Wireless communication apparatus and methods

Abstract

A wireless communication device and method are disclosed that are capable of optimizing uplink transmissions from a communication object to the wireless communication device. The method can be performed by the device and includes receiving an uplink performance estimate, determining uplink adjustment information including resource unit configuration and target received signal strength indication (target RSSI) based on the estimate, generating a target channel quality indicator based on previous uplink sounding information including channel quality indicator, RSSI and bandwidth, and based on the uplink adjustment information, wherein the previous uplink sounding information indicates characteristics of the uplink transmission, determining uplink transmission settings including modulation and coding scheme and dual carrier modulation settings based on the target channel quality indicator and a type of error correction technique, transmitting a control signal to the communication object based on the uplink transmission settings, and updating the uplink performance estimate based on a received signal from the communication object, wherein characteristics of the received signal are related to the uplink transmission settings.

Description

TECHNICAL FIELD

[0001] The present application relates to communication devices and methods, and more particularly to wireless communication devices and methods. BACKGROUND

[0002] New generation of wireless local area network (WLAN) standards, such as IEEE 802.11ax standard, incorporate a channel quality indicator (CQI) feedback through a sounding protocol. The CQI is an array, each element of which corresponds to the average signal-to-noise ratio (SNR) of a resource unit (RU). If the frequency width of the RUs is divided into units, each of which has about 26 tones (i.e., 26 subcarriers of a specific frequency width), such a unit is called RU26. The definition of the channel quality indicator (CQI) corresponding to the ith RU26 is as follows: i

[0003]

[0004] In formula (1), the definitions of the parameters are shown in Table 1 below.

[0005] Table 1

[0006]

[0007] The CQI can be used for modulation and coding scheme adaptation (MCS adaptation) function, which can convert the value of a CQI into the MCS of the RU corresponding to the CQI, so that the access point (AP) adopts the appropriate MCS to reduce the trial error transmission rate, shorten the time of adjusting the transmission rate, and improve the system performance.

[0008] ​IEEE 802.11ax standard only defines downlink (DL) CQI sounding, but does not define uplink (UL) CQI sounding; uplink and downlink refer to transmission from a "non-AP station (non-AP STA)" to an "Access Point (AP)" and transmission from an "AP" to a "non-AP STA", respectively, in the technical field. DL CQI sounding can be generated by a station (STA) from a signal transmitted by an AP, and the CQI is reported by the STA to the AP. Although the IEEE 802.11ax standard mentions UL closed-loop power control, the control does not use CQI.The uplink closed loop power control comprises: an AP first transmits a trigger frame to at least one STA in an uplink orthogonal frequency division multiple access (UL OFDMA) flow, wherein the trigger frame is a control frame but not a non-control frame (e.g. a data frame or a management frame); a common field of the trigger frame carries information indicating an AP transmission power (AP Tx Power); after receiving the trigger frame, the STA estimates a received signal strength indicator (RSSI), wherein the difference between the AP Tx Power and the RSSI can be regarded as a path loss (PL); when transmitting a high efficiency trigger-based physical layer conformance procedure (PLCP) protocol data unit (HB_TB_PPDU) to the AP, the STA compensates the path loss by power adjustment, so as to make the power of the HB_TB_PPDU received by the AP meet an uplink target RSSI (UL Target RSSI) indicated by a user field of the trigger frame; a medium access control (MAC) header in the HE_TB PPDU carries information indicating an uplink power headroom (UL Power Headroom; UPH), which indicates the distance between the current transmission power of the STA and the maximum transmission power of the STA; the header also carries a minimum flag, which indicates whether the power of the signal transmitted by the STA reaches a minimum power; the UPH and the minimum flag can be used by the AP to adjust the AP Tx Power and the target RSSI in the next UL OFDMA flow, so as to achieve the effect of uplink closed loop power control.

[0009] Since the definition and acquisition of the aforementioned CQI, the downlink CQI sounding and the uplink closed loop power control are known technologies, the details of which are omitted here. SUMMARY

[0010] One of the purposes of the present disclosure is to provide a wireless communication device and method capable of optimizing uplink transmission by using a channel quality indicator (CQI) to make up for the deficiencies of the prior art.

