Wireless transmit receive unit

Wireless transmitting and receiving unit

This model is related to the wireless communication system.

For the Evolved Universal Terrestrial Radio Access (E-UTRA) uplink (UL), there are many transmission power control (TPC) proposals delivered to the 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) Working Group 1( WG1). These proposals are usually divided into (slow) open loop TPC and slow closed loop or TPC based on channel quality information (CQI).

Open-loop TPC is based on path loss measurement and system parameters, where path loss measurement is performed at a wireless transmit/receive unit (WTRU), and system parameters are provided by an evolved node B (eNodeB).

The closed-loop TPC is typically based on TPC feedback information periodically sent from the eNodeB (such as TPC commands), where the feedback information is usually obtained by using the signal-to-interference and noise ratio (SINR) measured at the eNodeB.

Open-loop TPC can compensate for long-term channel changes (such as path loss and shadow fading), for example, in an effective way that does not require recording of transmission power. However, open loop TPC typically causes path loss measurement errors and transmission power setting errors. On the other hand, because based on the feedback signal sent by the eNodeB, the slow closed-loop or CQI-based TPC is less sensitive to errors in measurement and transmission power settings. However, when there is no feedback available due to interruption of UL transmission, or interruption of feedback transmission, or very drastic channel changes, the performance of slow closed-loop or CQI-based TPC is degraded.

For UL E-UTRA, many in-cell PC proposals have been delivered to the 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) Working Group (WG) #1. These proposals can usually be divided into slow open-loop PC and slow closed-loop (or CQI-based PC). Open-loop PC can compensate for long-term channel changes, (such as path loss and shadow fading), for example, in an effective way, no transmission power recording is required, but it typically suffers from path loss measurement and transmission power setting errors. On the other hand, slow closed-loop or CQI-based PCs are less sensitive to errors in measurement and transmission power settings because it is based on the feedback signal sent by the eNodeB. However, its performance decreases when there is no feedback available due to interruption of UL transmission, or interruption of feedback transmission.

Therefore, there is a need for an improved transmission power control method.

A method and apparatus for E-UTRA including a combined open loop/closed loop uplink power control scheme are disclosed. The open-loop and closed-loop method for the combination of PCs in the UL cell controls the transmission power spectral density (PSD) PSD of the wireless transmit and receive unit (WTRU)_Tx(For example, power per RB).

When mentioned below, the term "wireless transmit/receive unit (WTRU)" includes but is not limited to user equipment (UE), mobile station, fixed or mobile subscriber unit, pager, mobile phone, personal digital assistant (PDA), computer Or any other type of user equipment that can operate in a wireless environment. When mentioned below, the term "base station" includes but is not limited to node B, site controller, access point (AP) or any other type of interface device capable of operating in a wireless environment.

Figure 1 shows an example of a wireless communication network (NW) 10, which includes a WTRU 20, one or more Node Bs 30, and one or more cells 40. Each cell 40 includes one or more Node Bs (NB or eNB) 30, and the Node B 30 includes a transceiver 120 configured to implement the disclosed transmission power control (TPC) method. The WTRU 20 includes a transceiver 110 that is also configured to implement the disclosed TPC method.

Figure 2 is a functional block diagram of the transceivers 110, 120 configured to perform the disclosed method. In addition to the components included in a typical transmitter/receiver, that is, a WTRU or Node B, the transceiver 110, 120 includes a processor 115, 125, a receiver 116, 126 communicating with the processor 115, 125, and a processor The transmitters 117, 127 that communicate with the receivers 115, 125 and the antennas 118, 128 that communicate with the receivers 116, 126 and the transmitters 117, 127 to facilitate wireless data transmission and reception. Also, the receiver 126, the transmitter 127, and the antenna 128 may be a single receiver, transmitter, and antenna, or may include a plurality of individual receivers, transmitters, and antennas, respectively. The transmitter 110 may be located in the WTRU or the multiple transmitting circuits 110 may be located in the base station. The receiver 120 may be located at the WTRU or the Node B, or at the WTRU and the Node B at the same time.

The disclosed TPC method includes a combined open-loop and closed-loop scheme for uplink (UL) intra-cell power control. The method includes controlling channels and sound reference symbols (SRS) for UL data channels to control WTRU transmission power spectral density (PSD) or PSD transmission (PSD)_TX), such as power per resource block (RB), or WTRU transmission power using open loop and periodic closed loop power control (PC). If the UL MCS/authorized representative receives the signal-to-interference and noise ratio (SINR) at Node B, the WTRU uses the UL channel quality indicator (CQI) (or modulation code set (MCS)/authorization information) to correct the open loop And/or measurement error. If there is no CQI available, only open loop is performed. Implicit command signaling can be used for closed-loop components, for example, there is no signaling overhead. Or, for the closed-loop component, explicit TPC command signaling can be used in the DL control channel. Moreover, the disclosed method can quickly correct open loop errors and obtain good performance.

