JP2007502074A - Multicast SDMA training polling - Google Patents

Abstract

  When initiating an SDMA training sequence, the base station polls multiple mobile devices with the same multicast training poll, and the polled mobile stations are separated at different times based on the delay period assigned to each mobile station. Respond to.

Description

  The present invention relates to training polling for multicast SDMA.

  Wireless data communication systems are constantly placed on the demand for increased bandwidth, and a variety of devices that can communicate with a single base station by having multiple devices share a single channel to address that problem. Technology has been developed. One such technique is that if the mobile device is located in a sufficiently different direction from the base station, the base station can simultaneously transmit and receive individual signals with multiple mobile devices on the same frequency. For transmission from the base station, different signals are transmitted simultaneously from each of the spatially separated-apart antennas, and the combined transmission is directed, i.e., the signal directed for each mobile device is It is relatively strong in the direction of the mobile device and relatively weak in other directions. In a similar manner, the base station receives the combined signal from multiple independent mobile devices simultaneously through the respective spatially separated antennas on the same frequency, and the reception is directional so that appropriate signal processing By performing the above, it is possible to separate combined signals received from a plurality of antennas into individual signals from each mobile device.

  In specifications currently under development, such as IEEE 802.11 (IEEE is an acronym for the Institute of Electrical and Electronics Engineers, located on the 17th floor of Park Avenue 3 in New York, NY), each mobile device has variable length data. Send the block, then wait for a predetermined timeout period after the Acknowledgment data block from the base station to indicate that the base station has received the data block. If the base station transmits and receives on the same frequency, the fact may preclude the base station from transmitting and receiving at the same time, so that all incoming data blocks are sent before sending an acknowledgment. The base station waits until is completed. However, because the data block is variable length, a mobile device sending a short data block may receive an acknowledgment timeout while the base station still receives a long data block from another mobile device. Will experience. Unnecessary retransmissions that occur in short data blocks can make the entire data communication inefficient and cause service interruption under certain circumstances.

  The present invention will be understood by reference to the following description and accompanying drawings that are used to illustrate embodiments of the invention.

In the following description, numerous specific details are set forth. However, it should be understood that embodiments of the invention may be practiced without these specific details. In other embodiments, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description. “One Example”, “Example”, “Example” Indications such as “various embodiments” indicate that embodiments of the present invention include specific functions, structures or characteristics, but not all embodiments necessarily include the specific functions, structures or characteristics. Indicates. Furthermore, repeated use of the phrase “in one embodiment” does not necessarily refer to the same embodiment.

  In the following description and claims, the terms “coupled” and “connected” are used with their derivatives. It should be understood that these terms are not intended as synonyms for each other. Rather, in particular embodiments, “connected” may be used to indicate that two or more elements are in direct physical or electrical contact with each other. “Coupled” means that two or more elements are in direct physical or electrical contact, or two or more elements are not in direct contact with each other but cooperate to interact with each other Can mean any of the conditions

  As used herein, unless otherwise specified, the use of adjectives indicating the order of “first”, “second”, “third”, etc. to represent a common object is a different example of similar objects. Is intended only to indicate that the subject matter is quoted, and that the subject must be in the given order, whether temporally, spatially, rated, or otherwise is not.

  Unless otherwise stated, as will be apparent from the following discussion, discussions that use terms such as “process”, “compute”, “calculate”, etc. are used throughout the specification to refer to computers, computers Related to the operation or processing of a system or similar electronic computing device, which is understood as manipulating or converting data represented as physical quantities, such as electrons, quanta, etc., to other data represented in the same way as physical quantities The

  Similarly, the term “processor” refers to any device or device that processes electronic data from any device or register and / or memory and transforms the electronic data into other electronic data that can be stored in the register and / or memory. It is about a part of. A “computing platform” may include one or more processors.

  In the context of this document, the term “wireless” and its derivatives refer to circuits, devices, systems, methods, technologies, communication channels, etc., that transmit data through the use of modulated electromagnetic radiation via non-solid media. connect. The term does not imply that the associated device does not include any wire and is not included in some embodiments.

