First and second communication devices and methods

Abstract

A first communication device configured to transmit data to a second communication device, comprising circuitry configured to: generate a second number of mutually orthogonal sequences; generate a third number of one or more spatial streams, each spatial stream carrying payload data; divide each of a first number of training symbols into a fourth number of sets of tones, each training symbol spanning a plurality of tones; divide each orthogonal sequence into a fourth number of portions; generate a training field by mapping elements of a corresponding portion of an orthogonal sequence onto a set of tones of a training symbol; and arrange the training field before and / or between the payload data of the spatial streams to enable channel estimation by the second communication device.

Description

Technical Field

[0001] This disclosure relates to first and second communication devices and methods configured to communicate with each other. Background Technology

[0002] Wireless communication can be interfered with when several transmitters simultaneously access the channel at the same frequency. In distributed access technologies like WLANs, transmitters compete for the channel, potentially leading to collisions. Furthermore, in scenarios with high-density stations (STAs) and access points (APs), many basic service sets (BSS) may overlap, causing unwanted interference. Additionally, WLANs operate in unlicensed spectrum, meaning other transmitters from other technologies can use the same wireless channel. For these reasons, interference can occur during communication between STAs and APs, and vice versa, resulting in communication interruptions. That is, the receiver cannot decode information because the transmitter will need to retransmit messages, leading to decreased reliability, reduced throughput, and increased latency.

[0003] The “background” description provided herein is intended to provide a general context for this disclosure. To the extent described in this background section, the work of the currently named inventor and aspects of the description that may not be considered prior art at the time of filing are neither explicitly nor implicitly considered prior art to this disclosure. Summary of the Invention

[0004] The objective is to improve detection, channel estimation, and interference suppression at the receiver, and to provide corresponding communication equipment and methods. Another objective is to provide corresponding computer programs and non-transitory computer-readable recording media for implementing the methods.

[0005] According to one aspect, a first communication device is provided, configured to transmit data to a second communication device, the first communication device including circuitry configured to:

[0006] - Generate a second number of mutually orthogonal sequences;

[0007] - Generate a third number of one or more spatial streams, each carrying payload data;

[0008] - Divide each of the first number of training symbols into a fourth number of tone sets, with each training symbol spanning multiple tones;

[0009] - Divide each orthogonal sequence into a fourth number of parts;

[0010] - Training fields are generated by mapping elements of corresponding parts of orthogonal sequences to the tone set of training symbols; and

[0011] - Set training fields before and / or between the payload data of the spatial stream to enable channel estimation by a second communication device.

[0012] According to another aspect, a second communication device is provided, configured to receive data from a first communication device, the second communication device including circuitry configured to:

[0013] - Based on at least a portion of the training field, obtain one or more expected channel observations of one or more channels between a first communication device and a second communication device, wherein the training field is set before and / or between payload data of a third number of spatial streams received from the first communication device, wherein each spatial stream carries payload data, each of a first number of training symbols is divided into a fourth number of tone sets and spans multiple tones, and each of a second number of mutually orthogonal sequences is divided into a fourth number of parts, wherein elements of corresponding parts of the orthogonal sequences are mapped to tone sets of training symbols to generate the training field;

[0014] - Perform interference channel estimation for one or more potential interference channels based on another portion of the training field; and

[0015] - Perform interference suppression based on the interference channel estimation information obtained from the interference channel estimation.

[0016] According to yet another aspect, a computer program is provided, comprising program means for causing a computer to perform the steps of the methods disclosed herein when the computer program is executed on a computer, and a non-transitory computer-readable recording medium therein storing a computer program product, which, when executed by a processor, causes the methods disclosed herein to be performed.

[0017] The embodiments are defined in the dependent claims. It should be understood that the disclosed communication method, the disclosed computer program, and the disclosed computer-readable recording medium have other embodiments similar to and / or identical to the claimed communication device, and as defined in the dependent claims and / or herein.

[0018] One aspect of this disclosure is enabling the receiver (i.e., the second communication device) to obtain observations of the interfering channel. Therefore, this disclosure maintains the desired low signaling overhead and high channel estimation quality for the transmitter.

[0019] In this context, the terms "intended transmitter" and "intended STA" refer to the device (also referred to as the "first communication device" in this disclosure) that transmits a signal that the receiver (e.g., another station or AP; also referred to as the "second communication device" in this disclosure) wants to decode. This means that for a data unit transmitted by the intended transmitter, such as a PHY protocol data unit (PPDU; also generally referred to as a "data unit" in this disclosure), the receiver can synchronize and decode a signaling field that may precede the training field. "Interference transmitter" or "jammer" (also referred to as the "third communication device" in this disclosure) refers to another device (e.g., an STA or AP) that is transmitting a signal that interferes with communication between the intended transmitter and receiver.

[0020] This disclosure enables interference detection, interference channel estimation, and interference suppression at the receiver by designing a detection method that increases the number of channel observations at the receiver compared to current standard implementations. In the implementation for increasing the number of channel observations, orthogonal (training) sequences are mapped around several frequency tones. This allows the receiver to improve decoding performance in the presence of interference, increase reliability, and reduce the number of data retransmissions. Fewer data retransmissions reduce latency and increase throughput.

[0021] The foregoing paragraphs are provided by way of general description and are not intended to limit the scope of the appended claims. The described embodiments and further advantages will be best understood by referring to the following detailed description taken in conjunction with the accompanying drawings. Attached Figure Description

[0022] A more complete understanding of this disclosure and its many accompanying advantages will be readily available when considered in conjunction with the accompanying drawings and by referring to the following detailed description, in which:

[0023] Figures 1A to 1C A schematic diagram illustrating the three different HE-LTF types defined in the WLAN 802.11ax amendment is shown;

[0024] Figure 2 A schematic diagram illustrating an example of an orthogonal sequence mapping with four spatial flows is shown.

[0025] Figure 3 A schematic diagram is shown of a generator used to generate the probe field described in WLAN 802.11ax;

[0026] Figure 4 A flowchart is shown illustrating a method for dynamically adjusting the number of training symbols within each data exchange between communication devices;

[0027] Figure 5 A schematic diagram of a communication system including a first communication device and a second communication device according to the present disclosure is shown;

[0028] Figure 6 A flowchart illustrating an embodiment of a first communication method of a first communication device according to the present disclosure is shown;

[0029] Figure 7 A flowchart illustrating an embodiment of a second communication method of a second communication device according to the present disclosure is shown;

[0030] Figure 8 A schematic diagram illustrating an example of an orthogonal sequence mapping with three spatial flows according to this disclosure is shown;

[0031] Figure 9 A schematic diagram illustrating an example of a training field with two training symbols according to this disclosure is shown;

[0032] Figures 10A to 10D A schematic diagram illustrating the amplitude and phase of the autocorrelation function between tones in a typical WLAN channel model is shown.

[0033] Figure 11 A flowchart is shown for a method of selecting the number of adjacent non-empty tones in a mapping;

[0034] Figure 12 A flowchart illustrating another embodiment of the first communication method of the first communication device according to the present disclosure is shown; and

[0035] Figure 13 A flowchart of another embodiment of a second communication method according to the second communication device of the present disclosure is shown. Detailed Implementation

[0036] According to the WLAN 802.11 standard, the transmitter can adapt the modulation and coding scheme (MCS) to channel conditions in order to control the redundancy level of the transmitted information. This can provide robustness against interference at the cost of lower throughput and increased latency.

[0037] For decades, MIMO technology has been incorporated into WLANs, offering the possibility of combating interference through signal processing without incurring significant overhead. If the receiver is equipped with several antennas, it can use probe signals transmitted by the transmitter to estimate the channel and suppress interference between different spatial streams transmitted by one or more other (i.e., third-party) transmitters.

