WO2014179978A1

WO2014179978A1 - Method for controlling transmit power of device-to-device link of user equipment

Info

Publication number: WO2014179978A1
Application number: PCT/CN2013/075451
Authority: WO
Inventors: 仲崇显; 杨涛; 刘瑾
Original assignee: 上海贝尔股份有限公司
Priority date: 2013-05-10
Filing date: 2013-05-10
Publication date: 2014-11-13
Also published as: CN105191430A; CN105191430B

Abstract

Provided is a method for controlling a transmit power of a device-to-device link of a user equipment. The method comprises: obtaining condition of interference generated by a device-to-device link to a cellular link; and determining a transmit power of the device-to-device link of the user equipment according to the condition of interference of the device-to-device link to the cellular link, the transmit power being reduced when the interference condition is serious. By using the method, cellular communication can be normally performed when device-to-device communication occurs, and cellular communication performance attenuation caused by the device-to-device communication is avoided.

Description

Method for controlling transmission power of a device of a user equipment to a link of a device

The present invention relates to wireless communications, and more particularly to device-to-device communication in wireless communications.

Device-to-device (D2D) communication over cellular networks offers many advantages, such as efficient radio resource utilization, low power consumption, high spectral efficiency, and short latency, so it has received widespread attention. In addition, it provides an efficient solution for cellular systems such as load balancing, cell edge performance enhancement, and more. Recently, the 3GPP organization has initiated a new study of D2D, focusing on device discovery and D2D direct communication. In RANl#72bis, the topic of D2D is mainly discussed, focusing on the scenarios and requirements of deployment, evaluation methods and performance measurement. Also, some agreement has been reached on the measurement of device discovery and direct communication.

There are still some important issues in D2D communication that require further research, such as how the transmit power of the D2D link is determined. Summary of the invention

Currently, there is a method of controlling the transmission power of a cellular link in cellular communication, as defined by TS 36.213, which uses closed-loop fractional power control techniques. Specifically, the path loss of the cellular link, resource block utilization, modulation and coding mode, and other user equipment or cell-specific parameters are considered to determine the transmit power of the cellular link, and the calculation is as follows:

P = mind , P ₀ + cPL + lQ \gM + A _TF + /(Δ)} ( 1 ) where ^P max is the maximum available transmit power of the user equipment, for example, its rated maximum transmit power;

^P o and "is the open loop power control parameters configured by the network; Is the path loss of the cellular link;

M is the number of allocated resource blocks (RBs);

^A TF is an offset value corresponding to the modulation coding mode;

( ^Δ ) is a closed loop power control value sent by the base station.

The link loss, resource block condition, modulation and coding mode, open-loop power control parameters, and closed-loop power control offset value set by the base station can be referred to as the power control parameters of the link. In formula (1)', the second term calculated from the power control parameters of the link is pspecifted, ie -

P ^specif ' ^ed = P ₀ + ccPL + lOlg + A _TF + (△) (2) In the case of spectrum resource sharing, the D2D link and the cellular link use the same spectrum resource. Therefore, the D2D link may cause interference to the receiver of cellular communication.

Figure 1 shows a schematic diagram of the interference (referred to as uplink interference) caused by D2D communication to uplink cellular communication. As shown in FIG. 1, when the base station eNB receives the uplink cellular signal sent by the user equipment, the signal between the UE_i and the UE_j that performs the D2D communication is also propagated to the base station eNB (in the case of time-division UE_i and UE_j does not transmit signals at the same time. The figure is only for the purpose of describing the uplink interference caused by UE-i and UE-j respectively. The signal of the D2D link is an interference for uplink cellular communication. FIG. 2 is a schematic diagram showing interference caused by D2D communication to downlink cellular communication (referred to as downlink interference). The principle is similar. When the user equipment UE-k receives the downlink cellular signal sent by the base station eNB, the UE performing D2D communication- The signal between i and UE_j is also propagated to the user equipment UE-k (in the case of time division, UE-i and UE-j do not transmit signals at the same time, the figure shows only for the purpose of describing UE_i and UE_j The downlink interference caused by the D2D link is a kind of interference for downlink cellular communication.

