Method for sending preamble sequence and user equipment

Abstract

The present disclosure discloses a method and user equipment for sending a preamble sequence. The method includes determining a transmit power for sending a preamble sequence, and sending the preamble sequence according to the determined transmit power.

Claims

1. A method for sending a preamble sequence, the method comprising: determining, by user equipment, a transmit power for sending the preamble sequence, wherein the transmit power meets: Power=min{P.sub.max, PREAMBLE_RECEIVED_TARGER_POWER.sub.i.sup.preamble_transmission_counter+PL}; sending, by the user equipment, the preamble sequence according to the determined transmit power through a resource i; wherein Power is a determined transmit power, P.sub.max is a maximum transmit power of the user equipment, PL is obtained by estimating according to a downlink path loss, PREAMBLE_RECEIVED _TARGET_POWER.sub.i.sup.preamble_transmission_counter is a target receive power of the preamble sequence, and the resource i is a preamble sequence resource for coverage enhancement random access; wherein PREAMBLE_RECEIVED _TARGET_POWER.sub.i.sup.preamble_transmission_counter meets: PREAMBLE_RECEIVED _TARGET_POWER.sub.i.sup.preamble_transmission_counter=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X.sub.i+(preamble_transmission _counter−1)*powerRampingStep, preambleInitialReceivedTargetPower is an initial target receive power of the preamble sequence, DELTA_PREAMBLE is a power offset based on a preamble sequence format of the preamble sequence, powerRampingStep is a power ramp step, preamble_transmission _counter is a transmission count of the preamble sequence with an initial value of 1, and X.sub.i is a power offset corresponding to a repetition count, the repetition count corresponding to a preamble sequence resource i, and wherein the power offset X.sub.i meets: PREAMBLE_RECEIVED _TARGET_POWER.sub.i.sup.preamble_transmission_counter+PL−P.sub.max≤Δ, wherein Δ≥0, and Δ is a constant and a preset threshold.

2. The method according to claim 1, further comprising: determining the power offset X.sub.i, wherein determining the power offset X.sub.i comprises: searching for the power offset X.sub.i in ascending order of power offsets, or searching for the power offset X.sub.i in ascending order of repetition counts for transmitting the preamble sequence.

3. The method according to claim 1, wherein the sending, by the user equipment, the preamble sequence comprises: sending, by the user equipment, the preamble sequence using the repetition count corresponding to the preamble sequence resource i.

4. The method according to claim 1, wherein the determined transmit power is PREAMBLE_RECEIVED _TARGET_POWER.sub.i.sup.preamble_transmission_counter+PL.

5. The method according to claim 1, wherein the repetition count corresponding to the preamble sequence resource i is comprised in information about the preamble sequence resource i.

6. The method according to claim 5, wherein the information about the preamble sequence resource i for coverage enhancement random access is obtained from system information or is preset.

7. An apparatus, comprising: one or more processors, and a non-transitory storage medium in communication with the one or more processors, the non-transitory storage medium including program instructions, wherein, when executed by the one or more processors, the instructions cause the apparatus to perform: determining a transmit power for sending a preamble sequence, wherein the transmit power meets the following formula: Power=min{P.sub.max, PREAMBLE_RECEIVED _TARGET_POWER.sub.i.sup.preamble_transmission_counter+PL}; and sending the preamble sequence according to the determined transmit power through a resource i; wherein Power is the determined transmit power, P.sub.max is a maximum transmit power of the apparatus, PL is obtained by estimating according to a downlink path loss, PREAMBLE_RECEIVED _TARGET_POWER.sub.i.sup.preamble_transmission_counter is a target receive power of the preamble sequence, and the resource i is a preamble sequence resource for coverage enhancement random access; wherein PREAMBLE_RECEIVED _TARGET_POWER.sub.i.sup.preamble_transmission_counter meets PREAMBLE_RECEIVED _TARGET_POWER.sub.i.sup.preamble_transmission_counter=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X.sub.i+(preamble_transmission _counter−1)*powerRampingStep, preambleInitialReceivedTargetPower is an initial target receive power of the preamble sequence, DELTA_PREAMBLE is a power offset based on a format of the preamble sequence, powerRampingStep is a power ramp step, preamble_transmission _counter is a transmission count of the preamble sequence with an initial value of 1, and X.sub.i is a power offset corresponding to a repetition count, the repetition count corresponding to a preamble sequence resource i, and wherein the power offset X meets: PREAMBLE_RECEIVED _TARGET_POWER.sub.i.sup.preamble_transmission_counter+PL−P.sub.max≤Δ, wherein Δ≥0, and Δ is a constant and a preset threshold.

8. The apparatus according to claim 7, wherein the method further comprises: determining the power offset X.sub.i, wherein determining the power offset X.sub.i comprises: searching for the power offset X.sub.i in ascending order of power offsets; or searching for the power offset X.sub.i in ascending order of repetition counts for transmitting the preamble sequence.

9. The apparatus according to claim 7, wherein the sending the preamble sequence further comprising: sending the preamble sequence by using the repetition count corresponding to the preamble sequence resource i.

10. The apparatus according to claim 7, wherein the determined transmit power is: PREAMBLE_RECEIVED _TARGET_POWER.sub.i.sup.preamble_transmission_counter+PL.

11. The apparatus according to claim 7, wherein the repetition count corresponding to the preamble sequence resource i is comprised in information about the preamble sequence resource i.

12. The apparatus according to claim 11, wherein the information about the preamble sequence resource i for coverage enhancement random access is obtained from system information or is preset.

13. A non-transitory computer-readable medium having program instructions recorded thereon, wherein, when executed by a processor of a terminal device, the instructions cause the terminal device to: determine a transmit power for sending a preamble sequence, wherein the transmit power meets the following formula: Power=min{P.sub.max, PREAMBLE_RECEIVED _TARGET_POWER.sub.i.sup.preamble_transmission_counter+PL}; send the preamble sequence according to the determined transmit power through a resource i; wherein Power is the determined transmit power, P.sub.max is a maximum transmit power of the terminal device, PL is obtained by estimating according to a downlink path loss, PREAMBLE_RECEIVED _TARGET_POWER.sub.i.sup.preamble_transmission_counter is a target receive power of the preamble sequence, and the resource i is a preamble sequence resource for coverage enhancement random access; PREAMBLE_RECEIVED _TARGET_POWER.sub.i.sup.preamble_transmission_counter meets: PREAMBLE_RECEIVED _TARGET_POWER.sub.i.sup.preamble_transmission_counter=preambleInitialReceivedTargetPower+DELTA_PREAMBLE—X.sub.i+(preamble_transmission _counter−1)*powerRampingStep, preambleInitialReceivedTargetPower is an initial target receive power of the preamble sequence, DELTA_PREAMBLE is a power offset based on a format of the preamble sequence, powerRampingStep is a power ramp step, preamble_transmission _counter is a transmission count of the preamble sequence with an initial value of 1, and X.sub.i is a power offset corresponding to a repetition count, the repetition count corresponding to a preamble sequence resource i, wherein the power offset X.sub.i meets: PREAMBLE_RECEIVED _TARGET_POWER.sub.i.sup.preamble_transmission_counter+PL−P.sub.max≤Δ, wherein Δ≥0, and Δ is a constant and a preset threshold.