[0011] An embodiment of the wireless communication device of the present disclosure is capable of optimizing uplink transmission from a communication object to the wireless communication device, and comprises an uplink setting circuit, a CQI updating circuit, an uplink transmission setting decision circuit, and a performance estimation circuit. The uplink setting circuit is arranged to determine uplink adjustment information according to an uplink performance estimation after receiving the uplink performance estimation. The CQI updating circuit is arranged to generate a target CQI according to previous uplink sounding information and the uplink adjustment information, wherein the previous uplink sounding information indicates characteristics of the uplink transmission. The uplink transmission setting decision circuit is arranged to determine uplink transmission setting according to the target CQI and a type of error correction technique adopted by the wireless communication device, so that the wireless communication device transmits a control signal to the communication object according to the uplink transmission setting, and the control signal affects uplink transmission performance between the communication object and the wireless communication device. The performance estimation circuit is arranged to update the uplink performance estimation according to a received signal from the communication object. In the above embodiment, the wireless communication device is an access point, and the communication object is a station.

[0012] An embodiment of the wireless communication method of the present disclosure is performed by a wireless communication device. The embodiment is capable of optimizing uplink transmission from a communication object to the wireless communication device, and comprises the following steps: determining uplink adjustment information according to an uplink performance estimation after receiving the uplink performance estimation; generating a target CQI according to previous uplink sounding information and the uplink adjustment information, wherein the previous uplink sounding information indicates characteristics of the uplink transmission; determining uplink transmission setting according to the target CQI and a type of error correction technique adopted by the wireless communication device, so as to transmit a control signal to a communication object according to the uplink transmission setting; and updating the uplink performance estimation according to a received signal from the communication object, wherein characteristics of the received signal are related to the uplink transmission setting.

[0013] The features, implementations, and technical effects of the present disclosure are described in detail below with reference to preferred embodiments and the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 An embodiment of the wireless communication device of the present disclosure is shown;

[0015] Figure 2 A format of an existing trigger frame is shown;

[0016] Figure 3 An example of calculation results of channel quality indicators (CQIs) of each resource unit is shown; and

[0017] Figure 4 An embodiment of the wireless communication method of the present disclosure is shown.

[0018] SYMBOL DESCRIPTION

[0019] 100: wireless communication device

[0020] 110: uplink setting circuit

[0021] 120: CQI (channel quality indicator) updating circuit

[0022] 130: uplink transmission setting decision circuit

[0023] 140: performance estimation circuit

[0024] CQI i : channel quality indicator of the ith RU (resource unit)

[0025] NV i : total noise power of the ith RU 26

[0026] avgsigpow i (dB): signal power within the ith RU 26

[0027] Chgain i (dB): channel gain

[0028] S410-S440: steps DETAILED DESCRIPTION

[0029] The present disclosure includes a wireless communication device and method capable of optimizing uplink transmission by using a channel quality indicator (CQI).

[0030] Current wireless local area network (WLAN) standards (e.g., IEEE 802.11ax) do not define uplink sounding (UL Sounding), only downlink sounding (DL Sounding). The present disclosure proposes an uplink adjustment procedure comprising: when a wireless communication device is both a receiver and a decider (e.g., a transmitter of a control frame) in an uplink transmission procedure (e.g., an uplink orthogonal frequency division multiple access (UL OFDMA) flow), the wireless communication device can determine a target CQI according to channel state information (CSI) of a communication object, and determine the content of a control signal (e.g., the content of the general field and the user field of a trigger frame) according to the target CQI, and then the wireless communication device 100 transmits the control signal to the communication object, so that the communication object adjusts according to the control signal, thereby optimizing the uplink transmission from the communication object to the wireless communication device. Depending on the implementation requirements, the wireless communication device can perform the uplink adjustment procedure only once or several times, or periodically, or aperiodically. It is worth noting that the CSI can be obtained by known or self-developed channel estimation techniques; since the channel estimation techniques are not within the scope of the present disclosure, the details are omitted here.

[0031] Figure 1 An embodiment of a wireless communication device of the present disclosure is shown. Figure 1 The wireless communication device 100 (e.g., an access point (AP)) comprises an uplink setting circuit 110, a CQI updating circuit 120, an uplink transmission setting determination circuit 130, and a performance estimation circuit 140. The description of the circuits is as follows.

[0032] The uplink setting circuit 110 is configured to determine uplink adjustment information based on the uplink performance estimate provided by the performance estimation circuit 140. An example of the uplink performance estimate includes, but is not limited to, "the transmission time of a received signal (e.g., a physical layer conformance procedure (PLCP) protocol data unit (PPDU)) from a communication object" or "the throughput of the uplink transmission between the communication object and the wireless communication device 100". An example of the uplink adjustment information includes, but is not limited to, resource unit allocation (RU allocation) and a target Received Signal Strength Indicator (target RSSI).

[0033] The CQI updating circuit 120 is configured to generate a target CQI based on the previous uplink sounding information and the uplink adjustment information. The target CQI includes M values ({CQI i}) corresponding to M resource units (RUs), where M is a positive integer and the subscript "i" is an integer between 0 and (M-1). An example of the previous uplink sounding information includes, but is not limited to, the CQI ({CQI i}) and the RSSI and BW obtained when the wireless communication device 100 performs the last uplink sounding procedure. Details of the generation of the CQI are described later.

[0034] The uplink transmission setting determination circuit 130 is configured to determine the uplink transmission setting based on the target CQI ({CQI ithe type of error correction technology (e.g., forward error correction (FEC) such as Low Density Parity Check Code (LDPC) or Binary Convolution Code (BCC)) employed by the wireless communication device 100. For example, the uplink transmission setting determination circuit 130 can select an appropriate modulation and coding scheme (MCS) according to the target CQI and the type of error correction technology, as shown in Table 2 below, such that the uplink transmission setting includes the MCS; since MCS, LDPC and BCC are common knowledge in the art, details thereof are omitted. The wireless communication device 100 determines the content of a control signal (e.g., a trigger frame) according to the uplink transmission setting, and transmits the control signal to a communication object (e.g., a non-AP station (non-AP STA)) so as to cause the communication object to make an adjustment according to the control signal. In an implementation example, the format of the control signal is the format of an existing trigger frame as shown in Table 4 below, including general fields and user fields; the descriptions of the fields shown in Table 4 below; an example of the content of the control signal determined according to the uplink transmission setting includes, but is not limited to, the content of the fields shown in Table 5 below. It is noted that only part of the trigger frame is shown to avoid hindering the presentation of the ideas of the present application. Figure 2 Figure 2 Figure 2 Figure 2

[0035] Table 2

[0036]

[0037]

[0038] Table 3

[0039]

[0040] ​​​​It is noted that Table 2 is applicable to transmissions using RU 26 (the smallest RU with 26 subcarriers) and is in the case where space-time region coding is not used. The bandwidth based on RU 26 (2 MHz) is less than a coherence bandwidth (6.7 MHz) as will be described later, Table 2 is established based on the performance of an Additive White Gaussian Noise (AWGN) channel, which is typically based on a Required SNR (rSNR), i.e. a signal-to-noise ratio (SNR) of 0.1 for a packet error rate (PER) when the length of a Presentation Service Data Unit (PSDU) is 1000 Bytes. In addition, for larger RUs, other known or self-developed conversion methods (e.g. Exponential effective SNR mapping (EESM) as described in the following reference: Jobin Francis, Student Member, IEEE, and Neelesh B. Mehta, Senior Member, IEEE, "EESM-based Link Adaptation in OFDM: Modeling and Analysis", Globecom 2013 - Wireless Communications Symposium) can be used to convert the target CQI of the RU to an MCS given the type of error correction technique.

[0041] The performance estimation circuit 140 is configured to update the uplink performance estimate based on a received signal (e.g. a high efficiency trigger-based physical layer conformance procedure (PLCP) protocol data unit (HB_TB_PPDU)) from the communication object. An example of the received signal carries information including but not limited to an uplink power headroom (UL Power Headroom; UPH) and a minimum flag, the definition of which is within the common knowledge of the art. Figure 1In the embodiments, in addition to generating the uplink adjustment information based on the uplink performance estimation, the uplink setting circuit 110 may also selectively generate the uplink adjustment information based on the information of the received signal; in addition, before receiving the uplink performance estimation (that is, before receiving any uplink performance estimation), the uplink setting circuit 110 may output preset information (e.g., preset RU configuration and preset target RSSI) as the uplink adjustment information.

[0042] The following explanation details the generation of CQI. Please refer to [link / reference]. Figure 1 The wireless communication device 100 can calculate the CQI for the communication object based on the received signal of the aforementioned communication object; for example, the wireless communication device 100 includes a CQI calculation circuit (not shown) for calculating the CQI; for another example, the CQI update circuit 120 of the wireless communication device 100 includes the aforementioned CQI calculation circuit to calculate the CQI; the CQI calculation circuit can be implemented by known or self-developed technologies, and is not within the scope of this invention, so details are omitted here. The formula for calculating the CQI is shown in the aforementioned formula (1). Based on the fact that the logarithmic function (log) is a concave function, an inequality can be derived from formula (1) as follows:

[0043]

[0044] Since the maximum indoor delay spread of WLAN is approximately 150ns, its equivalent coherence bandwidth (BW) is " (The signal bandwidth of RU26)”, so the change in WLAN signal within the 2MHz bandwidth is very small. This signal change is close to the noise of the channel of additive white Gaussian noise (AWGN). Therefore, the left side of equation (2) can be approximated by the right side of equation (2) as shown in equation (3) below. The right side of equation (3) can be regarded as the average signal power (dB) of the i-th RU26 minus the signal power of the noise (dB), where NV i It is independent of the signal transmission end and can be obtained by long-term statistical analysis of the radio frequency characteristics through known or self-developed circuits at the signal receiving end.

[0045]

[0046] As described above, after the wireless communication device 100 calculates the CQI for the communication object, the wireless communication device 100 can obtain the CQI of each minimum resource unit (RU26) within the uplink bandwidth (BW) of the communication object. For example, the wireless communication device 100 receives a physical layer aggregation procedure protocol data unit (PPDU) with an uplink bandwidth of 20MHz from the communication object; based on the signal bandwidth of one RU26 being 2MHz, 20MHz can be divided into nine RU26s (i = 0~8), therefore, the wireless communication device 100 can obtain {CQI}. i |i∈0~8}}as Figure 3 As shown; the CQI calculated by the wireless communication device 100 i Adding NV (Non-real-time) computation i (dB)( Figure 3 The portion shown by the dot matrix will be equal to the signal power (avgsigpow) within the i-th RU26. i (dB)); avgsigpow of all RU26 i The total area is as follows Figure 3 As shown in the dashed box, this box indicates that an average signal power represents an RSSI, which is equivalent to the transmission power of the communication object minus the path loss (PL). If the uplink setting circuit 110 increases (decreases) a target RSSI to require the communication object to increase its transmission power, the RSSI of the received signal from the communication object will then become higher (lower). This indicates that... Figure 3 The signal strength within each RU26 will increase (decrease) together; Figure 3 In this context, the RSSI is related to the signal power (avgsigpow) of the i-th RU26. i The difference (dB) is equivalent to the channel gain (Chgain) of the i-th RU26. i (dB)); Different RU26 correspond to different channel gains, and in a slow-changing indoor environment, the channel gain of each RU26 will not change in a short time, which allows the wireless communication device 100 to select RU26 according to the channel gain requirements.

