WO2011020217A1

WO2011020217A1 - Method for assigning downlink transmission power and apparatus thereof

Info

Publication number: WO2011020217A1
Application number: PCT/CN2009/000948
Authority: WO
Inventors: 王栋耀; 沈钢; 王伟; 刘建国; 陈继明
Original assignee: 上海贝尔股份有限公司; 阿尔卡特朗讯
Priority date: 2009-08-18
Filing date: 2009-08-18
Publication date: 2011-02-24
Also published as: CN102415167B; CN102415167A

Abstract

A scheme for assigning downlink transmission power in a wireless communication network with relay node (RN) is provided by the present invention. A method for assigning downlink transmission power in a wireless communication network with relay node (RN) comprises the following steps: for the sub-frames used for transmitting signal from a base station to relay nodes (RNs) or user equipments (UEs) which belong to the base station, assigning different transmission power for respective resource unit. Based on the present invention, the system interference level can be reduced, and the system performance can be improved.

Description

Method for allocating downlink transmission power and corresponding device

The invention relates to the field of communications. More particularly, the present invention relates to a method for allocating downlink transmission power in a wireless communication network having a relay node and a corresponding base station. Background technique

The relay technology has been accepted and adopted by the 3GPP (the 3rd Generation Partnership Project) long-term evolution project LTE-Advanced for forwarding service/signaling data between the base station eNodeB and the user equipment UE for better coverage or Better throughput. Undoubtedly, the coverage of the cell can be extended by using the relay node RN. However, from the point of view of system capacity, it is still a problem to obtain benefits from the relay due to loss of spectral efficiency on the backhaul link. However, an important feature of cellular networks introducing interference is interference suppression. On some spectrum resources, the system will arrange for the relay node RN to send wireless signals and turn off the base station eNodeB. Since the transmission power of the relay node RN is much smaller than the transmission power of the base station eNodeB, the system interference will be suppressed to a certain extent, thereby improving the system. Performance. In R1 - 091456 ("Initial evaluation of relay performance on DL" ₅ Qualcomm Europe, Seoul, March 2009), it is proposed that the relay network can achieve an improvement in system performance through interference coordination techniques. Summary of the invention

The present invention proposes a scheme for allocating downlink transmission power in a wireless communication network having a relay node.

According to a first aspect of the present invention, a method for allocating downlink transmission power in a wireless communication network having a relay node is proposed, comprising the steps of:

For a subframe for transmitting a signal from a base station to a relay node RN or user equipment UE to which it belongs, different transmission powers are allocated for different resource units.

According to a second aspect of the present invention, a base station is provided, comprising: A power allocation unit for allocating different transmission powers for different resource units for a subframe for transmitting signals from a base station to a relay node _RN or user equipment UE to which it belongs.

According to a third aspect of the invention, a method is proposed comprising the steps of:

A subframe from the base station for transmitting a signal from the base station to the relay node RN or user equipment UE to which it belongs is correctly received and demodulated based on the received transmission power information of the corresponding resource unit.

According to a fourth aspect of the present invention, a relay node RN or user equipment is proposed

UE, including:

And a receiving and demodulating unit, configured to correctly receive and demodulate a subframe from the base station for transmitting a signal from the base station to the relay node RN or the user equipment UE to which it belongs based on the received corresponding power information of the corresponding resource unit .

According to the present invention, system interference levels can be reduced and system performance can be improved. DRAWINGS

Other objects and effects of the present invention will become more apparent and easier to understand from the following description of the appended claims.

Fig. 1 schematically shows an example of an environment in which the present invention can be implemented; Fig. 2 shows an example of one subframe;

FIG. 3 shows a schematic diagram of association of UEs based on received power;

Fig. 4 schematically shows a block diagram of a base station eNodeB according to an embodiment of the present invention.

In all of the above figures, the same reference numerals indicate the same or similar features or functions. Detailed ways

The basic idea of the invention is to allocate different transmission powers for different resource elements for a subframe for transmitting signals from a base station to a relay node RN or user equipment UE to which it belongs. Fig. 1 schematically shows an example of a situation in which the present invention can be implemented.

As shown in FIG. 1, the environment 100 includes a base station eNodeB 101 and a relay node RN 102 belonging to the base station eNodeB 101, a user equipment UE 103, and a user equipment UE 104 belonging to the relay node RN 102.

In the downlink direction, the base station eNodeB 101 transmits CRS (Cell Specific Reference Signal), control signals and data signals to the relay node RN 102, the user equipment UE 103, and the relay node RN 102 transmits CRS to the user equipment UE 104 (for type Π Relay, can not transmit CRS), control signals and data signals.

In the present invention, the concern is how the base station eNodeB 101 transmits CRS, control signals and data signals to the relay node RN 102, the user equipment UE 103.

It can be understood by those skilled in the art that the CRS is used for channel estimation, and the control signal is used for corresponding control of the relay node RN or the user equipment UE.

