RU2437211C2 - Combined method to control capacity of mobile station upperlink in open and closed circuits - Google Patents

Abstract

FIELD: information technologies.

SUBSTANCE: method and a device are disclosed, including a combined circuit for control of upperlink capacity in the closed and opened circuit for E-UTRA. The combined method of open and closed circuit for intracell power control (PC) in the upperlink (UL) controls spectral density of transfer power in a wireless reception/transmission module.

EFFECT: improved method of power transfer control.

11 cl, 8 dwg

Description

FIELD OF THE INVENTION

The present invention relates to wireless communication systems.

BACKGROUND

For the Uplink (UL) based on Enhanced Universal Terrestrial Radio Access (E-UTRA), there are several transmit power control (TPC) proposals that are presented to Working Group 1 (WG1) on the development of a Long Term Evolution (LTE) standard from the Third Generation Partnership Project (3GPP). These offers can generally be divided into (slow) open-loop TPC and slow closed-loop TPC or based on channel quality information (CQI).

The open loop TPC is based on the measurement of path loss and system parameters, while the path loss measurement is performed in a wireless transmit / receive unit (WTRU), and system parameters are provided through Advanced Node B (eNodeB).

The closed loop TPC is typically based on TPC feedback information (such as a TPC command) that is periodically sent from the eNodeB, and the feedback information is generally extracted using the signal-to-noise and noise ratio (SINR) measured in the eNodeB.

An open-loop TPC can compensate for long-term channel changes (for example, path loss and shielding) in an efficient way, for example, without transmit power statistics. However, open-loop TPCs usually lead to errors in the measurement of losses in the transmission path and errors in setting the transmission power. On the other hand, slow TPC in a closed loop or based on CQI is less sensitive to errors in the measurement and setting of transmit power, since it is based on feedback transmitted in signaling from the eNodeB. However, slow closed loop or CQI-based TPCs degrade performance when there is no feedback available due to UL transmission pause or feedback transmission pauses, or channel changes are strictly dynamic.

For UL E-UTRA, there are several intra-cell PC proposals that are presented to Working Group 1 (WG1) for the Development of Long-Term Development Standard (LTE) from the Third Generation Partnership Project (3GPP). These projects, in general, can be divided into slow open-loop power control and slow closed-loop PC (or based on CQI). An open-loop PC can compensate for long-term channel changes (for example, path loss and shielding) in an efficient way, for example, without statistics on transmission power, but it is usually prone to errors in measuring path loss and setting transmission power. On the other hand, a slow PC in a closed loop or based on CQI is less sensitive to errors in measuring and setting the transmit power, since it is based on the feedback transmitted in the signaling from the eNodeB. However, it degrades performance when there is no feedback available due to a pause in UL transmission or pauses in feedback transmission.

Essentially, there is a need for an improved method for controlling transmit power.

SUMMARY OF THE INVENTION

A method and apparatus are disclosed comprising an integrated closed loop / open loop uplink power control circuit for an E-UTRA. A method for combined open and closed loops for an intra-cell PC in UL controls the transmit power spectral density (PSD) of a wireless transmit / receive module (WTRU), PSD _Tx (for example, power based on RB).

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding of the invention can be obtained from the following description of a preferred embodiment presented by way of example, which should be understood in conjunction with the accompanying drawings, in which:

Figure 1 is an exemplary wireless communication system;

Figure 2 is an exemplary block diagram of a transmitting device and a receiving device configured to implement the disclosed power control (PC) method;

Figure 3 illustrates an example of synchronization in the disclosed integrated PC method;

4 illustrates an example of the disclosed combined power control method when the interval between TTIs is 1 (unit);

5 illustrates another example of the disclosed synchronization of a federated PC when the interval between TTIs is two (2);

6 illustrates an example of a disclosed integrated PC circuit including intermittent transmission (DTX);

7 illustrates an example of the disclosed PC method for the nth update point; and

FIG. 8 illustrates a flowchart of an open joint method for determining TPC in open and closed loops.

DETAILED DESCRIPTION OF THE INVENTION

The term “wireless transmit / receive unit (WTRU)” as mentioned below includes, but is not limited to, user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a pager, a cell phone, a personal digital device (PDA), a computer or any other type of user device configured to operate in a wireless environment. The term “base station” referred to hereinafter includes, without limitation, node B, node controller, access point (AP), or any other type of interface device configured to operate in a wireless environment.

FIG. 1 illustrates an example wireless communication network (NW) 10 comprising a WTRU 20, one or more nodes B 30, and one or more cells 40. Each cell 40 contains one or more nodes B (NB or eNB) 30 including a reception a transmitting device 120, configured to implement the disclosed transmit power control (TPC) method. The WTRU 20 comprises a transceiver 110 also configured to implement the disclosed TPC method.

Figure 2 shows a functional block diagram of a transceiver 110, 120, configured to implement the disclosed method. In addition to the components included in a typical transmitter / receiver, i.e. in a WTRU or node B, the transceivers 110, 120 include processors 115, 125, receivers 116, 126 communicating with processors 115, 125, transmitters 117, 127 communicating with processors 115, 125, and antennas 118, 128 communicating with receivers 116, 126 and transmitters 117, 127 to facilitate wireless data transmission and reception. Additionally, the receiving device 126, the transmitting device 127 and the antenna 128 may be one receiving device, a transmitting device and an antenna, or may include many separate receiving devices, transmitting devices and antennas, respectively. Transmitter 110 may reside in a WTRU, or multiple transmitter circuits 110 may reside in a base station. Receiver 120 may reside in a WTRU, Node B, or both.