As noted above, the disclosed method includes controlling WTRU transmission power spectral density (PSD) or PSD transmission (PSD)_Tx), such as power per resource block (RB) or transmission power. It should be noted that although the disclosed method includes controlling transmission PSD, it is equivalent to controlling transmission power. PSD_Txdefined as:

<i>PSD</i>_<i>Tx</i>=<i>PSD</i>_<i>open</i>+αΔ_{<i>closed</i>}+Δ_<i>MCS</i>; Formula (1) where PSD_openRepresents the open-loop PSD based on path loss expressed in dBm; Δ_closedIt is the power correction factor determined based on the closed-loop component, which will be described in detail below; Δ_MCSIs the power offset of each authorized MCS; a is the weighting factor that enables the closed-loop component to be valid (a=1) or invalid (a=0) according to the availability of the downlink (DL) control channel, which is embedded in the closed-loop PC (correction ) In command signaling (explicit or implicit). The weighting factor may be determined by the WTRU 20 via spontaneous detection of the presence of closed-loop PC command signaling. Alternatively, the WTRU 20 is notified via advanced signaling from the eNodeB 30 about where the command signaling exists. Transmission PSD should not exceed the maximum transmission PSD PSD_max, Where PSD_maxBased on the maximum allowable power P_maxObtained, the maximum allowable power P_maxDepends on UE power level, such as PSD_max=P_max/M, where M is the size of the UL channel resource allocation represented by the number of resource blocks that is effective for a given subframe.

The intracellular PC scheme proposed in formula (1) can use an absolute power correction factor compared with the open-loop-based PSD. According to equation (1), the WTRU Tx PSD at the nth update time can be expressed as:

<maths><img file="TWM350187U_D0001.tif" /></maths>

in<maths><img file="TWM350187U_D0002.tif" /></maths>Represents the (n-1)th Tx PSD that does not include the power offset of each authorized MCS, by<maths><img file="TWM350187U_D0003.tif" /></maths> Given.

Typically, both the WTRU and the eNodeB know the power offset for a single authorized MCS.

The processor 115 of the WTRU 20 combines the path loss-based open-loop and closed-loop PC to determine the PSD_TX. According to the disclosed method, the WTRU 20 first performs an open loop PC (PSD) based on path loss measurement and system parameters._open). PSD_openThe calculation is as follows:

<maths><img file="TWM350187U_D0004.tif" /></maths>

Of which PSD_targetIt is the target PSD received at the serving eNodeB 30, which is preferably a dedicated parameter of a WTRU (or a subgroup of WTKU). The target PSD can be adjusted according to the quality of service (QoS) (for example, the target block error rate (BLER)) through an outer loop mechanism, or it can be a function of the path loss measurement result to compensate for a part of the path loss. Target PSD_targetThe signaling of is performed via higher-layer signaling from Node B 30 to WTRU 20 according to slow-based adjustments; and<maths><img file="TWM350187U_D0005.tif" /></maths>It is the filtered path loss expressed in dB from the serving eNodeB 30 to the WTRU 20, including shadow fading, where the WTRU 20 first measures the instantaneous path loss based on a DL reference signal (RS) with a known transmission power. The WTRU 20 then applies the filtering method to the path loss. For example, the filtered path loss at the kth moment,<maths><img file="TWM350187U_D0006.tif" /></maths>, Can be calculated like this:

<maths><img file="TWM350187U_D0007.tif" /></maths>

in<maths><img file="TWM350187U_D0008.tif" /></maths>And L_<i>k</i>Represents the filtered path loss at the (k-1)th moment and the instantaneous path loss at the kth moment; ρ is the filter coefficient, 0<img file="TWM350187U_D0009.tif" />ρ<img file="TWM350187U_D0009.tif" />1. Usually determined by the WTRU 20, depending on, for example, path loss variation, fast fading rate, UL transmission time, and others. Path loss filtering can be done at the physical (PHY) layer and/or the L 2/3 layer.

Once the WTRU 20 determines the open loop component, the processor 115 calculates the closed loop component. As those skilled in the art know, there are open-loop related errors, including path loss estimation errors due to the lack of complete reciprocity in FDD UL and DL, and WTRU Tx damage due to non-linear power amplifiers. In order to compensate for such errors and maintain the quality of the power-controlled channel together with the target quality, the WTRU applies correction to the open-loop-based PSD in the form of a closed-loop PC as in equation (1) (or equation (2)).

The serving eNodeB 30 determines WTRU-specific (absolute and/or cumulative) PC correction commands for each UL scheduled WTRU (or a subgroup of scheduled WTRUs). Preferably, the eNodeB 30 uses the power-controlled data channel as a reference for the calibration command. The generated correction command is signaled to the WTRU 20 (or a subgroup of the scheduled WTRU) through the UL grant and/or DL scheduled channel sent on the DL layer 1 or 2 control channel. The correction command may only be signaled in the UL grant associated with a specific (pre-defined) HARQ procedure, for example, each HARQ procedure 1.

When the correction command is received at the WTRU 20, the processor 115 of the WTRU 20 determines the correction factor Δ based on the proposed correction command (or accumulated correction command)_closed:Δ_{<i>closed</i>}=<i>f</i>(<i>PC correction command(s)</i>); Formula (5) where Δ_{<i>closed</i>}A set of multi-step values can be used, for example, {+/-4,+/-1 dB) using a 3-bit command.

Alternatively, the eNodeB 30 uses multiple command bits, such as 3 bits, for each scheduled WTRU 20 (or a subgroup of scheduled WTRUs) in the UL authorization and possibly DL scheduling of the DL control channel. The transmit power correction factor, where the correction command is preferably determined based on the link quality of the UL power controlled data channel (such as received PSD or SINR) (and possible UL sound reference symbols, if available). For example, suppose a set of power correction factor values is {-7,+/-5,+/-3,+/-1,0 dB) with 3 bits, the correction factor can be determined as follows

<maths><img file="TWM350187U_D0011.tif" /></maths>

in<i>ESINR</i>_<i>est</i>and<i>SINR</i>_{<i>target</i>}Respectively represent the effective SINR (ESINR) estimation and target SINR at the receiver of the power-controlled channel expressed in dB. [<i>x</i>] Represents the closest in the calibration set<i>x</i>The correction value. The samples observed at the eNodeB for ESINR estimation include (part or all) of the SC-FDMA symbols of the UL power controlled frequency channel, which have been received since the last correction command signaling in the DL.

In order to reduce command signaling overhead, there is no need to have a correction command in every UL grant (and if used, in every DL schedule). That is, the correction command can be sent at a pre-configured signal transmission time (for example, at every N authorized channels or every N transmission time interval (TTI), where N is a configurable parameter less than or equal to the minimum UL PC update period) .

The correction command signaling timing is configured at the eNodeB 30 (or at the RRC level) on a per WTRU basis, and the correction command signaling timing is then known to the eNodeB 30 and the WTRU 20 via higher layer signaling.

When the correction command is signaled in the UL grant, assuming that the UL HARQ is synchronized, the signaling timing configuration can be simplified so that the command signaling is in a specific UL grant, such as a UL grant associated with a predefined HARQ procedure, For example, it is executed in HARQ program #1. However, even in this case, there is no need to signal the correction command in all relevant UL authorized channels. For example, the signaling may appear in every N related authorized channels, N&gt;=1, which is equivalent to one command signaling in every N HARQ cycle period. The signaling timing (or related parameters) can be reconfigured at a semi-static rate.

Figure 3 shows an example of the PC method disclosed when the PC correction command is transmitted in the UL grant associated with HARQ program #1, and N is set to 2. In this example, the PC update rate is 8 milliseconds, it is assumed that the number of HARQ procedures is 4, and the transmission time interval (TTI) of the interval is equal to 1.

When the WTRU 20 has received a correction command from the serving eNodeB 30 in the UL grant (or possibly a cumulative correction command in multiple UL grants) since the last Tx PSD adjustment, it will add a correction command from the received correction command (or if When more than one command is received, multiple correction commands are combined) to obtain the correction factor Δ_{<i>closed</i>}, Used for the next PSD adjustment.

The WTRU 20 then uses the obtained correction factor, the most recent open loop PSD, and the power offset associated with the authorized MCS to adjust the transmission PSD of the data channel according to equation (1) (or equation (2)). The resulting Tx PSD will be applied to the very beginning of the next UL TTI used as the data channel (the first SC-FDMAA symbol) and will remain unchanged until the next PSD adjustment, as shown in Figure 3.

Figure 4 shows an example of the timing of the disclosed combined PC method. It is assumed that UL HARQ is a synchronization scheme with 4 HARQ procedures, and the WTRU 20 is scheduled for each TTI (for example, the interval TTI=1) Send a data packet (for example, a HARQ program). In addition, the eNodeB 30 only sends the PC correction command in the UL grant associated with HARQ procedure 1. In this case, the WTRU Tx power update period is 4 TTIs (for example, 4 milliseconds).

As shown in Figure 4, in the initial UL transmission, because there is no PC correction command available, the WTRU 20 sets its transmission power based only on the open loop component (that is, the weighting factor a in equation (1) is zero). Before the next HARQ transmission time (one HARQ cycle time), the eNodeB 30 sends a correction command in the authorized channel in the DL control channel associated with HARQ procedure 1, where the command is based on the link quality (power or SINR of the first two HARQ procedures). )determine. If WTRU 20 receives the correction command correctly, WTRU 20 then calculates its transmission PSD based on the combined open-loop and closed-loop scheme_TXAnd put the PSD_TXIt is used in the HARQ program that follows.

Figure 5 illustrates another example of the disclosed combined PC timing, where the TTI of the interval is 2. In this case, the UL PC update cycle is 8 TTI (8 milliseconds).

When there is no recent closed-loop calibration command (for example, because of newly scheduled UL data transmission, ie, UL DTX), the WTRU 20 can set its Tx PSD by relying on the open loop. In this case, the weighting factor a in equation (1) is set to 0 as in the initial Tx PSD setting.

Alternatively, the WTRU 20 may set the TxPSD based on the path loss change between the time before DTX and the time before resuming UL transmission. If the UL DTX is very short, the WTRU can use equation (2) by setting a to 0, so

<maths><img file="TWM350187U_D0012.tif" /></maths>

Where n is the Tx PSD setting time before resuming UL transmission, and (n-1) is the PSD setting time before DTX. An example of timing in this case is shown in Figure 6.

In another alternative, the WTRU 20 may apply a power offset relative to the latest PSD to the physical uplink control channel (PUCCH), if available. Even if there is no UL data transmission, there are UL control signaling (such as CQI and ACK/NACK) for DL. In this case, because the UL control channel is also power controlled based on equation (1) (but using different parameters and update speeds), the UL control channel Tx PSD used for the data channel Tx PSD can be used as follows:<i>PSD</i>_<i>Tx</i>(<i>data</i>)=<i>PSD</i>_<i>Tx</i>(<i>control</i>)+Δ_{<i>control</i>}(<i>data,control</i>) Formula (8) where<i>PSD</i>_<i>Tx</i>(<i>control</i>) Is the latest PSD of the UL control channel (or the average PSD in the latest update), Δ_{<i>control</i>}(<i>data,control</i>) Represents the control channel power offset related to the Tx PSD of the data.

If the DTX period is very long, then the PSD of WTRU 20_TXCan be as initial PSD_TXIn the case of setting, it is only determined immediately after the DTX based on the open loop.

Figure 7 shows an example of the proposed combined PC solution, including DTX.

Typically, the allocation of UL grants in the DL control channel (for example, the assigned MCS and TBS) is closely related to the link quality of UL data transmission (such as the received PSD or SINR). Another method is disclosed in which the eNodeB 30 processor 125 can allocate UL grants (MCS and TBS) to the WTRU 20 so that the grant allocation represents the link quality (e.g., SINR) received at the eNodeB 30. In this case, WTRU 20 can obtain its Tx PSD as follows:<i>PSD</i>_<i>Tx</i>=<i>PSD</i>_<i>open</i>+α<i>f</i>(<i>UL</i>Authorized distribution,<i>SINR</i>_<i>T</i>)+Δ_<i>MCS</i>(dBm); where<i>PSD</i>_<i>open</i>, Α, and Δ_<i>MCS</i>They are the same as the above definitions.<i>f</i>(<i>UL</i>Authorized distribution,<i>SINR</i>_<i>T</i>) Is the correction factor expressed in dB, which replaces the power correction factor Δ in formula (1)_{<i>closed</i>}。<i>SINR</i>_<i>T</i>It is the target SINR expressed in dB. Authorization-based correction factor<i>f</i>(<i>UL</i>Authorized distribution,<i>SINR</i>_<i>T</i>) Can be expressed as follows:<i>f</i>(<i>UL</i>Authorized distribution,<i>SINT</i>_<i>T</i>)=<i>SINR</i>_<i>T</i>-<i>E</i>{<i>SINR</i>_<i>est</i>(<i>UL</i>Authorized distribution)}; formula (10) where<i>SINR</i>_<i>est</i>(<i>UL</i>Grant allocation) represents the SINR estimation received by the eNodeB, and the SINR estimation received by the eNodeB is obtained by the WTRU 20 from the UL grant allocation.<i>E</i>{<i>SINR</i>_<i>est</i>} Represents the time average of the estimated SINR, for example<i>E</i>{<i>SINR</i>_<i>est</i>(<i>grant</i>^<i>k</i>)}=ρ<i>E</i>{<i>SINR</i>_<i>est</i>(<i>grant</i>^<i>k</i>^-1)}+(1-ρ)<i>E</i>{<i>SINR</i>_<i>est</i>(<i>grant</i>^<i>k</i>)) Formula (11) where<i>grant</i>^<i>k</i>Represents the k-th received UL authorization allocation, ρ is the average filter coefficient, 0<img file="TWM350187U_D0009.tif" />ρ<img file="TWM350187U_D0009.tif" />1. In WTRU<i>SINR</i>_<i>est</i>(<i>UL</i>Authorization allocation) estimation can be based on authorization (MCS, TBS) mapping table, which can be configured by the network through higher-layer signaling on a semi-static basis.

Similar to equation (1), the correction factor in equation (8) can be used to compensate for open loop errors. The main advantage of using equation (8) is that no explicit correction command signaling is required in the UL grant of the DL L1/L2 control channel (resulting in reduced signaling overhead), and equation (1) (and equation (2)) An explicit command to be sent in the UL grant (and/or DL schedule) is required. Using equation (3), the closed-loop component can be allocated based on UL authorization (for example, MCS and/or TBS), and there is no explicit correction command signaling in the UL authorization of the DLL1/L2 control channel.

However, in certain situations such as continuous scheduling and authorization (eg MCS) mismatch (that is, the assigned MCS cannot correctly represent the received SINR), Equation (9) cannot be applied. Therefore, the WTRU Tx PSD setting can be switched between equation (1) and equation (8).

Through higher layer correction factor type signaling, where the eNodeB 30 (or network 10) signals to the WTRU 20 which equation (equation (1) or equation (8)) is used for the WTRU Tx power setting. In this case, preferably the correction factor type signal can be configured by the network 10 on a semi-static basis and on a per WTRU basis.

Alternatively, a 1-bit MCS mismatch indicator can be introduced into the DL L1/2 control signaling. For example, bit 1 can be used to indicate the use of formula (1), and bit 0 can be used to indicate the use of formula (8).

In another alternative, one of the explicit correction command levels can be used to indicate the use of equation (8). This alternative example assumes that equation (1) is the default PC method. Similarly, the eNodeB 30 sets one of the correction command levels in the UL grant to indicate the use of equation (8). For example, when the correction command in equation (8) is 3 bits long, set one of the eight command levels for the WTRU 20, such as '000', to use equation (8).

Figure 8 shows a flow chart of the disclosed open-loop and closed-loop method for determining the combination of TPC. By determining the target power spectral density PSD_target(Step 800) and filtered path loss (L) (Step 801), the processor 115 of the WTRU 20 performs open loop power control based on the path loss measurement. The WTRU 20 then uses the power control correction command received at the receiver 116 through the UL authorized channel to determine the closed loop component (step 802). Once the correction command is received, the receiver 116 forwards the correction command to the processor 115 in order to determine the correction factor Δ_{<i>closed</i>}(Step 803). Then the processor 115 calculates the correction factor Δ_{<i>closed</i>}(Step 804). The processor 115 then combines the open-loop PC and the closed-loop components to determine the transmission power control (step 805).

In the disclosed TPC method for irregular data (such as VoIP), the WTRU has a variety of options to set its TX PSD: i) only rely on the open-loop PSD, ii) for the closed-loop part, the eNodeB at a specific moment (in real time) The UL authorization is transmitted, where the UL authorization transmits the correction command. In this case, the UL authorization format (and/or correction command format) may be different from the format used for the scheduled data; or iii) if available, it will be compared to the latest PSD (or averaged in recent updates) PSD) power offset is applied to PUCCH.