14. The non-transitory computer-readable medium according to claim 13, wherein the instructions cause the terminal device further to: send the preamble sequence by using the repetition count corresponding to the preamble sequence resource i.

15. The non-transitory computer-readable medium according to claim 13, wherein the repetition count corresponding to the preamble sequence resource i is comprised in information about the preamble sequence resource i.

16. The non-transitory computer-readable medium according to claim 15, wherein the information about the preamble sequence resource i for coverage enhancement random access is obtained from system information or is preset.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) To describe the technical solutions in the embodiments of the present disclosure or in the prior art more clearly, the following briefly introduces the accompanying drawings required for describing the embodiments or the prior art. Apparently, the accompanying drawings in the following description show some embodiments of the present disclosure, and a person of ordinary skill in the art may still derive other drawings from these accompanying drawings without creative efforts.

(2) FIG. 1 is a schematic diagram in which in the prior art, user equipment repeatedly sends a sequence, and powers collected in a corresponding resource pool by a target base station are different;

(3) FIG. 2 is a flowchart of an implementation manner of a method for sending a preamble sequence according to the present disclosure;

(4) FIG. 3 is a schematic structural diagram of a first implementation manner of user equipment according to the present disclosure; and

(5) FIG. 4 is a schematic structural diagram of a second implementation manner of user equipment according to the present disclosure.

DETAILED DESCRIPTION

(6) The following describes the present disclosure in detail with reference to the accompanying drawings and implementation manners.

(7) Referring to FIG. 2, FIG. 2 is a flowchart of an implementation manner of the method sending a preamble sequence according to the present disclosure. As shown in FIG. 2, the method includes the following steps:

(8) Step 201: Determine a transmit power for sending a preamble sequence, where the transmit power is as follows:

(9) Power=min{P max,PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter+PL}

(10) Power is the determined transmit power, P max is a maximum transmit power of user equipment, PL is a path loss value obtained by estimating according to a downlink path loss, and PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter is a target receive power of the preamble sequence, where

(11) PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X.sub.i+(preamble_transmission_counter−1)*powerRampingStep.

(12) preambleInitialReceivedTargetPower is an initial target receive power of the preamble sequence, where the initial target receive power of the preamble sequence may be notified by a target base station by using system information, and the initial target receive power preambleInitialReceivedTargetPower of the preamble sequence may be set to −120 dBm, −118 dBm, −116 dBm, or the like. DELTA_PREAMBLE is a power offset based on a format of the preamble sequence, and values are shown in the following table:

(13) TABLE-US-00002 Values of DELTA_PREAMBLE Format of a preamble sequence Value of DELTA_PREAMBLE 0 0 dB 1 0 dB 2 −3 dB  3 −3 dB  4 8 dB

(14) X.sub.i is a power offset corresponding to a preamble sequence resource pool i for coverage enhancement random access. preamble_transmission_counter is a repetition count for transmitting the preamble sequence, where preamble_transmission_counterϵ{1, 2, . . . , preambleTransMax} and is set to 1 during initial access, and preambleTransMax is a system parameter and is a maximum transmission count of the preamble sequence, powerRampingStep is a power ramp step, where the power ramp step may be notified by the target base station by using the system information, and the power ramp step powerRampingStep that is of the preamble sequence and is broadcast by the target base station may be set to 0 dB, 2 dB, 4 dB, 6 dB, or the like.

(15) It can be learned from the foregoing MIN formula that, when PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter+PL is less than P max, a transmit power value of the preamble sequence of the user equipment is set to PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter+PL; otherwise, a transmit power value of the preamble sequence of the user equipment is set to P max.

(16) For X.sub.i, it should further be noted that, information that is used for a preamble sequence resource pool for coverage enhancement random access and is set by the base station includes a corresponding repetition count (that is, occupied transmission time intervals) and/or information about a corresponding coverage enhancement amount (dB), and may be obtained by notifying the system information of the base station, or may be obtained in a predefined manner. The information about the preamble sequence resource pool for coverage enhancement random access includes the corresponding repetition count R, that is, a quantity of the occupied transmission time intervals, and/or the information X about the corresponding coverage enhancement amount (dB), and there is a correspondence between the repetition count, that is, the quantity of the occupied transmission time intervals, corresponding to the preamble sequence resource pool for coverage enhancement random access, and the corresponding coverage enhancement amount (dB). Therefore, the information can still be finally obtained even if the information about the coverage enhancement amount (dB) does not exist.

(17) The power offset X.sub.i is a coverage enhancement amount corresponding to the preamble sequence resource pool i for coverage enhancement random access, or the power offset X.sub.i is a coverage enhancement amount that is corresponding to the repetition count, that is, occupied transmission time intervals, corresponding to the preamble sequence resource pool i for coverage enhancement random access. Further, the power offset X.sub.i is obtained from the information about the preamble sequence resource pool for coverage enhancement random access, where the information about the preamble sequence resource pool for coverage enhancement random access is obtained by notifying the system information, or is obtained in a manner predefined by a current device.

(18) In an implementation manner of the present disclosure, the target receive power preambleInitialReceivedTargetPower, in the system information, of the preamble sequence resource pool for coverage enhancement random access may be defined, so that the target receive power includes the coverage enhancement amount X dB. For example, for common user equipment, an initial target receive power of a preamble sequence resource pool for random access is preambleInitialReceivedTargetPower, and a target receive power of a preamble sequence resource pool for coverage enhancement random access is preambleInitialReceivedTargetPower−X, where X is a power offset; then:

(19) PREAMBLE_RECEIVED_TARGET_POWER=preambleInitialReceivedTargetPower+DELTA_PREAMBLE+(preamble_transmission_counter−1)*powerRampingStep.

(20) In another implementation of the present disclosure, if the initial target receive power that is of the preamble sequence and is broadcast by a system is preambleInitialReceivedTargetPower, the target receive power of the preamble sequence resource pool for coverage enhancement random access is as follows:

(21) PREAMBLE_RECEIVED_TARGET_POWER=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X+(preamble_transmission_counter−1)*powerRampingStep.

(22) In this case, the power offset X is a coverage enhancement amount. The user equipment needs to use the preamble sequence resource pool for coverage enhancement random access; and a transmit power of the user equipment at each transmission time interval is:

(23) Power=min{Pmax,PREAMBLE_RECEIVED_TARGET_POWER+PL} [dBm], where

(24) min{ } is a MIN function, and P.sub.max is the maximum transmit power of the user equipment.

(25) PREAMBLE_RECEIVED_TARGET_POWER is the target receive power of the preamble sequence resource pool.