The disclosed TPC method comprises an integrated closed and open loop circuit for intra-cell uplink (UL) power control. The method comprises the step of controlling a spectral density of a transmit power (PSD) of a WTRU or a PSD of transmit (PSD _TX ), for example, power per resource block (RB) or transmit power of a WTRU using closed loop aperiodic power control (PC) and open loop both for UL data link control channels and for sounding reference symbols (SRS). The UL channel quality indicator (CQI) (or modulation coding set (MCS) / transmission authorization information) is used by the WTRU to correct open loop and / or measurement errors provided that the MCS / UL grant is the signal-to-noise interference to noise ratio (SINR) received at node B. If CQI is not available, then only an open loop is implemented. Implicit overhead transmission can be used, for example, without additional overhead for a closed loop component. Alternatively, the application of a TPC command signaling transmission in a DL control channel may be used for a closed loop component. Additionally, the disclosed method allows for quick correction of errors in an open loop, which leads to good performance.

The disclosed method, as described above, comprises the step of controlling the transmit power spectral density (PSD) of the WTRU or the transmit PSD (PSD _TX ), for example, power per resource block (RB) or transmit power. It should be noted that although the disclosed method includes the step of controlling the PSD of the transmission, this is equivalent to controlling the transmission power. PSD _TX is defined as follows:

equation (1)

where _open PSD is an open loop PSD based on path loss in dBm; Δ _closed - power correction coefficient, which is determined based on the component of the closed loop, which is described in more detail below; Δ _MCS - power offset per authorized MCS; and α is the weighting factor to activate (α = 1) or deactivate (α = 0) the closed loop component depending on the availability of the downlink control channel (DL), which transmits command signaling to the PC (correction) in the closed loop ( explicitly or implicitly). The weighting factor can be determined by the WTRU 20 through an autonomous detection of the presence of a command signaling transmission for the PC in a closed loop. Alternatively, the WTRU 20 is informed through the transmission of the upper layer signaling from the eNodeB 30 as to where the signaling is being transmitted. PSD transmission should not exceed the maximum transmission PSD, PSD _max , while PSD _max is extracted based on the maximum allowed power, P _max , which depends on the power class of the UE, for example, PSD _max = P _max / M, where M is the size of the resource assignment UL channel expressed as the number of resource blocks allowed for a given subframe.

The proposed intra-cell PC circuit in equation (1) can use an absolute power correction factor compared to an open loop PSD. From equation (1), the PSD Tx WTRU at the nth update time can be expressed as follows:

equation (2)

.where PSD ' _Tx (n-1) represents the (n-1) -th PSD Tx without power offset per allowed MCS, which is specified by

.

Typically, power offsets for a single enabled MCS are known by both the WTRU and the eNodeB.

The processor 115 of the WTRU 20 combines a closed loop PC and an open loop PC based on path loss to determine the PSD _TX . According to the disclosed method, the WTRU 20 first executes an open-loop PC based on the measurement of path loss and system parameters (PSD _open ). PSD _{open is} calculated as follows:

equation (3)

Where

- PSD _target — The target PSD received at the serving eNodeB 30, which is preferably a specific parameter for the WTRU (or subgroup of the WTRU). The target PSD can be adjusted via the external loop mechanism according to the quality of service (QoS) (for example, the target block error rate (BLER)), as well as the function of the measurement of losses in the transmission path to compensate for part of the losses in the transmission path. The signaling of the target PSD _target is transmitted through the transmission of the upper level signaling from the Node B 30 to the WTRU 20 when controlling based on a slow speed; and

- фильтрованные потери в тракте передачи в дБ, включая затенение, от обслуживающего eNodeB 30 к WTRU 20, где WTRU 20 сначала измеряет мгновенные потери в тракте передачи на основе опорного сигнала (RS) DL, мощность передачи которого известна. WTRU 20 затем применяет способ фильтрации к потерям в тракте передачи. Например, фильтрованные потери в тракте передачи в k-й момент,

, могут быть вычислены следующим образом:-

- filtered path loss in dB, including shadowing, from the serving eNodeB 30 to the WTRU 20, where the WTRU 20 first measures the instantaneous path loss based on the DL reference signal, the transmit power of which is known. WTRU 20 then applies a filtering method to path loss. For example, filtered path loss at the kth moment,

can be calculated as follows:

equation (4)

и

представляют фильтрованные потери в тракте передачи в (k-1)-й момент и мгновенные потери в тракте передачи в k-й момент; ρ - это коэффициент фильтрации, 0≤ρ≤1, который, в общем, определяется посредством WTRU 20 в зависимости, например, от изменения потерь в тракте передачи, скорости быстрого затухания, времени передачи по UL и других параметров. Фильтрация потерь в тракте передачи может выполняться на PHY-уровне и/или L 2/3-уровне.Where

and

represent filtered losses in the transmission path at the (k-1) th moment and instantaneous losses in the transmission path at the k-th moment; ρ is the filtering coefficient, 0≤ρ≤1, which, in general, is determined by the WTRU 20 depending, for example, on the change in losses in the transmission path, fast decay rate, UL transmission time and other parameters. The filtering of losses in the transmission path can be performed at the PHY level and / or L 2/3 level.

