregation Header are summarized in Table 2.

TABLE 2 Type of Aggregation Header In this exemplary embodiment, all management and control frames that are encapsulated in an aggregated frame use the uncompressed frame header with the Aggregate Header type 00. The following management frames can be encapsulated along with data frames in a aggregate plot: association request, association response, re-association request, re-association response, research request, research response, dissociation, authentication and de-authentication. The following control frames can be encapsulated along with data frames in an aggregated frame: Block Recognition and Block Recognition Request. In alternative modalities any type of frames can be encapsulated.

Adaptive Coordination Function The Adaptive Coordination Function (ACF) is an extension of HCCA and EDCA that allows programmed operation of low latency, highly efficient and flexible, convenient for operation with the high data speeds enabled by PHY MIMO. Figure 41 illustrates an exemplary mode of a Scheduled Access Period Frame (SCAP) for use in the ACF. When using a SCHED 4120 message, an AP can simultaneously program one or more TXOP AP-STA, STA-AP or STA-STA during the period known as the Programmed Access Period 4130. These scheduled transmissions are identified as programmed transmissions 4140. The SCHED message 4120 is an alternative to the HCCA Legacy Registry, which was detailed above. In the exemplary mode, the maximum allowed value of the SCAP is 4 ms. Exemplary programmable transmissions 4140 are shown in figure 41 for illustration, including transmissions from AP to STA 4142, transmissions from STA to AP 4144, and transmissions from STA to STA 4146. In this example, the AP transmits to STA B 4142A, then to STA D 4142B, and then to STA G 4142C. It can be seen that there is no need to enter spaces between these TXOPs, since the source (the AP) is the same for each transmission. The spaces are shown between TXOP when the source changes (exemplary space separations are detailed below). In this illustration, after the AP to STA 4142 transmissions, STA C transmits to AP 4144A, then, after a space, STA G transmits to AP 4144B, and then, after a space, STA E transmits to AP 4144C. A par-to-peer TXOP is then programmed 4146. In this case, STA E remains as the source (transmitting to STA F) so no space is needed to enter if the transmission power of STA E remains unchanged, otherwise a BIFS space can be used.

Additional STA to STA transmissions can be programmed, but they are not shown in this example. Any combination of TXOP can be programmed, in any order. The order of the TXOP types shown is an example only. Although it may be desirable to program TXOP to minimize the number of spaces required, this is not mandatory. The Programmed Access Period 4130 can also contain a FRACH 4150 Period dedicated to the Transmissions of the Rapid Random Access Channel (FRACH) (where an STA can make a request for an assignment) and / or an EDDA OFDM MIMO 4160 period where the STA MIMO can use EDCA procedures. These access periods based on contention are protected by the NAV configured for the SCAP. During the EDDA OFDM MIMO 4160 period, the MIMO STAs use EDCA procedures to access the medium without having to fight with the legacy STAs. Transmissions during any protected contention period use the PLCP MIMO header (detailed below). The AP does not provide TXOP programming during the protected contention period, in this mode. When only STA MIMO is present, the NAV for the SCAP can be configured through a Duration field in the SCHED frame (the SCHED frame is detailed below). Optionally, if the protection of the legacy STAs is desired, the AP may precede the SCHED frame 4120 with a CTS-a-Own 4110 to establish the NAV for the SCAP in all STAs in the BSS. In this modality, the MIMO STAs obey the SCAP limit. The last STA to transmit on a SCAP must terminate its TXOP for the duration of PIFS before the end of the SCAP. STA MIMOs also obey the programmed TXOP limits and complete their transmission before the end of the assigned TXOP. This allows the later scheduled STA to start its TXOP without detecting that the channel is inactive. The message SCHED 4120 defines the program. The TXOP assignments (AP-STA, STA-AP, and / or STA-STA) are included in the elements CTRLJ (4515-4530 in Figure 45, which is detailed below) in the SCHED frame. The SCHED message can also define the portion of SCAP 4100 dedicated to FRACH 4150, if it exists, and a protected portion for operation EDCA 4160, if it exists. If programmed TXOP assignments are not included in the SCHED frame, then all of the SCAP is configured separately for the EDCA transmissions (including any FRACH) protected against the legacy STAs by the NAV configured for the SCAP. The maximum length of TXOPs programmed or based on contention allowed during the SCAP can be indicated in an ACF capability element. In this mode, the length of the SCAP does not change during a beacon interval. The length can be indicated in the ACF capability element. An exemplary ACF element comprises a SCAP Length (10 bits), a Maximum SCOP TXOP Length (10 bits), a Guard IFS Duration (GIFS) (4 bits), and a FRACH RESPONSE (4 bits). The SCAP Length indicates the length of the SCAP for the current beacon interval. The field is encoded in units of 4 μs. The Maximum TXOP SCAP Length indicates the maximum permissible TXOP length during a SCAP. The field is encoded in units of 4 μs. The GIFS Duration is the guard interval between TXOP of consecutive scheduled STAs. The field is encoded in units of 800 ns. The FRACH RESPONSE is indicated in units of SCAP. The AP must respond to a request received using a FRACH PPDU by provisioning the STA with a TXOP programmed within the FRACH RESPONSE SCAP. Figure 42 shows an example of how SCAP can be used together with HCCA and EDCA. In any beacon interval (illustrated with beacons 4210A-C), the AP has complete flexibility to adaptively interchange the access duration based on EDCA contention with the CAP 802. lie and the MIMO OFDM SCAP. Therefore, when using the ACF, the AP can operate as in HCCA, but with the additional ability to assign periods for SCAP. For example, the AP can use CFP and CP as in the PCF, assign a CAP for registered operation as in HCCA, or assign a SCAP for scheduled operation. As shown in Figure 42, in a beacon interval, the AP may use any combination of periods for containment-based access (EDCA) 4220A-F, CAP 4230A-F, and SCAP 4100A-I. (For simplicity, the example in Figure 42 does not show any CFP). The AP adapts the proportion of the medium occupied by different types of access mechanisms based on its programming algorithms and its observations of media occupancy. You can deploy any programming technique. The AP determines whether the admitted QoS flows are being satisfied and can use other observations including the