[0038] The main limitation of WLAN is that only the intended transmitter sends a probe signal. If the interference source is from an unintended transmitter, due to collisions or external sources, there is no probe signal or procedure to detect the presence of interference in ongoing transmissions or to estimate the interfering channel.

[0039] The probe signals in the latest WLAN 802.11ax revision are called High-Efficiency Long Training Fields (HE-LTF). These signals are added to the preamble of the PHY Protocol Data Unit (PPDU), or between PPDUs, as intermediate codes inserted at a given period to counteract rapid channel changes.

[0040] Referring now to the accompanying drawings, in which the same reference numerals denote the same or corresponding parts in several views. Figures 1A to 1C A schematic diagram illustrating the three different HE-LTF types 1, 2, and 3 defined in the WLAN 802.11ax amendment is shown. Each HE-LTF corresponds to an OFDM symbol (also referred to herein as a “training symbol” or “HE-LTF symbol”), which consists of a number of tones spanning the bandwidth of the channel used. There are three types of HE-LTF symbols 1, 2, and 3, which have different durations and numbers of fill tones, namely, Type 1 (… Figure 1A The one shown is called 1xHE-LTF, with each training symbol lasting 3.2 μs, and the second type 2 ( Figure 1B The one shown is called 2xHE-LTF, with each training symbol lasting 6.4 μs, and a third type 3 ( Figure 1C The example shown is called 3xHE-LTF, with each training symbol lasting 12.8 μs. The more pitches filled, the longer each HE-LTF symbol becomes. The number of HE-LTF symbols is determined by N. HE-LTF This is expressed as, and based on the total number of spatial flows (denoted as N). sts To choose, so that

[0041]

[0042] Similarly, Figures 1A to 1C As shown, each of the training symbols 1, 2, and 3 has multiple reserved tones set to "0", an empty LTF tone set to "0", and a non-empty LTF tone set to "+1" or "-1".

[0043] Based on the design of these HE-LTF signals, the receiver can estimate the MIMO channel between itself and the transmitter at each non-empty tone. The channel estimation corresponding to the empty tone is obtained by interpolation techniques that are beyond the scope of this disclosure and depend on the implementation, but are generally known to those skilled in the art. For each non-empty data tone, based on the transmitter at N HE-LTF Orthogonal length sequence N sent during symbol period HE-LTF The MIMO channel estimate is calculated at the receiver. These orthogonal sequences are stored in the array denoted as P. HE-LTF(Also referred to in this paper as the orthogonal sequence mapping matrix or HE-LTF mapping matrix) is a square matrix (i.e., having the same number of rows and columns), and each spatial stream is assigned one row of this matrix for transmission, as follows. Figure 2 and 3 China targets N HE-LTF As shown in the case where =4.

[0044] Figure 2 A schematic diagram illustrating an example of an orthogonal sequence mapping with four spatial flows (SS). In this case, the term "orthogonal" means P HE-LTF Matrix multiplication across different rows results in zero. Therefore, the receiver can retrieve channel observations between itself and each spatial stream transmitted by the transmitter without interference between spatial streams.

[0045] Figure 3 A schematic diagram (shown as Figures 27-32) of a (transmitter) generator 40 for generating the HE-LTF described in WLAN 802.11ax is shown. For the data tones in the HE-LTF, orthogonal sequences supporting MIMO channel estimation are stored in matrix A. k HE-LTF = P HE-LTF A k HE-LTF The first N of the matrix sts Each row of the row is assigned to generate N. HE-LTF A spatial flow of HE-LTF symbols. If A k HE-LTF The matrix has more than N rows sts If so, no extra lines will be transmitted.

[0046] More specifically, in this case, the training symbols are referred to as HE-LTF. Initially, the following parameters are chosen: HE-LTF pitch sequence (HELTF), the number of HE-LTF symbols (N). HE-LTF ) and the number of spatial flows (N) sts Obtain an orthogonal sequence as the square P of mutually orthogonal rows. HE-LTF The matrix has the same number of rows as columns. The number of elements in each orthogonal sequence is equal to N. HE-LTF For each spatial stream, an orthogonal sequence is assigned. For each tone (indexed by k, the process is the same for all tones), each orthogonal sequence is multiplied by the corresponding HE-LTF tone sequence in multiplier module 41. This produces N for each spatial stream. HE-LTF 1 HE-LTF symbol. For example, if N sts =2, N HE-LTF =2, then keep:

[0047] Following the cyclic shift in Cyclic Shift Diversity (CSD) module 42, symbols from all spatial streams are combined with the Q matrix via matrix multiplication in combination module 43 to produce symbols transmitted by each transmit antenna. This CSD module introduces a cyclic time shift for the signal of each spatial stream to avoid unintentional beamforming effects when transmitting several spatial streams. The Q matrix has a cyclic time shift relative to the transmit antenna (N... TX The number of rows equal to 45 and the space flow (N) sts The same number of columns. It should be noted that for subsets of tones, the Q matrix can be chosen differently, but the mapping process remains unchanged. For each tone, it maintains that the training symbols can be derived from matrix A. k Indicate that matrix A k Having spatial flow (N) sts The same number of lines and HE-LTF symbols (N HE-LTF The same number of columns as ).

[0048] QA on matrix multiplication k The result rows are read from which transmit symbols are used for each Inverse Discrete Fourier Transform (IDFT) module 44 and each transmit antenna 45. Following the example mentioned above, and assuming a direct spatial mapping, where N TX =2 and each spatial flow is assigned to one antenna, i.e., Q is the identity matrix, which holds:

[0049]

[0050] The transmission of training symbols for each antenna is as follows:

[0051]

[0052] Alternative examples with different Q matrices assume indirect spatial mappings, where N TX =3 and Read the transmitted symbols for each transmit antenna from the rows of the following matrix:

[0053]

[0054]

[0055] The maximum number of channels that can be estimated at the receiver is subject to P. HE-LTF The limitation on the number of rows, i.e., the number N of HE-LTF symbols in the WLAN 802.11ax correction. HE-LTF This means that in order to detect and estimate the spatial flow N... sts A greater number of channels, such as interfering channels, P HE-LTF The size needs to be larger.

[0056] To suppress interference signals using MIMO, the receiver needs to obtain an estimate of the interference channel, which means observing the interference in the absence of the expected STA. However, this is not possible in the current implementation of WLAN 802.11ax because, in most cases, the number of HE-LTF symbols is designed to match the number of spatial streams. Furthermore, several observations are required to obtain a good estimate of the interference channel, and the maximum number of unused HE-LTF symbols is 1.

[0057] This disclosure attempts to achieve interference detection, channel estimation, and suppression at the receiver by designing a novel detection method that increases the number of channel observations compared to current standard implementations. Therefore, for this purpose, an enhanced long training field (E-LTF) based on a modified HE-LTF signal is envisioned. Several implementations for this modification will be discussed below.

[0058] The modifications disclosed in this article occurred in A k E-LTF In the generation of the matrix, this matrix will replace Figure 2 A shown k HE-LTF Matrix. These modifications include changes to A. k E-LTF The elements of the matrix and its size are changed because A k E-LTF The number of columns in the matrix corresponds to the number of E-LTF symbols (also referred to as "training symbols" in this paper). These changes will enable interference channel estimation and suppression at the receiver.

[0059] To create an E-LTF signal, the number of E-LTF symbols to be transmitted is defined. In WLAN 802.11ax amendments, the number of E-LTF symbols is selected solely based on the number of spatial flows, while according to this disclosure, the number of E-LTF symbols is selected to balance time overhead and MIMO interference suppression performance. Therefore, in addition to different implementations of the proposed detection method, a method for selecting the number of E-LTF symbols will be disclosed, as described below.

[0060] First, starting with the minimum number of E-LTF symbols, evaluate the boundary of how many E-LTF symbols can be emitted. As mentioned above, use at least as many orthogonal sequences as the number of spatial streams (i.e., instead of...). Figure 2 P shown HE-LTF P E-LTF The rows of the matrix), denoted as N sts Therefore, the minimum number of E-LTF symbols supports the use of a minimum size of N. sts ×N sts P E-LTFMatrix. Furthermore, to obtain an estimate of the interference, a spatial flow N is required at the receiver. sts The number of symbols must be at least one more channel observation available. Based on these conditions, a minimum number of E-LTF symbols can be set, determined by N. minE-LTF express.

[0061] The following factors need to be considered regarding the maximum number of E-LTF symbols. Since E-LTF symbols are used for channel estimation, the channel must remain approximately static for the duration of the PPDU or until the transmission of the intermediate code (referred to as the coherence time). This can be estimated on any device based on statistical measurements of the signal (e.g., during the association process between the device and the BSS). Therefore, the number of E-LTF symbols ensures that the duration of the E-LTF is at least one OFDM symbol shorter than the coherence time.

[0062] However, in practice, a smaller number of training symbols is desirable compared to the number of data symbols, in order to achieve high throughput and / or low latency with low time overhead. Therefore, the maximum number of E-LTF symbols (denoted as N) is... maxE-LTF The specific receiver implementation and channel conditions are used to limit time overhead and achieve the desired performance in terms of throughput and latency.

[0063] The performance of MIMO suppression techniques at the receiver depends on the specific implementation and channel conditions. Therefore, it is desirable to adjust the number of E-LTF symbols based on each specific situation. Figure 4 A flowchart is shown for a method 100 for dynamically adjusting the number of E-LTF symbols within each data exchange between communication devices. Here, N 余量 It is the number of E-LTF symbols to be added or subtracted in each data exchange, and Δ 余量 It is the margin of the interference indicator.

[0064] In the first step 101, prior to the first PPDU exchange, the transmitter sets the number of E-LTF symbols to a minimum of N. minE-LTF Then, after evaluating the performance of MIMO interference suppression in past PPDUs, the number of E-LTF symbols can be increased or decreased based on notifications from the receiver. Indicators in the signaling field of the response message (e.g., Ack or MCS feedback) can be envisioned, allowing the receiver to suggest to the transmitter whether to increase or decrease the number of E-LTF symbols, which is then checked and decided by the transmitter in step 102.

[0065] If no notification is received, and step 103 detects that the average interference index over a period of time is higher than the set minimum value plus a margin Δ, 余量In step 105, the transmitter can increase the number of E-LTF symbols. This metric can be created based on one or more of the following: Signal-to-Interference-plus-Noise (SINR) level, received power level, number of active BSSs, and number of past collisions. If the time-averaged interference metric is higher than the aforementioned values, it means there are many potential interfering devices, and the receiver will benefit from having more E-LTF symbols for interference suppression. Conversely, if the time-averaged interference metric checked in step 104 is lower than the minimum value minus a margin Δ... 余量 This indicates a low number of potential interferences, and therefore the number of E-LTF symbols is reduced in step 106 to reduce time overhead.

[0066] If neither of the above two conditions is met, the number of E-LTF symbols will remain unchanged in the next transmission. If there is notification, such as that checked in step 102, the number of E-LTF symbols will be increased in step 105 or decreased in step 106 according to the notification. To support... Figure 4 The method shown allows the transmitter to, for example, add an indicator to the signaling field of the PHY preamble to indicate how many E-LTF symbols the receiver transmitted in the PPDU. maxE-LTF Δ 余量 N 余量 The values ​​of the minimum interference indicator depend on the receiver implementation, channel conditions, and target throughput and / or delay constraints.

[0067] Regarding N maxE-LTF It should be noted that a rule of thumb in MIMO communication, which typically involves channel estimation, suggests that 50% of the coherence time should be used for training symbols. Therefore, N maxE-LTF It should not exceed 70% of the coherence time, and for N set to 50% of the coherence time... maxE-LTF This can yield favorable results.

[0068] Regarding Δ 余量 Note that this parameter controls how frequently the E-LTF quantity changes without notification. In highly dynamic environments, such as shopping malls or airports, a smaller value may be needed to adjust the E-LTF quantity more quickly. Conversely, in more static environments, such as in private apartments, a larger value may be needed. 余量 Set to a large value to avoid unnecessary changes to the E-LTF. Specifically, if the interference metric is based on SINR or power level, then Δ... 余量The minimum value is approximately 3 dB (meaning a coefficient of x2), while the maximum value will be between 10-20 dB (i.e., a coefficient of x10 to x100). Values ​​below 1 dB are generally considered impractical (as they cause too frequent changes), and values ​​above 30 dB will result in almost no change in E-LTF. However, if the indicator is based on the number of BSSs or the number of past retransmissions, the margin will have a different value. For example, if high reliability is desired, the E-LTF should be changed after a retransmission or if more than one BSS is present nearby. A general range can be given in terms of the interference indicator. For example, the margin value would range from 0.5 to 100 times the average interference indicator value.

[0069] Regarding N 余量 Note that this number should be a positive integer, as only an integer number of signs can be added. The value can range from 1 to N. maxE-LTF -1 is used to indicate that the amount of E-LTF can be changed one at a time or made to a large extent. Preliminary results show that doubling the amount of E-LTF can yield significant benefits. Therefore, a typical action could be to increase N... 余量 Set to a factor equal to the previous E-LTF number (e.g., 0.5x to 2x). Alternatively, since the maximum number of spatial flows allowed in IEEE 802.11ax is 8, typical operation can be set between 1 and 16.

[0070] Figure 5 A schematic diagram is shown of a first communication device 10 (also referred to herein as a intended transmitter, e.g., a station STA) for communicating with a second communication device 20 (also referred to herein as a receiver, e.g., representing an access point AP) according to one aspect of this disclosure. The first communication device 10 is capable of exchanging (receiving and / or transmitting) data with the second communication device 20, and the second communication device may optionally communicate with other communication devices (e.g., Figure 5 Data is exchanged with other stations (not shown in the text). This communication, and in particular one or more channels used for this communication, may be subject to interference, such as interference from the transmission of a third communication device 30 (also referred to herein as an unintended or interfering transmitter, e.g., indicating another station).

[0071] Each of the communication devices 10, 20, and 30 includes circuits 11, 21, and 31 configured to perform specific operations. These circuits may be implemented by a corresponding processor or computer, i.e., as hardware and / or software, or by dedicated units or components. For example, separately programmed processors may represent the corresponding circuits 11, 21, and 31.

[0072] Figure 6A flowchart illustrating an embodiment of a first communication method 200 according to a first communication device 10 of the present disclosure, which can be executed by circuit 11, is shown. In a first step 201, a second number of mutually orthogonal sequences are generated. In a second step 202, a third number of one or more spatial streams are generated, each spatial stream carrying payload data. In a third step 203, each of the first number of training symbols is divided into a fourth number of tone sets, each training symbol spanning multiple tones. In a fourth step 204, each orthogonal sequence is divided into a fourth number of portions. In a fifth step 205, a training field is generated by mapping elements of corresponding portions of the orthogonal sequences to the tone sets of the training symbols. In a sixth step 206, the training field is arranged before and / or between the payload data of the spatial streams to enable channel estimation by a second communication device.

[0073] Figure 7 A flowchart illustrating an embodiment of a second communication method 300 according to a second communication device 20 of the present disclosure is shown, the method being executed by circuit 21. In a first step 301, one or more expected channel observations of one or more channels between a first communication device and a second communication device are obtained based on at least a portion of a training field. Therefore, the training field is arranged before and / or between payload data of a third number of one or more spatial streams received from the first communication device, wherein each spatial stream carries payload data, each of a first number of training symbols is divided into a fourth number of tone sets and spans multiple tones, and each of a second number of mutually orthogonal sequences is divided into a fourth number of portions, wherein elements of corresponding portions of the orthogonal sequences are mapped onto the tone sets of the training symbols to generate the training field. In a second step 302, interference channel estimation of one or more potential interference channels is performed based on another portion of the training field. In a third step 303, interference suppression is performed based on the interference channel estimation information obtained from the interference channel estimation.