Once the WTRU 20 determines the open loop component, the processor 115 calculates the closed loop component. As is known to those skilled in the art, there are open loop errors, including error in estimating path loss due to imperfect interaction in UL and DL in FDDs and the degradation of Tx WTRU due to a non-linear power amplifier. In order to compensate for these errors and maintain the quality of the channel with power control, along with the target quality, the WTRU applies the correction to the open loop PSD in the form of a closed loop PC, as in equation (1) (or in equation (2)).

The serving eNodeB 30 determines a WTRU-specific (absolute and / or accumulated) PC correction command for each UL-scheduling WTRU (or a subset of scheduling WTRUs). Preferably, the eNodeB 30 uses a power-controlled data channel as a reference channel for the correction command. The resulting correction command is transmitted in signaling to the WTRU 20 (or a subset of the dispatched WTRUs) via UL grant and / or DL scheduling channel sent over the control channels of level 1 or level 2 in DL. The correction command can be transmitted in signaling only in the UL grant associated with a particular (predefined) HARQ process, such as each HARQ process 1.

After receiving correction commands in the WTRU 20, the processor 115 of the WTRU 20 determines the correction coefficient, Δ _closed , based on the correction command (or accumulated correction commands) defined as follows:

equation (5)

where Δ _closed can take a set of many step levels, for example, {+/- 4, +/- 1 dB}, using 3 bits of the command.

Alternatively, the eNodeB 30 sends a power correction factor to each scheduled WTRU 20 (or a subset of scheduled WTRUs) using a plurality of instruction bits, for example 3 bits, in UL grant and possibly in DL scheduling on a DL control channel, wherein the command the correction is preferably determined based on the quality of the communication link (eg, received PSD or SINR) of the UL power control data channel (and possibly the UL sounding reference symbol, if available). For example, provided that the set of values of the power correction coefficient is {-7, +/- 5, +/- 3, +/- 1, 0 dB} with 3 bits, the correction coefficient can be defined as follows:

equation (6)

where ESINR _est and SINR _target denote an estimate of the actual SINR (ESINR) at the receiver and the target SINR, respectively, of the channel (s) with power control in dB. [x] denotes the correction value in the correction set that is closest to x. The observed samples in the eNodeB for evaluating ESINR include (some or all) the SC-FDMA symbols of the UL power control channel (s) that have been received since the last transmission of the correction correction signaling to DL.

In order to reduce the amount of signaling transmitted, a correction command is not required in every UL grant (and in every DL scheduling, if used). Thus, a correction command can be sent at a predetermined signaling transmission time (for example, in each Nth channel of transmission permission or in each Nth transmission time interval (TTI), where N is a configurable parameter less than or equal to the minimum period PC updates in UL).

The synchronization of the transmission of the correction command signaling is configured in the eNodeB 30 (or at the RRC level) according to each WTRU and then becomes known in both the eNodeB 30 and the WTRU 20 through the transmission of the upper level signaling.

When a correction command is transmitted in a signaling in UL transmission authorization, provided that the HARQ UL is synchronous, the signaling transmission synchronization configuration can be simplified such that signaling transmission is performed in specific UL transmission permissions, for example, in UL transmission permission UL associated with a predetermined HARQ process, for example, HARQ process # 1. But even in this case, it is not necessary to transmit correction commands in all associated channels of UL transmission permission in signaling. For example, signaling can be transmitted in each Nth associated channel of transmission permission for N> = 1, which should be equivalent to one command signaling transmission in each Nth period of the HARQ cycle. Alarm transmission timing (or associated parameters) can be reconfigured at a semi-static speed.

FIG. 3 illustrates an example of the PC method disclosed when the PC correction command is transmitted in UL grant associated with HARQ process # 1 and N is set to 2. In this example, the PC update rate is 8 ms, provided that the number HARQ processes is 4, and the interval between transmission time intervals (TTI) is 1.

When the WTRU 20 receives one correction command from the serving eNodeB 30 in UL grant (or possibly accumulated correction commands in a plurality of UL grants) since the last PSD Tx adjustment, it must extract the correction factor, Δ _closed , from the received command correction (or after combining multiple correction commands if more than one command is received) for the next PSD control.

The WTRU 20 then adjusts the transmission channel PSDs of the data channel according to equation (1) (or equation (2)) using the extracted correction factor, the latest open loop PSD and the power offset associated with the allowed MCS. The resulting Tx PSD must be applied to the very beginning (the first SC-FDMA symbol) of the next UL TTI for the data channel and remain constant until the next PSD control, as illustrated in FIG.

4 illustrates an example synchronization of the disclosed integrated PC method, provided that the UL HARQ is a synchronous circuit with 4 HARQ processes and that the WTRU 20 is scheduled to send a data packet (e.g., a HARQ process) to each TTI (e.g., the interval between TTI = 1). In addition, the eNodeB 30 sends the PC correction command only in the UL grant associated with the HARQ process 1. In this case, the WTRU Tx power update period is 4 TTI (for example, 4 ms).

As illustrated in FIG. 4, in the initial UL transmission, since the PC correction command may not be available, the WTRU 20 sets its transmit power only based on the open loop component (i.e., the weight coefficient α is zero in equation (1)) . Before the next HARQ transmission time (time of one HARQ cycle), the eNodeB 30 sends a correction command on the transmission permission channel in the DL control channel associated with the HARQ process 1, the command being determined based on the quality of the communication line (power or SINR) of the first two HARQ- processes. If the WTRU 20 correctly receives the correction command, the WTRU 20 then calculates its PSD _TX transmission based on the combined closed and open loop scheme and applies the PSD _TX to the following HARQ processes.