(26) X is the power offset corresponding to the preamble sequence resource pool, that is, the coverage enhancement amount (dB).

(27) PL is a path loss value obtained by estimating according to the downlink path loss. More generally, the base station may set N preamble sequence resource pools for coverage enhancement random access, where N is a positive integer. Each preamble sequence resource pool for coverage enhancement random access includes a corresponding repetition count, that is, occupied transmission time intervals, and/or information about a corresponding coverage enhancement amount (dB) that is represented by X.sub.i, where iϵ{1, . . . , N}, that is, there are at least two power offsets X.sub.i. For ease of description, the preamble sequence resource pool for coverage enhancement random access is referred to as a preamble sequence resource pool for short in the following.

(28) If the initial target receive power of the preamble sequence of a system is preambleInitialReceivedTargetPower, a target receive power of the i.sup.th preamble sequence resource pool for coverage enhancement random access is as follows:

(29) PREAMBLE_RECEIVED_TARGET_POWER=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X.sub.i+(preamble_transmission_counter−1)*powerRampingStep.

(30) It is assumed that there are N preamble sequence resource pools for coverage enhancement random access in the system, where N is a positive integer. From the first preamble sequence resource pool for coverage enhancement random access to the N.sup.th preamble sequence resource pool for coverage enhancement random access, corresponding sequence repetition counts (occupied transmission time intervals) are {R.sub.1, . . . , R.sub.N}, and power offsets corresponding to the first preamble sequence resource pool for coverage enhancement random access to the N.sup.th preamble sequence resource pool for coverage enhancement random access are {X.sub.1, . . . , X.sub.N}. A definition of a power offset is a coverage enhancement amount corresponding to the resource, or may be any power offset defined by the system.

(31) If the initial target receive power of the preamble sequence defined by the system is preambleInitialReceivedTargetPower, the power ramp step is powerRampingStep, and generally, when the first random access is initiated and preamble_transmission_counter=1, step 201 may further be specifically as follows:

(32) during transmit power calculation, superposing power offsets in ascending order or descending order of repetition counts R or power offsets X; and stopping until X.sub.i that meets the following formula is found according to calculation of the following formulas, or if the following inequality cannot be met after all R.sub.i or X.sub.i are traversed, performing transmission according to the maximum transmit power P max, where:

(33) PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.1=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X.sub.i+(preamble_transmission_counter−1)*powerRampingStep; and

(34) PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.1+PL−P max≤Δ, where Δ≥0, and Δ is a constant and a preset threshold.

(35) If the user equipment uses the preamble sequence resource pool i for coverage enhancement random access, during initial access of the user equipment, a transmit power at each transmission time interval is:

(36) Power=min{P max,PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.1+PL} [dBm].

(37) However, it is not ensured that successful access can be implemented when the first random access is initiated, and successful access may be implemented only after power ramping is performed. In an original resource pool, a target power requirement that is imposed after power ramping is performed may be met; and the resource pool does not need to be changed. Alternatively, in an original resource pool, a target power requirement that is imposed after power ramping is performed cannot be met; and the resource pool need to be changed to a resource pool corresponding to a larger repetition count/a larger coverage enhancement amount. Therefore, the following uses an example of multiple times of random access so as to ensure that a process thereof can be clearly described.

(38) It is assumed that there are N preamble sequence resource pools for coverage enhancement random access in the system, where N is a positive integer. From the first preamble sequence resource pool for coverage enhancement random access to the N.sup.th preamble sequence resource pool for coverage enhancement random access, corresponding sequence repetition counts are {R.sub.1, . . . , R.sub.N}, and power offsets corresponding to the first preamble sequence resource pool for coverage enhancement random access to the N.sup.th preamble sequence resource pool for coverage enhancement random access are {X.sub.1, . . . , X.sub.N}. A definition of a power offset is a coverage enhancement amount corresponding to the resource, or may be any power offset defined by the system due to coverage enhancement.

(39) If the initial target receive power of the preamble sequence defined by the system is preambleInitialReceivedTargetPower, and the power ramp step is powerRampingStep, when preamble_transmission_counter=1, a procedure is as follows:

(40) During transmit power calculation, the user equipment superposes power offsets in ascending order of repetition counts R{R.sub.1, . . . , R.sub.N} or power offsets X{X.sub.1, . . . , X.sub.N}; and may stop until X.sub.i that meets the following formula is found according to calculation of the following formulas, or if the following inequality cannot be met after all R.sub.i or X.sub.i are traversed, perform transmission according to the maximum transmit power P max, where

(41) an initial value of preamble_transmission_counter is 1; and

(42) the following is calculated in ascending order of X.sub.i:

(43) PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.1=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X.sub.i+(preamble_transmission_counter−1)*powerRampingStep; and

(44) PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.1+PL−P max≤Δ, where Δ≥0, and Δ is a constant and a preset threshold.

(45) When the foregoing inequality is met, calculation is stopped, the preamble sequence resource pool i for coverage enhancement random access is selected, and the transmit power of the preamble sequence is set to PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.1+PL [dBm]; or the inequality is not met after all X.sub.i are traversed, and the transmit power of the preamble sequence is set to.

(46) Step 202: Send the preamble sequence according to the determined transmit power.

(47) Further, if the user equipment has not received a response from the base station side within a set time window after sending the preamble sequence, it is considered that current transmission fails. preamble_transmission_counter=preamble_transmission_counter+1, where preamble_transmission_counterϵ{1, 2, . . . , preambleTransMax}. Power ramping (power ramping) is performed according to the power ramp step powerRampingStep broadcast by the system. According to the formulas, first, it is assumed that the preamble sequence resource pool for coverage enhancement random access is not changed, that is, X.sub.i is not changed, and the calculation is performed again:

(48) PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X.sub.i+(preamble_transmission_counter−1)*powerRampingStep; and

(49) PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter+PL−P max≤Δ, where Δ≥0, and Δ is a constant and a preset threshold.

(50) If the inequality is still met, the preamble sequence resource pool i for coverage enhancement random access continues to be selected. A target receive power that is of the preamble sequence and is corresponding to preamble_transmission_counter (that is already increased by 1 for itself) in this case is PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter. The transmit power of the preamble sequence is set to PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter+PL [dBm].

(51) If the inequality cannot be met, i=i+1, the preamble sequence resource pool for coverage enhancement random access is changed in ascending order of X.sub.i, and the calculation is performed again:

(52) PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X.sub.i+(preamble.sub.—transmission_counter−1)*powerRampingStep; and and PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter+PL−P max≤Δ, where Δ≥0, and Δ is a constant and a preset threshold.

(53) Until the inequality is met, a preamble sequence resource pool for coverage enhancement random access corresponding to X.sub.i in this case is selected. A target receive power that is of the preamble sequence and is corresponding to preamble_transmission_counter in this case is PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter. The transmit power of the preamble sequence is set to (PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter) [dBm].