In addition, for the sake of simplicity, only one base station eNodeB101 and the relay node RN 102 belonging to the base station eNodeB 101, the user equipment UE 103, and the user equipment UE 104 belonging to the relay node RN 102 are shown in Fig. 1. However, those skilled in the art should understand that the base station eNodeB101 may have more relay nodes RN and user equipment UEs, and the relay node RN 102 may also have more user equipment UEs, or the base station eNodeB101 only has the user equipment UE103. Or only the relay node RN 102.

In addition, those skilled in the art will appreciate that although the embodiments of the present invention are described below using a base station eNodeB as a specific embodiment of a base station, the present invention is not limited to the base station eNodeB.

While the system is running, the base station eNodeB 101 will schedule and allocate resources to all relay nodes and user equipment (including RN 102, UE 103 and UE 104) within the cell according to the scheduling policy used (e.g., rate fair or polling schedule). Thus, some subframes will be allocated for transmitting signals from the base station eNodeB101 to the relay node RN 102 or user equipment UE 103 to which it belongs, while other subframes will be used for transmission from the relay node RN 102 to the user equipment UE 104 to which it belongs. signal.

In the present invention, for the relay node to which the base station eNodeB101 belongs The RN 102 or the user equipment UE 103 transmits subframes of signals, and different transmission powers are allocated for different resource units.

Fig. 2 shows an example of a subframe for transmitting a signal from the base station eNodeB101 to the relay node RN102 or user equipment UE103 to which it belongs.

As shown in FIG. 2, the subframe 20Q includes three resource units:

(1), predefined as a resource unit 201 for transmitting a cell-specific reference signal;

(2), a resource unit 202 for transmitting a control signal (which constitutes a physical downlink control channel PDCCH); here only the PDCCH is taken as an example, and in fact, the transmission control signal may also include a physical broadcast/multicast channel (PBCH, PMCH). , Physical Control Format Indicator Channel (PCFICH) and Physical HARQ Indicator Channel (PHICH).

(3) a resource unit 203 for transmitting a data signal (which constitutes a physical downlink shared channel PDSCH);

In a read implementation of the present invention, a first transmission power is allocated for a resource unit pre-defined to transmit a cell-specific reference signal and a resource unit for transmitting a control signal, and for a resource unit for transmitting a data signal, A second transmission power is allocated, wherein the first transmission power is greater than the second transmission power.

Of course, those skilled in the art can understand that different resources can be allocated separately for resource units predefined for transmitting cell-specific reference signals, resource units for transmitting control signals, and resource units for transmitting data signals. power.

In the LTE-A system, the base station eNodeB determines the energy EPRE (transmission power) of each resource element in the downlink transmission. The transmission EPRE of the downlink cell-specific reference signal is constant in all subframes and the entire system bandwidth, and the value is determined according to the downlink reference signal transmission power provided by the upper layer.

In the present invention, the transmission ERPE for the downlink cell-specific reference signal determined by the base station eNodeB 101 is defined as high TXERPE P _H (first transmission power).

In addition, the transmission ERPE used to transmit the control signal is also high TXERPE P _H . In addition, the base station eNodeB 101 introduces another transmission ERPE P _L (P _{L ≤} P _H ), ie low TXERPR (second transmission power), for transmitting data signals.

The ratio between low TXERPE and high TXERPE is p=^ _a According to the present invention, since the first transmission power is allocated for the resource unit pre-defined to transmit the cell-specific reference signal and the resource unit for transmitting the control signal, and the second transmission is allocated for the resource unit for transmitting the data signal The power, where the first transmission power is greater than the second transmission power, not only maintains the coverage performance and ensures the correctness of the channel estimation, but also reduces interference to neighboring cells.

In order to enable the receiving side (the user equipment UE 103 or the relay node RN 102) to perform correct signal reception and demodulation, the corresponding transmission power information of the corresponding resource unit will be transmitted on the PBCH (Physical Broadcast Channel) or transmitted on the PDCCH. The user equipment UE 103 or the relay node RN 102 is notified.

For example, since ^ is known in advance to UE 103 or RN 102 and is always constant, and can always change, p can be broadcast only on the PBCH or on the PDCCH.

In the situation is always constant, in a relay node or a user equipment UE103 also know in advance RN102 _Ρ Λ case, the transmission may not be required transmission power information corresponding to respective resource units.

For those subframes used to transmit signals from the relay node RN 102 to the user equipment UE 104 to which it belongs, the transmission ERPE is for all resource elements.

In the present invention, when the UE performs a network entry procedure, it is determined whether the UE is associated with the base station eNodeB or the relay node RN based on a third transmission power. This will result in more UEs being served by the RN.

Fig. 3 shows a schematic diagram of the association of UEs based on received power.

In a wireless communication network with relay nodes, different cells periodically broadcast their different synchronization signals (usually transmitted by the base station eNodeB). The user equipment UE 303 will select the cell with the received power of the largest synchronization signal as its serving cell. Based on this information, the user equipment UE 303 will transmit a random access preamble on the physical random access channel PRACH. The base station eNodeB 301 and relay node RN 302 in the serving cell will receive the preamble.