5 illustrates another example of the disclosed synchronization of a federated PC, where the interval between TTI is two. In this case, the UL PC update period is 8 TTI (8 ms).

When there is no last closed loop correction command (for example, due to the last scheduled UL data transmission, say DTX UL), the WTRU 20 can set its PSD Tx based on the open loop. In this case, the weight coefficient α in equation (1) is set equal to zero, as in the case of the initial job PSD Tx.

Alternatively, the WTRU 20 may determine the PSD Tx based on a change in the path loss between the time before DTX and the time before resuming UL transmission. If the DTX UL is short, the WTRU can use equation (2) by setting α to zero, so that:

equation (7)

where n is the PSD Tx reference time before resuming UL transmission, and (n-1) is the PSD reference time before DTX. An example of synchronization of this case is illustrated in Fig.6.

In another alternative, the WTRU 20 may apply a power offset relative to the last PSD for the physical uplink control channel (PUCCH), if available. Even if there was no UL data transmission, there may be UL control overheads (such as CQI and ACK / NACK) for DL. In this case, since the UL control channel is also power controlled based on equation (1) (but using other parameters and the update rate), the PSD Tx of the UL control channel for the PSD Tx data channel can be used as follows:

equation (8)

where PSD _Tx (control) is the last PSD (or PSD averaged over the latest updates) for the UL control channel, and Δ _control (data, control) represents the power offset of the control channel relative to the PSD Tx for the data.

If the DTX period is long, then the PSD _TX for the WTRU 20 can only be determined immediately after the DTX based on an open loop, as in the case of the initial PSD _TX job.

7 illustrates an example of a proposed PC circuit in integrated loops, including DTX.

Typically, the assignment of UL transmission permission (for example, assigned by MCS and TBS) in the DL control channel is related to the quality of the communication line (for example, received PSD or SINR) of the UL data transmission. Another method is disclosed, wherein the processor 125 of the eNodeB 30 may assign UL transmission permission (MCS and TBS) to the WTRU 20 so that the assignment of the transmission permission represents the quality of the communication line (eg, SINR) received at the eNodeB 30. In this case, the WTRU 20 can retrieve its PSD Tx as follows:

equation (9)

и

соответственно являются такими же, как задано; f(UL grant assignment, SINR_T) - коэффициент коррекции в дБ, который заменяет коэффициент коррекции мощности Δ_closed в уравнении (1). SINR_T - целевой SINR в дБ. Коэффициент коррекции на основе разрешения на передачу, f(UL grant assignment, SINR_T), может быть выражен следующим образом:Where

and

respectively, are the same as specified; f (UL grant assignment, SINR _T ) is the correction factor in dB, which replaces the power correction factor Δ _closed in equation (1). SINR _T - Target SINR in dB. A correction factor based on transmission permission, f (UL grant assignment, SINR _T ), can be expressed as follows:

equation (10)

where SINR _est (UL grant assignment) represents the received SINR score in the eNodeB, which the WTRU 20 extracts from the UL grant assignment. E {SINR _est } denotes the estimated SINR averaged over time, such as:

equation (11)

where grant ^k represents the kth accepted UL grant assignment, and ρ is the average filtering coefficient, 0≤ρ≤1. The SINR _est (UL grant assignment) estimate in the WTRU may be based on a transmission authorization mapping table (MCS, TBS), which is configured by the network via a semi-static upper layer signaling transmission.

Similar to equation (1), the correction factor in equation (8) can be used to compensate for errors in the open loop. The main advantage of using equation (8) is that it does not require explicit transmission of the correction correction signaling in UL permission in the DL L1 / L2 control channel (leading to a decrease in the amount of overhead information), while equation (1) (and equation (2)) requires an explicit command that must be transmitted in signaling in the UL permission (and / or in DL scheduling). Using equation (3), the closed loop component can be based on the assignment of UL transmission permission (for example, MCS and / or TBS) without explicit transmission of correction correction signaling in UL permission on the DL L1 / L2 control channel.

However, equation (9) may not be applicable for some cases, such as continuous dispatch and transmission permissions (for example, MCS) (i.e., the designated MCS does not represent the exactly received SINR). Accordingly, the PSD Tx WTRU setting may be switched between equation (1) and equation (8).

By signaling like a top-level correction coefficient, the eNodeB 30 (or network 10) signals to the WTRU 20 which of equation (1) or equation (8) should be used to set the Tx power of the WTRU. In this case, it is preferable that the signal of the correction coefficient type is configured by the network 10 on a semi-static basis and based on the WTRU.

Alternatively, a one-bit MCS mismatch indicator may be presented in the L1 / 2 DL control signaling. For example, bit 1 may indicate the use of equation (1), and bit 0 may be used to indicate equation (8).

In another alternative, one of the levels of the explicit correction command may be used to indicate the use of equation (8). This alternative assumes that equation (1) is the default PC mode. Essentially, the eNodeB 30 sets one of the levels of the correction command in the UL grant to indicate the use of equation (8). For example, when the correction command in equation (8) is three bits long, one of 8 levels of the command, for example, “000”, is set for the WTRU 20 to use equation (8).

The flowchart of the disclosed combined method for determining open and closed loop TPCs is illustrated in FIG. The processor 115 of the WTRU 20 performs open loop power control based on the measurement of the path loss by determining the target power spectral density PSD _Target (step 800) and the filtered path loss (L) (step 801). The WTRU 20 then determines the closed loop component using the power control correction command received at the receiver 116 via the UL grant channel (step 802). After receiving the correction command, the receiver 116 redirects the correction command to the processor 115 to determine the correction coefficient Δ _closed (step 803). The processor 115 then calculates a correction coefficient Δ _closed (step 804). The processor 115 then combines the open loop PC with the closed loop component to determine transmission power control (block 805).

