CN101730255B - Method and device for selecting PRACH - Google Patents

Abstract

A method and device for selecting a PRACH, comprising: in a random access process, determining a PRACH selection window of a user equipment, and selecting a physical random access channel PRACH for random access within the PRACH selection window. The implementation of the embodiments of the present invention can take into account the selected random access delay and the utilization rate of the PRACH during the random access process of the user equipment, and then achieve as much as possible between the smaller random access delay and the balanced PRACH utilization rate. in a balanced manner.

Description

A method and device for selecting PRACH

technical field

The present invention relates to the field of communication technology, in particular to a technology for selecting PRACH.

Background technique

The LTE (LoNg TerM EvolutioN, long-term evolution) mobile communication architecture in 3GPP (Third Generation Partnership Project) has the advantages of higher spectrum utilization, transmission speed, and lower transmission delay.

Currently, in the LTE architecture, the corresponding random access methods include contention mode and non-competition mode, where:

The random access of the contention mode uses the non-dedicated PreaM ble (preamble) contained in the PRACH (Physical Random Access Channel), and the corresponding non-dedicated PreaM ble will tell the UE (user equipment) in the cell broadcast, so that the UE can initiate When accessing, randomly select a PreaM ble to access. Specifically, in the contention mode, the UE can select one access among all PRACHs.

The random access in the non-contention mode uses a dedicated PreaM ble, and the eNB (evolved base station) uses dedicated signaling to inform the UE of the dedicated PreaM ble included in the corresponding PRACH, so as to randomly select a PreaM ble for access when initiating access. enter. Specifically, in the non-contention mode, the eNB will limit several PRACHs that the UE can use while notifying the UE of the dedicated PreaM ble, so that the UE can select one of the several PRACHs to access.

In both the contention mode and the non-contention mode, the UE needs to select corresponding time-frequency resources (ie, the PRACH used for access) during random access to the network.

At present, in the process of selecting the PRACH, the UE first performs frequency domain selection, and then performs time domain selection. Moreover, the UE does not consider the configuration of the PRACH on each frequency band when performing frequency domain selection.

However, in the existing solution, since the UE does not consider the PRACH configuration on each frequency band when performing frequency domain selection, if the UE selects a frequency band with a low PRACH density, the delay in sending Msg1 by the UE may be increased, which may further increase random access delay;

For example, as shown in Figure 1, if the UE prepares to send a random access message Msg1 (message 1) at subframe 5 and selects the frequency band f1, the UE needs to wait until subframe 4 of the next radio frame before sending Msg1, thus, The time delay for the UE to send the random access message Msg1 is greatly increased, which in turn leads to an increase in the random access time delay of the UE.

Contents of the invention

Embodiments of the present invention provide a method and device for selecting a PRACH, so that when a user selects a time-frequency resource for random access, the UE random access time delay is reduced on the basis of taking into account the utilization rate of the PRACH.

A method of selecting PRACH, including:

Set the PRACH selection window;

A physical random access channel PRACH used for random access is selected within the PRACH selection window.

A device for selecting PRACH, comprising:

The window setting unit is used to set the PRACH selection window;

A selecting unit, configured to select a PRACH used for random access within the PRACH selection window.

It can be seen from the technical solution provided by the above-mentioned embodiments of the present invention that the selection of the time-frequency resource for random access is carried out within the determined PRACH selection window, so that the selected random access can be considered during the random access process of the user equipment. The access delay and the utilization rate of the PRACH are balanced as much as possible between a small random access delay and a balanced PRACH utilization rate.

Description of drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the accompanying drawings that need to be used in the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For Those of ordinary skill in the art can also obtain other drawings based on these drawings without any creative effort.

FIG. 1 is a schematic diagram of a PRACH configuration structure in the prior art;

FIG. 2 is a schematic diagram of R(x) values when the starting point of the window is located in different subframes in an embodiment of the present invention;

FIG. 3 is a schematic diagram of PRACH configuration and selection in an embodiment of the present invention;

FIG. 4 is a first schematic diagram of P(x) values when the starting point of the window is located in different subframes in the embodiment of the present invention;

FIG. 5 is a first schematic diagram of delay values when the starting point of the window is located in different subframes in the embodiment of the present invention;

FIG. 6 is a second schematic diagram of the P(x) value when the starting point of the window is located in different subframes in the embodiment of the present invention;

FIG. 7 is a second schematic diagram of delay values when the starting point of the window is located in different subframes in the embodiment of the present invention;

Fig. 8 is a schematic diagram of the position of the starting point of the window in the embodiment of the present invention;

FIG. 9A is a first schematic diagram of PRACH selection in the second implementation scheme in the embodiment of the present invention;

FIG. 9B is a second schematic diagram of PRACH selection in the second implementation scheme in the embodiment of the present invention;

FIG. 9C is a third schematic diagram of PRACH selection in the third implementation scheme in the embodiment of the present invention;

Fig. 10A is a first schematic diagram of the device structure provided by the embodiment of the present invention;

FIG. 10B is a second schematic diagram of the device structure provided by the embodiment of the present invention.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

The embodiment of the present invention provides an implementation scheme for users to select random access time-frequency resources. In this scheme, the PRACH selection window of the UE is firstly determined, which is used to determine the range for the UE to select the PRACH during the random access process.

Afterwards, the user equipment determines the position of the initial subframe, from which the user equipment can send a random access preamble (ie message 1).

The physical random access channel PRACH is selected according to the position of the initial subframe, which improves the utilization rate of the PRACH.

The position of the initial subframe is taken as the starting point of the PRACH selection window (hereinafter referred to as "window"), and the size of the window is M subframes, and M is determined according to the configuration of the PRACH. The selection probability of each PRACH is determined according to the time delay of each PRACH in the window, and the corresponding PRACH is selected as the time-frequency resource for random access of the user equipment according to the selection probability corresponding to each PRACH. Wherein, the corresponding process of determining the selection probability of each PRACH in the window may include:

(1) Determine the selection coefficient R(x) of the xth PRACH in the window: from the starting point of the window, and number the subframes in the window in descending order, numbering from M to 1; R(x) is The number of the subframe where the x-th PRACH is located or the kth power of the number, and k is greater than 1. If there are multiple PRACHs in a subframe (TDD system), the selection coefficient R(x) of the PRACH is the same;

(2) Calculate the selection probability of the xth PRACH according to the selection coefficient R(x) of the xth PRACH as: $P\left(x\right)=\frac{R\left(x\right)}{\underset{i=1}{\overset{\mathrm{no}}{\mathrm{\Σ}}}R\left(i\right)},$ Wherein, N is the number of PRACHs included in the window, and R(i) represents the selection coefficient of the i-th PRACH.

Optionally, in this embodiment of the present invention, the corresponding relationship between the subframe position in the PRACH selection window and the PRACH may also be determined in advance, and when the initial subframe is located at a different subframe position in the window, the PRACH corresponding to the subframe is selected.

You can set the starting point and size of the window as follows:

(1), select a PRACH continuous block in MM consecutive subframes, the PRACH continuous block is the continuous block that contains the most PRACH in the MM subframes, the PRACH continuous block is a continuous PRACH in the time domain, and is included in PRACHs belonging to different frequency domains at the same time domain position.

(2), if there are 2 or more continuous blocks that contain the most PRACH, then select a continuous block with a larger distance (number of subframes) from the next continuous block;

(3) Determine that the first subframe after the PRACH continuous block is the starting point of the window, and the window size is MM subframes.

The process of determining the corresponding relationship between the subframe position in the window and the PRACH may specifically include:

(1) Number the NN PRACHs included in the window sequentially in the order of the frequency domain first and then the time domain, that is, the numbers are from 0 to (N-1).

All subframes are numbered sequentially within the window, numbered from 0 to (M-1).

Determine the corresponding relationship as:

If the PRACH corresponding to subframe x is y, then y=Floor(x/(M/N)), 0<=x<M.

or,

(2), when there are N PRACHs in the window, the window is divided into N groups of subframes from the starting point of the window, and each group contains M/N subframes, that is, N groups of subframes correspond to N PRACHs in turn, then Each PRACH corresponds to M/N subframes.