(54) Alternatively, the inequality is not met after all X.sub.i are traversed, and the transmit power of the preamble sequence is set to P max.

(55) In brief, step 201 may also include:

(56) obtaining the transmit power according to the power offset X.sub.i, and sending the preamble sequence according to the transmit power, to perform the preamble_transmission_counter.sub.th random access;

(57) if the preamble_transmission_counter.sub.th random access fails, making preamble_transmission_counter=preamble_transmission_counter+1, keeping X.sub.i unchanged, and calculating the following again:

(58) PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X.sub.i+(preamble_transmission_counter−1)*powerRampingStep; and

(59) if a condition that PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter+PL−P max≤Δ is met, performing transmission by using the repetition count corresponding to the preamble sequence resource pool i for coverage enhancement random access, where the transmit power is PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter+PL; or

(60) if a condition that PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter+PL−P max≤Δ is not met, searching for the power offset X.sub.i in ascending order of repetition counts, that is, occupied transmission time intervals, or the power offsets X.sub.i, and determining whether the found power offset X.sub.i meets that PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter+PL−P max≤Δ; and if a minimum value of X.sub.i that meets the foregoing formula is found, performing transmission by using the repetition count corresponding to the preamble sequence resource pool i for coverage enhancement random access, where the transmit power is PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter+PL; or if the foregoing inequality cannot be met after all X.sub.i are traversed, performing transmission by using a repetition count corresponding to a preamble sequence resource pool i for coverage enhancement random access that is found at last, where the transmit power is P max, and Δ≥0, and Δ is a constant and a preset threshold.

(61) In this implementation manner of the present disclosure, when user equipment performs transmission by using a preamble sequence resource pool for coverage enhancement random access, during transmit power calculation, a power offset is introduced, that is, a power gain brought by means of repeated transmission performed by using the preamble sequence resource pool for coverage enhancement random access is introduced, and the gain is converted for the transmit power calculation. Because the repeated transmission itself brings a coverage enhancement amount (dB) X, when a target receive power of a preamble sequence is calculated, the gain is deducted, and

(62) PREAMBLE_RECEIVED_TARGET_POWER=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X.sub.i+(preamble_transmission_counter−1)*powerRampingStep. That is, the target receive power of the preamble sequence may be correspondingly decreased by X dB. After such calculation is performed, according to the prior art, PREAMBLE_RECEIVED_TARGET_POWER+PL is also correspondingly decreased by X dB, and a transmit power Power=min{P max,PREAMBLE_RECEIVED_TARGET_POWER+PL} [dbm] is calculated. For user equipments whose coverage enhancement requirements are less than or equal to X dB, that is, all users who meet PREAMBLE_RECEIVED_TARGET_POWER+PL−P max≤X, because PREAMBLE_RECEIVED_TARGET_POWER+PL has been correspondingly decreased by X dB, in this case, PREAMBLE_RECEIVED_TARGET_POWER+PL is less than P max, that is, according to calculation of the formulas, a transmit power is PREAMBLE_RECEIVED_TARGET_POWER+PL. In this way, it may be ensured that receive powers received on a base station side are close to each other and are PREAMBLE_RECEIVED_TARGET_POWER, thereby overcoming a near-far effect. Likewise, all user equipments whose coverage enhancement requirements are less than or equal to X dB perform transmission according to the transmit power: PREAMBLE_RECEIVED_TARGET_POWER+PL, so that a path loss is overcome, a same target receive power is achieved, and no power is wasted.

(63) Referring to FIG. 3, FIG. 3 is a schematic structural diagram of a first implementation manner of user equipment according to the present disclosure. As shown in FIG. 3, user equipment 30 includes a determining module 301 and a sending module 302.

(64) The determining module 301 is configured to determine a transmit power for sending a preamble sequence, where the transmit power meets the following formula:

(65) Power=min{P max,PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter+PL}

(66) Power is the determined transmit power, P max is a maximum transmit power of the user equipment, PL is a path loss value obtained by estimating according to a downlink path loss, and PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter is a target receive power of the preamble sequence, where

(67) PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X.sub.i+(preamble_transmission_counter−1)*powerRampingStep.

(68) preambleInitialReceivedTargetPower is an initial target receive power of the preamble sequence, where the initial target receive power of the preamble sequence may be notified by a target base station by using system information, and the initial target receive power preambleInitialReceivedTargetPower of the preamble sequence may be set to −120 dBm, −118 dBm, −116 dBm, or the like. DELTA_PREAMBLE is a power offset based on a format of the preamble sequence, and values are shown in the following table:

(69) TABLE-US-00003 Values of DELTA_PREAMBLE Format of a preamble sequence Value of DELTA_PREAMBLE 0 0 dB 1 0 dB 2 −3 dB  3 −3 dB  4 8 dB

(70) X.sub.i is a power offset corresponding to a preamble sequence resource pool i for coverage enhancement random access. preamble_transmission_counter is a repetition count for transmitting the preamble sequence, where preamble_transmission_counterϵ{1, 2, . . . , preambleTransMax} and is set to 1 during initial access, and preambleTransMax is a system parameter and is a maximum transmission count of the preamble sequence. powerRampingStep is a power ramp step, where the power ramp step may be notified by the target base station by using the system information, and the power ramp step powerRampingStep that is of the preamble sequence and is broadcast by the target base station may be set to 0 dB, 2 dB, 4 dB, 6 dB, or the like.

(71) It can be learned from the foregoing MIN formula that, when PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter+PL is less than P max, a transmit power value of the preamble sequence of the user equipment is set to PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter+PL; otherwise, a transmit power value of the preamble sequence of the user equipment is set to P max.

(72) For X.sub.i, it should further be noted that, information that is used for a preamble sequence resource pool for coverage enhancement random access and is set by the base station includes a corresponding repetition count (that is, occupied transmission time intervals) and/or information about a corresponding coverage enhancement amount (dB), and may be obtained by notifying the system information of the base station, or may be obtained in a predefined manner. The information about the preamble sequence resource pool for coverage enhancement random access includes the corresponding repetition count R, that is, a quantity of the occupied transmission time intervals, and/or the information X about the corresponding coverage enhancement amount (dB), and there is a correspondence between the repetition count, that is, the quantity of the occupied transmission time intervals, corresponding to the preamble sequence resource pool for coverage enhancement random access, and the corresponding coverage enhancement amount (dB). Therefore, the information can still be finally obtained even if the information about the coverage enhancement amount (dB) does not exist.

(73) The power offset X.sub.i is a coverage enhancement amount corresponding to the preamble sequence resource pool i for coverage enhancement random access, or the power offset X.sub.i is a coverage enhancement amount that is corresponding to the repetition count, that is, occupied transmission time intervals, corresponding to the preamble sequence resource pool i for coverage enhancement random access. Further, the power offset X.sub.i is obtained from the information about the preamble sequence resource pool for coverage enhancement random access, where the information about the preamble sequence resource pool for coverage enhancement random access is obtained by notifying the system information, or is obtained in a manner predefined by a current device.