<maths><img file="TWM350187U_D0015.tif" /></maths>

in<i>P</i>₀It is a cell-specific parameter (expressed in dBm) including UL interference level, etc., which is sent by the eNodeB via higher layer signaling.

SINR_TargetIt is a dedicated parameter (in dB) of the WTRU (or a subset of the WTRU), allowing the eNodeB to set the service level for the UE (or a subset of the UE). For the service cell and some neighboring cells,<i>SINR</i>_<i>T</i>_arg_<i>et</i>Can be a function of path loss.<i>SINR</i>_<i>T</i>_arg_<i>et</i>It can be configured on a semi-static basis by the serving eNodeB, and then sent to the UE (or a subset of the UE) via higher layer signaling;<i>PL</i>Is the downlink path loss (expressed in dB); <i>λ</i>It is a cell-specific path loss compensation factor for partial power control, where 0&lt;α&lt;=1. α can be configured by eNodeB on a semi-static basis and signaled via higher layer signaling; Δ_{<i>closed</i>}It is the power correction factor expressed in dB, which is determined based on the closed loop mechanism;<img file="TWM350187U_D0016.tif" />Is to make the closed loop component effective (<img file="TWM350187U_D0016.tif" />=1) or invalid (<img file="TWM350187U_D0016.tif" />The weighting factor of =0) depends on the availability of the DL control channel that carries the closed-loop correction command. The weighting factor is automatically determined by the WTRU by detecting the presence of the PC correction command. It is assumed that the WTRU is notified via higher layer signaling from the eNodeB about where and when the command signaling exists. For example, in the initial UL transmission, because there is no available correction command from the eNodeB, the WTRU sets<img file="TWM350187U_D0016.tif" />=0; Δ_<i>MCS</i>Is the power offset of each authorized MCS. Typically, both the WTRU and the eNodeB know the power offset of a single authorized MCS.

Because eNodeB 30 knows the Δ used in a given situation_<i>MCS</i>When it determines the correction command by comparing the received PSD (or SINR) as a result with the target level determined by the network 10, the eNodeB 30 can obtain Δ from the received PSD_<i>MCS</i>Value.

As mentioned above, compared with the open-loop based PSD, the disclosed method uses an absolute power correction factor. Similarly, according to equation (12), the WTRU Tx PSD in the nth update case is expressed as follows:

<maths><img file="TWM350187U_D0020.tif" /></maths>

in<maths><img file="TWM350187U_D0021.tif" /></maths>Represents the (n-1)th Tx PSD without the power offset of each authorized MCS, which is determined by<maths><img file="TWM350187U_D0022.tif" /></maths>Given.

Because the total WTRU transmission power is represented by<i>P</i>_maxThe maximum transmission power level of the WTRU is limited by<i>P</i>_<i>Tx</i>The total WTRU transmission power expressed as:<i>P</i>_<i>Tx</i>=min{<i>P</i>_max,(10log₁₀(<i>M</i>)+<i>PSD</i>_<i>Tx</i>)}(dBm); Equation (14) where M is the number of allocated RBs.

Therefore, the actual WTRU transmission PSD can be expressed as:

<maths><img file="TWM350187U_D0023.tif" /></maths>

It should be noted that the UL PC in equation (15) is implemented by the processor 115 of the WTRU 20.

According to the disclosed PC method for irregular data, the WTRU 20 calculates the open-loop PSD as follows:<i>PSD</i>_<i>open</i>=<i>P</i>₀+<i>SINR</i>_<i>T</i>_arg_<i>et</i>+<i>λ</i>‧<i>PL</i>(dBm) Equation (16) where target SINR,<i>SINR</i>_<i>T</i>_arg_<i>et</i>, The serving eNodeB 30 can be adjusted according to the quality of service (QoS) (such as the target BLER) through the outer loop mechanism, and for the serving cell and neighboring cells, it can also be a function of path loss measurement; and<i>PL</i>It is the filtered path loss from the serving eNodeB to the WTRU in dB, including shadow fading. The WTRU continuously (or periodically) measures the instant path loss based on the DL RS, and the WTRU knows the transmission power of the DL RS. Then apply the filtering method to the measurement of path loss, for example<i>PL</i>_<i>k</i>=ρ<i>PL</i>_<i>k</i>_-1+(1-ρ)<i>PL</i>_<i>k</i>Formula (17) where<i>PL</i>_<i>k</i>and<i>PL</i>_<i>k</i>_-1Denote the filtered path loss at the kth and (k-1)th moments, respectively.<i>L</i>_<i>k</i>Is the instant path loss at the k-th moment. ρ is the filter coefficient, 0<img file="TWM350187U_D0009.tif" />ρ<img file="TWM350187U_D0009.tif" />1. It is usually determined by the WTRU 20 and depends on path loss changes, fast fading rate, UL transmission time, and so on. Alternatively, the moving average method can be considered for path loss filtering.

Similar to the above disclosure, the closed-loop component is determined by the processor 115.

<maths><img file="TWM350187U_D0026.tif" /></maths>

in<i>ESINR</i>_<i>est</i>and<i>SINR</i>_<i>t</i>_arg_<i>et</i>Respectively represent the effective SINR (ESINR) estimation and target SINR of the power-controlled channel in the receiver expressed in dB. [<i>x</i>] Represents a correction value in the correction set, which is closest to<i>x</i>。

Similar to the method disclosed above, when the correction command is signaled in the UL grant, it is assumed that the UL HARQ is synchronized, and the signal transmission time configuration can be simplified so that the command signaling is associated with a predefined HARQ program in a specific UL grant. Executed in the UL authorization.