measured occupancy of the means for adaptation. HCCA and associated CAPs were described above. An exemplary exemplary CAP 4230 is shown in Figure 42. An AP TXOP 4232 is followed by a 4234A Register. TXOP HCCA 4236A follows Record 4234A. Another Record 4234B is transmitted, followed by another respective HCCA 4236B TXOP. The EDCA was described above. An exemplary exemplary EDCA 4220 is shown in Figure 42. Several TXOP EDCA 4222A-C are shown. In this example, a CFP is omitted. A SCAP 4100, as shown in Figure 42, may be of the format detailed in Figure 41, including an optional CTS-a-Prop 4110, SCHED 4120, and Programmed Access Period 4130. The AP indicates the operation programmed using the Message of Delivery Traffic Indication (DTIM) in the following way. The DTIM contains a bitmap of Access ID (AID) for which the AP or other STA in the BSS has pending data. Using the DTIM, all STAs with MIMO capability are signaled to remain dormant after the beacon. In a BSS where legacy STA and STA MIMO are present, the legacy STAs are programmed first, immediately after the beacon. Right after the legacy transmissions, the SCHED message is transmitted which indicates the composition of the Programmed Access Period. STAs with MIMO capability not programmed in a particular Scheduled Access Period can remain dormant for the rest of the SCAP and wake up to listen to subsequent SCHED messages. Other operating modes are enabled with ACF. Figure 43 shows an exemplary operation in which each beacon interval comprises a number of SCAP 4100 interleaved with access periods based on containment 4220. This mode allows "fair" sharing of the medium where the MIMO QoS flows are scheduled during the SCAP while flows without MIMO QoS use containment periods along with legacy STA, if present. Interleaved periods allow low latency service for STA MIMO and legacy. As described above, the SCHED message in the SCAP can be preceded by a CTS-a-Own for protection against the legacy STAs. If legacy STAs are not present, no CTS-a-Own (or other legacy clearing signal) is required. The beacon 4210 can be set to a prolonged CFP to protect all SCAPs against any arriving legacy STAs. A CP at the end of the beacon interval allows the legacy STAs arriving to access the medium. The low latency operation optimized with a large number of MIMO STAs can be enabled using the exemplary operation shown in Figure 44. In this example, the assumption is that legacy STAs, if present, only require limited resources. The AP transmits a beacon, establishing a prolonged CFP 4410 and a short CP 4420. A beacon 4210 is followed by any broadcast / multicast messages for the legacy STAs. Then the SCAP 4100s are programmed consecutively. This mode of operation also provides optimized power management, since STAs need to wake up periodically to listen to SCHED messages and can sleep during the SCAP interval if they are not programmed in the current SCAP. Access based on protected contention for STA MIMO is provided through EDMA MIMO or FRACH periods included in the Programmed Access Period 4130 of SCAP 4100. Legacy STAs can obtain media-based access during CP 4420. Consecutive scheduled transmission of the AP can be scheduled immediately after the transmission of the SCHED frame. The SCHED frame can be transmitted with a preamble. Subsequent scheduled AP transmissions can be transmitted without a preamble (an indicator can be transmitted that mentions whether or not a preamble is included). An exemplary PLCP preamble is detailed below. Scheduled STA transmissions will begin with a preamble in the exemplary mode.

Error recovery The AP can use several procedures to recover the reception errors of the SCHED. For example, if an STA can not decode a SCHED message, it can not use its TXOP. If a scheduled TXOP does not start at the assigned start time, the AP can initiate recovery by transmitting in a PIFS after the start of the programmed unused TXOP. The AP can use the period of the programmed TXOP not used as a CAP. During the CAP, the AP can transmit to one or more STAs or register an STA. The Registry may be for the STA that lost the scheduled TXOP or other STA. The CAP ends before the next scheduled TXOP. The same procedures can also be used when a programmed TXOP ends in advance. The AP can initiate recovery by transmitting in a PIFS after the end of the last transmission in the programmed TXOP. The AP can use the unused period of a TXOP programmed as a CAP, as just described.

Protected Containment As described above, a SCAP can also contain a portion dedicated to FRACH transmissions and / or a portion where the MIMO STAs can use EDCA procedures. These access periods based on containment can be protected by the NAV established for the SCAP. Protected containment complements the scheduled low-latency operation by allowing STAs to indicate that TXOP requests assist the AP in programming. In the protected EDCA period, the MIMO OFDM STAs can transmit frames using EDCA-based access (protected against containment with legacy STA). Using legacy techniques, the STAs can indicate the TXOP duration request or buffer status in the QoS 802 Control field. Lie in the MAC Header. However, FRACH is a more efficient means to provide the same function. During the FRACH period, STAs can use slotted Aloha-type contention to access the channel in fixed-size FRACH slots. The FRACH PPDU can include the TXOP duration request. In the exemplary mode, the MIMO frame transmissions use the PLCP MIMO Header, which is detailed below. Because the legacy STAs 802.11b, 802.11a, and 802. llg can decode only the SIGNAL 1 field of the MIMO PLCP header (which is detailed with respect to Figure 50, below), in the presence of STA not MIMO, MIMO frames must be transmitted with protection. When both legacy STA and STA MIMO are present, STAs using EDCA access procedures can use a legacy RTS / CTS sequence for protection. Legacy RTS / CTS refers to the transmission of RTS / CTS frames using legacy preamble formats, PLCP header and MAC frame. MIMO transmissions can also use the protection mechanisms provided by HCCA 802. lie. Therefore, to the transmissions from the AP to the STA, registered transmissions from the STA to the AP, or from one STA to another STA (using the Direct Link Protocol) can be provided with protection using the Controlled Access Period (CAP) . The AP may also use CTS-a-Own legacy for the protection of the MIMO Programmed Access Period (SCAP) against legacy STAs. When an AP determines that all STAs present in the BSS have the ability to decode the PLCP MIMO header, this is indicated in an element with MIMO capabilities in the beacon. This is referred to as a MIMO BSS. In a MIMO BSS, under EDCA and HCCA, frame transmissions use the MIMO PLCP header and the MIMO OFDM Training symbols in accordance with the time-step rules of the MIMO OFDM Training Symbols. Transmissions in the MIMO BSS use the MIMO PLCP.