[0074] For 2xE-LTF and 4xE-LTF signals, the duration of an E-LTF symbol is twice and four times longer, respectively, compared to 1xE-LTF, thus multiplying the number of non-empty tones by 2 and 4, respectively. This means that the frequency space between non-empty tones is divided by 2 and 4, respectively. The wireless channel varies with frequency according to the multipath characteristics of the propagation environment. However, the channels experienced in adjacent tones are often highly correlated. This means that channel estimation can be performed by incorporating observations from adjacent tones.

[0075] By P E-LTF The size of the matrix indicates the number of orthogonal sequences used to estimate the spatial flow. In standard WLAN operation, P E-LTFThe size of the matrix is ​​equal to the number of E-LTF symbols. In one implementation, a P matrix with a dimension greater than the number of E-LTF symbols is proposed. E-LTF The matrix is ​​used to map its rows around non-empty neighboring tones. This results in more orthogonal sequences (i.e., P...). E-LTF (The rows of the matrix) to obtain more observations for channel estimation of expected STA and interference. Because the sequence is preferably mapped around non-empty tones, the number and location of non-empty tones do not change. Figure 8 and Figure 9 The mapping technique is shown in the figure. Figure 8 A P with a size of 4×4 is shown. E-LTF A matrix consisting of four orthogonal sequences (one per row) with four elements. These orthogonal sequences are mapped to two E-LTF symbols (i.e., N...). E-LTF =2) and two adjacent non-empty data tones (represented as N) wt =2), such as Figure 9 The diagram depicts a probe field with two training symbols (8). In this example, the transmission duration corresponds to two E-LTF symbols. Furthermore, three spatial streams from the intended transmitter are assigned to three orthogonal sequences. Therefore, there is one unused orthogonal sequence that can be used to estimate the interference channel.

[0076] Therefore, in this example, it applies to data tone:

[0077]

[0078]

[0079] Wherein, index k indicates the tone, index n indicates the E-LTF symbol to be emitted, and index m indicates the spatial stream. Figure 8 and Figure 9 In the example shown, the number of adjacent tones to be mapped (also known as the "fourth number") is N. wt =2, the number of E-LTF symbols (also known as the "first quantity") is N E-LTF =2, the number of mutually orthogonal sequences (also known as the "second quantity") is equal to the number of elements in the orthogonal sequence, which is N. col-PE-LTF =4, and the number of space flows (also known as the "third quantity") is N. sts =3.

[0080] Create Indicator I n k Mapping P E-LTF Which columns of the matrix are mapped to which E-LTF symbol and data tone? This is important to consider because P is required. E-LTF The channel estimate is calculated using all columns of the matrix, so P E-LTFThe mapping of matrix columns should include adjacent data tones. However, within each E-LTF symbol, some tones are reserved (e.g., guard frequencies, DC), and others are assigned to pilots. Therefore, the following conditions should be met:

[0081] a) P E-LTF The size of the matrix should be (N) wt ·N E-LTF × N wt ·N E-LTF ).

[0082] b) The number of adjacent non-empty data tones to be mapped (denoted as N) wt The number of uninterrupted non-empty data tones on the total transmission bandwidth should not exceed the minimum number (denoted as N) of tones. ut Here, "uninterrupted" means that there are no reserved or pilot tones between non-empty data tones.

[0083] c) Indicator I n k P should be E-LTF The columns of the matrix are divided into N wt Each group is assigned a number of notes and mapped to adjacent tones. An example of this mapping is as follows:

[0084]

[0085] Where k corresponds to the pitch index and n corresponds to the E-LTF symbol index.

[0086] As described above, the number of available orthogonal sequences is determined by the product of the number of E-LTF symbols and the number of adjacent non-empty data tones to be mapped (the fifth number of adjacent tones forming a set of adjacent tones), i.e., N. E-LTF ·N wt It can be done through Figure 4 The method shown selects the number of E-LTF symbols and requires that the following conditions be met.

[0087] N E-LTF · N wt ≥N sts +1

[0088] Therefore, the minimum number of E-LTFs is given by the following formula.

[0089]

[0090] Operators This indicates rounding to the nearest integer (e.g., ...). =1, = 2).

[0091] To determine the number (N) of adjacent non-empty data tones to be mapped wt Considering channel properties is crucial. A key characteristic of mapping adjacent tones is that only one channel estimate can be obtained for each orthogonal sequence. This means that if several adjacent non-empty tones are mapped, their channel estimates will come from the same observations. Therefore, if the channel changes significantly between tones, mapping techniques may give poor channel estimates.

[0092] For the transmitter to determine how many adjacent tones can be mapped together, it can estimate the channel correlation between the tones. This can be done by looking at the LTF (e.g., Clear Transmission (CTS), Ack, MCS Feedback) in the response PPDU message. If no response message is available in previous transmissions, the transmitter can use a default mapping in the first PPDU, which is selected based on initial measurements of interference (e.g., the level of average received power and / or the number of active BSSs near the device, and / or SINR). However, when the channel itself changes rapidly, the correlation between tones changes at a slower rate, allowing the transmitter to track this correlation between tones over longer time periods.

[0093] Based on measurements of channel correlation between tones, the transmitter can determine how many tones can be mapped. Figures 10A to 10D An example of the amplitude and phase of the autocorrelation function between tones in a typical WLAN channel model is shown. Figure 10A and Figure 10B A graph showing the amplitude and phase of the tone autocorrelation of a randomized implementation of a 20MHz channel with all 256 tones is presented. Figure 10C and Figure 10D Only the amplitude and phase diagrams for the first 16 tones are shown.

[0094] from Figures 10A to 10D It can be seen from this that adjacent tones ( Figures 10A to 10D The small pitch lag in the [channel autocorrelation function] exhibits very similar amplitudes and small phase deviations. In this standard, the minimum amplitude (M) of the channel autocorrelation function, expressed as r(k), can be defined. min-ac ) and maximum phase (θ) max-ac ), to determine the maximum number of tones that can be mapped together, denoted as N. max-wt .Right now,

[0095] ,in,

[0096] Make and

[0097] The arg() function returns the phase of the argument. Note that Nwt The minimum possible value is "1", which essentially corresponds to the standard implementation where no adjacent tones are mapped together. Recall that N ut This corresponds to the minimum number of uninterrupted, non-empty data tones on the total transmission bandwidth.

[0098] The exact number of mapped tones can be indicated to the receiver in one of the PHY signaling fields in the preamble of the PPDU. After each PPDU is transmitted by the transmitter, the receiver can evaluate the effectiveness of the interference suppression method (e.g., the SINR level and / or the value of the log-likelihood ratio per decoded symbol) and suggest another number of mapped tones to be used in the next PPDU. Indicators in the signaling fields of the response message (e.g., Ack, MCS feedback) can be envisioned, allowing the receiver to suggest another number of mapped tones to the transmitter. The choice of the number of mapped tones depends on the receiver implementation and channel conditions. Therefore, Figure 4 The process of selecting the number of E-LTF symbols shown can be adapted as follows: Figure 11 The number of selected mapping tones is shown.

[0099] Figure 11 A flowchart of a method 600 for selecting the number of adjacent non-empty tones in a mapping is shown. N T-余量 This refers to the number of mapped tones that are added or subtracted in each data exchange. Before the first PPDU exchange, in the first step 601, the transmitter sets the number of mapped adjacent tones to "2", which is the minimum value to support tone mapping for longer orthogonal sequences compared to the standard. Then, in step 602, the number of mapped adjacent tones is compared with the maximum value N allowed by the channel. max-wt Compare them.