In the existing standards, it can be seen from equations (1) and (2) that determining the transmit power of the link basically considers the path loss of the link itself, regardless of the ongoing communication on the same spectrum. Therefore, when the prior art is directly used to determine the transmit power of the D2D, the path loss of the D2D link is considered, and thus it is possible to cause serious interference to the cellular communication. However, in the D2D communication technology, it is a basic requirement that cellular communication does not cause serious deterioration due to the occurrence of D2D communication. It can be seen how to determine the transmission of the D2D link. Shooting power without deteriorating the performance of cellular communication is a technical problem that needs to be solved.

At least in part to solve the technical problem, an aspect of the present invention provides a method for controlling a transmission power of a device-to-device link of a user equipment, wherein the method includes the following steps: i. obtaining the device to The interference caused by the device link to the cellular link; ii. determining the transmit power of the device-to-device link of the user equipment according to the interference situation of the device-to-device link to the cellular link, where When the situation is severe, the read transmission power is reduced.

In the "i" aspect of the present invention, since the interference of the D2D link to the cellular link is considered in determining the transmission power of the D2D link, when the interference situation is severe, the transmission power is lowered, and thus the appearance of the D2D link occurs. It will not deteriorate the performance of the cellular link, ensure the normal operation of the cellular communication, and improve the overall performance of the system. Here, the cellular link and cellular communication refer to the uplink and downlink communication between the user equipment and the cellular base station (eNB). .

In a preferred implementation, the step i includes: obtaining a measured path loss of the device to the receiver of the read cellular link; the step ii includes: obtaining a power control parameter of the device to the device link, The read power control parameters include any of the following: the path loss of the device-to-device link, the resource block condition, the modulation and coding mode, the open-loop power control parameters, and the closed-loop power control value set by the base station; Calculating the initial power of the user equipment to the equipment link; adjusting the initial power of the reading as the transmission power according to the interference condition of the equipment to the equipment link to the cellular link, where When the interference situation is serious, the initial power is reduced as the transmission power.

In this embodiment, based on the existing standards, the transmission power determined according to the existing standard is adaptively adjusted, and when the interference of the D2D link to the cellular link is severe, the existing standard is lowered. The determined power is taken as the transmit power. Since the present embodiment utilizes existing standards, it is relatively easy to integrate with existing standards.

In another embodiment, the method is performed in a base station, where the step i includes: obtaining a receiver of the cellular link affected by interference of the user equipment; the step ii includes: When the influence exceeds a certain range, based on the influence, a change value is determined, and the change value is used for consideration by the user equipment to change the reading. The current transmit power of the device to the device link of the user equipment; the 谚 change value is sent to the user equipment; the above steps i and ii are repeated.

Correspondingly, a method for controlling the transmit power of the device-to-device link of the user equipment in the user equipment is provided, including the following steps: obtaining a power control parameter of the device-to-device link, the power control The parameter includes any one of the following: a path loss of the device to the device link, a resource block condition, a modulation and coding mode, an open loop power control parameter, and a closed loop power control value set by the base station; and calculating the power control parameter based on the power control parameter The device-to-device link transmission power of the user equipment, and performing device-to-device communication based on the transmission power; and, further comprising the steps of: receiving a change value from the read base station, the change value is based on the device-to-device link Determining the interference condition of the cellular link; using the change value to adjust the aforementioned transmit power; continuing device-to-device communication using the changed transmit power, and repeating the receive, adjust, and communicate steps as necessary.

In the 谚 implementation mode, the transmission power determined by the existing standard is adjusted in real time according to the interference situation in the actual communication, and the true communication situation can be accurately reflected, and the existing standard is utilized, so that it can be There are standards that are easier to fuse.

Preferably, in the step ii, a value is selected from the predetermined set of values as the change value according to the influence beyond the certain range. In this embodiment, complicated calculations are not required, and an appropriate change value can be determined relatively easily.

In a further embodiment, the step ii calculates the transmit power of the device to the device link of the device according to the channel condition of the device to the device link to the interference channel of the cell link, where the method includes the following steps: a. obtaining a power ratio, the read power ratio is the ratio between the interference received by the receiver of the cellular link and the received cellular signal; b. the received power of the cellular signal received by the receiver obtaining the cellular link c. based on the read power ratio, and the received power of the cellular signal received by the receiver reading the cellular link, and the channel condition of the interference channel of the receiver to the receiver of the read cellular link, calculating the device's device to The transmit power of the device link.