Reduced frame spacing Several techniques were previously detailed to reduce in general the Separation Between Frames. Several examples of reducing separation between frames in this exemplary embodiment are illustrated here. For programmed transmissions, the start time of the TXOP is indicated in the SCHED message. The transmitting STA can start its scheduled TXOP at the precise start time indicated in the SCHED message without determining that the medium is inactive. As described above, consecutive scheduled AP transmissions during a SCAP are transmitted without minimal IFS. In exemplary mode, consecutive scheduled STA transmissions (from different STAs) are transmitted with an IFS of at least Guard IFS (GIFS). The default value of GIFS is 800 ns. You can choose a larger value up to the Burst IFS value (BIFS) that is defined below. The value of GIFS can be indicated in the element with ACF capabilities, described above. Alternative modes can use any values for GIFS or BIFS. Consecutive transmissions of the OFDM MIMO PPDU from the same STA (TXOP in bursts) are separated by a BIFS. When operating in the 2.4 GHz band, the BIFS is equal to 10 μs and the OFDM MIMO PPDU does not include the OFDM signal extension of 6 μs. When operating in the 5 GHz band, the BIFS is 10 μs. In an alternative mode, the BIFS can be set to a smaller or larger value, including 0. To allow the Automatic Gain Control (AGC) of the receiving STA to switch between transmissions, a larger space can be used than 0 when the transmission power of the STA that is transmitting is changed. Frames that require immediate response from the receiving STA are not transmitted using a MIMO OFDM PPDU. Rather, they are transmitted using the underlying legacy PPDU, that is, Clause 19 in the 2.4 GHz band or Clause 17 in the 5 GHz band. Here are some examples of how the MIMO and legacy OFDM PPDUs are multiplexed in the middle. First, consider a legacy RTS / CTS followed by a bursty OFDM MIMO PPDU. The transmission sequence is as follows: Legacy RTS - SIFS - Legacy CTS - SIFS - PPDU OFDM MIMO - BIFS - PPDÜ OFDM MIMO. At 2.4 GHz, the legacy STD or RTS PPDU uses the OFDM signal extension and the SIFS is 10 μs. At 5 GHz, there is no OFDM extension but the SIFS is 16 μs. Second, consider an EDCA TXOP using OFDM MIMO PPDU. The transmission sequence is as follows: PPDU OFDM MIMO - BIFS - Request for Recognition of Legacy Block - SIFS - ACK. The EDOP TXOP is obtained using EDCA procedures for the appropriate Access Class (AC). As detailed above, EDCA defines the access classes that different parameters can use per AC, such as AIFS [AC], CWmin [AC] and CWmax [AC]. The Block Recognition Request is transmitted with any signal extension or SIFS of 16 μs. If the Block Recognition Request is transmitted in the aggregation frame within the OFDM MIMO PPDU, there is no ACK. Third, consider consecutive TXOPs scheduled. The transmission sequence is as follows: PPDU OFDM MIMO DE STA A - GIFS - PPDU OFDM MIMO DE STA B. There may be an inactive period after transmission of the PPDU OFDM MIMO DE STA A if the transmission of the PPDU is shorter than the maximum allowed TXOP time assigned. As described above, the decoding and demodulation of the encoded OFDM transmissions impose additional processing requirements on the reception STA. To allow this, 802.11a and 802. llg allow additional time for the receiving STA before the ACK is transmitted. In 802.11a, the time of the SIFS is set to 16 μs. At 802. llg, the time of the SIFS is set to 10 μs but an additional OFDM signal extension of 6 μs is introduced. Because the decoding and demodulation of MIMO OFDM transmissions can impose even more difficult processing, following the same logic, a modality can be designed to increase the SIFS or the extension of the OFDM signal, leading to a further reduction in efficiency. In exemplary mode, by extending the Block ACK and ACK mechanisms of the 802. lie Delay Block, the immediate ACK requirement for all MIMO OFDM transmissions is eliminated. Instead of increasing the SIFS or signal extension, signal extension is eliminated and for many situations the required frame spacing between consecutive transmissions is reduced or eliminated, leading to greater efficiency.

SCHED message Figure 45 illustrates the SCHED message, mentioned above with respect to Figure 41, and which is further detailed below. The SCHED message 4120 is a multiple register message that assigns one or more TXOPs of AP-STA, STA-AP and STA-STA for the duration of a Programmed Access Period (SCAP). The use of the SCHED message allows for reduced registration and containment overload, as well as eliminating unnecessary IFS. The SCHED Message 4120 defines the program for the SCAP. The SCHED message 4120 comprises a MAC Header 4510 (15 octets in exemplary mode). In the exemplary embodiment, each of the segments CTRLO, CTRLl, CTRL2 and CTRL3 (generally referred to herein as CTRLJ, where J may be 0 to 3 to illustrate the segments 4515-4530, respectively) are of variable length and they can be transmitted at 6, 12, 18 and 24 Mbps, respectively, when they are present. The exemplary MAC header 4510 comprises the Frame Control 4535 (2 bytes), the Duration 4540 (2 bytes), the BSSID 4545 (6 bytes), the Power Management 4550 (2 bytes), and the MAP 4555 (3 octets) . Bits 13-0 of the Duration field 4540 specify the length of the SCAP in microseconds. The Duration field 4540 is used by the STAs that have the capability for MIMO OFDM transmissions to configure the NAV for the duration of the SCAP. When STAs are present in the BSS, the AP may use other means to protect the SCAP, for example, a CTS-a-Own legacy. In the exemplary mode, the maximum value of the SCAP is 4 ms. The field of BSSID 4545 identifies the AP. The Power Management field 4550 is shown in Figure 46. The Power Management 4550 comprises the SCHED Count 4610, a reserved field 4620 (2 bits), Transmission Power 4630, and Reception Power 4640. The transmission power of the AP and the reception power of the AP are as indicated in the Power Management field and the reception power level of the STA is measured in the STA. The SCHED Count is a field that increments in each SCHED transmission (6 bits in this example). The SCHED Count is reset on each beacon transmission. The SCHED Count can be used for several purposes. As an example, a power saving function using the SCHED Count is described below. The Transmission Power field 4630 represents the level of transmission power that is being used by the AP. In exemplary mode, the 4-bit field is encoded as follows: The value represents the number of steps of 4 dB that the transmit power level is below the Maximum Transmit Power Level (in dBm) for that channel, as indicated in an information element of the beacon. The Reception Power field 4640 represents the expected power level of reception in the AP. In the exemplary mode, the 4-bit field is encoded as follows: The value represents the number of steps of 4 dB that the reception power level is above the Minimum Sensitivity Level of the Receiver (-82 dBm). Based on