For irregular data (such as VOIP), when there is no recent closed-loop calibration command (for example, because of the most recently scheduled UL data transmission, that is, UL DX), the WTRU 20 can set its Tx PSD by relying on the open loop: In the case, the weighting factor in formula (13)<img file="TWM350187U_D0016.tif" />, Set to 0 as in the case of the initial Tx PSD setting. Alternatively, the WTRU 20 can set its TX PSD based on the path loss change between the time before DTX and the time before resuming UL transmission: If the UL DTX is very short, the WTRU can use equation (2) by setting β to 0 ,thereby

<maths><img file="TWM350187U_D0028.tif" /></maths>

Where n is the Tx PSD setting time before resuming UL transmission, and (n-1) is the PSD setting time before DTX. Figure 4 shows an example of this situation.

Alternatively, if available, the WTRU 20 may apply the power offset relative to the most recent PSD to the PUCCH. Even if there is no UL data transmission, there may also be UL control signaling (such as CQI and ACK/NACK) for DL. In this case, because the UL control channel (PUCCH) is also power-controlled based on equation (12), (but using different parameters and update speeds), the UL control channel (PUCCH) Tx PSD can be used for data as follows Tx PSD of the channel (PUSCH):<i>PSD</i>_<i>Tx</i>(<i>PUSCH</i>)=<i>PSD</i>_<i>Tx</i>(<i>PUCCH</i>)+Δ_{<i>control</i>}(<i>PUSCH,PUCCH</i>); where<i>PSD</i>_<i>Tx</i>(<i>PUCCH</i>) Is the most recent PSD used in the UL control channel (PUCCH) (or the average of the latest update of the PSD), Δ_{<i>control</i>}(<i>PUSCH,PUCCH</i>) Represents the Tx PSD control channel (PUCCH) power offset relative to the PUSCH.

For voice pilot, its Tx PSD <i>PSD</i>_<i>Tx</i>(<i>pilot</i>) Can be relative to the data TX PSD <i>PSD</i>_<i>Tx</i>(<i>data</i>) To offset a pilot power offset, thus<i>PSD</i>_<i>Tx</i>(<i>pilot</i>)=<i>PSD</i>_<i>Tx</i>(<i>data</i>)+Δ_<i>pilot</i>(<i>data,pilot</i>) Formula (21) where Δ_<i>pilot</i>(<i>data,pilot</i>) Represents the pilot power offset, which may be a WTRU-specific parameter configured by the eNodeB on a semi-static basis.

For the control signaling in UL, it is better to use different parameters (such as target PSD) and a faster update speed relative to the data. In addition, it is more preferable that the reference channel measured for the calibration command used for the control signaling is the control channel itself, and the calibration command for control is transmitted in the DL schedule. The number of bits of the correction command used for control may be different from that used for the data, where the number of command bits may be a semi-static configurable parameter based on each WTRU. However, we can maintain the relative average power offset between the data and control channels, for example<i>E</i>(<i>PSD</i>_<i>Tx</i>(<i>data</i>))=<i>E</i>(<i>PSD</i>_<i>Tx</i>(<i>control</i>))+Δ_{<i>control</i>}(<i>data,control</i>) Formula (22) where *<i>E</i>(<i>PSD</i>_<i>Tx</i>(<i>data</i>)) means the average PSD for the data channel expressed in dBm; *<i>E</i>(<i>PSD</i>_<i>Tx</i>(<i>control</i>)) represents the average PSD for the control channel expressed in dBm; and *Δ_{<i>control</i>}(<i>data,control</i>) Is the power offset between the data channel and the control channel.

In another disclosed ULPC method, a combined open-loop/closed-loop UL PC with interference mitigation for shared data channels is used. According to this method, the WTRU 20 controls the PSD transmitted by the UL channel. If the bandwidth allocation (e.g., RB allocation) of the WTRU 20 changes, the total transmission power of the WTRU also changes to keep the PSD unchanged.

As described in the method disclosed above, the WTRU 20 performs an open-loop PC based on path loss measurement and system parameters. The WTRU 20 then uses some form of closed-loop PC to correct its PSD to compensate for open-loop errors. It should be noted that for each UL scheduled WTRU, the eNodeB 30 periodically signals CQI information for AMC and scheduling. Therefore, the closed-loop PC component of the method of the present disclosure does not require any additional PC commands sent by the eNodeB. In order to suppress the inter-cell interference between neighboring cells, the WTRU 20 incorporates the interference load indicator from the strongest neighboring cell.

According to this method, for the UL shared data channel, in the initial transmission stage, the WTRU 20 obtains its transmitted PSDPSD based on the DL reference signal (RS)_Txas follows:<i>PSD</i>_<i>Tx</i>=<i>SINR</i>_<i>T</i>+<i>PL</i>+<i>IN</i>₀+<i>K</i>+Δ(<i>IoT</i>_<i>S</i>)-10log10(<i>BW</i>_<i>RU</i>‧<i>N</i>_<i>RU</i>); Formula (23) where SINR_TIt is the target SINR expressed in dB in the serving eNodeB 30. PL is the path loss from the serving eNodeB 30 to the WTRU 20 expressed in dB, including shadow fading, where the WTRU 20 measures the path loss based on the DL RS, and the WTRU 20 knows the transmission of the DL RS through DL layer 2/layer 3 signaling Power, IN₀It is the UL interference and noise power expressed in dBm, which is measured at the serving eNodeB 30. K is the power control tolerance set by the serving eNodeB30.