In the disclosed TPC method for non-dispatchable data (for example, VoIP) there are several options for the WTRU to set their PSD TX: i) based only on the open loop PSD, ii) for the closed loop part, the eNodeB transmits UL transmission permissions to specific moments (time), while the permission to transmit on UL transmits a correction command. In this case, the UL permission format (and / or the correction command format) may be different from the scheduled data format; or iii) applying a power offset relative to the latest PSD (or PSD averaged over recent updates) for the PUCCH, if available.

equation (12)

where P ₀ is the cell-specific parameter (in dBm) including the interference level of UL, etc., which is transmitted in the signaling via the eNodeB through the transmission of the upper level signaling.

- SINR _Target - specific to the WTRU (or subset of the WTRU) parameter (in dB), allowing the eNodeB to set the service classes for the UE (or subset of the UE). SINR _Target may be a function of losses in the transmission path to the serving cell and some neighboring cells. The SINR _Target can be configured by serving the eNodeB on a semi-static basis and then transmitted in signaling to the UE (or subset of the UE) through the transmission of the upper layer signaling;

- PL - loss in the transmission path of the downlink (in dB);

- λ is the cell-specific loss compensation factor in the transmission path for partial power control, where 0 <α≤1. α can be configured by the eNodeB on a semi-static basis and transmitted in signaling through the transmission of higher level signaling;

- Δ _closed - power correction coefficient in dB, which is determined on the basis of a closed loop mechanism;

- ∝ - weighting factor to activate (∝ = 1) or deactivate (∝ = 0) the closed loop component depending on the availability of the DL control channel carrying the correction command in the closed loop. The weighting factor is determined autonomously by the WTRU by detecting the presence of a PC correction command. It is assumed that the WTRU is informed through the transmission of the upper layer signaling from the eNodeB 30 regarding where and when the overhead transmission is carried out. For example, in the initial UL transmission, since the correction command from the eNodeB may not be available, the WTRU sets ∝ = 0;

- Δ _MCS - power offset per authorized MCS. Typically, power offsets for a single enabled MCS are known by both the WTRU and the eNodeB.

Since the eNodeB 30 knows the Δ _MCS used in this case, the eNodeB 30 can extract the Δ _MCS value from the received PSD when it determines the correction command by comparing the resulting received PSD (or SINR) with the target level determined by the network 10.

As described above, this disclosed method uses an absolute power correction factor compared to an open loop PSD. In fact, from equation (12), the PSD Tx WTRU at the nth update moment is expressed as follows:

equation (13)

.where PSD ' _Tx (n-1) represents the (n-1) -th PSD Tx without power offset per allowed MCS, which is specified by

.

Since the total transmit power of the WTRU is limited by the maximum transmit power level denoted by P _max , WTRU, the total transmit power of the WTRU denoted by P _Tx is expressed as follows:

equation (14)

where M is the number of assigned RBs.

Accordingly, the actual WTRU transmission PSD can be represented as follows:

equation (15)

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

According to the disclosed PC method for non-dispatchable data, the WTRU 20 calculates an open loop PSD as follows:

equation (16)

Where

- the target SINR, SINR _Target , can be adjusted through the external loop mechanism in the serving eNodeB 30 according to the quality of service (QoS) (for example, the target BLER) and also be a function of loss measurements in the transmission path to the serving cell and neighboring cells; and

- PL - filtered path loss in dB, including shadowing, from the serving eNodeB to the WTRU. The WTRU continuously (or periodically) measures instantaneous path loss based on RS DL, the transmit power of which is known in the WTRU. The filtering method is then applied to measurements of losses in the transmission path, for example:

equation (17)

where PL _k and PL _k-1 represent the filtered path loss at the kth moment and the (k-1) th moment, respectively. L _k - instantaneous losses in the transmission path at the k-th moment. ρ is the filtering coefficient, 0≤ρ≤1, which, in general, is determined by the WTRU 20 depending on the change in the loss in the transmission path, fast decay rate, UL transmission time, etc. Alternatively, the moving average method can be considered to filter losses in the transmission path.

The closed loop component is determined by the processor 115 in the same way as disclosed above:

equation (18)

where ESINR _est and SINR _target denote an estimate of the actual SINR (ESINR) at the receiver and the target SINR, respectively, of the channel (s) with power control in dB. [x] denotes the correction value in the correction set that is closest to x.

Similar to the methods disclosed above, when a correction command is transmitted in signaling in UL grant, provided that the HARQ UL is synchronous, the signaling transmission synchronization configuration can be simplified such that signaling transmission is performed in specific UL grants, such as a UL grant associated with a predefined HARQ process.

For non-dispatchable data (for example, VOIP), when there is no last closed loop correction command (for example, due to the last scheduled data transfer via UL, say DTX UL), the WTRU 20 can set its PSD Tx based on open loop. In this case, the weight coefficient ∝ in equation (13) is set equal to zero, as in the case of the initial job PSD Tx. The WTRU 20 can alternatively set its PSD Tx based on the change in path loss between the time before DTX and the time before resuming UL transmission. If the DTX UL is short, the WTRU can use equation (2) by setting β to zero, so that:

equation (19)

where n is the PSD Tx reference time before resuming UL transmission, and (n-1) is the PSD reference time before DTX. An example of this case is illustrated in FIG.