the power level received in a STA, an STA can calculate its transmission power level in the following way: Power of Transmission of STA (dBm) = Power of Transmission of the AP (dBm) + Power of Reception of the AP (dBm) - Reception Power of STA (dBm). In exemplary mode, during programmed STA-STA transmissions, the control segment is transmitted at a power level that can be decoded in both the AP and the reception STA. A power control report from the AP or the 4550 Power Management field in the SCHED frame allows the STA to determine the level of transmit power that is required for the control segment to be decoded in the AP. This general aspect was detailed above with respect to Figure 22. For a programmed STA-STA transmission, when the power required to decode in the AP is different from the power required to decode in the receiving STA, the PPDU is transmitted to the highest level of the two power levels. The MAP 4555 field, shown in Figure 47, specifies the presence and duration of protected contention-based access periods during the SCAP. The MAP 4555 field comprises the FRACH 4710 Count, the FRACH 4720 Compensation, and the EDCA 4730 Compensation. The exemplary FRACH 4710 Count (4 bits) is the number of FRACH slots programmed starting at the FRACH Compensation 4720 (10 bits). Each FRACH slot is 28 μs. A FRACH Count value of "O" indicates that there is no FRACH period in the Current Programmed Access Period. The EDCA 4730 Compensation is the start of the protected EDCA period. The EDCA 4730 Compensation is 10 bits. Both the FRACH 4720 Compensation and the EDCA 4730 Compensation are in units of 4 μs starting from the beginning of the transmission of the SCHED frame. The message SCHED 4120 is transmitted as a special SCHED 5100 PPDU (Type 0010), which is detailed below with respect to figure 51. The presence within the message SCHED 4120 and the length of the segments CTRLO 4515, CTRLl 4520, CTRL2 4525 and CTRL3 4530 are indicated in the SIGNAL field (5120 and 5140) of the PLCP Header of the SCHED 5100 PPDU. Figure 48 illustrates the SCHED control frames for the TXOP assignment. Each of the segments CTRLO 4515, CTRLl 4520, CTRL2 4525 and CTRL3 4530 is of variable length and each comprises zero or more allocation elements (4820, 4840, 4860 and 4880, respectively). A 16-bit FCS (4830, 4850, 4870, and 4890, respectively) and 6 queue bits (not shown) are added by segment CTRLJ. For the CTRLO segment 4515, the FCS is calculated on the MAC Header 4510 and any CTRLO 4820 assignment elements (therefore the MAC Header is appended to CTRLO 4515 in Figure 48). In exemplary mode, FCS 4830 for CTRLO 4515 is appended even if assignment elements are not included in the CTRLO segment. As detailed in the present invention, the AP transmits assignments for AP-STA, STA-AP and STA-STA transmissions in the SCHED frame. The assignment elements to different STAs are transmitted in a CTRLJ segment as indicated by the STA in the SCHED Rate field of the PLCP header of their transmissions. It can be seen that CTRLO to CTRL3 correspond to a reduction in robustness. Each STA begins to decode the PLCP Header of the SCHED PPDU. The SIGNAL field indicates the presence and length of the CTRLO, CTRLl, CTRL2 and CTRL3 segments in the SCHED PPDU. The receiver of the STA begins with the decoding of the MAC Header and the CTRLO segment, decoding each assignment element up to the FCS, and then continues with the decoding of CTRLl, CTRL2 and CTRL3 stopping at the CTRLJ segment whose FCS can not verify. Five types of allocation elements are defined as shown in Table 3. A number of allocation elements can be packed in each CTRLJ segment. Each assignment element specifies the Access ID of the STA that is transmitting (AID), the AID of the STA that it is receiving, the start time of the programmed TXOP and the maximum allowed length of the programmed TXOP, TABLE 3 Types of allocation elements The preamble can be deleted in consecutive transmissions of the AP. The Present Preamble bit is set to 0 if the AP will not transmit a preamble during a transmission of the programmed AP. An exemplary benefit of preamble elimination is when the AP has a low bandwidth, low latency streams for several STAs, such as in a BSS with many Voice over IP (VoIP) streams. Therefore, the SCHED frame allows aggregation of transmissions from the AP to several reception STAs (ie, aggregation of the PPDU, as described above). Frame Aggregation, as defined above, allows the aggregation of frames to an STA that is receiving. The Start Compensation field is in multiples of 4 μs referenced from the starting time of the preamble of the SCHED message. The AID is the Access ID of the assigned STA. For all types of assignment elements, except scheduled STA-STA transmissions, the TXOP Duration field is the maximum allowed length of the TXOP programmed in multiples of 4 μs. The size of the actual PPDU of the transmitted PPDU is indicated in the field of SIGNAL1 of the PPDU (which is detailed below). For scheduled STA-STA transmissions (Types of Assignment Elements 011 and 100), the field of Maximum PPDU size is also the maximum allowed length of the TXOP programmed in multiples of 4 μs, however additional rules may apply. In exemplary mode, for programmed STA-STA transmissions, the TXOP contains only one PPDU. The receiving STA uses the Maximum PPDU Size indicated in the allocation element to determine the number of OFDM symbols in the PPDU (because the PPDU Size field is replaced by a Request field in SIGNAL1, which is detailed below with respect to Figure 51). If the STA-STA flow uses OFDM symbols with the standard Guard Interval (GI), the receiving STA sets the PPDU Size for the programmed TXOP to the Maximum PPDU Size indicated in the allocation element. If the STA-STA flow uses OFDM symbols with shortened GI, the receiving STA determines the size of the PPDU by scaling the Maximum PPDU size field by a factor of 10/9 and rounding it down. The transmission STA may transmit a PPDU shorter than the Maximum Size of the PPDU assigned. The PPDU Size does not provide the length of the MAC frame added to the receiver. The length of the encapsulated frames is included in the Aggregation Header of each MAC frame. The inclusion of the transmission and reception STAs in the assignment elements allows the energy saving in the STAs that are not programmed to transmit or receive during the SCAP. Remember the SCHED Count field presented above. Each assignment programmed by the SCHED message specifies the AID of the transmitting STA, the AID of the receiving STA, the start time of the programmed TXOP, and the maximum allowed length of the programmed TXOP. The SCHED Count is increased in each SCHED transmission and is reset in each beacon transmission. The STAs can indicate an energy saving operation for the AP, and therefore they are provided with specific SCHED Count values during which they can be assigned TXOPs of programmed transmission or reception assigned by the AP. STAs can then awaken periodically only to listen to SCHED messages with an appropriate SCHED Count.