It is assumed that the measured power of the preamble received on the side of the base station eNodeB 301 is and is P _{2 on the} side of the relay node RN 302 (the relay node RN 302 will report its measured corpse ₂ to it) The base station eNodeB 301), then the base station eNodeB 301 will decide whether the user equipment UE 303 should be associated with the base station eNodeB 301 or the relay node RN 302 according to: If ( - Ρ ₂ ) ≥ ( - S), the user equipment UE 303 should be associated with the base station eNodeB 301 ;

Otherwise, the user equipment UE 303 should be associated to the relay node RN 302.

Here, the third transmission power is equal to P _H - P _L .

In the prior art, it is determined whether the user equipment UE 303 should be associated with the base station eNodeB 301 or the relay node RN 302 according to whether the Pi-P is greater than 0 or less than 0.

If greater than 0, the user equipment UE 303 should be associated with the base station eNodeB

301;

Of course, those skilled in the art should understand that the third transmission power may also be other values, such as P _H or P _L , and not necessarily P _H -P _L .

At the receiving side relay node RN or the user equipment UE, since the corresponding transmission power information of the corresponding resource unit is known, the base station eNodeB can be correctly received and demodulated for use from the base station eNodeB to the relay node RN to which it belongs or The user equipment UE transmits a subframe of the signal.

The solution of the present invention provides better system performance due to reduced interference.

The reduced interference comes from two aspects:

First, since the data signal is transmitted with a low TX ERPE, interference to neighboring cells will be reduced. Second, according to the present invention, more user equipment UEs will be associated with the relay node RN, and therefore, the base station eNodeB will have more opportunities to mute, thereby further reducing interference to neighboring cells.

As shown in FIG. 4, the base station eNodeB 400 includes a power allocation unit 410 for allocating different transmissions to different resource units for a subframe for the base station eNodeB 400 to transmit signals to the relay node RN or user equipment UE to which it belongs. power.

One of the subframes has 3 different resource units: Predefined as a resource unit used to transmit a cell-specific reference signal;

a resource unit for transmitting a control signal;

a resource unit for transmitting a data signal;

Wherein, for a resource unit predefined to transmit a cell-specific reference signal and a resource unit for transmitting a control signal, a first transmission power is allocated, and for a resource unit used to transmit the data signal, a second transmission power is allocated, where The first transmission power is greater than the second transmission power.

The base station eNodeB 400 further includes a notifying unit 420 for notifying the relay node RN or the user equipment UE of the respective transmission power of the corresponding resource unit.

The base station eNodeB 400 further includes a decision unit 430 for determining whether the user equipment UE should be associated with the base station eNodeB or should be associated with the relay node RN based on the third transmission power.

The relay node RN or the user equipment UE according to the present invention comprises a receiving and demodulating unit for correctly receiving and demodulating from the base station eNodeB for transmitting from the base station eNodeB based on the corresponding transmission power information of the received corresponding resource unit The relay node RN to which it belongs or the subframe in which the user equipment UE transmits a signal.

The table below shows the parameters used in the simulation and their values, and the advantages realized with respect to the prior art. Table 1 shows the parameters used in the simulation and their values. Table 2 gives the advantages achieved over the prior art.

Table 1:

Table 2 (relative to the case where the same power is used for 46 dBm for all resource units) It should be noted that in order to make the present invention easier to understand, the above description is omitted for those skilled in the art and for this. Implementation of the invention may be required to be more specific of some technical details.

The description of the present invention is intended to be illustrative and not restrictive or For those of ordinary skill in the art, Many modifications and changes are obvious.

Therefore, the embodiments were chosen and described in order to explain the embodiments of the invention and the embodiments of the invention It is intended to be within the scope of the invention as defined.

Claims

Claim

A method for allocating downlink transmission power in a wireless communication network having a relay node, comprising the steps of:

2. The method of claim 1 ,

One of the subframes has 3 different resource units:

Predefined as a resource unit used to transmit a cell-specific reference signal;

a resource unit for transmitting a control signal;

a resource unit for transmitting a data signal;

3. The method of claim 1 further comprising:

The relay node RN or the user equipment UE is notified of the corresponding transmission power of the corresponding resource unit.

4. The method of claim 1 further comprising:

Based on the third transmission power, it is determined whether the user equipment UE should be associated with the base station or should be associated with the relay node RN.

5. A base station comprising:

A power allocation unit for allocating different transmission powers for different resource elements for a subframe for transmitting signals from a base station to a relay node RN or user equipment UE to which it belongs.

6. The base station according to claim 5,

One of the subframes has 3 different resource units:

a resource unit for transmitting a control signal; a resource unit for transmitting a data signal;

7. The base station according to claim 5, further comprising:

And a notification unit, configured to notify the relay node RN or the user equipment UE of the corresponding transmission power of the corresponding resource unit.

8. The base station according to claim 5, further comprising:

And a determining unit, configured to determine, according to the third transmission power, whether the user equipment UE should be associated with the base station or should be associated with the relay node RN.

9. A method comprising the steps of:

10. A relay node RN or user equipment UE, including: