CN1192513C - Method for controlling downward special physical channel power under compressed mode - Google Patents

Abstract

The invention discloses a method for controlling the power of a downlink dedicated physical channel in a compressed mode. The key point of the method is: when the uplink dedicated physical channel adopts a compressed mode, the pilot bits of the first time slot after each transmission interval are sent Before, the transmission power control bit is sent; the base station immediately adjusts the channel power of the downlink dedicated physical channel after receiving the pilot bit from the uplink dedicated physical channel and the transmission power control bit before the pilot bit. By adopting the method, the base station can restore the control of the transmission power as soon as possible after the interval time slot, thereby reducing the time required for the actual SIR value to approach the target SIR value, thereby improving the transmission quality of the signal.

Description

A method for power control of downlink dedicated physical channel in compressed mode

technical field

The invention relates to a channel power control technology, especially a method for controlling the channel power of a downlink DPCH by changing the time slot structure of an uplink dedicated physical channel (DPCH) in a compressed mode.

Background of the invention

Generally, DPCH channels include Dedicated Physical Data Channel (DPDCH) and Dedicated Physical Control Channel (DPCCH). DPCH channels have two transmission formats: normal mode and compressed mode. The time channel will be interrupted for a period of time, that is, there is a gap time slot, and the data originally transmitted at the gap time slot position is compressed and transmitted together with the original data before or after the gap respectively. Generally, the time slot structure of the uplink DPCH channel in compressed mode is shown in Figure 1, where each time slot of the DPCCH channel includes: a pilot frequency (pilot) field, a transport format combination indicator (TFCI) field, and a feedback information (FBI) field and the Transmit Power Control (TPC) field. The downlink DPCH channel in the compressed mode has two time slot structures: the first one is shown in Figure 2, and each time slot includes the data 1 (Data1) field, TPC field, TFCI field, data 2 (Data2) field and guide In the frequency (PL, pilot) domain, there are transmission gap slots between data slots. The second type is shown in Figure 3. The overall time slot structure distribution of the downlink DPCH channel and the composition of each time slot are basically the same as those of the first type of downlink DPCH channel, except that the TPC of the DPCCH channel in the first gap time slot The TPC bit is added to the field, which is used to control the transmit power of the first time slot after the gap in the uplink channel.

In order to ensure the quality of data transmission, it is usually necessary to adjust the transmission power of the downlink through power control. According to the agreement, the specific process of downlink inner loop power control is as follows:

First, the user equipment (UE) measures the signal-to-interference ratio (SIR) of the pilot bits in the current time slot in the downlink DPCCH, and compares the measurement result with the preset outer-loop target SIR value; then, the UE As a result, a TPC command to control the downlink power is generated, and the TPC value is determined at the same time, and the TPC command and the TPC value are transmitted to the base station in a subsequent time slot of the uplink DPCCH channel; after the base station NodeB receives the uplink time slot, according to the TPC command to adjust the transmit power of the DPCH channel in the latest time slot. Furthermore, after receiving the TPC command sent by the uplink DPCCH channel, the base station NodeB will, according to the TPC value and related information conveyed in the TPC command, start from the nearest unsent downlink DPCH channel to the current moment. The pilot bit starts to adjust the downlink transmission power. The adjustment of the downlink DPCH channel power is not performed from the beginning of a time slot, that is, the data1 bit shown in FIG. 2 , but from the pilot bit of the previous time slot.

In the above inner loop power control process, when the time slot structure of the uplink DPCH channel is in compressed mode, as shown in Figure 1, the TPC command cannot be transmitted due to the existence of the transmission gap time slot, and the base station NodeB will stop the inner loop at this time Power control process until a new uplink TPC command is sent to the base station NodeB.

As shown in FIG. 4 , the reason why the TPC cannot be delivered can be explained in more detail. Figure 4 is a diagram of the corresponding relationship between the uplink and downlink DPCH channel time slots in the compressed mode on the UE antenna side. In Figure 4, the time slots filled with oblique lines are data time slots; the blank time slots are gap time slots; The part filled in the grid is the pilot bit in the last gap time slot; the shown A and B areas represent the areas where the gaps in the uplink channel and the downlink channel do not overlap.