In this embodiment, the transmit power of the D2D link is calculated by a power ratio, and the actual received power and interference channel conditions, so that the D2D link is on the bee. The interference generated by the socket can meet the requirements of the power ratio, so that the interference of the cellular link is not stronger than the cellular signal, thereby ensuring the normal detection of the cellular signal and ensuring the excellent performance of the cellular communication. Moreover, the channel condition of the interference channel is generally fast, so that the obtained channel condition can ensure high real-time performance, so that the transmission power of the device-to-device link can be controlled in time to ensure the performance of the cellular communication. Therefore, this embodiment is very attractive for joint optimization of dynamic resource allocation, link adaptation, and transmit power control.

In a preferred embodiment, the read power ratio is preset at the base station. In this case, the system complexity is relatively low.

Alternatively, the base station calculates the power ratio using the following sub-steps: obtaining a signal to interference and noise ratio required by the receiver of the cellular link for cellular communication; obtaining a measured signal to noise ratio of the receiver of the cellular link, The signal-to-noise ratio is measured by the base station or measured by the user equipment; based on the signal to interference and noise ratio and the signal to noise ratio, the interference received by the receiver reading the cellular link and the received cellular are calculated. The power ratio between the signals.

In this embodiment, starting from the target SINR of the receiver and the SN of the actual communication, the power ratio between the D2D interference allowed by the receiver and the cellular signal can be accurately calculated, and the receiving performance of the receiver is taken into account. accurate.

Preferably, the receiver of the cellular link is a base station, and the channel conditions of the received power and the interference channel obtained in the steps b and c are measured by the base station. This embodiment is for the case where the D2D link interferes with the uplink communication of the cellular UE to the cellular base station.

Alternatively, the method is used to control the transmit power of the first user equipment, the receiver of the cellular link is the second user equipment, and the received power and the channel condition of the interference channel obtained in the step b and the step c It is measured by the read second user equipment and fed back to the base station.

This embodiment is directed to the case where the D2D link interferes with the downlink communication of the cellular base station to the cellular UE.

Preferably, said steps a, b and c are performed at the user equipment to determine the transmit power, or at the base station and the base station informs the user of the determined read transmit power Equipment.

In this implementation manner, the determining operation of the transmit power of the D2D link can be performed directly in the user equipment, and the real-time performance is good. Alternatively, the user equipment can be performed and notified in the base station, which can reduce the computational burden of the user equipment.

Further preferably, the actual transmit power of the user equipment is a smaller of the aforementioned determined transmit power and the transmit power calculated by the user equipment based on the power control parameters of the device-to-device link.

In this embodiment, the transmission power is also made to comply with the provisions of existing standards, and it is relatively easy to integrate with existing standards.

In an embodiment, the receiver of the cellular link is a base station or a second user equipment in a cell to which the user equipment belongs. In this embodiment, the interference caused by the D2D link to the cellular communication of the own cell is considered.

In an alternative implementation, the receiver of the cellular link is a base station or a second user equipment in a neighboring cell of a cell to which the user equipment belongs, and the steps of &, b, and c receive the neighboring cell. The power ratio or the signal-to-noise ratio, the received power, and the channel condition of the interference channel, which are sent by the base station to the base station of the cell to which the cell belongs, and which is forwarded to the user equipment by the base station of the cell to which the cell belongs. In the implementation manner, the interference caused by the D2D link to the cellular communication of the neighboring cell is considered, which is more advantageous for ensuring the overall cellular communication performance.

Preferably, the actual transmit power of the read user equipment is not greater than the maximum transmit power of the user equipment. In this embodiment, the maximum (e.g., nominal) transmit power of the user equipment is taken into account, in accordance with the actual functionality of the device.

Other advantages of the invention will be described hereinafter or will be understood by those of ordinary skill in the art from the following detailed description. DRAWINGS

Other features, objects, and advantages of the present invention will become more apparent from the Detailed Description of Description

FIG. 1 is a schematic diagram showing interference caused by D2D communication to uplink cellular communication; 2 is a schematic diagram showing interference caused by D2D communication to downlink cellular communication; FIG. 3 is a diagram showing the determination of transmission power by considering interference channel conditions according to an embodiment of the present invention when D2D communication causes interference to uplink cellular communication as in FIG. Schematic diagram

4 is a diagram showing the determination of transmission power in consideration of an interference channel condition according to an embodiment of the present invention when D2D communication causes interference to downlink cellular communication as in FIG. 2;

5 is a diagram showing a determination of transmission power in consideration of an interference channel condition in accordance with an embodiment of the present invention when D2D communication causes interference to uplink cellular communication in a cross-cell case;

Fig. 6 is a diagram showing the determination of the transmission power in consideration of the interference channel condition when the D2D communication causes interference to the uplink cellular communication in another cross-cell case similar to Fig. 5.