Alternatively, the WTRU 20 may apply a power offset relative to the last PSD for the PUCCH, if available. Even if there was no UL data transmission, there may be UL control overheads (such as CQI and ACK / NACK) for DL. In this case, since the UL control channel (PUCCH) is also power controlled based on equation (12) (but using other parameters and the refresh rate), the UL control channel PSD Tx (PUCCH) can be used for the PSD Tx data channel (PUSCH ) in the following way:

equation (20)

where PSD _TX (PUCCH) is the last PSD (or PSD averaged over the latest updates) for the UL control channel (PUCCH), and Δ _control (PUSCH, PUSCH) represents the power offset of the control channel (PUCCH) relative to the PSD Tx for PUSCH.

For the probing pilot, its PSD Tx, PSD _Tx (pilot), can be offset by the offset of the pilot power relative to the PSD Tx data, PSD _Tx (data), so that:

equation (21)

where Δ _pilot (data, pilot) represents the pilot power offset, which may be a WTRU-specific parameter configured by the eNodeB on a semi-static basis.

For control signaling in UL, it is preferable to use other parameters (for example, the target PSD) and a higher update rate than for data. In addition, it is preferable that the reference channel measured for correction commands for transmitting control signaling is the control channel itself, and the correction command for control is transmitted in DL scheduling. The number of bits for the correction command for control may be different than for data, where the number of bits of the command can be a semi-static configurable parameter per WTRU. However, you can save the relative average power offset between the data channels and control channels, for example:

equation (22)

Where

- E (PSD _Tx (data)) represents the average PSD for the data channel in dBm;

- E (PSD _Tx (control)) represents the average PSD for the control channel in dBm; and

- Δ _control (data, control) is the power offset between the data channel and the control channel.

In another disclosed method, the PC UL uses a combined PC UL in a combined open and closed noise reduction circuit for a shared data channel. In accordance with this method, the WTRU 20 controls the transmitted PSD for UL channels. If the bandwidth allocation (for example, RB allocation) of the WTRU 20 varies, then the total transmit power of the WTRU varies so that the PSD is kept constant.

As described in the disclosed methods above, the WTRU 20 runs an open-loop PC based on a measurement of path loss and system parameters. The WTRU 20 then corrects its PSD using some form of closed loop PC to compensate for open loop errors. It should be noted that for each UL-dispatched WTRU, CQI information is periodically transmitted in signaling from the eNodeB 30 for AMC and scheduling. Therefore, the closed loop PC component of this disclosed method does not require any additional PC command transmitted in signaling by the eNodeB. In order to reduce inter-cell interference in the neighboring cell (s), the WTRU 20 turns on an interference load indicator from the strongest neighboring cell.

According to this method, for a shared UL data channel, in the initial phase of transmission, the WTRU 20 retrieves its transmitted PSD, PSD _Tx , based on the DL (RS) reference signal as follows:

equation (23)

where SINR _T is the target SINR in dB in the serving eNodeB 30, PL is the path loss in dB, including shadowing, from the serving eNodeB 30 to the WTRU 20, and the WTRU 20 measures the path loss based on RS DL, the transmission power of which is known in WTRU 20 through signaling transmission over DL level 2 / level 3, IN ₀ is the noise and interference power in UL in dBm measured in the serving eNodeB 30, K is the allowable power control margin specified in the serving eNodeB 30.

It is preferable that the target SINR for the WTRU 20 (or a subgroup of the WTRU) is correctable using an external loop PC circuit according to a link quality metric (such as BLER) in the serving eNodeB 30. In addition, in the case of UL with many inputs and many outputs (MIMO ), the target SINR also depends on the selected MIMO mode, which takes into account the fact that different MIMO modes require a different SINR for a given link quality. Δ (IoT _S ) represents the load control step size in UL, which is a function of the UL interference load indicator (for example, interference to thermal noise ratio) of the strongest neighboring cell, IoT _S , with the strongest neighboring cell being determined in WTRU 20 based on measurements of losses in the transmission path from a separate neighboring cell to the WTRU 20. It is assumed that each cell 40 periodically broadcasts the interference load bit in UL (similar to the relative transmit permission in HSUPA) so that the WTRU 20 can decode the indication bit ora selected from the strongest neighboring cell.

For example, Δ (IoT _S ) may have the following meanings:

where δ is a predetermined system parameter, for example, δ = -1 or -2 dB. By using Δ (IoT _S ), inter-cell interference in neighboring cells can be reduced.

Since the WTRU in the center of the cell introduces less interference to other cells than the WTRU at the cell boundary, the fraction of the size of the load control step is considered as follows:

The WTRU 20 may decide whether it is located on the cell boundary or in the inner region of the cell, for example, based on the ratio of the path loss between its serving cell and the strongest neighboring cell. If (pathloss_serving_cell - pathloss_strongest_neighboring_cell) <R (dB), x = 4; where R represents the virtual boundary level between the inner zone of the cell and the boundary zone of the cell. The parameter R may be broadcast in the eNodeB 30 semi-statically.