Preferably, the target SINR of the WTRU 20 (or a subgroup of the WTRU) is adjusted according to the link quality metric (such as BLER) of the serving eNodeB 30 using the outer-loop PC scheme. In addition, in the case of UL Multiple Input Multiple Output (MIMO), the target SINR also depends on the selected MIMO mode, which takes into account that for a given link quality, different MIMO modes require different SINRs. Δ(<i>IoT</i>_<i>S</i>) Represents the UL load control step length, which is an indicator of the strongest neighboring cell's UL interference load (for example, heat interference)<i>IoT</i>_<i>S</i>Here, the strongest neighbor cell is determined by the WTRU 20 based on the path loss measurement from a single neighbor cell to the WTRU 20. Assume that each cell 40 periodically broadcasts UL interference load bits (similar to the relative grant in HSUPA) so that the WTRU 20 can decode the indicator bits from the selected strongest neighbor cell.

For example, Δ(<i>IoT</i>_<i>S</i>) Can be calculated as follows:

<maths><img file="TWM350187U_D0029.tif" /></maths>

Where d is a predefined system parameter, for example, d=-1 or -2dB. By using Δ(IoT_s), which can reduce the interference between adjacent cells.

Because the WTRU in the center of the cell causes less interference to other cells than the WTRU at the edge of the cell, the segmentation of the load control step is considered as follows:

<maths><img file="TWM350187U_D0030.tif" /></maths>

The WTRU 20 may, for example, determine whether it is located at the edge of the cell or inside the cell based on the path loss ratio between its serving cell and the strongest neighboring cell.

If (path loss_service_cell-path loss_strongest_adjacent_cell)&lt;R (dB),<i>x</i>=4; where R represents the virtual boundary layer between the area inside the cell and the area at the edge of the cell. The parameter R can be broadcast semi-statically by the eNodeB 30.

After the initial transmission phase, the WTRU 20 PSD_TXThe calculation is as follows:<i>PSD</i>_<i>Tx</i>=<i>SINR</i>_<i>T</i>+<i>PL</i>+<i>IN</i>₀+<i>K</i>+Δ(<i>IoT</i>_<i>S</i>)+α<i>f</i>(<i>CQI, SINR</i>_<i>T</i>)-10log10(<i>BW</i>_<i>RU</i>‧<i>N</i>_<i>RU</i>) Formula (24) where f(CQI, SINR_T) Is a correction factor based on the UL CQI and the corresponding target SINR, where the serving eNodeB 30 signals the CQI and the target SINR; α, here 0<img file="TWM350187U_D0009.tif" />α<img file="TWM350187U_D0009.tif" />1, is a weighting factor determined based on channel conditions and CQI availability (or UL transmission interruption). For example, in the case where UL CQI (UL MCS or authorization information) from eNodeB 30 is not available due to no scheduled UL data transmission, the weighting factor α is set to 0, which means that WTRU 20 only relies on open-loop PCs (e.g., PC for Random Access Channel (RACH); otherwise, it is set to be less than or equal to 1 (1).

The correction factor f (CQI, SINR_T), used to compensate open-loop PC-related errors. The correction factors include path loss measurement errors caused by incomplete reciprocity between UL and DL in FDD and WTRU 20 caused by nonlinear amplification of WTRU transmitter power. Launcher damage (impairment). In addition, the correction factor is used to compensate for target quality mismatches caused by different channel conditions. Thus, the quality of the power-controlled channel is maintained along with the given target quality (such as the target SINR).

Considering that UL CQI (UL MCS or authorization information) represents the SINR received at eNodB30, the correction factor can be calculated like this,<i>f</i>(<i>CQI, SINR</i>_<i>T</i>)=<i>SINR</i>_<i>T</i>-<i>E</i>{<i>SINR</i>_<i>est</i>(<i>CQI</i>)}(dB); where<i>SINR</i>_<i>est</i>(<i>CQI</i>) Represents the SINR estimate received by the eNodeB, and the WTRU obtains this value from the UL CQI feedback.<i>E</i>{<i>SINR</i>_<i>est</i>(<i>CQI</i>)} represents the average of the estimated SINR over time, for example, by the following formula:<i>E</i>{<i>SINR</i>_<i>est</i>(<i>CQI</i>^<i>k</i>)}=ρ<i>E</i>{<i>SINR</i>_<i>est</i>(<i>CQI</i>^<i>k</i>^-1)}+(1-ρ)<i>E</i>{<i>SINR</i>_<i>est</i>(<i>CQI</i>^<i>k</i>)}; formula (26) where<i>CQI</i>^<i>k</i>Represents the k-th received CQI, ρ is the average filter coefficient, 0<img file="TWM350187U_D0009.tif" />ρ<img file="TWM350187U_D0009.tif" />1。

The correction factor in equation (25) given by the difference between the target SINR and the estimated SINR (obtained from the reported CQI) above represents the open-loop PC-related error that needs to be compensated.

The total transmission power of the WTRU shall be at the maximum power value P expressed in dBm respectively_maxAnd minimum power value P_minIn between, the maximum and minimum power values here are determined based on the WTRU level.