(74) In an implementation of the present disclosure, the target receive power preambleInitialReceivedTargetPower, in the system information, of the preamble sequence resource pool for coverage enhancement random access may be defined, so that the target receive power includes the coverage enhancement amount (dB) X. For example, for common user equipment, an initial target receive power of a preamble sequence resource pool for random access is preambleInitialReceivedTargetPower, and a target receive power of a preamble sequence resource pool for coverage enhancement random access is preambleInitialReceivedTargetPower−X, where X is a power offset; then:

(75) PREAMBLE_RECEIVED_TARGET_POWER=preambleInitialReceivedTargetPower+DELTA_PREAMBLE+(preamble.sub.—preamble_transmission_counter−1)*powerRampingStep.

(76) In another implementation of the present disclosure, if the initial target receive power that is of the preamble sequence and is broadcast by a system is preambleInitialReceivedTargetPower, the target receive power of the preamble sequence resource pool for coverage enhancement random access is as follows:

(77) PREAMBLE_RECEIVED_TARGET_POWER=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X+(preamble_transmission_counter−1)*powerRampingStep.

(78) In this case, the power offset X is a coverage enhancement amount. The user equipment needs to use the preamble sequence resource pool for coverage enhancement random access; and a transmit power of the user equipment at each transmission time interval is:

(79) Power=min{Pmax,PREAMBLE_RECEIVED_TARGET_POWER+PL} [dBm], where

(80) min{ } is a MIN function, and P.sub.max is the maximum transmit power of the user equipment.

(81) PREAMBLE_RECEIVED_TARGET_POWER is the target receive power of the preamble sequence resource pool.

(82) X is the power offset corresponding to the preamble sequence resource pool, that is, the coverage enhancement amount (dB).

(83) PL is a path loss value obtained by estimating according to the downlink path loss. More generally, the base station may set N preamble sequence resource pools for coverage enhancement random access, where N is a positive integer. Each preamble sequence resource pool for coverage enhancement random access includes a corresponding repetition count, that is, occupied transmission time intervals, and/or information about a corresponding coverage enhancement amount (dB) that is represented by X.sub.i, where iϵ{1, . . . , N}, that is, there are at least two power offsets X.sub.i. For ease of description, the preamble sequence resource pool for coverage enhancement random access is referred to as a preamble sequence resource pool for short in the following.

(84) If the initial target receive power of the preamble sequence of a system is preambleInitialReceivedTargetPower, a target receive power of the i.sup.th preamble sequence resource pool for coverage enhancement random access is as follows:

(85) PREAMBLE_RECEIVED_TARGET_POWER=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X.sub.i+(preamble_transmission_counter−1)*powerRampingStep.

(86) It is assumed that there are N preamble sequence resource pools for coverage enhancement random access in the system, where N is a positive integer. From the first preamble sequence resource pool for coverage enhancement random access to the N.sup.th preamble sequence resource pool for coverage enhancement random access, corresponding sequence repetition counts are {R.sub.1, . . . , R.sub.N}, and power offsets corresponding to the first preamble sequence resource pool for coverage enhancement random access to the N.sup.th preamble sequence resource pool for coverage enhancement random access are {X.sub.1, . . . , X.sub.N}. A definition of a power offset is a coverage enhancement amount corresponding to the resource, or may be any power offset defined by the system.

(87) If the initial target receive power of the preamble sequence defined by the system is preambleInitialReceivedTargetPower, the power ramp step is powerRampingStep, and generally, when the first random access is initiated and preamble_transmission_counter=1, the determining module 301 may further be specifically as follows:

(88) during transmit power calculation, superposing power offsets in ascending order or descending order of repetition counts R or power offsets X; and stopping until X.sub.i that meets the following formula is found according to calculation of the following formulas, or if the following inequality cannot be met after all R.sub.i or X.sub.i are traversed, performing transmission according to the maximum transmit power P max, where:

(89) PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.1=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X.sub.i+(preamble_transmission_counter−1)*powerRampingStep; and

(90) PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.1+PL−P max≤Δ, where Δ≥0, and Δ is a constant and a preset threshold.

(91) If the user equipment uses the preamble sequence resource pool i for coverage enhancement random access, during initial access of the user equipment, a transmit power at each transmission time interval is:

(92) Power=min{P max,PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.1+PL} [dBm].

(93) However, it is not ensured that successful access can be implemented when the first random access is initiated, and successful access may be implemented only after power ramping is performed. In an original resource pool, a target power requirement that is imposed after power ramping is performed may be met; and the resource pool does not need to be changed. Alternatively, in an original resource pool, a target power requirement that is imposed after power ramping is performed cannot be met; and the resource pool needs to be changed to a resource pool corresponding to a larger repetition count/a larger coverage enhancement amount. Therefore, the following uses an example of multiple times of random access so as to ensure that a process thereof can be clearly described.

(94) It is assumed that there are N preamble sequence resource pools for coverage enhancement random access in the system, where N is a positive integer. From the first preamble sequence resource pool for coverage enhancement random access to the N.sup.th preamble sequence resource pool for coverage enhancement random access, corresponding sequence repetition counts are {R.sub.1, . . . , R.sub.N}, and power offsets corresponding to the first preamble sequence resource pool for coverage enhancement random access to the N.sup.th preamble sequence resource pool for coverage enhancement random access are {X.sub.1, . . . , X.sub.N}. A definition of a power offset is a coverage enhancement amount corresponding to the resource, or may be any power offset defined by the system due to coverage enhancement.

(95) If the initial target receive power of the preamble sequence defined by the system is preambleInitialReceivedTargetPower, and the power ramp step is powerRampingStep, when preamble_transmission_counter=1, a procedure is as follows:

(96) During transmit power calculation, the user equipment superposes power offsets in ascending order of repetition counts R{R.sub.1, . . . , R.sub.N} or power offsets X{X.sub.1, . . . , X.sub.N}, and may stop until X.sub.i that meets the following formula is found according to calculation of the following formulas, or if the following inequality cannot be met after all R.sub.i or X.sub.i are traversed, perform transmission according to the maximum transmit power P max, where

(97) an initial value of preamble_transmission_counter is 1; and

(98) the following is calculated in ascending order of X.sub.i:

(99) PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.1=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X.sub.i+(preamble_transmission_counter−1)*powerRampingStep; and

(100) PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.1+PL−P.sub.max≤Δ, where Δ≥0, and Δ is a constant and a preset threshold.

(101) When the foregoing inequality is met, calculation is stopped, the preamble sequence resource pool i for coverage enhancement random access is selected, and the transmit power of the preamble sequence is set to PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.1+PL [dBm]; or the inequality is not met after all X.sub.i are traversed, and the transmit power of the preamble sequence is set to P max.

(102) The sending module 302 is configured to send the preamble sequence according to the determined transmit power.