PPDU formats Figure 49 shows a legacy 802.11 PPDU 4970, comprising a PLCP preamble 4975 (12 OFSM symbols), a PLCP header 4910, a variable length PSDU 4945, a 6-bit tail 4950, and a variable-length adapter 4955. A portion 4960 of the 4970 PPDU comprises a SIGNAL field (1 OFDM symbol) transmitted using BPSK at a velocity = 1/2, and a variable length data field 4985, transmitted with the modulation format and the speed indicated in SIGNAL 4980. The PLCP 4910 header comprises SIGNAL 4980 and a 16-bit Service field 4940 (which is included in DATA 4985, and is transmitted according to its format ). The field of SIGNAL 4980 comprises the Speed 4915 (4 bits), the reserved field 4920 (1 bit), the Length 4925 (12 bits), the Parity bit 4930, and the Queue 4935 (6 bits). The extended SIGNAL fields (listed below) in the exemplary PLCP Header (detailed below) is backwards compatible with the 802.11 Legacy SIGNAL 4980 field. The unused values of the SPEED field 4915 in the field of Legacy SIGNAL 4980 are configured to define new types of PPDUs (which are detailed below). Several new types of PPDU are presented. For backward compatibility with legacy STA, the SPEED field in the SIGNAL field of the PLCP Header is modified to a SPEED / Type field. Unused SPEED values are designated as the PPDU Type. The PPDU Type also indicates the presence and length of a SIGNAL field extension designated SIGN2. In table 4, new values of the SPEED / Type field are defined. These values of the SPEED / Type field are not defined for the legacy STAs. Therefore, the legacy STAs will abandon the decoding of the PPDU after successfully decoding the SIGNAL1 field and finding an undefined value in the SPEED field. Alternatively, the Reserved bit in the Legacy SIGNAL field can be set to "1" to indicate a MIMO OFDM transmission to a new class STA. The receiving STAs can ignore the Reserved bit and may continue trying to decode the SIGNAL field and the remaining transmission. The receiver can determine the length of the SIGNAL2 field based on the PPDU Type. The FRACH PPDU appears only in a designated portion of the SCAP and needs to be decoded only by the AP.

TABLE 4 Types of MIMO PPDU Figure 50 shows the MIMO 5000 PPDU format for data transmissions. PPDU 5000 is referred to as Type of PPDU 0000. The PPDU 5000 comprises a PLCP preamble 5010, a SIGNAL 1 5020 (1 OFDM symbol), a SIGN 2 5040 (1 OFDM symbol), 5060 Training Symbols (0, 2, 3, or 4 symbols), and a variable length 5080 Data field. The PLCP 5010 preamble, when present, is 16 μs in the exemplary mode. SIGNAL 1 5020 and SIGNAL 2 5040 are transmitted using the modulation format and the speed of the PPDU control segment. The 5080 Data comprises the Service 5082 (16 bits), the Feedback 5084 (16 bits), a PSDU of variable length 5086, a Queue 5088 (6 bits per stream) wherein a separate convolutional channel code is applied to each stream, and a 5090 variable length adapter. The 5080 data is transmitted using the modulation format and the speed of the PPDU data segment. The PLCP MIMO header for PPDU type 0000 comprises the SIGNAL fields (including SIGNAL1 5020 and SIGNAL2 5040), SERVICE 5082 and FEEDBACK 5084. The SERVICE field remains unchanged for the 802.11 legacy, and is transmitted using the format and the speed of data segments. The FEEDBACK 5048 field is transmitted using the format and speed of data segments. The FEEDBACK field includes the ES field (1 bit), the Data Velocity Vector Feedback field (DRVF) (13 bits) and a Power Control field (2 bits). The ES field indicates the preferred orientation method. In the exemplary mode, Own Vector Orientation (ES) is selected when the ES bit is set, and Space Spatial (SS) is otherwise selected. The Data Velocity Vector Feedback (DRVF) field provides feedback to the peer station with respect to the sustainable velocity in each of up to four spatial modes. Explicit speed feedback allows stations to quickly and accurately maximize their transmission speeds, dramatically improving system efficiency. Low latency feedback is desirable. However, feedback opportunities do not need to be synchronous. Transmission opportunities can be obtained in any form, such as based on containment (ie, EDCA), recorded (ie, HCF), or scheduled (ie, ACF). Therefore, varying amounts of time may pass between transmission opportunities and speed feedback. Based on the elapsed time of the speed feedback, the transmitter can apply a backward movement to determine the transmission speed. The adaptation of the PPDU data segment rate for transmissions from STA A to STA B is based on the feedback provided by STA B to STA A (described above, see figure 24, for example). Either for the ES or SS operation mode, whenever STA B receives the OFM MIMO Training Symbols from STA A, it calculates the data rates that can be achieved in each space current. In any further transmission from STA B to STA A, STA B includes this calculation in the DRVF field of FEEDBACK 5084. The DRVF field is transmitted at the data segment 5080 speed. When transmitted to STA B, STA A determines the type of transmission speeds to be used based on the DRVF that it received from STA B, with an optional backspace as necessary to consider delays. The SIGNAL field (detailed below) contains the 13-bit DRV field 5046 which allows the receiving STA B to decode the frame transmitted from STA A. The DRVF field is encoded and comprises a STR field (4 bits), a field R2 (3 bits), a field R3 (3 bits), and a field R4 (3 bits). The STR field indicates the Velocity for Current 1. This field is encoded as the STR value shown in Table 5. R2 indicates the difference between the STR Value for Current 1 and the STR value for Current 2. An R2 value of "111" indicates that Current 2 is off. R3 indicates the difference between the STR Value for Current 2 and the STR Value for Current 3. An R3 value of "111" indicates that Current 3 is off. If R2 = "111", then R3 is set to "111". R4 indicates the difference between the STR value for Current 3 and the STR Value for Current 4. An R4 value of "111" indicates that Current 4 is off. If R3 = "111", then R4 is set to "111". When ES = 0, that is, spatial spread, an alternate coding of the DRVF is as follows: Number of Currents (2 bits), Speed per Current (4 bits). The Current Speed field is encoded as the previous STR value. The remaining 7 bits are reserved, TABLE 5 STR coding In addition to the DRVF, STA B also provides power control feedback to the STA A transmission. This feedback is included in the field of Power Control and is also transmitted at the speed of the data segment. This field is 2 bits and indicates either increase or decrease the power or leave the power level unchanged. The resulting transmission power level is designated as the Power Level of the Data Segment Transmission. The exemplary Power Control field values are illustrated in Table 6. Alternate modes can display power control fields of various sizes, and with alternate power adjustment values.