According to the normal situation, that is, in the normal transmission mode, the TPC bit in the uplink slot 1 shown in Figure 4 is used to control the downlink slot 3 (or downlink slot 4, when the delay of the inner loop power control is two slots ) power. When the uplink channel and the downlink channel use the compressed mode at the same time, due to the existence of the pilot bit in the downlink DPCH channel slot 4, the UE can perform SIR measurement on the pilot bit of the slot, and generate a TPC command to control the power adjustment of the base station. However, since the uplink time slot 4 is in a gap, the TPC command generated by the UE cannot be transmitted through the uplink channel, thus causing the downlink time slot 6 (or downlink time slot 7) to fail to perform power adjustment. When the uplink channel uses the compressed mode and the downlink channel uses the uncompressed mode, similarly, the TPC command normally generated by the downlink DPCH channel cannot transmit a new TPC command to the base station because the current time slot of the uplink DPCH channel is a gap time slot. The purpose of the recovery period after the gap is to reduce the deviation between the actual SIR value and the target SIR value caused by power control interruption during the gap as soon as possible, but due to the above reasons, the base station does not wait until the third ( or the 4th) time slot to start power control.

Contents of the invention

In view of this, the main purpose of the present invention is to provide a method for controlling the power of the downlink dedicated physical channel in compressed mode, so that the base station can resume the control of the transmission power as soon as possible after the gap, thereby reducing the time when the actual SIR value is close to the target SIR value. It takes time to improve the transmission quality of the signal.

Another object of the present invention is to further optimize the downlink power control when the uplink channel is in compressed mode and the downlink channel is in uncompressed mode.

In order to achieve the above object, the technical solution of the present invention is specifically realized in the following way:

A method for power control of a downlink dedicated physical channel in compressed mode, the method at least includes the following steps:

When the uplink dedicated physical channel adopts the compressed mode, transmit the transmit power control bit before the pilot bit of the first time slot after each transmission interval;

The base station immediately adjusts the channel power of the downlink dedicated physical channel after receiving the pilot bits and the transmit power control bits before the pilot bits from the uplink dedicated physical channel. Wherein, the transmission power of the transmission power control bit is determined according to the method for determining the transmission power of the first time slot after each transmission interval of the uplink dedicated physical channel.

The method further includes: when the downlink dedicated physical channel adopts the compressed mode, sending the transmit power control bit at the position of the transmit power control field in the first transmission interval.

It can be seen from the above scheme that the key of the present invention is to add TPC bits in the last gap time slot of the uplink DPCCH channel to perform downlink closed-loop power control one time slot in advance and improve link performance.

It can be seen that the method for power control of the downlink dedicated physical channel under the compressed mode provided by the present invention, when the uplink and downlink DPCH channels use the compressed mode simultaneously, increases the TPC bit in the last gap time slot of the uplink DPCCH channel, which can make the base station In the recovery period, the downlink closed-loop power control is performed one time slot in advance, so as to speed up the process of the actual SIR value approaching the target SIR value, improve link performance, and improve signal transmission quality.

Even if only the uplink DPCH channel uses the compressed mode, the TPC bit is added in the last gap time slot of the uplink DPCCH channel, and the closed-loop power control is performed one time slot in advance, which can realize the optimization of the downlink power control and further improve the link performance.

Description of drawings

FIG. 1 is a schematic diagram of a time slot structure of an uplink DPCH channel in a compressed mode in the prior art;

FIG. 2 is a schematic diagram of a time slot structure of a downlink DPCH channel in compressed mode in the prior art;

FIG. 3 is a schematic diagram of another time slot structure of a downlink DPCH channel in compressed mode in the prior art;

FIG. 4 is a corresponding relationship diagram of uplink and downlink compression modes in the prior art;

Fig. 5 is a schematic diagram of the time slot structure of the uplink DPCH channel in compressed mode in the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

When the uplink DPCH channel uses the compressed mode, in order to shorten the process of the actual SIR value approaching the target SIR value and restore the power control of the downlink DPCH channel as soon as possible, it is necessary for the uplink DPCCH channel to transmit the current downlink DPCH channel before the end of the gap. The new TPC command is sent to the base station, then, as shown in Figure 5, adding TPC bits in the last gap time slot of the uplink DPCCH channel Transmission gap can enable the base station to perform closed-loop power control by one time slot in advance.