Throughout the drawings, the same or similar reference numerals indicate the same or corresponding parts or features. detailed description

As shown in Figures 1 and 2, in general, two D2D devices that perform D2D communication may be located within the coverage of the base station eNB. The resources and control of the radio link of the D2D communication are managed by the network (base station). The base station eNB is capable of performing radio resource configuration of D2D communication and performing interference control by using the downlink cellular signaling transmitted to the D2D device. It will be appreciated that the invention is not limited to such a topology.

According to a basic concept of the present invention, a method for controlling a transmission power of a device-to-device link of a user equipment is provided, which includes the following steps:

i. obtaining interference from the device-to-device link to the cellular link; ii. determining the device-to-device link transmission of the user device based on the device-to-device link interference to the cellular link Power, where, when the interference situation is severe, the read transmission power is reduced.

Based on the above inventive concept, the present invention further proposes several different implementations The methods will be described separately below.

Embodiment 1

The path loss between the D2D link to the cellular link, ie the transmitter of the D2D communication to the receiver of the cellular link, is recorded as ^PL interf. In uplink communication, the receiver of the cellular link is the base station eNB; and in downlink communication, the receiver of the cellular link is the UE, such as UE_k.

Applicable to equation (2) in the existing standard, the transmission power p _{fied = o + aPi +} 101 _§ + Δ _{Γ ί} . + (Δ) based on the existing standard can be obtained, and the embodiment of the present invention proposes adaptability to the _{psp rf} Change, the change is based on the path loss of the D2D link to the cellular link

^PL int _e} f . More specifically, for quantitative discussion, the change value is recorded as

That is, the change value is a function of the path loss / /, which can be called a penalty function. Then the actual transmit power used may be dead ^D

P ^D2D = P ^spedfied ~ g{PL _interf ) (3) The penalty function can be configured by the network (base station) or predetermined by the user equipment.

More specifically, the penalty function can have a monotonically decreasing function of the path loss, ie, the larger the path loss (the smaller the interference is, the smaller the penalty); and vice versa. More specifically, the present embodiment proposes a specific penalty function expression g( , ^) = ^ where, and is a positive real number, which may be predefined by the network or user equipment, or may also be flexible through signaling And configuration. Thus, equation (3) can reflect: less penalty when the path loss is large, allowing the resulting transmit power Ρ ^{ΰ 2 ΰ to be} larger; and vice versa.

Considering the maximum transmit power of the user equipment, such as the rated maximum transmit power, the minimum calculation can be performed on the aforementioned calculation result and the maximum transmit power ^ρ ^, namely:

P ^D1D =min bribe, strict ~ g{PL _interf )} ( 3 ' ) In actual implementation, the path loss ^PL interf can be used by the receiver of the cellular link, ie, the base station eNB in uplink communication or the user in downlink communication The device UE is measured by a k. The gU may be calculated by the base station eNB according to its measurement, ^PL int _er f or ^^ _e r/, which is fed back by the UEJc, and signaling the user of the D2D communication. Device UE_i. Alternatively, the base station eNB read path loss ^PL int _eK f inform the user equipment UE-i of the D2D communication through signaling, the user equipment UE- i is calculated. The user equipment UE-i calculates P ^D2D according to P- and the gU calculated based on existing standards. Embodiment 2

In this embodiment, a power control method for performing feedback is used to adjust the transmission power of the D2D link in real time based on the interference generated by the D2D link to the cellular link. The specific plan is as follows:

The user equipment UE_i first obtains a certain transmit power of the device-to-device link of the user equipment. Specifically, the user equipment can be calculated UE_i p fwd ₌ p _o existing standards-based _{_{_{+ + ιοΐ δ + Δ Ί.}}} + (Δ), or read to obtain the transmit power based on other schemes. Other solutions are for example: Transmit power is a fixed value, and so on.

Next, the user equipment UE-i performs device-to-device communication based on the certain transmit power.

A receiver performing cellular communication, such as a base station eNB or a user equipment UE_k, is subject to interference from device-to-device communication of the user equipment UEJ. The base station eNB or user equipment UE-k detects the impact of the interference, such as obtaining the SINR of the cellular communication.