TABLE 6 Values of the Power Control Field The level of transmission power remains constant for the entire PPDU. When the Transmission Power Level of the Data Segment and the Open Loop Power Transmission STA (ie, the power level that is required for the AP to decode the transmission, which was detailed above) are different, the PPDU is transmitted to the maximum level of the two power levels. That is, the Transmission Power Level of the PPDU is the maximum level of the Open Loop Power Transmission (dBm) and the Power Transmission of the Data Segment (dBm). In the exemplary mode, the Power Control field is set to "00" in the first frame of any frame exchange sequence. In subsequent frames, this indicates the increase or reduction of the power in graduations of 1 dB. The receiving STA will use this feedback information in all subsequent frame transmissions for that STA. The SIGNAL1 5020 comprises the field Type / SPEED 5022 (4 bits), 1 Bit Reserved 5024, Request / Size PPDU 5026 (12 bits), Parity bit 5028, and a 6-bit Queue 5030. The field of SIGNAL1 5020 is transmitted using the format and speed of the control segment (6 Mbit / s, in the exemplary mode). The Type / SPEED 5022 field is set to 0000. The Reserved Bit 5024 can be set to 0. The Request / Size PPDU 5026 field has two functions, depending on the transmission mode. In STA transmissions based on containment and all AP transmissions, this field denotes the size of the PPDU. In this first mode, Bit 1 indicates that the PPDU uses expanded OFDM symbols, Bit 2 indicates that the PPDU uses OFDM symbols with shortened GI, and Bits 3-12 indicate the number of OFDM symbols. In STA transmissions without scheduled APs, the Field Request / Size PPDU 5026 denotes Request. In this second mode, Bits 1-2 indicate the SCHED Speed. The SCHED speed indicates the highest numbered SCHED field (0, 1, 2 or 3) that can be used to transmit an assignment to the STA. During AP training symbol transmissions, each non-AP STA calculates the speed at which it can robustly receive SCHED frame transmissions from the AP. In later scheduled transmissions of the STA, this maximum allowable speed is included in the SCHED Speed field. This field is decoded by the AP. The AP uses this information to program subsequent TXOPs for the STA and determines the CTRLJ (0, 1, 2 or 3) to issue those assignments to the STA. In the second mode, Bits 3-4 indicate the QoS field, which identifies the fraction (in thirds) of the request that is for TC 0 or 1 (that is, 0%, 33%, 67%, 100%) . Bits 5-12 indicate the requested length of TXOP (in multiples of 16 μs, in the exemplary mode). The field of SIGNAL1 5020 is reviewed by 1 bit of Parity 5028 and ends with a 6-bit 5030 Queue for the convolutional encoder. The presence and length of the field of SIGNAL2 5040 is indicated by the field of Type / SPEED 5022 in SIGNAL1 5020. The field of SIGNAL2 5040 is transmitted using the format and speed of the control segment. SIGNAL2 5040 comprises a Reserved Bit 5042, Training Type 5044 (3 bits), Data Speed Vector (DRV) 5046 (13 bits), Parity Bit 5048, and Queue 5050 (6 bits). The 3-bit Training Type field indicates the length and format of the MIMO OFDM Training symbols. Bits 1-2 indicate the number of OFDM MIMO 5060 Training symbols (0, 2, 3, or 4 OFDM symbols). Bit 3 is the Training Type field: 0 indicates SS, 1 indicates ES. The DRV 5046 field provides the speed for each of up to four spatial modes. DRV 5046 is coded in the same way as DRVF (included in FEEDBACK 5084, which was detailed above). The field of SIGNAL2 5040 is reviewed by 1 bit of Parity 5048 and ends with a 6-bit Queue 5050 for the convolutional encoder. Figure 51 shows the SCHED 5100 PPDU (Speed / Type = 0010). The SCHED 5100 PPDU comprises a PLCP 5110 preamble, SIGNAL 1 5120 (1 OFDM symbol), SIGNAL 2 5140 (1 OFDM symbol), Training Symbols 5160 (0, 2, 3, 6 4 symbols), and a SCHED frame variable length 5180. The PLCP 5010 preamble, when present, is 16 μs in the exemplary mode. SIGNAL 1 5020 and SIGNAL 2 5040 are transmitted using the modulation format and the speed of the PPDU control segment. The SCHED 5180 frame may include several speeds, as detailed above, with respect to the description of ACF. SIGNAL1 5120 comprises the field of Type / SPEED 5122 (4 bits), a Reserved Bit 5124, the Size CTRLO 5126 (6 bits), the Size CTRLl 5128 (6 bits), the Parity Bit 5130 and a Queue 5132 (6 bits). The Type / SPEED field 5122 is set to 0010. The Reserved bit 5124 can be set to 0. The CTRLO size 5126 indicates the length of the segment of the SCHED PPDU transmitted at the lowest speed (6 Mbps in this example). This segment includes the SERVICE field of the PLCP Header, the MAC Header and the CTRLO segment 5126. The value is encoded in multiples of 4 μs, in this example. CTRLl Size 5128 indicates the segment length of the SCHED PPDU transmitted to the next higher speed (12 Mbps in this example). The value is encoded in multiples of 4 μs, in this example. A CTRLL size of "0" indicates that the corresponding CTRLl segment is not present in the SCHED PPDU. The field of SIGNAL1 5120 is reviewed by 1 Parity bit 5130 and ends with a 6-bit Queue 5132 for the convolutional encoder. SIGNAL2 5140 comprises a Reserved Bit 5142, Training Type 5144 (3 bits), Size CTRL2 5146 (5 bits), Size CTRL3 5148 (5 bits), FCS 5150 (4 bits) and a Queue 5152 (6 bits) ). Reserved bit 5142 can be set to 0. Training Type 5144 is as specified for PPDU Type 0000 (Training Type 5044). Size CTRL2 5146 indicates the segment length of the SCHED PPDU transmitted at the next higher speed (18 Mbps in this example). The value is encoded in multiples of 4 μs, in this example. A CTRL2 size of "0" indicates that segment CTRL2 is not present in the SCHED PPDU. Size CTRL3 5148 indicates the segment length of the SCHED PPDU transmitted at the next higher speed (24 Mbps in this example). The value is encoded in multiples of 4 μs, in this example. A CTRL2 size of "0" indicates that the corresponding CTRL3 segment is not present in the SCHED PPDU.