After the initial transmission phase, the PSD _TX WTRU 20 is calculated as follows:

equation (24)

where f (CQI, SINR _T ) is a correction coefficient based on CQI UL and the corresponding target SINR, where both CQI and target SINR are transmitted in signaling from the serving eNodeB 30; α, where 0≤α≤1, is the weight coefficient, which can be determined according to the characteristics of the channel and the availability of CQI (or pause transmission on UL). For example, in the case where there is no available CQI UL (MCS information or permission to transmit over UL) from the eNodeB 30 due to the lack of scheduled data transmission on UL, the weight coefficient α is set to zero, which means that the WTRU 20 is based only on PC in open loop (such as a PC for a random access channel (RACH)); otherwise, it is set less than or equal to unity (1).

The correction factor, f (CQI, SINR _T ), in Equation 24 is used to compensate for errors associated with open loop PCs, including the error in measuring the path loss due to imperfect reciprocity in UL and DL in FDD and the degradation in the transmitter WTRU 20 due to non-linear power gain of the WTRU transmitter. In addition, a correction factor is used to compensate for a mismatch in the target quality due to various channel characteristics. Therefore, the quality of the power control channel (s) is maintained along with this target quality (e.g., target SINR).

Taking into account the fact that the CQI UL (MCS information or UL transmission authorization) represents the SINR received in the eNodeB 30, the correction coefficient can be calculated as follows:

equation (25)

where SINR _est (CQI) represents the received SINR score in eNodeB, which the WTRU extracts from the UL CQI feedback. E {SINR _est (CQI)} denotes the estimated SINR averaged over time, for example, by the following:

equation (26)

where CQI ^k represents the k-th received CQI, and ρ is the average filtering coefficient, 0≤ρ≤1.

The correction factor presented above in equation (25), by the difference between the target SINR and the estimated SINR (extracted from the transmitted CQIs), represents errors associated with an open-loop PC that need to be compensated.

The total transmit power of the WTRU should be within the maximum power level, Pmax, and the minimum power level, Pmin, in dBm, respectively, where the maximum and minimum power levels are determined based on the WTRU class.

The ENodeB 30 preferably transmits in the signaling parameters, including the target SINR level, SINR _T , which is specific to the WTRU (or a subgroup of the WTRU) parameter, while the target SIR can be controlled through an external circuit based on QoS, for example, the target BLER. The target SINR may also be a function of the measurement of path loss. Target SIR signaling is performed through the in-band L1 / 2 control signaling after it is configured. The allowable power control margin, K, which is specific to the eNodeB, is also transmitted in signaling by the eNodeB 30. K is preferably semi-static and is signaled via a broadcast channel (BCH). It should be noted that even if it is assumed that K is signaled separately, along with other parameters, it can be included in the target SINR, i.e. SINR _T (after switching on) = SINR _T + K (dB). In this case, explicit K signaling in the WTRU 20 is not required.

ENodeB 30 additionally signals the total noise and interference level in UL, IN ₀ , which is averaged over all used subcarriers (or RB) or over a subset of subcarriers. This parameter is preferably retrieved by the serving eNodeB 30 (and possibly signaled via the BCH). The update rate for this alarm is generally relatively slow. The maximum and minimum power levels of UL, P _max and P _min , are also signaled by the eNodeB 30. Each of them may be dependent on the WTRU parameters determined by its functionality, or may be signaled explicitly by the eNodeB 30.

UL channel quality indicator, CQI (for example, MCS information or UL transmission authorization), which is signaled initially for the UL AMC target (with a maximum signal transmission rate once per TTI, for example, 1000 Hz).

The CQI mapping rule (or the offset between the CQI and the measured SINR) that the eNodeB uses to generate CQI feedback. This rule or parameter can be combined in the target SINR. In this case, explicit signaling of the rule (or parameter) is not required.

UL interference load indicator from each eNodeB.

The semi-static parameter R, which represents the virtual boundary level between the inner zone of the cell and the boundary zone of the cell.

The disclosed PC method does not require additional PC commands in feedback, in addition to the above system parameters, including the target SINR, the noise / noise level in the cell and the transmit power of the reference signal, as well as a constant value that can be transmitted in broadcast mode (or transmitted directly to signaling) in the WTRU based on slow speed.

It is designed to be flexible and adaptive to the dynamic parameters of the system / line of communication (target SINR and inter-cell interference loading condition) and channel characteristics (path loss and shadowing) in order to comply with E-UTRA requirements.

Additionally, this disclosed method is compatible with other link adaptation schemes such as AMC, HARQ, and adaptive MIMO mode.

In an alternative method for suppressing inter-cell interference, instead of broadcasting a load indicator of interference from each eNodeB, the serving eNodeB 30 can coordinate the levels of inter-cell interference with other cells 40 and enable them by adjusting the target SIR, the allowable margin of power control K, or possibly P _max, respectively .

OPTIONS FOR CARRYING OUT

1. A method for controlling the transmit power of a wireless transmit / receive module (WTRU), comprising the steps of:

- determine the component of the power control (PC) in the uplink (UL) open loop based on the measurement of losses in the transmission path;

- determine the closed loop power control component including a correction coefficient; and

- combine the open loop component and the closed loop component with a power offset to determine the transmit power.

2. The method of embodiment 1, further comprising the step of:

- accept the correction command PC, and the correction coefficient is based on the correction command or the accumulated correction command.

3. The method of embodiment 2, wherein the PC correction command is received at a predetermined signaling time.

4. The method of embodiment 3, wherein the predetermined signaling time is in a specific UL grant.

5. The method of embodiment 4, wherein the UL grant is a hybrid automatic retransmission request (HARQ) process.

6. The method according to any one of embodiments 2-5, wherein the open-loop PC component is based on a change in path loss.