Then, the base station eNB obtains the influence of the interference, and determines the impact: when the influence exceeds a certain range, based on the impact, determines a change value ΔΡ, which is used by the user equipment. Consider changing the transmit power of the device-to-device link that is currently in the user equipment. In the case where the maximum transmission power ^Ρ TM 考虑 is considered, the changed transmission power can be expressed by the following equation

P ^D2D = rn certificate, -ΔΡ} ₍₄ ) The base station transmits the change value to the user equipment UE_i, correspondingly. The user equipment UE_i receives the change value from the base station, uses the change value to adjust the certain transmit power, and continues the device-to-device communication using the changed transmit power.

The above steps may be performed cyclically until the base station eNB or the user equipment UE-k detects that the impact caused by the interference is within a certain range, that is, no unacceptable interference to the cellular link is caused. In a relatively simple implementation manner, the base station eNB selects a value from the predetermined set of values as the change value according to how much the influence exceeds the certain range.

ΔΡ. The set of values is, for example, {- ³ , -1, 0, 1, ...}. For example, the certain range is the SINR range (or minimum value) required for the normal reception of the receiver of the cellular communication. When the SINR of the cellular communication is greater than the SINR range, indicating that the cellular communication is not severely disturbed, the D2D communication can be maintained. The transmit power is constant (select OdB as ΔΡ), and even the transmit power can be increased (select -3dB as ΔΡ); instead, the transmit power of D2D communication should be reduced (select l dB as AP). Embodiment 3

In this embodiment, the transmit power of the read device to the device link of the device is calculated based on the channel condition of the interference channel from the device to the device link to the cellular link. Among them, do the following:

a. obtaining a power ratio that is the ratio between the interference experienced by the receiver of the cellular link and the received cellular signal;

b. obtaining the received power of the cellular signal received by the receiver of the cellular link;

c calculating the device-to-device chain of the device based on the power ratio, and the received power of the cellular signal received by the receiver of the cellular link, and the channel condition of the interference channel of the receiver to the receiver of the cellular link The transmission power of the road.

The present embodiment will be described in detail by exemplifying two scenarios of uplink communication and downlink communication, respectively.

• Uplink communication

Uplink communication is shown in Figure 3. The base station eNB receives an uplink signal from the cellular user equipment UE-k. The channel condition between the two, such as the channel gain, is denoted as _Gk , and the transmit power of the cellular user equipment UE-k is recorded as / and the power of the additive white Gaussian noise is also recorded.

And, the base station eNB also receives signal interference from the D2D user equipment UE-i. Record the channel conditions between the two, such as channel gain, and the D2D user The transmit power of the device UE-i is recorded as (or written as κ).

There is a required power ratio A which is the ratio between the interference experienced by the receiver of the cellular link and the received cellular signal.

Understanding of the cellular link receiver interference suffered by the received signal should be equal to the cell equal to Ρ Α ₆ ^. In other words, Α should be equal to Λ, 6ν _Α <^.

Then, the required transmission power of the user equipment UE_i can be calculated accordingly.

pUL ntf _ Pjfik β (5) of the honeycomb channel gain _A measurable obtained, the transmission power of the user equipment UEJc _Α are known in advance; or cellular signal power is measured directly. Moreover, the gain of the interference channel is measurable. In the case of A, the base station eNB or the D2D user equipment UE_i can calculate the transmit power of the D2D link.

For Α·, there are several implementations, as follows – Description: Case 1: The power ratio is preset at the base station. For example, in network planning, an appropriate power ratio is determined according to the detection capability of the receiver of the cellular communication: at the power ratio, the receiver can correctly ensure that the cellular signal is correctly detected.

Case 2: The power ratio Α is obtained by calculation, specifically:

At base station eNB to the cellular uplink signal to interference noise signal than the cellular user equipment UE_k _57Λ¾ Α expressed by the following equation:

Since Α· should be equal to, Gy _A G _A can be replaced

PkG _k

1 ( 6 )

So get

2

σ

丄"丄 w

Tk PA

SINR _k SNR _k

In the equation, Λ _Α is the signal-to-noise ratio at the receiver of cellular communications and is measurable. For a given receiver, the signal to interference plus noise ratio required for signal detection, denoted SINRT', is dependent on the performance of the receiver itself and is therefore also known. Based on this, it is possible to calculate the power ratio β _{ when the SINR satisfies SINR _k ' ^arsct in the case of the SNR.

1 1

_SINR target SNR _k (8) The power ratio A can be calculated by the base station eNB; or the base station can transmit the parameters required for calculation to the D2D user equipment UE_i, and the D2D user equipment UE_i calculates the power ratio A.

In the foregoing case 1 and case 2, the base station eNB that obtains the power ratio can directly calculate the transmit power JPi of the D2D user equipment UE_i, and then send the calculated transmit power to the user equipment UE-i through signaling. Alternatively, the base station eNB may send the power ratio A to the user equipment UE_J by the user equipment UE_i, and in this implementation, calculate other parameters required, such as the gain of the cellular channel (? _A The transmit power P _{k of the} user equipment UE_k, the gain Gi of the interference channel is provided by the base station eNB by the D2D user equipment UE i. Further, in order to comply with the existing standards, the D2D user equipment UE_i also calculates the transmission power ΡΓ -P, + cPL _D2D + 1 OlgM + Δ + / (Δ) based on the existing standard, and the calculation formula corresponds to the present There is the equation (2) in the standard. Moreover, the D2D user equipment UE_i can also consider the maximum transmit power /. Thus, the D2D user equipment UE_i finally determines the transmit work

Downlink communication

Downlink communication is shown in Figure 4. The cellular user equipment UE_k receives the downlink signal from the base station eNB. The channel conditions between the two, for example, referred to as the channel gain G _k, and the cellular user equipment transmit power UEJc referred to as P _A. The power of additive white Gaussian noise is also recorded as.

And, the cellular user equipment UE-k also receives signal interference from the D2D user equipment UE-i. The channel condition between the two, such as channel benefit, is recorded as and the transmit power of the D2D user equipment UE-i is recorded as Ρ, (or written as P " ^LJ " ^tf ).

Similar to the above embodiment, a power ratio A can be obtained which is the ratio between the interference experienced by the receiver of the cellular link and the received cellular signal.

Therefore, the transmit power P? ^LJ "' ^{f of the} D2D user equipment UE-i can be calculated as follows:

_ jPk ^G k

Similar to the foregoing embodiments, the power ratio A may be predetermined by the network; or may be determined by the base station eNB according to the required signal to interference and noise ratio siNR' of the cellular user equipment UE-k and the user equipment UE-k The signal-to-noise ratio SNR _{k is} calculated by the foregoing equation (8), wherein the actual signal-to-noise ratio 5 V3⁄4 at the user equipment UE_k is fed back to the base station eNB by the user equipment UE_k. The read power ratio A can be calculated by the base station eNB; The base station may send the parameters required for the calculation to the D2D user equipment UE-i through signaling, and the D2D user equipment UE-i calculates the power ratio A.

Furthermore, in order to comply with the existing standards, the D2D user equipment UE_i also calculates the transmission power aPL _mD + 101 _§ + Δ^ + /(Δ) based on the existing standard. The calculation formula corresponds to equation (2) in the existing standard. Moreover, the D2D user equipment UEJ can also consider the maximum transmit power P _raMii . Thus, the D2D user equipment UE_i finally determines the transmit work

It can be understood that in the above embodiment, the sum S is calculated. The cellular user equipment UE_k targeted in K shall be the user equipment most affected by the D2D link.

Comparing the uplink and downlink schemes, comparing the formula (5) with the formula (9), it can be seen that the difference is: the channel gain Gi of the D2D user equipment 126" to the base station eNB in the uplink scheme; the D2D user in the downlink scheme The channel gain of the device UE_i to the cellular user equipment UE_k is <3⁄4t. In general, it is possible to relatively easily obtain the channel gain G,., And the channel gain _Α it more difficult to obtain a suitable value. This is because:

- Unlike the base station eNB, the transmit power of the SRS for each user equipment is variable, so it is difficult to estimate Gi, _k based on detecting the SRS.

- The cellular user equipment UE_k may be non-static with respect to the base station eNB being in a quiescent state, which makes the estimation of the channel gain difficult.

- Considering the resource allocation and scheduling of cellular user equipment, the interfered cellular user equipment may change from time to time.

Therefore, the uplink scheme should have a wider applicability.

In both of the above embodiments, the receiver of the interfered cellular link is within the cell. The principle of the above embodiment can also be extended to determine the transmit power of a suitable D2D link to resolve the interference of the D2D link to the cellular link in the neighboring cell. The extension is illustrated by the following two scenarios of uplink interference, it being understood that the downlink communication is similar.