[0100] Then, after evaluating the performance of MIMO interference suppression in past PPDUs, the number of mapped adjacent tones can be increased (step 604) or decreased (step 605) based on notifications issued by the receiver (as checked in step 603). Indicators in the signaling field of the response message (e.g., Ack, MCS feedback) can be envisioned, allowing the receiver to suggest to the transmitter whether to increase or decrease the number of mapped adjacent tones.

[0101] If no notification is received, the maximum number of adjacent tones in the mapping is updated in step 606 as follows:

[0102] ,in,

[0103] Make and

[0104] The autocorrelation function of the most recently received signal based on the response message from the receiver. If neither of the above two conditions is met, then the number of mapped adjacent tones will remain unchanged in the next transmission. N max-wt and N T-余量 The value of N depends on the receiver implementation, channel conditions, and target throughput and / or delay constraints, and therefore will not be discussed in more detail in this disclosure. T-余量 The range can be from 1 to N ut -1. Typical values ​​can be between 1 and 4, but higher values ​​can also be used.

[0105] P was designed separately HE-LTF HE-LTF sequences and orthogonal sequences in the matrix. P HE-LTF The matrix requires that the rows be orthogonal, and its design helps to separate channels from different spatial streams. HE-LTF sequences are designed to reduce PAPR, and in the standard implementation, the same orthogonal sequences (i.e., P...) are assigned to the spatial streams. HE-LTF The rows of the matrix are copied for all non-empty tones and then multiplied by an HE-LTF sequence (e.g., as shown in the image). Figure 3 As shown, all HE-LTF symbols in the k-th tone are multiplied by the same HELTF. k (Value). This ensures that the pitch value variation is determined solely by the HE-LTF sequence, and that PAPR remains within acceptable levels.

[0106] When mapping P between adjacent non-empty tones E-LTF When dealing with orthogonal sequences of matrices, the E-LTF sequence may be modified, thereby altering PAPR performance. For example, changing the E-LTF sequence of the second E-LTF symbol.

[0107] To avoid altering the structure of the E-LTF sequence or mitigate its impact on PAPR, P can be formed in blocks based on the Hadamard method. E-LTF Matrix. P E-LTF The matrix design creates blocks that are copied across rows and columns (with some negative multiplication in some cases). This means that rows in each block will have N repetitions. wt The column values ​​are calculated, and the E-LTF sequence remains unchanged when the mapping is complete. Therefore, PAPR performance will not change when the number of spatial streams is less than the number of E-LTF symbols.

[0108] In P E-LTF When the design of the matrix introduces changes in the E-LTF sequence structure, the PAPR values ​​should be evaluated to ensure they are within acceptable ranges. Note that since the pitch mapping has indicators I... n kThe given well-defined patterns allow for the modification of existing E-LTF sequences to reduce PAPR. If correlations exist between non-empty tones (a common occurrence in WLAN channels), the number of orthogonal sequences can be significantly increased without incurring additional time overhead, making this approach highly attractive for latency-sensitive services.

[0109] Therefore, based on the implementation method explained above, the following parameters are initially selected: E-LTF tone sequence (ELTF), number of E-LTF symbols (N). E-LTF ("First quantity") and the quantity of spatial flow (N) sts (“Third Quantity”). Obtain an orthogonal sequence as the square P of mutually orthogonal rows. E-LTF The matrix has the same number of rows as columns. The orthogonal sequence is divided into several ("fourth quantity") parts, which are mapped to different frequency tones from different tone sets. The number of parts is determined by the number of mapped tones, N. wt (The "fourth quantity") is given. The number of elements in each part is N. E-LTF The total number of elements in each orthogonal sequence ("second quantity") is equal to N. col-PE-LTF =N wt ·N E-LTF Each spatial flow is assigned an orthogonal sequence. There are more orthogonal sequences than spatial flows, i.e., N. sts +1≤N col-PE-LTF .

[0110] In an exemplary implementation of the disclosed mapping method, N wt A set of tones is defined such that each part of an orthogonal sequence is assigned to each set of tones. Each part of an orthogonal sequence is associated with N. E-LTF Multiply the corresponding tone sets of each E-LTF symbol.

[0111] In one example, it holds: N sts =2, N E-LTF =2, N wt =2, N col-PE-LTF =N wt ·N E-LTF =4. There are N wt The two tone sets are defined as even-numbered tones and odd-numbered tones. The odd-numbered tone portion can be, for example,... Figure 8 P shown E-LTF The first two columns of the matrix, the even-numbered tone portion, can be, for example, Figure 8 P shown E-LTF The last two columns of the matrix. For odd-numbered tones (indexed by k), it preserves:

[0112] For even-numbered tones (indexed k+1), it preserves:

[0113]

[0114] In another example, it remains: N sts =2, N E-LTF =1, N wt =4, N col-PE-LTF =N wt ·N E-LTF =4. Modular arithmetic is defined with N. wt =4 tone sets:

[0115] The portion used for tone set 1 can be, for example... Figure 8 P shown E-LTF The first column of the matrix, the part used for tone set 1, can be, for example, P. E-LTF The first column of the matrix, and so on. Then, for k in tone set 1, it holds:

[0116]

[0117] For k in tone set 2, it holds that:

[0118] For k in tone set 3, it retains:

[0119] For k in tone set 4, it retains:

[0120]

[0121] Therefore, according to this disclosure, each spatial stream is identified by different orthogonal sequences that have been mapped to training symbols. Since there may be more than one spatial stream, after mapping different orthogonal sequences with training symbols, there are different sets of training symbols, one for each spatial stream. These different sets of training symbols are then mapped to the transmit antenna along with the payload data for each spatial stream.

[0122] Different parts of each orthogonal sequence are mapped to different tones, and it should always be found that a complete orthogonal sequence is mapped to adjacent tones. For example, if an orthogonal sequence is divided into four parts, then in any (non-reserved) set of four adjacent tones, all parts should be mapped.

[0123] Any group of adjacent tones that contains all parts of an orthogonal sequence needs to undergo similar channel implementations. Therefore, to determine the maximum number of parts (also referred to herein as the fifth number), one can examine how similar the channels are between adjacent tones, which can be done by measuring the channel correlation between tones. For example, if the channel correlation is measured and the channel variation between four adjacent tones is very small, the orthogonal sequence can be divided into four parts. However, if the channel varies significantly between eight adjacent tones, it is preferable not to use eight parts.

[0124] The channel correlation between tones changes gradually as the tones become more distant. Therefore, as in the example above, if the channel variation is small between four adjacent tones, the optimal number of tones to be mapped could be, for example, 2, 3, or 4. Then, perhaps after 5 or 6 tones, the correlation begins to decrease, and for 8 tones, the channel correlation may be too low. Therefore, the maximum number of tones to be mapped (the "fifth number") could be set to, for example, around 4, 5, or 6 tones.

[0125] The fifth quantity represents the maximum number of adjacent tones that can map the different parts of an orthogonal sequence. In other words, the fifth quantity can be the maximum value that the fourth quantity can have. If the orthogonal sequence is divided into four parts, each tone set will contain all four parts if they do not include reserved tones.

[0126] Adjacent tones are tones that are adjacent to each other in frequency. An OFDM symbol consists of a set of tones, each with a frequency value. Tones are typically indexed by a set of integers. For example, the indices of 256 tones range from -127 to +128 (inclusive). Therefore, a set of four adjacent tones can refer to the following set: , , wait.