(103) Further, if the user equipment 30 has not received a response from the base station side within a set time window after sending the preamble sequence, it is considered that current transmission fails. preamble_transmission_counter=preamble_transmission_counter+1, where preamble_transmission_counterϵ{1, 2, . . . , preambleTransMax}. Power ramping (power ramping) is performed according to the power ramp step powerRampingStep broadcast by the system. According to the formulas, first, it is assumed that the preamble sequence resource pool for coverage enhancement random access is not changed, that is, X.sub.i is not changed, and the calculation is performed again:

(104) PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X.sub.i+(preamble_transmission_counter−1)*powerRampingStep; and

(105) PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter+PL−P max≤Δ, where Δ≥0, and Δ is a constant and a preset threshold.

(106) If the inequality is still met, the preamble sequence resource pool i for coverage enhancement random access continues to be selected. The target receive power that is of the preamble sequence and is corresponding to preamble_transmission_counter (that is already increased by 1 for itself) in this case is PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter. The transmit power of the preamble sequence is set to PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter+PL [dBm].

(107) If the inequality cannot be met, i=i+1, the preamble sequence resource pool for coverage enhancement random access is changed in ascending order of X.sub.i, and the calculation is performed again:

(108) PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X.sub.i+(preamble_transmission_counter−1)*powerRampingStep; and

(109) PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter+PL−P max≤Δ, where Δ≥0, and Δ is a constant and a preset threshold.

(110) Until the inequality is met, a preamble sequence resource pool for coverage enhancement random access corresponding to X.sub.i in this case is selected. The target receive power that is of the preamble sequence and is corresponding to preamble_transmission_counter (that is already increased by 1 for itself) in this case is PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter. The transmit power of the preamble sequence is set to (PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter) [dBm].

(111) Alternatively, the inequality is not met after all X.sub.i are traversed, and the transmit power of the preamble sequence is set to P max.

(112) In brief, the determining module 301 may also be specifically configured to: obtain the transmit power according to the power offset X.sub.i, and send the preamble sequence according to the transmit power, to perform the preamble_transmission_counter.sub.th random access;

(113) if the preamble_transmission_counter.sub.th random access fails, make preamble_transmission_counter=preamble_transmission_counter+1, keep X.sub.i unchanged, and calculate the following again:

(114) PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X.sub.i+(preamble.sub.—transmission_counter−1)*powerRampingStep; and

(115) if a condition that PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter+PL−P max≤Δ is met, perform transmission by using the repetition count corresponding to the preamble sequence resource pool i for coverage enhancement random access, where the transmit power is PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter+PL; or

(116) if a condition that PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter+PL−P max≤Δ is not met, search for the power offset X.sub.i in ascending order of repetition counts, that is, occupied transmission time intervals, or the power offsets X.sub.i, and determine whether the found power offset X.sub.i meets that PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter+PL−P max≤Δ; and if a minimum value of X.sub.i that meets the foregoing formula is found, performing transmission by using the repetition count corresponding to the preamble sequence resource pool i for coverage enhancement random access, where the transmit power is PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter+PL; or if the foregoing inequality cannot be met after all X.sub.i are traversed, performing transmission by using a repetition count corresponding to a preamble sequence resource pool i for coverage enhancement random access that is found at last, where the transmit power is P max, and Δ≥0, and Δ is a constant and a preset threshold.

(117) In this implementation manner of the present disclosure, when the user equipment performs transmission by using a preamble sequence resource pool for coverage enhancement random access, during transmit power calculation, a power offset is introduced, that is, a power gain brought by means of repeated transmission performed by using the preamble sequence resource pool for coverage enhancement random access is introduced, and the gain is converted for the transmit power calculation. Because the repeated transmission itself brings a coverage enhancement amount (dB) X, when a target receive power of a preamble sequence is calculated, the gain is deducted, and

(118) PREAMBLE_RECEIVED_TARGET_POWER=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X.sub.i+(preamble_transmission_counter−1)*powerRampingStep. That is, the target receive power of the preamble sequence may be correspondingly decreased by X dB. After such calculation is performed, according to the prior art, PREAMBLE_RECEIVED_TARGET_POWER+PL is also correspondingly decreased by X dB; and a transmit power Power=min{P max,PREAMBLE_RECEIVED_TARGET_POWER+PL} [dbm] is calculated. For user equipments whose coverage enhancement requirements are less than or equal to X dB, that is, all users who meet PREAMBLE_RECEIVED_TARGET_POWER+PL−P max≤X, because PREAMBLE_RECEIVED_TARGET_POWER+PL has been correspondingly decreased by X dB, in this case, PREAMBLE_RECEIVED_TARGET_POWER+PL is less than P max, that is, according to calculation of the formulas, a transmit power is PREAMBLE_RECEIVED_TARGET_POWER+PL. In this way, it may be ensured that receive powers received on a base station side are close to each other and are PREAMBLE_RECEIVED_TARGET_POWER, thereby overcoming a near-far effect. Likewise, all user equipments whose coverage enhancement requirements are less than or equal to X dB perform transmission according to the transmit power:

(119) PREAMBLE_RECEIVED_TARGET_POWER+PL, so that a path loss is overcome, a same target receive power is achieved, and no power is wasted.

(120) Referring to FIG. 4, FIG. 4 is a schematic structural diagram of a second implementation manner of user equipment according to the present disclosure. As shown in FIG. 4, user equipment 40 includes a processor 401 and a sender 402.

(121) The processor 401 is configured to execute the following operation by using an operation instruction:

(122) determining a transmit power for sending a preamble sequence, where the transmit power meets the following formula: Power=min{P max,PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter+PL}

(123) Power is the determined transmit power, P max is a maximum transmit power of the user equipment, PL is a path loss value obtained by estimating according to a downlink path loss, and PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter is a target receive power of the preamble sequence, where

(124) PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X.sub.i+(preamble_transmission_counter−1)*powerRampingStep.

(125) preambleInitialReceivedTargetPower is an initial target receive power of the preamble sequence, where the initial target receive power of the preamble sequence may be notified by a target base station by using system information, and the initial target receive power preambleInitialReceivedTargetPower of the preamble sequence may be set to −120 dBm, −118 dBm, −116 dBm, or the like. DELTA_PREAMBLE is a power offset based on a format of the preamble sequence, and values are shown in the following table:

(126) TABLE-US-00004 Values of DELTA_PREAMBLE Format of a preamble sequence Value of DELTA_PREAMBLE 0 0 dB 1 0 dB 2 −3 dB  3 −3 dB  4 8 dB

(127) X.sub.i is a power offset corresponding to a preamble sequence resource pool i for coverage enhancement random access. preamble_transmission_counter is a repetition count for transmitting the preamble sequence, where preamble_transmission_counterϵ{1, 2, . . . , preambleTransMax} and is set to 1 during initial access, and preambleTransMax is a system parameter and is a maximum transmission count of the preamble sequence, powerRampingStep is a power ramp step, where the power ramp step may be notified by the target base station by using the system information, and the power ramp step powerRampingStep that is of the preamble sequence and is broadcast by the target base station may be set to 0 dB, 2 dB, 4 dB, 6 dB, or the like.