FCS 5150 is calculated in the complete fields of SIGNAL1 and SIGNAL2. The field of SIGNAL2 5152 ends with a 6-bit Queue 5152 for the convolutional encoder. Figure 52 shows the FRACH PPDU 5200 (Speed / Type = 0100). The FRACH PPDU 5200 comprises a PLCP preamble 5210, SIGNAL 1 5220 (1 OFDM symbol), and SIGNAL 2 5240 (2 OFDM symbols). The PLCP 5210 preamble, when present, is 16 μs in the exemplary mode. SIGNAL 1 5220 and SIGNAL 2 5240 are transmitted using the modulation format and the speed of the PPDU control segment. The FRACH 5200 PPDU is transmitted by an STA during the FRACH period within the MIMO Scheduled Access Period. The FRACH period is established by the AP and, therefore, of the AP knowledge (as detailed above). The SIGNAL1 5220 comprises the Type / SPEED field 5222 (4 bits), a Reserved Bit 5224, the Request 5226 (12 bits), the Parity bit 5228 and a Queue 5230 (6 bits). The Type / SPEED 5222 field is set to 0100. The Reserved Bit 5124 can be set to 0. Request Field 5226 is as specified for PPDU Type 0000 (5000), which was detailed above. The SIGNAL field 5220 is reviewed by 1 parity bit 5228 and ends with a 6-bit queue 5230 for the convolutional encoder.

The SIGNAL2 5240 comprises a Reserved Bit 5242, AID Source 5244 (16 bits), AID of Destination 5246 (16 bits), FCS 5248 (4 bits), and a Queue 5250 (6 bits). The Reserved Bit 5242 can be set to 0. AID Source 5244 identifies the STA that is transmitting on the FRACH. Destination AID 5246 identifies the destination STA for which a TXOP is being requested. In exemplary mode, in the case where the destination is the AP, the value of the destination AID field 5246 is set to 2048. A 4-bit FCS 5248 is calculated on the total fields of the SIGNAL1 and SIGNAL2. A 6-bit 5250 Queue is added before convolutional coding. In exemplary mode, STAs can use slotted Aloha to access the channel and transmit the request message in the FRACH. If it is successfully received by the AP, the AP provides the requesting STA with a scheduled TXOP in a later scheduled access period The number of FRACH slots for the current scheduled access period is indicated in the message SCHED, N_FRACH. STA can also contain a variable B_FRACH.After a transmission in the FRACH, if the STA receives a TXOP assignment from the AP, it resets THE B_FRACH.If the STA does not receive a TXOP assignment within a predetermined number, the ANSWER FRACH, of SCHED transmissions of the AP, B_FRACH is incremented by 1 up to a maximum value of 7. The FRACH RESPONSE parameter is included in an ACF element of the beacon During any FRACH, the STA chooses a FRACH slot with probability (N_FRACH) _1 * 2"B-FRACH. If no FRACH period is programmed by the AP, the MIMO STAs may fight during the protected contention period during the SCAP using the EDCA rules. Those skilled in the art will understand that information and signals can be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols and chips, which can be referenced throughout the preceding description, can be represented by voltages, currents, electromagnetic waves, fields or magnetic particles, fields or optical particles, or any combination thereof. Those skilled in the art will further appreciate that the various illustrative logic blocks, modules, circuits, and algorithm steps described in connection with the embodiments shown herein, may be executed as electronic hardware, computer software, or combinations of both. To clearly illustrate this hardware and software exchange capability, various illustrative components have been described above in terms of their functionality., blocks, modules, circuits and steps. Whether such functionality is executed as hardware or software depends on the particular application and the design restrictions imposed on the entire system. Those skilled in the art can execute the described functionality in various ways for each particular application, but such execution decisions should not be interpreted as a cause for departing from the scope of the present invention. The various illustrative logic blocks, modules and circuits described in relation to the embodiments described in the present invention can be executed or realized with a general-purpose processor, a digital signal processor (DSP), a specific application integrated circuit (ASIC) , a programmable field gate layout (FPGA) signal or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described in the present invention. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any processor, controller, microcontroller, or conventional state machine. A processor may also be executed as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a central DSP, or any other configuration. The steps of a method or algorithm described in connection with the embodiments described in the present invention can be incorporated directly into hardware, into a software module executed by a processor, or into a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor so that the processor can read the information from, and write information to, the storage medium. In the alternative, the storage medium can be an integral part of the processor. The processor and storage medium can reside in an ASIC. The ASIC can reside in a user terminal. In the alternative, the processor and the storage medium may reside as discrete components in a user terminal. The headers are included in the present invention by reference and to assist in the location of several sections. These headings are not intended to limit the scope of the concepts described with respect to them. These concepts can be applied to the entire detailed description. The prior description of the described embodiments is provided to enable those skilled in the art to make or use the present invention. Various modifications to these modalities will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not intended to be limited to the modalities shown herein but will be accorded the broadest scope consistent with the principles and novel features described herein.