[0127] Figure 12 Flowchart 400 is shown, which summarizes the main operations performed at the transmitter according to this disclosure. In the first step 401, E-LTF sequences are defined from several types, for example, from the three types (1xHE-LTF, 2xHE-LTF, and 4xHE-LTF) defined in the standard amendment IEEE 802.11ax. In the second step 402, the number of E-LTF symbols (N) is defined based on the number of spatial streams and interference conditions. E-LTF (This represents the first quantity). In the third step 403, N is generated for each spatial stream to be emitted. E-LTFTraining symbols (each spanning many tones). In step 404, the symbols of each spatial stream are mapped to the transmit antenna via a spatial mapping defined by the Q matrix, as defined in standard modification IEEE 802.11ax. In step 405, OFDM modulation is a standard process involving the creation of a time-domain signal that combines all frequency tones of each E-LTF symbol. In step 406, the digital signals assigned to each antenna are converted into analog signals and mapped to the waveform ultimately transmitted via radio frequency (RF) waves.

[0128] As proposed in this disclosure, adding more orthogonal sequences can also enable the transmission of more spatial streams, for example, supporting 16 spatial streams for IEEE 802.11be. Furthermore, in the case of overlapping BSSs (OBSSs), if there is coordination between BSSs to simultaneously initiate PPDUs, orthogonal sequences can be allocated in a manner where different sequences are used by the BSSs, thereby reducing their cross-interference.

[0129] The receiver aspects used for interference channel estimation and suppression will be described below.

[0130] In addition to the signaling fields corresponding to the latest standard revisions, the PPDU preamble also contains several traditional training and signaling fields. This means that before receiving the E-LTF signal, the receiver should have already achieved synchronization and successfully decoded all the parameters required to process the E-LTF signal.

[0131] Figure 13 A flowchart 500 is shown, summarizing the main operations performed at the receiver according to this disclosure to suppress the impact of interference on E-LTF symbol-based MIMO processing. In a first step 501, the PPDU is processed in the RF analog domain, then converted into a digital signal, and demodulated by OFDM in step 502. At this point, the receiver can obtain the received E-LTF symbol and data payload symbol for each tone. The received E-LTF symbol can be represented as...

[0132]

[0133] Among them, H k Indicates a size of N rx x N sts The equivalent channel matrix at pitch k (including beamforming effects), where N rx This refers to the number of antennas at the receiver. (Matrix) Corresponding to A k E-LTF The first N of the matrix sts Okay, because the rest are not transmitted. It's important to note that A... kE-LTF N of the matrix sts Rows are assigned the expected spatial flow of STA, and whether they are the first, last, or any other combination does not change the application of the proposed method. Matrix Representing noise, and matrix Y k Int This indicates interference.

[0134] In order to extract the representation as In step 503, the receiver performs the following operations: (1) observation of one or more expected channels (i.e., channels with expected STAs) using Y... k With ELTF k Multiplication to remove E-LTF sequence (ELTF) k This can be, for example, "1", "-1", or "0" or a complex number modulo 1. The received signal after removing the E-LTF sequence is represented as Y. k NE .

[0135] Subsequently, one or more expected channel observations are obtained for each spatial flow. This can be achieved by assigning N... wt Each adjacent tone selects all columns of the received matrix and concatenates them to make

[0136]

[0137] Among them, I k The chosen pitch index is such that k ≥ I. k and k≤I k +N wt -1.

[0138] After channel observations with the expected STA, in step 504, the P assigned to each spatial stream is used... E-LTF The channel estimate is found by performing matrix multiplication on the complex conjugates of the matrix rows. Therefore, the channel estimate can be obtained as follows:

[0139]

[0140] Where, N col-PE-LTF Corresponding to P E-LTF The number of columns in the matrix.

[0141] To extract one or more interference channel observations from one or more interference channels, denoted as (… The receiver can use the original E-LTF symbols and / or an expected channel removal method based on an estimate previously obtained from the expected channel. As an example, in step 505, the receiver can perform the following operation: by using Y... k With ELTFk Multiplication to remove E-LTF sequences (where ELTF) k This can be, for example, "1", "-1", or "0" or a complex number modulo 1. The received signal after removing the E-LTF sequence is represented as Y. k NE .

[0142] Subsequently, one or more interference channel observations are obtained. This can be achieved by setting N... wt This is done by selecting all columns of the received matrix from adjacent tones and concatenating them. Then, P, which has not been allocated any spatial stream, is used. E-LTF Matrix multiplication is performed using the complex conjugates of the rows of a matrix. That is,

[0143]

[0144] Among them, I k The chosen pitch index is such that k ≥ I. k and k≤I k +N wt -1.

[0145] Another variant performs the desired channel removal by subtracting the desired transmitter's channel estimate. This operation produces:

[0146]

[0147] In step 506, the interference channel estimate is obtained by simply normalizing the interference channel observations, such that:

[0148]

[0149] Here, tr(·) refers to the trace operator.

[0150] After obtaining the expected channel estimate and the interference channel estimate, the following MIMO combination matrix can be calculated for each data tone in step 507 to suppress the interference effects at the receiver:

[0151]

[0152] Wherein, scalar parameter a n and a i It is a regularization term.

[0153] Matrix V k Having size N rx × N sts Furthermore, in order to decode the data symbol received in the k-th tone, the receiver needs to multiply its transpose complex conjugate by the symbols received from all antennas corresponding to the data payload of the PPDU. That is,

[0154]

[0155] Among them, y k RX It is the signal received from the antenna for a given data symbol in the k-th tone, and ( This includes data symbol estimation for each transmitted spatial stream. Finally, in step 508, the receiver can decode the data from the data symbol estimation.

[0156] The demapping operation in the receiver application can work as follows (use example). Assume the 8 tones numbered -3 to 4 (i.e., The first, last, and middle tones are retained, meaning that tones indexed by -3, 0, and 4 are not used. The number of tones in the set (the fourth number) is 2, which is equal to the number of parts of the orthogonal sequence. The mapping performed on the transmitter side is to give odd tones part 1 and even tones part 2.

[0157] The table below contains a reference pitch index with partially orthogonal sequences:

[0158] Pitch Index:

[0159] The mapped part:

[0160] No reserved tones are emitted, so the mapping of these tones is not important. The number of symbols (the first number) is two, therefore the number of orthogonal sequences (the second number) is four (the product of the first and fourth numbers), and each sequence also has four elements.

[0161] The demapping at the receiver requires determining which tones and symbols to use to obtain the channel observation for each tone. The detailed demapping used to obtain this channel observation for each tone index (note that reserved tones are not processed) can be as follows: For the channel observation at tone index -2, extract part 1 from tone -1 in the two symbols and part 2 from tone -2 in the two symbols. For the channel observation at tone index -1, extract part 1 from tone -1 in the two symbols and part 2 from tone -2 in the two symbols. For the channel observation at tone index 1, extract part 1 from tone 1 in the two symbols and part 2 from tone 2 in the two symbols. For the channel observation at tone index 2, extract part 1 from tone 1 in the two symbols and part 2 from tone 2 in the two symbols. For the channel observation at tone index 3, extract part 3 from tone 1 in the two symbols and part 2 from tone 2 in the two symbols. The channel observation for each tone consists of four samples (with the same element size as the orthogonal sequence) obtained from two symbols of each tone (using two tone modulation mappings, in which case the fourth quantity is two).

[0162] To extract two parts, one for expected channel estimation and the other for interference channel estimation, the previously demapped channel observations for each tone (four samples in this example) are processed as follows: The part for expected channel estimation is extracted by projecting the channel observations using orthogonal sequences transmitted by each spatial stream. The part for interference channel estimation is extracted by projecting the channel observations using untransmitted orthogonal sequences (unused orthogonal sequences). A variant is to use the expected channel estimation to subtract the expected signal from the channel observations to improve the interference channel estimation.

[0163] According to this disclosure, it is assumed that the number of orthogonal sequences (the second number) is greater than the number of spatial streams (the third number). This provides unused orthogonal sequences that can be used for interference channel estimation.