As shown in FIG. 5, two D2D user equipments UE_i and UE_j performing D2D communication belong to two adjacent cells, respectively, and the two cells are respectively governed by the base stations eNB_s and eNB_n. The base station eNB-n receives the uplink signal from the cellular user equipment UE-k under its jurisdiction. The channel condition between the two, such as the channel gain, is denoted as G _k . And, the base station eNBjn also receives signal interference from the D2D user equipment UE_i, The channel conditions, such as channel gain, are recorded as _ϋ ^ _{ΝΒ ιι} . The appropriate transmit power i (or writing i^-) should be determined for the D2D User Equipment UE-i.

Alternatively, as shown in FIG. 6, two D2D user equipments UE_i and UE_j performing D2D communication belong to two adjacent cells, respectively, and the two cells are respectively governed by base stations eNB_s and eNB-nl. And, there is also a third cell, the base station eNB_n2 of the cell receiving the uplink signal from the cellular user equipment UE-k under its jurisdiction. The base station eNB-n2 also receives signal interference from the D2D user equipment UE-i, and records the channel condition between the two, for example, the channel gain as G^^_ ₂ . It should be suitable for the D2D user equipment UE-i. Transmit power*,. (or writing

In these scenarios, the power ratio A can be used to calculate the transmission power 类似于·, similar to the above embodiment. It is worth noting that the parameters required in the specific calculation, such as the channel gain C^v^ of the interference channel are cross-cell, and the gain of the cellular channel (^ is in the neighboring cell, so these parameters can be used by neighboring cells After the base station eNB-n or eNB-n2 is estimated, it is provided to the base station eNB_s of the local cell through the X2 interface between the base stations. Further, the power ratio A may be pre-set in the neighboring cell; or the receiver of the neighboring cell It also has the signal to interference and noise ratio S1NRr'" required to correctly detect the cellular signal, and has a corresponding actual SNR. Then these parameters can also be provided to the base station eNB_s of the cell through the X2 interface, which is convenient for the base station eNB of the cell. s obtains or calculates the power ratio A.

In these scenarios, if the D2D user equipment UE_i also interferes with the cellular link in the own cell (not shown), the transmit power of the cellular link for the cell should also be calculated according to the foregoing embodiment. _f (writing or "). Furthermore, in order to comply with the existing standards, the D2D user equipment UEj also calculates the transmission power ΡΓ = P ₀ + aPL _D2D + 10 l _g M + + / (Δ) based on the existing standard, and the calculation formula corresponds to the existing standard. Equation (2) in . Moreover, the D2D user equipment UE-i can also consider the maximum transmit power P _maXii . Thus, the final determined transmit power of the D2D user equipment UE-i is as follows:

Upstream (i i) down

It should be noted that the "device-to-device link interference to the cellular link" or the "device-to-device link-to-cellular link" to the cellular link receiver as described in the specification and claims The interference actually refers to the interference generated by the transmitter from the device to the device, and the receiver naturally does not cause interference. Moreover, the device-to-device link is usually time-division multiplexed, that is, the transmitter and the receiver are interchanged at different times, and in the case of interchange, the magnitude of the interference generated, or even the largest interference victim, may Different, then the transmit power should be determined accordingly.

The above-described embodiments are merely exemplary and not limiting of the invention. Any technical solution that does not depart from the spirit of the present invention should fall within the scope of the present invention, which includes the use of different technical features that appear in different embodiments, and the device method can be combined to achieve a beneficial effect. In addition, any reference signs in the claims should not be construed as limiting the claims. The term "comprising" does not exclude the means or steps that are not listed in the other claims.

Claims

Claim

A method for controlling a transmission power of a device-to-device link of a user equipment, comprising the steps of:

1. Obtain interference from the device-to-device link to the cellular link;

Ii. determining the transmit power of the device-to-device link of the user device according to the interference condition of the device-to-device link to the cellular link, wherein when the interference condition is severe, the read transmit power is reduced.

2. The method according to claim 1, wherein the step i comprises: obtaining a path loss of the measured read device to a receiver of the cellular link;

The step ii includes:

- Obtain the power control parameters of the device-to-device link. The read power control parameters include any of the following: path loss of the device-to-device link, resource block condition, modulation and coding mode, open-loop power control parameters, and base station Set closed loop power control value;

- calculating an initial power of the device-to-device link of the user equipment based on the power control parameter;

- adjusting the initial power according to the interference condition of the device-to-device link to the cellular link as the read transmit power, wherein when the read interference condition is severe, the initial fixed power is reduced as the transmit power.