Claims (2)

1. NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, the content of the following is claimed as a priority: CLAIMS 1. - An apparatus comprising: a transmitter for transmitting a signal, according to a first transmission format, for reserving a shared medium for a duration and for transmission according to a second transmission format for the reserved duration; and a receiver to receive according to the second transmission format for the reserved duration. 2. - An apparatus comprising: a transmitter to transmit according to, at least, a portion of a first communication format and to transmit according to a second communication format; a receiver to receive according to the second communication format; and means for reserving a shared medium for a duration for communication in accordance with the second transmission format during the reserved duration. 3. A wireless communication system comprising: means for transmitting a signal, according to a first transmission format, to reserve a shared medium for a duration; and means for initiating communication according to the second transmission format during the reserved duration. . - A method for interoperation in a shared medium between one or more devices that communicate according to a first transmission format and one or more devices that communicate according to a second transmission format, the method comprises: transmitting a signal, according to a first transmission format, to reserve the shared medium for a duration; and establish communication according to the second transmission format during the reserved duration. 5. - The method according to claim 4, further comprising fighting for access according to the first transmission format before transmitting the reservation signal. 6. The method according to claim 4, further comprising: requesting access to the shared medium; and receive an assignment in response to the request. 7. - The method according to claim 4, characterized in that the signal is a Transmission Opportunity (TXOP) according to an IEEE 802.11 protocol. 8. - The method according to claim 4, characterized in that the signal establishes a period free of containment. 9. The method according to claim 4, characterized in that the transmission of a signal to reserve the shared medium for a duration also comprises transmitting a message of Request to Send (RTS), the RTS message indicates a transmission duration. 10. The method according to claim 4, characterized in that the transmission of a signal to reserve the shared medium for a duration also comprises transmitting a message of Clear to Send (CTS), the CTS message indicates a transmission duration. 11. The method according to claim 4, characterized in that the first transmission format is an IEEE 802.11 format. 12. The method according to claim 4, characterized in that the second transmission format comprises a Time Division Duplex (TDD) frame interval comprising: a pilot; a consolidated record; zero or more access point to remote station frames according to the consolidated record; zero or more frames from remote station to access point according to the consolidated record; zero or more frames from remote station to remote station according to the consolidated record; and zero or more random access segments according to the consolidated record. 13. An apparatus, comprising: means for assigning a first duration for communication in a shared medium according to a first format of a plurality of communication formats; and means for assigning a second duration for communication in the shared medium according to a second format of a plurality of communication formats. 14. The apparatus according to claim 13, which also comprises means for spatial processing. 15. Computer-readable media that operate to execute the following steps: assign a first duration for communication in a shared medium according to a first format of a plurality of communication formats; and assigning a second duration for communication in the shared medium according to a second format of a plurality of communication formats. 16. The means according to claim 15, further operating to execute the following steps: transmit a Time Division Duplexing (TDD) frame interval comprising a consolidated record; transmit one or more frames according to the consolidated record; and receive one or more frames according to the consolidated record. 17. A method for communication in a shared medium, comprising: assigning a first duration for communication in the shared medium according to a first format of a plurality of communication formats; and assigning a second duration for communication in the shared medium according to a second format of a plurality of communication formats. 18. The method according to claim 17, characterized in that at least one of the plurality of communication formats comprises spatial processing. 19. The method according to claim 18, characterized in that the format of the plurality of communication formats comprising spatial processing is a communication format of Multiple Multiple Outputs (MIMO). 20. The method according to claim 19, characterized in that the communication format (MIMO) is a communication format of multiple single-output (MISO). 21. The method according to claim 17, characterized in that the format of the plurality of communication formats comprises a Time Division Duplexing frame interval. (TDD) comprising: a pilot; a consolidated record; one or more frames according to the consolidated record. 22. - The method according to claim 21, characterized in that the frame or frames comprise remote access point access communication. 23. The method according to claim 21, characterized in that the frame or frames comprise communication from remote station to access point. 24. The method according to claim 21, characterized in that the frame or frames comprise communication from remote station to remote station. The method according to claim 21, characterized in that the frame or frames comprise random access to the shared medium. 26. The method according to claim 17, characterized in that one of the plurality of communication formats is substantially the same as an EDCA 802.11 format. 27. The method according to claim 17, characterized in that one of the plurality of communication formats is substantially the same as a CAP 802.11 format. 28. The method according to claim 17, characterized in that one of the plurality of communication formats is substantially the same as a SCAP format. 29. The method according to claim 17, further comprising assigning a series of one or more third durations for communication in the shared medium according to a first format of the plurality of communication formats and a series of one or more fourth durations for communication in the shared medium according to a second format of the plurality of communication formats, the series of third durations and the series of fourth durations are interspersed. 30. The method according to claim 29, characterized in that the interleaving is selected to provide a maximum time interval between some of the series of third durations. 31. The method according to claim 17, characterized in that the first duration comprises one or more SCAP intervals. 32. The method according to claim 31, characterized in that the second duration comprises one or more EDCA 802.11 ranges. 33.- The method according to claim 17, which further comprises establishing a period free of containment for the first duration. 34. - The method according to claim 17, further comprising establishing a containment period for the second duration. 35.- An apparatus, comprising: means to fight for access to a shared medium according to a first communication protocol; and means for initiating communication in the shared medium according to a second communication protocol during the quarreling access. 36.- A method for communication in a shared medium, which includes: transmitting a radio beacon; fight for access to the shared medium according to a first communication protocol; and establish communication in the shared medium in accordance with a second communication protocol during the quarrel access. 37.- The method according to claim 36, which further comprises: establishing a period free of containment; and allocate records according to the first communication protocol during the contention-free period. 38.- The method according to claim 36, further comprising: fighting for a second access to a shared medium according to a first communication protocol; and establish communication in the shared medium according to the first communication protocol during the second accessed fight. 39.- The method according to claim 37, characterized in that: a first access point establishes the contention-free period; and a second access point fights for access in accordance with the first communication protocol and establishes communication with one or more remote stations according to the second communication protocol during the access contention. 40.- A device, which operates with an access point, the access point establishes a period free of contention and a period of containment according to a first communication protocol, the device comprises: means for fighting for access in accordance with the first communication protocol during the containment period; a transmitter to transmit according to a second communication protocol during the fought access; and a receiver for transmitting according to a second communication protocol during the quarried access. 41.- Computer-readable media that operate to execute the following steps: fight for access to the shared medium according to a first communication protocol; and establish communication in the shared medium in accordance with a second communication protocol during the quarrel access. 42.- A wireless communication system, comprising: a device for: fighting for access to the shared medium according to a first communication protocol; and transmitting a signal, in accordance with the first communication protocol, to reserve the shared medium for a duration; a first remote station for transmitting a pilot according to a second communication protocol; and a second remote station to: measure the pilot and determine the feedback from it; and transmit the feedback to the first remote station. 43. The wireless communication system according to claim 42, characterized in that the first remote station also transmits data according to the second communication protocol to the second remote station according to the feedback. 44.- A method for communication in a shared medium, which includes: fighting for access to the shared medium according to a first protocol; transmitting a signal according to the first communication protocol to reserve the shared medium for a duration; transmitting a pilot from a first remote station to a second remote station according to a second communication protocol; measure the pilot at the second remote station and determine the feedback from it; transmitting the feedback from the second remote station to the first remote station; and transmitting data according to the second communication protocol from the first remote station to the second remote station according to the feedback. 45.- A wireless communication system that operates with a shared medium for receiving and transmitting, comprising: a first access point to establish communication in accordance with a first communication format; and a second access point to establish communication according to a second communication format, the second access point operates to transmit a signal according to the first communication format to reserve a duration in the shared medium for communication in accordance with the second communication format.