[0047] Under the above conditions, when the uplink bandwidth is reduced (increased), all signal transmission needs to be performed through a smaller (larger) bandwidth, and thus the power spectral density (PSD) in the uplink bandwidth is increased (decreased). The change in the power spectral density is inversely proportional to the change in the uplink bandwidth. In addition, when the RSSI is increased (decreased), the signal strength in the same bandwidth is increased (decreased), and thus the power spectral density is increased (decreased). Furthermore, the RU configuration can be determined according to the channel gain (for example, RUs with higher channel gains are preferentially used for uplink transmission). Therefore, the wireless communication device 100 can optimize uplink transmission by setting a target RSSI, a target bandwidth, and an RU configuration for uplink transmission.

[0048] Based on the foregoing, the uplink setting circuit 110 determines the uplink adjustment information according to the uplink performance estimate from the performance estimation circuit 140, the CQI update circuit 120 determines a target CQI according to the uplink adjustment information and the previous uplink probe information (for example, the CQI, RSSI, and bandwidth of uplink transmission obtained through the last uplink probe), and the uplink transmission setting determination circuit 130 determines the content of the aforementioned control signal (for example, a trigger frame) using the target CQI and other information (for example, the aforementioned FEC, UPH, etc.). Then, the wireless communication device 100 transmits the control signal to the communication object, thereby affecting the signal power and CQI of the next uplink transmission. For example, the uplink adjustment information includes a target RSSI (RSSI') and a target bandwidth (BW'), and the CQI update circuit 120 generates a target CQI representing the CQI expected by the wireless communication device 100 for the next uplink transmission according to the following formula:

[0049] avgsigpow′ i = avgsigpow i +(BW-BW')+(RSSI'-RSSI)

[0050] CQI' i = avgsigpow' i -NV i

[0051] Formula (4)

[0052] The definitions of the parameters in Formula (4) are shown in Table 4 below.

[0053] Table 4

[0054]

[0055]

[0056] It is worth noting that the target RSSI cannot be increased indefinitely and is limited by the ability of the communicating object to increase its transmission power and by regulations, which the UPH carried by the communicating object informs the wireless communication device 100 about how much more power the communicating object can increase.

[0057] As can be seen from the above disclosure, the wireless communication device 100 can adjust the signal strength of the signals transmitted by the communicating object and the CQI of the uplink transmission by changing the uplink bandwidth, the uplink target RSSI and the RU configuration. It is worth noting that the wireless communication device 100 can communicate with one or more communicating objects and can perform uplink sounding for each communicating object to optimize the uplink transmission with the communicating object.

[0058] Figure 4 An embodiment of a wireless communication method according to the present disclosure is shown, which is performed by a wireless communication device to optimize uplink transmission from a communicating object to the wireless communication device and comprises the following steps:

[0059] S410: determining uplink adjustment information based on the uplink performance estimate;

[0060] S420: generating a target channel quality indicator based on previous uplink sounding information and the uplink adjustment information, wherein the previous uplink sounding information indicates characteristics of the uplink transmission;

[0061] S430: determining uplink transmission settings based on the target channel quality indicator and a type of error correction technique used by the wireless communication device to transmit a control signal to the communicating object according to the uplink transmission settings; and

[0062] S440: updating the uplink performance estimate based on a received signal from the communicating object, wherein characteristics of the received signal are related to the uplink transmission settings.

[0063] Since those skilled in the art can understand the implementation details and variations of the method invention by referring to the disclosure of the aforementioned device invention, that is, the technical features of the aforementioned device invention can be reasonably applied to the method invention, therefore, repeated and redundant descriptions are omitted here.

[0064] Please note that, as far as possible, those skilled in the art can selectively implement part or all of the technical features in any of the aforementioned embodiments, or selectively implement a combination of part or all of the technical features in the aforementioned embodiments, thereby increasing the flexibility of the implementation of the present invention.

[0065] In summary, the wireless communication device and method according to the present disclosure can optimize uplink transmission through uplink sounding.

[0066] Although the embodiments of the present application have been described above, the above-mentioned embodiments are not intended to limit the present application, and those skilled in the art can make various changes to the technical features of the present application according to the content disclosed or implied in the present application. Any such changes can be within the scope of the patent protection sought for the present application. In other words, the scope of the patent protection of the present application shall be defined by the claims of the present specification.

Claims

1. A wireless communication device capable of optimizing uplink transmissions from a communication object to the wireless communication device, wherein, The wireless communication device is an access point and the communication object is a non-access point station, the wireless communication device comprises: an uplink setting circuit configured to determine uplink adjustment information based on the uplink performance estimate after receiving the uplink performance estimate; a channel quality indicator updating circuit configured to generate a target channel quality indicator based on previous uplink sounding information and the uplink adjustment information, wherein the previous uplink sounding information indicates characteristics of the uplink transmission; an uplink transmission setting determination circuit configured to determine uplink transmission setting based on the target channel quality indicator and a type of error correction technique used by the wireless communication device, so that the wireless communication device transmits a control signal to a communication object based on the uplink transmission setting, the control signal affecting the uplink transmission performance between the communication object and the wireless communication device; and a performance estimation circuit configured to update the uplink performance estimate based on a received signal from the communication object, wherein the uplink performance estimate includes at least one of a transmission time of the received signal and a throughput of the uplink transmission, the uplink adjustment information includes at least one of a resource unit configuration, a target received signal strength indicator, and a target frequency width, and the uplink setting circuit is configured to adjust at least one of the resource unit configuration, the target received signal strength indicator, and the target frequency width based on the uplink performance estimate to update the uplink adjustment information.

2. The wireless communication device of claim 1, wherein the previous uplink sounding information comprises an uplink sounding channel quality indicator, an uplink sounding target received signal strength indicator, and an uplink sounding signal frequency width.

3. The wireless communication device of claim 1, wherein the uplink transmission setting comprises at least one of a modulation setting and a target received signal strength indicator setting.

4. The wireless communication device of claim 1, wherein the control signal comprises a trigger frame, and the received signal comprises a high efficiency trigger-based physical layer convergence procedure (HE-TB PPDU).

5. The wireless communication device of claim 4, wherein the trigger frame comprises a plurality of generic fields and a plurality of user fields, contents of at least a portion of the plurality of generic fields and the plurality of user fields are based on the uplink transmission setting, and the trigger frame is used to cause the communication object to determine characteristics of the received signal based on the contents of at least a portion of the plurality of generic fields and the plurality of user fields.

6. The wireless communication device of claim 5, wherein the HE-TB PPDU comprises an uplink power boost space and a minimum flag, and the uplink setting circuit is configured to generate the uplink adjustment information based on the uplink performance estimate and based on at least one of the uplink power boost space and the minimum flag.

7. A method of wireless communication performed by a wireless communication device, comprising: The wireless communication method is capable of optimizing uplink transmission from a communication object to a wireless communication device, the wireless communication device is an access point and the communication object is a non-access point station, the wireless communication method comprises: determining uplink adjustment information based on the uplink performance estimate after receiving the uplink performance estimate; generating a target channel quality indicator based on previous uplink sounding information and the uplink adjustment information, wherein the previous uplink sounding information indicates characteristics of the uplink transmission; determining uplink transmission settings based on the channel quality indicator and a type of error correction technique to transmit a control signal to the communication object based on the uplink transmission settings; and updating the uplink performance estimate based on a received signal from the communication object, wherein characteristics of the received signal are related to the uplink transmission settings, wherein the uplink performance estimate comprises at least one of a transmission time of the received signal and a throughput of the uplink transmission, the uplink adjustment information comprises at least one of a resource unit configuration, a target received signal strength indicator, and a target frequency width, and the uplink adjustment information is determined using one or more of the following steps: adjusting at least one of the resource unit configuration, the target received signal strength indicator, and the target frequency width based on the uplink performance estimate to update the uplink adjustment information.

8. The wireless communication method of claim 7, wherein the uplink transmission settings comprise at least one of a modulation setting and a target received signal strength indicator setting.

9. The wireless communication method of claim 7, wherein the control signal comprises a trigger frame and the received signal comprises a high performance trigger-based protocol data unit.

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