(128) It can be learned from the foregoing MIN formula that, when PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter+PL is less than P max, a transmit power value of the preamble sequence of the user equipment is set to PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter+PL; otherwise, a transmit power value of the preamble sequence of the user equipment is set to P max.

(129) For X.sub.i, it should further be noted that, information that is used for a preamble sequence resource pool for coverage enhancement random access and is set by the base station includes a corresponding repetition count (that is, occupied transmission time intervals) and/or information about a corresponding coverage enhancement amount (dB), and may be obtained by notifying the system information of the base station, or may be obtained in a predefined manner. The information about the preamble sequence resource pool for coverage enhancement random access includes the corresponding repetition count R, that is, a quantity of the occupied transmission time intervals, and/or the information X about the corresponding coverage enhancement amount (dB), and there is a correspondence between the repetition count, that is, the quantity of the occupied transmission time intervals, corresponding to the preamble sequence resource pool for coverage enhancement random access, and the corresponding coverage enhancement amount (dB). Therefore, the information can still be finally obtained even if the information about the coverage enhancement amount (dB) does not exist.

(130) The power offset X.sub.i is a coverage enhancement amount corresponding to the preamble sequence resource pool i for coverage enhancement random access, or the power offset X.sub.i is a coverage enhancement amount that is corresponding to the repetition count, that is, occupied transmission time intervals, corresponding to the preamble sequence resource pool i for coverage enhancement random access. Further, the power offset X.sub.i is obtained from the information about the preamble sequence resource pool for coverage enhancement random access, where the information about the preamble sequence resource pool for coverage enhancement random access is obtained by notifying the system information, or is obtained in a manner predefined by a current device.

(131) In another implementation of the present disclosure, if the initial target receive power that is of the preamble sequence and is broadcast by a system is preambleInitialReceivedTargetPower, the target receive power of the preamble sequence resource pool for coverage enhancement random access is as follows:

(132) PREAMBLE_RECEIVED_TARGET_POWER=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X+(preamble_transmission_counter−1)*powerRampingStep.

(133) In this case, the power offset X is a coverage enhancement amount. The user equipment needs to use the preamble sequence resource pool for coverage enhancement random access; and a transmit power of the user equipment at each transmission time interval is:

(134) Power=min{Pmax,PREAMBLE_RECEIVED_TARGET_POWER+PL} [dBm], where

(135) min{ } is a MIN function, and P.sub.max is the maximum transmit power of the user equipment.

(136) PREAMBLE_RECEIVED_TARGET_POWER is the target receive power of the preamble sequence resource pool.

(137) X is the power offset corresponding to the preamble sequence resource pool, that is, the coverage enhancement amount (dB).

(138) PL is a path loss value obtained by estimating according to the downlink path loss. More generally, the base station may set N preamble sequence resource pools for coverage enhancement random access, where N is a positive integer. Each preamble sequence resource pool for coverage enhancement random access includes a corresponding repetition count, that is, occupied transmission time intervals, and/or information about a corresponding coverage enhancement amount (dB) that is represented by X.sub.i, where iϵ{1, . . . , N}, that is, there are at least two power offsets X.sub.i. For ease of description, the preamble sequence resource pool for coverage enhancement random access is referred to as a preamble sequence resource pool for short in the following.

(139) If the initial target receive power of the preamble sequence of a system is preambleInitialReceivedTargetPower, a target receive power of the i.sup.th preamble sequence resource pool for coverage enhancement random access is as follows:

(140) PREAMBLE_RECEIVED_TARGET_POWER=preambleInitialReceivedTargetPower+DELTA_PREAMBLE_X.sub.i+(preamble_transmission_counter−1)*powerRampingStep.

(141) It is assumed that there are N preamble sequence resource pools for coverage enhancement random access in the system, where N is a positive integer. From the first preamble sequence resource pool for coverage enhancement random access to the N.sup.th preamble sequence resource pool for coverage enhancement random access, corresponding sequence repetition counts (occupied transmission time intervals) are {R.sub.1, . . . , R.sub.N}, and power offsets corresponding to the first preamble sequence resource pool for coverage enhancement random access to the N.sup.th preamble sequence resource pool for coverage enhancement random access are {X.sub.1, . . . , X.sub.N}. A definition of a power offset is a coverage enhancement amount corresponding to the resource, or may be any power offset defined by the system.

(142) If the initial target receive power of the preamble sequence defined by the system is preambleInitialReceivedTargetPower, the power ramp step is powerRampingStep, and generally, when the first random access is initiated and preamble_transmission_counter=1, step 201 may further be specifically as follows:

(143) during transmit power calculation, superposing power offsets in ascending order or descending order of repetition counts R or power offsets X; and stopping until X.sub.i that meets the following formula is found according to calculation of the following formulas, or if the following inequality cannot be met after all R.sub.i or X.sub.i are traversed, performing transmission according to the maximum transmit power P max, where:

(144) PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.1=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X.sub.i+(preamble_transmission_counter−1)*powerRampingStep; and

(145) PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.1+PL−P max≤Δ, where Δ≥0.

(146) If the user equipment uses the preamble sequence resource pool i for coverage enhancement random access, during initial access of the user equipment, a transmit power at each transmission time interval is:

(147) Power=min{P max,PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.1+PL} [dBm].

(148) However, it is not ensured that successful access can be implemented when the first random access is initiated, and successful access may be implemented only after power ramping is performed. In an original resource pool, a target power requirement that is imposed after power ramping is performed may be met; and the resource pool does not need to be changed. Alternatively, in an original resource pool, a target power requirement that is imposed after power ramping is performed cannot be met; and the resource pool needs to be changed to a resource pool corresponding to a larger repetition count/a larger coverage enhancement amount. Therefore, the following uses an example of multiple times of random access so as to ensure that a process thereof can be clearly described.

(149) It is assumed that there are N preamble sequence resource pools for coverage enhancement random access in the system, where N is a positive integer. From the first preamble sequence resource pool for coverage enhancement random access to the N.sup.th preamble sequence resource pool for coverage enhancement random access, corresponding sequence repetition counts are {R.sub.1, . . . , R.sub.N}, and power offsets corresponding to the first preamble sequence resource pool for coverage enhancement random access to the N.sup.th preamble sequence resource pool for coverage enhancement random access are {X.sub.1, . . . , X.sub.N}. A definition of a power offset is a coverage enhancement amount corresponding to the resource, or may be any power offset defined by the system due to coverage enhancement.