7. The method of embodiment 6, wherein the change in transmission path loss is a change between transmission path loss before discontinuous transmission and time before UL transmission resumes.

8. The method according to any one of embodiments 2-7, wherein the PC correction command uses a plurality of instruction bits determined based on the quality of the communication line.

9. The method according to any one of embodiments 1-8, wherein the correction coefficient is determined using the following equation:

where ESINR _est and SINR _target denote the actual signal-to-noise-noise ratio (ESINR) and the target SINR.

10. The method according to any one of embodiments 2-9, further comprising the step of:

calculate the correction command from the received PC correction command.

11. The method according to any one of embodiments 1-10, further comprising the step of:

apply transmit power to the beginning of the next uplink transmission time interval (TTI) until the next transmit power update.

12. The method according to any one of embodiments 1-11, wherein the correction coefficient is zero (0) in the initial uplink transmission.

13. The method according to any one of embodiments 1-12, wherein the correction factor is an assignment of uplink transmission permission.

14. The method of embodiment 13, wherein the correction coefficient based on the transmission permission is determined using the following equation:

where SINR _est (UL grant assignment) represents the received SINR score in the eNodeB, which the WTRU extracts from the UL grant assignment.

15. The method of embodiment 14, further comprising the step of:

determine whether to use the correction coefficient based on the transmission permission based on the sign of the received correction coefficient.

16. The method of embodiment 14, further comprising the step of:

determine whether to use a correction coefficient based on transmission permission based on the received MCS mismatch indicator.

17. The method of embodiment 14, further comprising the step of:

determine whether to use an explicit correction command based on the received MCS mismatch indicator.

18. The method according to any one of embodiments 1-17, further comprising the step of:

an interference load indicator is determined, while an interference load indicator is determined from the strongest neighboring cell.

19. The method of embodiment 18, wherein the transmit power is based on a downlink reference signal, wherein the interference load indicator is used to reduce inter-cell interference.

20. A wireless transmit / receive module (WTRU) comprising a processor configured to implement a method as in any one of embodiments 1-19.

21. Node B containing a processor configured to implement the method according to any one of embodiments 1-19.

Although features and elements are described above in specific associations, each feature or element can be used autonomously without other features and elements, or in various associations with or without other features and elements. The methods or flowcharts provided herein can be implemented in a computer program, software, or firmware included in a computer-readable storage medium for execution by a general purpose computer or processor. Examples of computer-readable storage media include read-only memory (ROM), random access memory (RAM), a register, cache memory, semiconductor storage devices, magnetic media such as internal hard drives and removable drives, magneto-optical media and optical media such like CD-ROMs and digital versatile discs (DVDs).

Suitable processors include, for example, a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, and specialized integrated circuits (ASICs) ), user programmable gate array (FPGA) circuits, any other type of integrated circuit (IC) and / or state machine.

A processor associated with the software may be used to implement a radio frequency transceiver for use in a wireless transceiver module (WTRU), user equipment (UE), terminal, base station, radio network controller (RNC), or any host computer. The WTRU can be used together with modules implemented in hardware and / or software, such as a camera, camcorder module, videophone, speakerphone, vibration device, speaker, microphone, television transceiver, handsfree headset, keyboard, Bluetooth® module , frequency-modulated (FM) radio module, liquid crystal display (LCD), organic light emitting diode (OLED) display, digital music player, multimedia player, video game device module, Intern t-browser, and / or any wireless local area network (WLAN) or Ultra standard radio (UWB).

Claims (11)

1. A method for controlling the transmit power of a wireless transmit / receive module (WTRU), comprising the steps of:
determining an open loop uplink (UL) power control component (PC) based on a path loss measurement;
determining a closed loop PC component including a correction factor;
combining the open loop PC component and the closed loop PC component with a delta coefficient associated with the offset value, the offset value being associated with a change in the modulation coding set (MCS) to determine the transmit power; and
receiving a PC correction command, the correction coefficient being based on the PC correction command or the accumulated correction command, wherein the PC correction command includes a plurality of instruction bits determined based on the quality of the communication line. 2. The method of claim 1, wherein the PC correction command is received at a predetermined signaling time. 3. The method according to claim 2, in which a predetermined signaling time is in permission to transmit on UL. 4. The method of claim 3, wherein the UL grant is a hybrid automatic retransmission request (HARQ) process. 5. The method according to claim 1, in which the correction factor is the appointment of permission to transmit on UL. 6. A wireless transmit / receive module (WTRU) comprising
a circuit configured to determine an open loop uplink (UL) power control component (PC) based on a path loss measurement and a closed loop PC component including a correction factor, wherein the open loop PC component and the closed loop PC component combined with a delta coefficient associated with the offset value to determine the transmit power of the WTRU, the offset value being associated with a change in the modulation coding set (MCS), and
a circuit configured to receive a PC correction command, wherein the correction coefficient is based on the PC correction command or the accumulated correction command, wherein the PC correction command includes a plurality of instruction bits determined based on the quality of the communication line. 7. The WTRU of claim 6, wherein the PC correction command is received at a predetermined signaling time. 8. The WTRU of claim 7, wherein the predetermined signaling time is in the UL grant. 9. The WTRU of claim 8, wherein the UL grant is a hybrid automatic retransmission request (HARQ) process. 10. The WTRU of claim 6, wherein the correction factor is a UL grant assignment. 11. The WTRU according to claim 6, further comprising a circuit configured to determine an interference load indicator, wherein the interference load indicator is determined from the strongest neighboring cell.

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