[0164] Therefore, according to this disclosure, the transmission training sequence contains different orthogonal sequences. The transmission training sequence is mapped onto training symbols, and the result forms a training field. Each spatial stream is identified by the different orthogonal sequences that have been mapped to the training symbols. Since there may be more than one spatial stream, after mapping the different orthogonal sequences with training symbols, there are different sets of training symbols, one for each spatial stream. Then, the different sets of training symbols are mapped together with the payload data of each spatial stream onto the transmit antenna.

[0165] This disclosure offers one or more of the following advantages. Adding more interference channel observations enables the receiver to estimate the interference channel and perform MIMO interference suppression. This increases communication robustness and avoids retransmissions, thereby reducing latency. Adding more orthogonal sequences further enables channel detection of more spatial streams with the same time overhead, and reduces interference between OBSSs by coordinating the allocation of orthogonal sequences among BSSs.

[0166] Therefore, the foregoing discussion has only disclosed and described exemplary embodiments of this disclosure. As those skilled in the art will understand, this disclosure may be implemented in other specific forms without departing from its spirit or essential characteristics. Thus, this disclosure is intended to be illustrative and not to limit the scope of this disclosure and the other claims. This disclosure (including any readily identifiable variations taught herein) partially defines the scope of the foregoing claim terms so that no inventive subject matter is exclusive to the public.

[0167] In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plural. A single element or other unit can perform the functions of several items listed in the claims. The fact that certain measures are recited in different dependent claims does not mean that combinations of these measures cannot be used advantageously.

[0168] Since embodiments of this disclosure have been described as being implemented at least in part by a data processing device controlled by software, it should be understood that non-transitory machine-readable media (e.g., optical discs, magnetic disks, semiconductor memories, etc.) carrying such software are also considered to represent embodiments of this disclosure. Furthermore, such software may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunications systems.

[0169] The components of the disclosed devices, apparatuses, and systems can be implemented by corresponding hardware and / or software components, such as dedicated circuits or circuit systems. A circuit is a structural combination of electronic components including conventional circuit elements, integrated circuits including application-specific integrated circuits (ASICs), standard integrated circuits, dedicated standard products, and field-programmable gate arrays (FPGAs). Furthermore, circuits include central processing units, graphics processing units, and microprocessors, which are programmed or configured according to software code. Circuits do not include pure software, although circuits include the aforementioned hardware executing software. Circuits or circuit systems can be implemented by a single device or unit, or multiple devices or units, chipsets, or processors.

[0170] The following is a list of further embodiments of the disclosed subject matter:

[0171] 1. A first communication device configured to transmit data to a second communication device, the first communication device including circuitry configured to:

[0172] - Generate a second number of mutually orthogonal sequences;

[0173] - Generate a third number of one or more spatial streams, each carrying payload data;

[0174] - Divide each of the first number of training symbols into a fourth number of tone sets, with each training symbol spanning multiple tones;

[0175] - Divide each orthogonal sequence into a fourth number of parts;

[0176] - Training fields are generated by mapping elements of corresponding parts of orthogonal sequences to the tone set of training symbols; and

[0177] - Set training fields before and / or between the payload data of the spatial stream to enable channel estimation by a second communication device.

[0178] 2. The first communication device as defined in any of the foregoing embodiments,

[0179] Among them, the product between the first quantity and the fourth quantity is greater than or equal to the third quantity.

[0180] 3. The first communication device as defined in any of the foregoing embodiments,

[0181] The number of elements in each orthogonal sequence is equal to the product of the first and fourth quantities.

[0182] 4. The first communication device as defined in any of the foregoing embodiments,

[0183] The circuit is configured to map the first part of each orthogonal sequence to the first tone set of the training symbols, and to map the second part of each orthogonal sequence to the second tone set of the training symbols.

[0184] 5. The first communication device as defined in any of the foregoing embodiments,

[0185] The circuit is configured to map a first portion of each orthogonal sequence to a first tone set containing odd tones including training symbols, and to map a second portion of each orthogonal sequence to a second tone set containing even tones including training symbols.

[0186] 6. The first communication device as defined in any of the foregoing embodiments,

[0187] The circuit is configured to map elements of the first part of the orthogonal sequence and elements of the second part of the same orthogonal sequence to adjacent tones of the training symbols.

[0188] 7. The first communication device as defined in any of the foregoing embodiments,

[0189] The circuit is configured to determine a fifth number of adjacent tones, which form a set of adjacent tones. By measuring the channel correlation between tones, a portion of the orthogonal sequence can be mapped onto a set of adjacent tones.

[0190] 8. The first communication device as defined in any of the foregoing embodiments,

[0191] The circuit is configured to obtain signaling information from a second communication device, the signaling information indicating whether a fifth number of a set of adjacent tones to which a portion of an orthogonal sequence can be mapped should be increased or decreased, and / or including information indicating a first number and / or a fourth number.

[0192] 9. The first communication device as defined in any of the foregoing embodiments,

[0193] The circuit is configured to identify spatial streams through different orthogonal sequences, wherein the training field contains a third number of different training symbol sets that have been mapped with different orthogonal sequences.

[0194] 10. The first communication device as defined in Embodiment 9,

[0195] The circuit is configured to use multiple-input multiple-output (MIMO) technology to directly or indirectly map the corresponding training symbol set and each spatial stream payload data onto the transmit antenna.

[0196] 11. A second communication device configured to receive data from a first communication device, the second communication device including circuitry configured to:

[0197] - Based on at least a portion of the training field, obtain one or more expected channel observations of one or more channels between a first communication device and a second communication device, wherein the training field is set before and / or between payload data of a third number of spatial streams received from the first communication device, wherein each spatial stream carries payload data, each of a first number of training symbols is divided into a fourth number of tone sets and spans multiple tones, and each of a second number of mutually orthogonal sequences is divided into a fourth number of parts, wherein elements of corresponding parts of the orthogonal sequences are mapped to tone sets of training symbols to generate the training field;

[0198] - Perform interference channel estimation for one or more potential interference channels based on another portion of the training field; and

[0199] - Perform interference suppression based on the interference channel estimation information obtained from the interference channel estimation.

[0200] 12. The second communication device as defined in embodiment 11,

[0201] The circuit is configured to demap a first portion of an orthogonal sequence from a first tone set of training symbols and a second portion of an orthogonal sequence from a second tone set of training symbols to obtain expected channel observations and optional interference channel observations.

[0202] 13. The second communication device as defined in embodiment 11 or 12,

[0203] The circuit is configured to send signaling information from a second communication device, the signaling information indicating whether a fifth number of a set of adjacent tones to which a portion of an orthogonal sequence can be mapped should be increased or decreased, and / or including information indicating a first number and / or a fourth number.

[0204] 14. A second communication device as defined in any one of embodiments 11-13,

[0205] The circuit is configured to obtain one or more interference channel observations based on another part of the training field.

[0206] 15. A second communication device as defined in any one of embodiments 11-14,

[0207] The circuit is configured to perform expected channel estimation of one or more channels and / or decode data from the received spatial stream based on the obtained expected channel observations.

[0208] 16. A second communication device as defined in any one of Examples 11-15,

[0209] The circuit is configured to use interference channel estimation to calculate an estimate of the covariance matrix of the interference channel describing the spatial direction from which the interference originates, and to generate a spatial filter to suppress the combination of signals from the receiving antenna in a manner that is achieved by the spatial direction traversed by the covariance matrix of the interference.

[0210] 17. A second communication device as defined in any one of embodiments 11-16,

[0211] The circuit is configured to extract a first portion of a training field for expected channel estimation by projecting channel observations from orthogonal sequences transmitted by each spatial stream, and / or to extract another portion of a training field for interference channel estimation by projecting channel observations from untransmitted orthogonal sequences.