(150) If the initial target receive power of the preamble sequence defined by the system is preambleInitialReceivedTargetPower, and the power ramp step is powerRampingStep, when preamble_transmission_counter=1, a procedure is as follows:

(151) During transmit power calculation, the user equipment superposes power offsets in ascending order of repetition counts R{R.sub.1, . . . , R.sub.N} or power offsets X{X.sub.1, . . . , X.sub.N}; and may stop until X.sub.i that meets the following formula is found according to calculation of the following formulas, or if the following inequality cannot be met after all R.sub.i or X.sub.i are traversed, perform transmission according to the maximum transmit power P max, where

(152) an initial value of preamble_transmission_counter is 1; and

(153) the following is calculated in ascending order of X.sub.i:

(154) PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.1=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X.sub.i+(preamble_transmission_counter−1)*powerRampingStep; and

(155) PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.1+PL−P max≤Δ, where Δ≥0.

(156) When the foregoing inequality is met, calculation is stopped, the preamble sequence resource pool i for coverage enhancement random access is selected, and the transmit power of the preamble sequence is set to PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.1+PL [dBm]; or the inequality is not met after all X.sub.i are traversed, and the transmit power of the preamble sequence is set to P max.

(157) The sender 402 is configured to send the preamble sequence according to the determined transmit power.

(158) Further, if the user equipment has not received a response from the base station side within a set time window after sending the preamble sequence, it is considered that current transmission fails. preamble_transmission_counter=preamble_transmission_counter+1, where preamble_transmission_counterϵ{1, 2, . . . , preambleTransMax}. Power ramping (power ramping) is performed according to the power ramp step powerRampingStep broadcast by the system. According to the formulas, first, it is assumed that the preamble sequence resource pool for coverage enhancement random access is not changed, that is, X.sub.i is not changed, and the calculation is performed again:

(159) PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X.sub.i+(preamble_transmission_counter−1)*powerRampingStep; and

(160) PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter+PL−P max≤Δ, where Δ≥0, and Δ is a constant and a preset threshold.

(161) If the inequality is still met, the preamble sequence resource pool i for coverage enhancement random access continues to be selected. A target receive power that is of the preamble sequence and is corresponding to preamble_transmission_counter (that is already increased by 1 for itself) in this case is PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter. The transmit power of the preamble sequence is set to PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter+PL [dBm].

(162) If the inequality cannot be met, i=i+1, the preamble sequence resource pool for coverage enhancement random access is changed in ascending order of X.sub.i, and the calculation is performed again:

(163) PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X.sub.i+(preamble.sub.—transmission_counter−1)*powerRampingStep; and

(164) PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter+PL−P max≤Δ, where Δ≥0, and Δ is a constant and a preset threshold.

(165) Until the inequality is met, a preamble sequence resource pool for coverage enhancement random access corresponding to X.sub.i in this case is selected. A target receive power that is of the preamble sequence and is corresponding to preamble_transmission_counter in this case is PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter. The transmit power of the preamble sequence is set to (PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter) [dBm.].

(166) Alternatively, the inequality is not met after all X.sub.i are traversed, and the transmit power of the preamble sequence is set to P max.

(167) In brief, the processor 401 may also include:

(168) obtaining the transmit power according to the power offset X.sub.i, and sending the preamble sequence according to the transmit power, to perform the preamble_transmission_counter.sub.th random access;

(169) if the preamble_transmission_counter.sub.th random access fails, making preamble_transmission_counter=preamble_transmission_counter+1, keeping X.sub.i unchanged, and calculating the following again:

(170) PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X.sub.i+(preamble_transmission_counter−1)*powerRampingStep; and

(171) if a condition that PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter+PL−P max≤Δ is met, performing transmission by using the repetition count corresponding to the preamble sequence resource pool i for coverage enhancement random access, where the transmit power is PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter+PL; or

(172) if a condition that PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter+PL−P max≤Δ is not met, searching for the power offset X.sub.i in ascending order of repetition counts, that is, occupied transmission time intervals, or the power offsets X.sub.i, and determining whether the found power offset X.sub.i meets that PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter+PL−P max≤Δ; and if a minimum value of X.sub.i that meets the foregoing formula is found, performing transmission by using the repetition count corresponding to the preamble sequence resource pool i for coverage enhancement random access, where the transmit power is PREAMBLE_RECEIVED_TARGET_POWER.sub.i.sup.preamble_transmission_counter+PL; or if the foregoing inequality cannot be met after all X.sub.i are traversed, performing transmission by using a repetition count corresponding to a preamble sequence resource pool i for coverage enhancement random access that is found at last, where the transmit power is P max, and Δ≥0, and Δ is a constant and a preset threshold.

(173) The processor 401 controls an operation of the user equipment 40, and the processor 401 may also be referred to as a CPU (Central Processing Unit, central processing unit). In a specific application, components of the user equipment 40 are coupled together by using a bus system 403, where in addition to a data bus, the bus system 403 may further include a power bus, a control bus, a status signal bus, and the like. However, for clear description, various types of buses in the figure are marked as the bus system 403.

(174) In this implementation manner of the present disclosure, when the user equipment performs transmission by using a preamble sequence resource pool for coverage enhancement random access, during transmit power calculation, a power offset is introduced, that is, a power gain brought by means of repeated transmission performed by using the preamble sequence resource pool for coverage enhancement random access is introduced, and the gain is converted for the transmit power calculation. Because the repeated transmission itself brings a coverage enhancement amount (dB) X, when a target receive power of a preamble sequence is calculated, the gain is deducted, and PREAMBLE_RECEIVED_TARGET_POWER=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X.sub.i+(preamble_transmission_counter−1)*powerRampingStep, that is, the target receive power of the preamble sequence may be correspondingly decreased by X dB. After such calculation is performed, according to the prior art, PREAMBLE_RECEIVED_TARGET_POWER+PL is also correspondingly decreased by X dB; and a transmit power Power=min{P max,PREAMBLE_RECEIVED_TARGET_POWER+PL} [dbm] is calculated. For user equipments whose coverage enhancement requirements are less than or equal to X dB, that is, all users who meet PREAMBLE_RECEIVED_TARGET_POWER+PL−P max≤X, because PREAMBLE_RECEIVED_TARGET_POWER+PL has been correspondingly decreased by X dB, in this case, PREAMBLE_RECEIVED_TARGET_POWER+PL is less than P max, that is, according to calculation of the formulas, a transmit power is PREAMBLE_RECEIVED_TARGET_POWER+PL. In this way, it may be ensured that receive powers received on a base station side are close to each other and are PREAMBLE_RECEIVED_TARGET_POWER, thereby overcoming a near-far effect. Likewise, all user equipments whose coverage enhancement requirements are less than or equal to X dB perform transmission according to the transmit power: PREAMBLE_RECEIVED_TARGET_POWER+PL, so that a path loss is overcome, a same target receive power is achieved, and no power is wasted.

(175) The foregoing descriptions are merely implementation manners of the present disclosure, and are not intended to limit the scope of the present disclosure. An equivalent structural or equivalent process alternation made by using the content of the specification and drawings of the present disclosure, or an application of the content of the specification and drawings directly or indirectly to another related technical field, shall fall within the protection scope of the present disclosure.