Preferably the eNodeB 30 signals the parameters, including the target SINR value SINR_T, Which should be SINR_T WTRU (or a subgroup of WTRU) specific parameters, where the target SIR can be adjusted through an outer loop mechanism based on QoS such as target BLER. The target SINR can also be a function of the path loss measurement. During adjustment, the signal transmission of the target SIR is performed via in-band L1/2 control signaling. The power control tolerance K, which is an eNodeB-specific parameter, may also be signaled by the eNodeB 30. K is preferably semi-static and signaled via the broadcast channel (BCH). It should be noted that even if K is used to send signals separately with other parameters, it can also be embedded in the target SINR, that is, SINR_T(After embedding)=SINR_T+K(dB). In this case, the WTRU 20 does not need explicit signaling of K.

The eNodeB 30 also signals the total UL interference and noise value, IN₀, Which is averaged over all used sub-carriers (or RBs) or a subset of sub-carriers. This parameter is preferably obtained by the serving eNodeB 30 (and possibly signaled via BCH). The update speed of this signaling is usually relatively slow. Maximum and minimum UL power value P_maxAnd P_minIt is also signaled by the eNodeB 30. Each of them may be a WTRU performance dependent parameter or may be explicitly signaled by the eNodeB 30.

The UL channel quality indicator CQI (such as UL MCS or authorization information) is initially signaled for UL AMC (with a maximum signal transmission rate per TTI, such as 1000 Hz).

The eNodeB uses the CQI mapping rule (or the offset between the CQI and the measured SINR) generated by the CQI feedback. This rule or parameter can be combined into the target SINR. In this case, no explicit signaling of rules (or parameters) is required.

UL interference load indicator from each eNodeB.

The semi-static parameter R represents the virtual boundary layer between the internal area of the cell and the boundary area of the cell.

The disclosed PC method does not require additional feedback PC commands other than the system parameters listed above, including target SINR, cell interference/noise value, interference signal transmission power and duration value, and it can be broadcast on a slow basis. (Or send a signal directly) to the WTRU.

In order to meet the requirements of E-UTRA, it is designed to be flexible and adapt to dynamic system/link parameters (target SINR and inter-cell interference load conditions) and channel conditions (path loss and shadow fading).

Further, the disclosed method is compatible with other link adaptation schemes such as AMC, HARQ and adaptive MIMO.

In an alternative method of inter-cell interference suppression, instead of broadcasting the interference load indicator from each eNodeB, the serving eNodeB 30 can adjust the inter-cell interference value with other cells 40, thereby adjusting the target SIR and power control capacity. Limited to K or possible P_maxCombine it.

Although the features and elements of the present invention are described above in a specific combination in the preferred embodiments, each feature or element can be used alone without the other features and elements in the preferred embodiment. , Or used in various situations in combination with or without other features and elements of the present invention. The method or flowchart provided by the present invention can be implemented in a computer program, software, or firmware executed by a general-purpose computer or processor, wherein the computer program, software, or firmware is included in a computer-readable storage medium in a tangible manner In, examples of computer-readable storage media include read-only memory (ROM), random access memory (RAM), register, buffer memory, semiconductor memory device, internal hard disk, and removable disk. Types of magnetic media, magneto-optical media, and optical media such as CD-ROM discs and digital versatile discs (DVD).

For example, suitable processors include: general-purpose processors, special-purpose processors, conventional processors, digital signal processors (DSP), multiple microprocessors, one or more microprocessors associated with the DSP core, Controller, microcontroller, dedicated integrated circuit (ASIC), field programmable gate array (FPGA) circuit, any kind of integrated circuit and/or state machine.

The software-related processor can be used to implement a radio frequency transceiver to be implemented in a wireless transmit and receive unit (WTRU), user equipment (UE), terminal, base station, radio network controller (RNC), or any kind of host computer use. WTRU can be used in conjunction with modules implemented in hardware and/or software, such as cameras, camera modules, video circuits, speaker phones, vibration devices, speakers, microphones, TV transceivers, hands-free headsets, keyboards, Bluetooth<img file="TWM350187U_D0035.tif" />Module, frequency modulation (FM) radio unit, liquid crystal display (LCD) display unit, organic light-emitting diode (OLED) display unit, digital music player, media player, video game console module, Internet browser and / Or any kind of wireless local area network (WLAN) module or ultra-wideband (UWB) module.

<p>20. WTRU. . . Wireless transmitting and receiving unit</p><p>118, 128. . . antenna</p><p>110, 120. . . transceiver</p><p>30. eNodeB. . . Node B</p><p>40. . . Cell</p><p>DL. . . Downlink</p><p>PC. . . Power Control</p><p>PSD. . . Transmission power spectral density</p><p>UL. . . Uplink</p><p>Tx. . . transmission</p><p>DTX. . . Discontinuous transmission</p><p>PSD_TX. . . PSD transmission</p><p>ESINR. . . Effective signal-to-interference to noise ratio</p>

According to the following description of the preferred embodiments, the present invention can be understood in more detail. These preferred embodiments are given by way of example and can be understood in conjunction with the accompanying drawings, in which:

Figure 1 is an example wireless communication system;

Figure 2 is an example block diagram of a transmitter and a receiver configured to implement the disclosed power control (PC) method;

Figure 3 shows an example of the timing of the disclosed combined PC method;

Figure 4 shows an example of the combined power control method disclosed when the inter-TTI (inter-TTI) is 1 (1);

Figure 5 shows another example of the combined PC timing disclosed when the TTI of the interval is 2(2);

Figure 6 shows an example of the disclosed PC solution including discontinuous transmission (DTX) combination;

Figure 7 shows an example of the PC method for the disclosure of the nth update time; and

Figure 8 shows a flow chart of the disclosed combined open-loop and closed-loop method for determining TPC.