[0212] 18. A first communication method for sending data to a second communication device, the first communication method comprising:

[0213] - Generate a second number of mutually orthogonal sequences;

[0214] - Generate a third number of one or more spatial streams, each carrying payload data;

[0215] - Divide each of the first number of training symbols into a fourth number of tone sets, with each training symbol spanning multiple tones;

[0216] - Divide each orthogonal sequence into a fourth number of parts;

[0217] - Training fields are generated by mapping elements of corresponding parts of orthogonal sequences to the tone set of training symbols; and

[0218] - Set training fields before and / or between the payload data of the spatial stream to enable channel estimation by a second communication device.

[0219] 19. A second communication method for receiving data from a first communication device, the second communication method comprising:

[0220] - Based on at least a portion of the training field, obtain one or more expected channel observations of one or more channels between a first communication device and a second communication device, wherein the training field is set before and / or between payload data of a third number of spatial streams received from the first communication device, wherein each spatial stream carries payload data, each of a first number of training symbols is divided into a fourth number of tone sets and spans multiple tones, and each of a second number of mutually orthogonal sequences is divided into a fourth number of parts, wherein elements of corresponding parts of the orthogonal sequences are mapped to tone sets of training symbols to generate the training field;

[0221] - Perform interference channel estimation for one or more potential interference channels based on another portion of the training field; and

[0222] - Perform interference suppression based on the interference channel estimation information obtained from the interference channel estimation.

[0223] 20. A non-transitory computer-readable recording medium storing a computer program code product that, when executed by a processor, causes the method according to embodiment 18 or 19 to be performed.

[0224] 21. A computer program, including program code means, which, when executed on a computer, causes the computer to perform the steps of the method according to embodiment 18 or 19.

Claims

1. A first communication device configured to transmit data to a second communication device, the first communication device including circuitry configured to: - Generate a second number of mutually orthogonal sequences; - Generate a third number of one or more spatial streams, each carrying payload data; - Divide each of the first number of training symbols into a fourth number of tone sets, with each training symbol spanning multiple tones; - Divide each orthogonal sequence into a fourth number of parts; - A training field is generated by mapping elements of corresponding portions of the orthogonal sequence to the tone set of the training symbols, wherein the training field is designed to provide at least one more channel observation at the second communication device than the number of spatial streams; as well as - The training field is set before and / or between the payload data of the spatial stream to enable channel estimation by the second communication device.

2. The first communication device according to claim 1, in, The product of the first quantity and the fourth quantity is greater than or equal to the third quantity.

3. The first communication device according to claim 1, in, The number of elements in each orthogonal sequence is equal to the product of the first number and the fourth number.

4. The first communication device according to claim 1, in, The circuit is configured to map a first portion of each orthogonal sequence to a first tone set of the training symbols, and to map a second portion of each orthogonal sequence to a second tone set of the training symbols.

5. The first communication device according to claim 1, in, The circuit is configured to map a first portion of each orthogonal sequence to a first tone set including the training symbols and odd tones, and to map a second portion of each orthogonal sequence to a second tone set including the training symbols and even tones.

6. The first communication device according to claim 1, in, The circuit is configured to map elements of the first part of an orthogonal sequence and elements of the second part of the same orthogonal sequence to adjacent tones of the training symbol.

7. The first communication device according to claim 1, in, The circuit is configured to determine a fifth number of adjacent tones, which form a set of adjacent tones, and by measuring the channel correlation between the tones, a portion of an orthogonal sequence can be mapped onto the set of adjacent tones.

8. The first communication device according to claim 1, in, The circuit is configured to obtain signaling information from the second communication device, the signaling information indicating whether a fifth number of a set of adjacent tones to which a portion of an orthogonal sequence can be mapped should be increased or decreased, and / or including information indicating the first number and / or the fourth number.

9. The first communication device according to claim 1, in, The circuit is configured to identify spatial streams through different orthogonal sequences, wherein the training field contains a third number of different training symbol sets that have been mapped with different orthogonal sequences.

10. The first communication device according to claim 9, in, The circuit is configured to use multiple-input multiple-output (MIMO) technology to directly or indirectly map the corresponding training symbol set and the payload data of each spatial stream onto the transmit antenna.

11. A second communication device configured to receive data from a first communication device, the second communication device including circuitry configured to: - Based on at least a portion of a training field, obtain one or more expected channel observations for one or more channels between the first communication device and the second communication device, wherein the training field is set before and / or between payload data of a third number of spatial streams received from the first communication device, wherein, The number of expected channel observations is at least one more than the third number, wherein each spatial stream carries payload data, each of the first number of training symbols is divided into a fourth number of tone sets and spans multiple tones, and each of the second number of mutually orthogonal sequences is divided into a fourth number of parts, wherein the elements of the corresponding parts of the orthogonal sequences are mapped to the tone sets of the training symbols to generate the training field. - Perform interference channel estimation for one or more potential interference channels based on another portion of the training fields; and - Perform interference suppression based on the interference channel estimation information obtained from the interference channel estimation.

12. The second communication device according to claim 11, in, The circuit is configured to demap a first portion of the orthogonal sequence from a first tone set of the training symbols and a second portion of the orthogonal sequence from a second tone set of the training symbols to obtain the expected channel observation and optional interference channel observation.

13. The second communication device according to claim 11, in, The circuit is configured to send signaling information from the second communication device, the signaling information indicating whether a fifth number of a set of adjacent tones to which a portion of an orthogonal sequence can be mapped should be increased or decreased, and / or including information indicating the first number and / or the fourth number.

14. The second communication device according to claim 11, in, The circuit is configured to obtain one or more interference channel observations based on another portion of the training field.

15. The second communication device according to claim 11, in, The circuit is configured to perform expected channel estimation of the one or more channels and / or decode data from the received spatial stream based on the obtained expected channel observations.

16. The second communication device according to claim 11, in, The circuit is configured to use interference channel estimation to calculate an estimate of the covariance matrix of the interference channel describing the spatial direction from which the interference originates, and to generate a spatial filter to suppress the combination of signals from the receiving antenna in a manner that is traversed by the covariance matrix of the interference across the spatial direction.

17. The second communication device according to claim 11, in, The circuit is configured to extract a first portion of the training field for expected channel estimation by projecting the channel observations with the orthogonal sequence transmitted by each spatial stream, and / or to extract another portion of the training field for interference channel estimation by projecting the channel observations with the untransmitted orthogonal sequence.

18. A first communication method for sending data to a second communication device, the first communication method comprising: - Generate a second number of mutually orthogonal sequences; - Generate a third number of one or more spatial streams, each carrying payload data; - Divide each of the first number of training symbols into a fourth number of tone sets, with each training symbol spanning multiple tones; - Divide each orthogonal sequence into a fourth number of parts; - A training field is generated by mapping elements of corresponding portions of the orthogonal sequence to the tone set of the training symbols, wherein the training field is designed to provide at least one more channel observation at the second communication device than the number of spatial streams; as well as - The training field is set before and / or between the payload data of the spatial stream to enable channel estimation by the second communication device.

19. A second communication method for receiving data from a first communication device, the second communication method comprising: - Based on at least a portion of a training field, obtain one or more expected channel observations of one or more channels between the first communication device and the second communication device, wherein the training field is set before and / or between payload data of one or more spatial streams received from the first communication device of a third number, wherein the number of expected channel observations is at least one more than the third number, wherein each spatial stream carries payload data, each of a first number of training symbols is divided into a fourth number of tone sets and spans multiple tones, and each of a second number of mutually orthogonal sequences is divided into a fourth number of parts, wherein elements of corresponding parts of the orthogonal sequences are mapped onto the tone sets of the training symbols to generate the training field; - Perform interference channel estimation for one or more potential interference channels based on another portion of the training fields; and - Perform interference suppression based on the interference channel estimation information obtained from the interference channel estimation.

20. A non-transitory computer-readable recording medium storing a computer program product that, when executed by a processor, causes to perform the method according to claim 18 or 19.

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