3. The method according to claim 2, wherein the method is performed in a first user equipment,

The receiver that reads the cellular link is a second user equipment or base station that performs cellular communication, and

The base station informs the first user equipment by signaling the path loss of the read device to the receiver of the cellular link.

The method according to claim 1, wherein the method is performed in a base station, wherein the step i comprises: obtaining, by the receiver of the read cellular link, the interference of the user equipment;

The step ii includes: - when the impact exceeds a certain range, based on the impact, determining a change value for the forcible user equipment to consider to change the current transmit power of the device-to-device link of the user equipment;

- sending the change value to the user equipment;

The above steps i and ii are repeated.

The method according to claim 4, wherein in the step ii, a value is selected from the predetermined set of values as the change value according to how much the influence exceeds the certain range.

The method according to claim 1, wherein the step ii calculates the transmission of the read device to the device link of the device according to the channel condition of the interference channel of the device to the device link to the cellular link. Power, which includes the following steps:

b. obtaining the received power of the cellular signal received by the receiver of the cellular link; c based on the power ratio, and the received power of the cellular signal received by the receiver reading the cellular link, and the device to the cellular link The channel condition of the interference channel of the receiver calculates the transmit power of the device to the device link.

The method according to claim 6, wherein the base station presets a power ratio, or the base station calculates the power ratio using the following substeps:

- obtaining a signal to interference and noise ratio required by the receiver of the cellular link for cellular communication; - obtaining a measured signal to noise ratio of the receiver of the cellular link, the signal to noise ratio being measured by the base station or by the user equipment Post-measurement feedback;

- calculating a power ratio between the received interference and the received cellular signal required by the receiver of the cellular link based on the signal to interference and noise ratio and the signal to noise ratio.

The method according to claim 7, wherein the receiver of the cellular link is a base station, and the received power and the channel condition of the interference channel obtained in the step b and the step c are measured by the base station. ;

Or,

The method is for controlling a transmit power of a first user equipment, and the cellular link is connected The receiving device is the second user equipment, and the channel conditions of the received power and the interference channel obtained in the step b and the step C are measured by the second user equipment and fed back to the base station.

9. The method according to claim 6, wherein the steps, b and c are performed at the user equipment to determine the transmit power, or at a base station and the base station notifies the determined transmit power. Forgive the user equipment.

The method according to claim 6, wherein the actual transmit power of the user equipment is the foregoing determined transmit power and the transmit power calculated by the read user equipment based on the power control parameter of the device to device link. The smaller value, i Xuan power control parameters include any of the following: read device to device link path loss, resource block situation, modulation and coding mode, open loop power control parameters, and base station set closed loop Control value.

The method according to claim 8, wherein the receiver of the cellular link is a base station or a second user equipment in a cell to which the user equipment belongs; or the receiver of the cellular link is a base station or a second user equipment in a neighboring cell of the cell to which the user equipment belongs, the base station receiving the neighboring cell in the steps b, c, and the base station sent to the base station of the cell to which the cell belongs, and the base station of the cell to which the cell belongs The power ratio or the signal to noise ratio, the received power, and the channel condition of the interference channel forwarded to the user equipment.

The method according to claim 1, wherein the actual transmission power of the user equipment is not greater than the maximum transmission power of the user equipment.

13. A method for controlling transmission power of a device-to-device link of a user equipment in a user equipment, comprising the steps of:

- obtaining a certain transmit power of the read device of the read user equipment to the device link; - performing device-to-device communication based on the certain transmit power;

And, it also includes the following steps:

- receiving a change value from the base station, the read change value being determined based on interference from the device-to-device link to the cellular link;

- use the change value to adjust the aforementioned certain transmit power;

- Continue device-to-device communication with the changed transmit power and repeat the read, receive, and communicate steps as necessary.

14. The method according to claim 13, wherein the method obtains the certain transmit power by the following steps:

- Obtaining the power control parameters of the device-to-device link, the power control parameters include any of the following: path loss of the device-to-device link, resource block condition, modulation and coding mode, open-loop power control parameters, and base station Set closed loop power control value;

- Calculate the certain transmit power based on the power control parameter.

The method according to claim 13, wherein the actual transmit power of the user equipment is not greater than the maximum transmit power of the user equipment.