  In accordance with common industry terminology, the terms “base station”, “access point”, and “AP” describe an electronic device that can communicate wirelessly and simultaneously with multiple other electronic devices. And the terms “mobile device” and “STA” refer to any other plurality of these electronic devices that do not require movement but still have the ability to communicate when moved. Used interchangeably. However, the scope of the present invention is not limited to devices with these terms. Similarly, the term “space division multiple access” and SDMA are used interchangeably. As used herein, these terms mean that different signals are transmitted substantially simultaneously from the same device by different antennas, so that the combined transmitted signals are directed to different devices in substantially different directions on the same frequency. Through any communication technology that results in different signals being transmitted and / or different signals are received substantially simultaneously from different devices in different directions through multiple antennas at the same frequency, and the different signals are through appropriate processing It is intended to encompass technologies that are separated from each other. The term “same frequency” as used herein may include slight variations from the exact frequency due to bandwidth tolerance, Doppler shift adaptation, parameter drift, and the like. Two or more transmissions to different devices are considered substantially simultaneous if at least part of each transmission to different devices occurs simultaneously, but the different transmissions must start and / or end simultaneously It does not imply that it should not be. Similarly, if at least a portion of each reception from different devices occurs simultaneously, two or more receptions from different devices are considered substantially simultaneous, but different transmissions begin and / or terminate simultaneously. It does not imply that it must be done. Differences in the word used for the term SDMA are often used by other words, for example, using “space” instead of “space” or “diversity” instead of “split”. There are no restrictions. The scope of the various embodiments of the invention is intended to encompass such differences in terminology.

  Some embodiments of the present invention may use a multicast signal that polls multiple mobile devices with a single transmission, with mobile devices responding in a particular order at different times.

  FIG. 1 shows a diagram of a communication network using multicast training casts according to an embodiment of the present invention. A poll is a request to an addressed device that seeks to respond by sending signals and / or information back to the polling device, and the training poll is a signal and / or information with one or more communication operating parameters Require that the format be appropriate to determine The embodiment illustrating an SDMA-based network shows an AP 110 communicating with a plurality of STAs 131-134 located in different directions from the AP. Although AP 110 is shown with four antennas 120, other embodiments may have other arrangements (eg, AP 110 may have two, three, or more than four antennas). Each STA has at least one antenna that communicates wirelessly with the AP 110. In some embodiments, the STA antenna is adapted to operate with omnidirectional, but in other embodiments, the STA antenna may be adapted to operate with directivity. In some embodiments, the STA is in a fixed location, but in other embodiments, at least some STAs may move during and / or during the communication sequence. In some embodiments, the AP is in a fixed location, but in other embodiments, the AP may move during and / or during the communication sequence.

FIG. 2 shows a timing diagram of a communication sequence for multicast training cast according to an embodiment of the present invention. The illustrated embodiment shows five STAs labeled STA1 to STA5, but the scope of the present invention is not limited to this number. To perform the training phase, the AP polls each STA in the training group (eg, in the illustrated embodiment, the training group consists of STA1-STA5), and that poll sends a training response back to the AP. The parameters for the SDMA communication performed with the STA are determined by the AP. Although each training response occurs at a different time, training responses from multiple STAs do not interfere with each other. In the illustrated embodiment, all five appropriate STAs are polled in a single transmission by using multicast transmission for training polling. Multicast transmission is expected to operate with common transmission contents by designating (addressing) a plurality of specific devices. This is in contrast to the more general single designated transmission (address to a specific single device) or broadcast (intended to work on any device that can receive), in some embodiments, Multicast training casts are sent in all directions so that all STAs in range receive training polls and only addressed respond to it, but the invention is limited in this respect There is no. Along with its individual addresses, each addressed STA receives this timing indicator directed to that STA and waits for a certain period of time before responding with a training response. In the example illustrated in FIG. 2A, the individual timing periods are shown as t ₁ -t ₅ for STA 1 -STA ₅ , respectively. In some embodiments, the timing indicator is a simple ranking (eg, 1, 2, 3, etc.), which is multiplied by a time increment that determines how long the STA should wait, but other embodiments other techniques (e.g., indicator may be directly expressed in time units, that is, each STA until STA that is higher ranked next to complete the response before sending, can wait, t ₁ May always be a short fixed delay such as 0). The time t _T for the training response is shown in FIG. 2A as the time between the training response start time (T _ST ) and the training response end time (T _ET ). After the training phase ends at time _ET , the AP can start a data phase (not shown) using the parameters derived in the training phase.

  In other embodiments, the timing indicator for each STA has already been determined. For example, the time delay may be transmitted to each STA in the previous communication, but the scope of the present invention is not limited to this or other embodiments.

  The decision on which STAs should include multicast training casts is evaluated by various factors. Each STA may have previously established a relationship with the AP and provides information about its address, wireless communication mode, possible data rate, and so on. These and other factors are evaluated by the AP in determining which STAs should be in the same multicast group. If the AP does not receive a satisfactory training response from a particular STA, that STA polls again (eg, in another multicast training group). In some operations, the data phase immediately follows the multicast training phase, while in other operations, the training phase is followed by another training phase due to a different set of STAs or different types of communication phases. Also good. The data phase may relate to the same STA that was in the previous training phase, or may include some, any, or all of the STAs that were in the previous training phase. Group STAs may be related.

  FIG. 3 shows a flowchart of a method of operation performed by a base station according to an embodiment of the present invention. In flowchart 300, a training polling group is formed at 310. Various criteria may be used to determine which currently available STAs are associated with a particular training polling group. For example, currently available SDMA parameters are known to some of the STAs, and these STAs are excluded from the polling group for other STAs for which SDMA parameters do not yet exist or need to be updated. May be.

  After determining which STAs to include in the group, at 320, the AP assigns a different time delay to each STA in the group. These time delays can be in any usable form, such as direct time delay, known time increment, ranking indicating the order in which the known time increment can be multiplied. In some embodiments, the time delay is determined such that the minimum time between any two time delays is sufficient for a mobile device sending a training response, so that two time delays from two different mobile devices Different training responses do not overlap. At 330, a multicast training cast is transmitted including the address of the polled STA, the time delay for the polled STA, and any other information that may be useful for training polling.

  After the poll is sent and the response period begins, the AP receives a first training response at 340. At 350, the AP processes the received training response and stores the processed information for further processing at a later time. The amount of processing performed at this point will vary (eg, digitize the signal, store it for further processing, calculate SDMA parameters, etc.).

  If more responses are expected, as indicated at 360, the AP returns to 340 to receive the next training response. The loop formed by 340, 350, 360 continues until all STAs in the polling group have time to respond, and the training phase ends when all have. If none of the polled STAs respond, or if the received response is not usable for its intended purpose (eg, due to corrupted data), the STA will be in another polling group at a later time if possible. Will be polled again. Although the maximum number of retries for such polling may be set, the scope of various embodiments of the present invention is not limited in this respect.

  FIG. 4 shows a flowchart of a method of operation performed by a mobile device according to an embodiment of the present invention. In flowchart 400, a multicast training cast is received 410, including the mobile device's address or other identifier. At 420, a timing indicator associated with the mobile device is extracted from the multicast poll and its time delay is determined from the timing indicator. At 430, the mobile device waits until the time delay determined at 420 expires. As described above, the time delay is measured from any feasible starting position. At the end of the time delay, the mobile device transmits its own training response at 440.

  Embodiments of the present invention can be implemented in hardware, firmware and / or software. Embodiments of the invention are also implemented with instructions stored on a machine-readable medium that are read and executed by a computing platform to perform the operations described herein. A machine-readable medium includes any mechanism for storing or transmitting information in a form readable by a machine (eg, a computer). For example, machine readable media include read only memory (ROM), random access memory (RAM), magnetic disk storage media, optical storage media, flash memory devices, electrical, optical, acoustic, Or other forms of propagated signals (eg, carrier waves, infrared signals, digital signals, etc.) and other forms.

  FIG. 5 shows a block diagram of a base station according to an embodiment of the present invention. Platform 550 performs processing suitable for a base station, but includes one or more processors, and in some embodiments, at least one of the one or more processors is a digital signal processor (DSP). In the illustrated embodiment, the AP 110 is equipped with four antennas 120, but in other embodiments, the AP 110 may be equipped with more than two, three, or four antennas. For each antenna, the base station 110 has a modem 520, an analog-to-digital converter (ADC) 530, and a digital-to-analog converter (DAC) 540. The demodulator-ADC combination converts the received radio frequency signal from the antenna into a digital signal suitable for processing by the computing platform 550. Similarly, the DAC-modulator combination converts the digital signal from the computing platform 550 into a radio frequency signal suitable for transmission by the antenna. Other components not shown may be included in the shown block if necessary, but are limited to amplifiers, filters, oscillators, multiple ADCs and / or DACs (only one is shown here). It is not something.

  FIG. 6 shows a block diagram of a mobile device according to an embodiment of the present invention. The illustrated components of the mobile device 131 include a computing platform 650, an antenna 621, a modem 620, an ADC 630, and a DAC 640, which are functionally similar to the similarly named components of FIG. Although the device is shown as a single antenna / modulator / ADC / DAC combination, the computing platform 650 performs the operations already described for mobile devices rather than base stations, The embodiments are not limited to these points.

  The above description is intended to be illustrative and not restrictive. Changes may be made by those skilled in the art. Such modifications are intended to be included in various embodiments of the present invention, and the present invention is limited only by the spirit and scope of the appended claims.

1 shows a diagram of a communication network according to an embodiment of the present invention. Fig. 4 shows a timing diagram of a training phase comprising a plurality of mobile devices according to an embodiment of the present invention. 3 shows a flowchart of a method of operating a base station according to an embodiment of the present invention. 3 shows a flowchart of a method for operating a mobile device according to an embodiment of the present invention. FIG. 4 shows a block diagram of a base station according to an embodiment of the present invention. 1 shows a block diagram of a mobile device according to an embodiment of the present invention.

Claims (29)

In the apparatus including the first electronic device, the first electronic device includes:
A first time delay indicator that indicates a first address of a second electronic device and a time that the second electronic device waits before sending a first training response;
A second time delay indicator that indicates a second address of a third electronic device and a time that the third electronic device waits before sending a second training response;
An apparatus adapted to wirelessly transmit multicast polling including:   The apparatus of claim 1, wherein the first and second training responses can be used to determine parameters for space division multiple access operation.   The apparatus of claim 1, wherein the first electronic device is further adapted to form a polling group by assigning the first and second addresses to the polling group.   The difference between the time delay indicated by the first time delay indicator and the time delay indicated by the second time delay indicator is at least as long as the second electronic device transmits the first training response. The apparatus of claim 1, wherein:   The first electronic device is further adapted to place the second address in another training poll in response to not receiving the second training response before the end of a training phase. The apparatus according to 1. A computing platform,
At least four antennas coupled to the computing platform;
The apparatus of claim 1 comprising:   The at least four modems further comprising at least four modems coupled between the computing platform and at least one of the antennas. 6. The apparatus according to 6. In an apparatus including an electronic device, the electronic device includes:
Receiving a poll comprising a plurality of addresses including a specific address associated with the electronic device;
Wirelessly sending a response to the poll following the expiration of a time delay associated with the particular address;
Equipment to fit for.   The apparatus of claim 8, wherein the response is a training response used to determine parameters for space division multiple access operation.   The apparatus of claim 8, wherein the polling includes a timing indicator indicating the time delay.   The apparatus of claim 10, wherein the electronic device is further adapted to determine the time delay from the timing indicator.   12. The apparatus of claim 11, wherein the timing indicator is ranking.   The apparatus of claim 10, wherein the timing indicator is a representation of a unit of time. A computing platform,
An antenna coupled to the computing platform;
9. The apparatus of claim 8, comprising: A modem coupled to the antenna;
An analog to digital converter coupled between the modem and the computing platform;
A digital analog converter coupled between the modem and the computing platform;
15. The apparatus of claim 14, further comprising: Sending multicast polling to multiple electronic devices;
Receiving a response from each of the plurality of electronic devices, wherein each of the responses is received at a different time;
A method comprising the steps of:   The method of claim 16, wherein the receiving comprises receiving a training response for determining parameters for space division multiple access operation.   Determining a polling group for the multicast polling prior to the transmitting, the polling group further comprising identifying information about the plurality of electronic devices. 17. A method according to claim 16, characterized in that   Further comprising transmitting a timing indicator to at least one of the plurality of electronic devices, wherein the timing indicator waits before transmitting one of the responses. The method of claim 16, wherein the method indicates a time delay for the at least one. Receiving a multicast poll including a specific identifier;
Sending a response to the multicast poll after a particular time delay associated with the particular identifier;
A method characterized by comprising.   The method of claim 20, wherein the transmitting comprises transmitting a response to determine parameters for space division multiple access operation. The receiving step includes
Receiving a timing indicator;
Determining the specific time delay from the timing indicator;
21. The method of claim 20, comprising: A machine readable medium that provides instructions, when executed by a processing platform,
Send multicast polls to multiple electronic devices,
Receiving a response from each of the plurality of electronic devices, each of the responses being received at a different time;
A machine-readable medium characterized in that   The medium of claim 23, wherein the act of receiving comprises receiving a training response that determines parameters for a space division multiple access operation.   24. The operation further includes determining a polling group for the multicast polling, the polling group indicating identifying information about each of the plurality of electronic devices. The medium described.   The operation further includes an operation of transmitting a timing indicator to a specific one of the plurality of electronic devices, wherein the timing indicator waits before transmitting the specific one of the responses. 24. The medium of claim 23, wherein the medium exhibits a time delay for a particular electronic device. A machine readable medium that provides instructions, when executed by a processing platform,
Receive a multicast poll with a specific identifier,
Sending a response to the multicast poll after a specific time delay associated with the specific identifier;
A machine-readable medium characterized in that   The medium of claim 27, wherein the transmitting operation includes an operation of transmitting a response for determining a parameter for a space division multiple access operation. The timing indicator is received,
Determining the specific time delay from the timing indicator;
28. A medium according to claim 27.

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