The modification of the time slot structure of the uplink DPCCH channel in the present invention will not reduce the effective time actually used for inter-frequency measurement in the gap. The so-called inter-frequency measurement means that when the UE is going to perform hard handover, that is, to switch to another frequency different from the current frequency, it needs to measure the frequency to be switched to in advance. Since the relevant parameters of the compressed mode are consistent for both uplink and downlink, when the system uses compressed mode together in the uplink and downlink, the uplink transmit channel and downlink receive channel at the UE end can be obtained The corresponding relationship is shown in Figure 4. It can be seen from the figure that the actual effective frequency switching area, that is, the time period that can be used for inter-frequency measurement, is smaller than the actual length of the gap. If viewed from the downlink channel, at about the first half of the first gap time slot and the last few bits of the last gap time slot, the receiving or transmitting frequency of the antenna actually stays in the current cell. The purpose of not performing frequency switching in the first half of the first gap time slot in the gap of the downlink channel is to wait for the signal of the current time slot of the uplink channel to be sent. Since the area A in Figure 4 actually still stays in the current cell, Therefore, it can be used to send some data. In this case, the downlink DPCH channel can adopt the second time slot structure shown in Figure 3, that is, add TPC bits in the TPC field of the DPCCH channel in the first gap time slot. Use this Time period to transmit TPC bits to control the power of the first time slot after the gap in the uplink channel. Similarly, since at the last few bits of the last gap time slot of the uplink channel, as shown in Figure 4, the antenna of the UE has actually been switched back to the cell, so it can be in the last time slot of the uplink channel gap, That is, a TPC bit is added to the uplink time slot 4 in Figure 4, so that the TPC bit obtained according to the SIR measurement result of the pilot bit in the downlink channel time slot 4 can be uploaded in the corresponding uplink time slot, thereby adjusting one more downlink The transmit power of the link slot.

The present invention can be applied to the compressed mode power control in the WCDMA communication system, and concrete implementation process is as follows:

When both the uplink channel and the downlink channel adopt the compressed mode, the uplink DPCH channel adopts the time slot format of the present invention, that is, add TPC bits in the last gaP time slot. At this time, the UE measures the SIR of the pilot bit in the last gap slot of the downlink DPCH channel, compares it with the target SIR value, and then sends the comparison result with the added TPC bit in the last gap slot of the uplink DPCH channel. In this way, the power control of the inner loop can be started one time slot earlier, and the influence of the gap on the power control of the inner loop can be reduced.

When only the uplink channel uses the compressed mode, and the downlink channel uses the normal mode, the length of the blank part vacated due to the temporary interruption of data transmission is the length of the measurement time. The longer the blank part, the longer the time available for measurement. Then, the additional Adding TPC bits will result in a reduction in measurement time. Therefore, according to actual application conditions, if the requirement for the inner loop power control is greater than the requirement for the effective measurement time length, the uplink DPCH channel also adopts the time slot format of the present invention.

Wherein, the transmission power of the added TPC bit can be determined according to the method for determining the transmission power of the first time slot after the uplink DPCH channel gap specified in the 3GPP TS 25.214 protocol.

Claims (3)

1, the method for under a kind of compact model downward special physical channel power being controlled is characterized in that this method may further comprise the steps at least:

When uplink special physical channel adopts compact model, before the pilot bits of first time slot behind each transmission intercal sends, send tpc bit;

The base station is adjusted the channel power of downward special physical channel after receiving the pilot bits and the tpc bit before the pilot bits that uplink special physical channel is sent immediately.

2, method according to claim 1 is characterized in that, this method further comprises: when descending DPCH adopts compact model, send tpc bit on the transmitting power control domain position in first transmission intercal.

3, method according to claim 1 is characterized in that, the transmitting power of described tpc bit according to each transmission intercal of uplink special physical channel after the transmitting power of first time slot determine that method determines.

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