If the subframe can correspondingly select two PRACHs, the method further includes:

The subframe corresponds to a PRACH earlier in time, and if the two PRACHs are the same in time, select one PRACH as the corresponding PRACH of the subframe according to the same selection probability;

or,

Selecting the PRACH earlier in the order as the corresponding PRACH of the subframe;

or,

If the two PRACHs belong to different frequency bands, according to the current air interface quality of different frequency bands, the PRACH in the frequency band with better air interface quality is selected as the corresponding PRACH of the subframe.

or,

The user equipment takes t1/(t1+t2) as the selection probability of the first PRACH in the two PRACHs, and uses t2/(t1+t2) as the selection probability of the second PRACH in the two PRACHs, wherein the corresponding t1 is The duration occupied by the first PRACH allocation in the subframe length, and t2 is the duration occupied by the second PRACH allocation in the subframe length.

It can be seen that the implementation scheme for the UE to select the PRACH provided by the above embodiments of the present invention not only reduces the time delay for the UE to perform random access, but also improves the utilization rate of the PRACH.

In the specific application process of the embodiment of the present invention, the following two implementation schemes may be adopted but not limited to, which will be described respectively below.

The specific implementation process of the first implementation solution for UE selection of PRACH provided by the embodiment of the present invention will be described in detail below.

In the first implementation scheme in which the UE selects the PRACH, the corresponding implementation process includes:

(1) The UE calculates the PRACH selection window, which specifically takes the subframe in which the UE is ready to send Msg1 as the starting point of the window. The size of the window can be 10 subframes or 10ms, and the 10ms PRACH window may not be related to a radio frame Coincidence, for example, the starting point of the 10s PRACH window is in the radio frame #N, and the end point is in the radio frame #N+1, wherein, the starting point of the corresponding window does not need to consider whether there is a PRACH in the subframe;

(2) The UE selects a PRACH among all the PRACHs included in the window as the PRACH used for sending Msg1;

The specific selection method may include: the UE may calculate a corresponding selection probability for each PRACH in the window, and select the PRACH according to the corresponding probability, and the corresponding probability calculation is based on: in the case of balanced PRACH utilization Under , the PRACH with smaller delay is more likely to be selected;

For example, the corresponding probability can be determined as follows:

First, from the start subframe of the window, number each subframe in the time domain in descending order; and use the number of the subframe where the PRACH is located as the selection coefficient R(x) of the PRACH, where x is PRACH iNdex (PRACH index); for PRACH, it is assumed that the numbering can start from the integer 10, and when the starting point of the window is located in different subframes, the R(x) of each PRACH can be as shown in Figure 2.

Secondly, after determining the R(x) of each PRACH, if there are N PRACHs in the window, the calculation method of the selection probability of each PRACH can be expressed as:

$P\left(x\right)=\frac{R\left(x\right)}{\underset{i=1}{\overset{\mathrm{no}}{\mathrm{\&Sigma;}}}R\left(i\right),}$ Wherein, P(x) refers to the probability of selection corresponding to the xth PRACH.

Alternatively, other methods may be used to select the PRACH, and the PRACH with the smallest delay may be selected for random access under the condition that the utilization rate of the PRACH is balanced.

The implementation scheme of the first UE selecting the PRACH will be further described below in conjunction with specific application embodiments.

Embodiment one

In the first embodiment, the process for the corresponding UE to select the PRACH may include:

(1) Let C=R(1)+R(2)+...+R(N);

(2) When the UE needs to select the PRACH, the UE can randomly select an integer between 1 and C, assuming that the integer selected by the UE is M,:

If R(1)+R(2)+...+R(x-1)<M<=R(1)+R(2)+...+R(x), the UE selects PRACHx as the random access PRACH applied when entering, specifically:

If M<=R(1), the UE selects PRACH1 as the PRACH applied during random access;

If R(1)<M<=R(1)+R(2), the UE selects PRACH2 as the PRACH applied during random access;

And so on,......

Specifically, as shown in Figure 3, it is assumed that the subframes are numbered from the integer 10, and the subframe 0 is used as the starting point of the window. The R(x) representation of each PRACH is shown in Figure 3, and the corresponding selection process includes:

(1) Calculate C=R(1)+R(2)+...+R(6)=32;

(2) When the UE needs to select the PRACH, the UE can randomly select an integer between 1 and 32, still assuming that the integer is M:

If M<=R(1), that is, M<=8, the UE selects PRACH1 as the PRACH used during random access;

If R(1)<M<=R(1)+R(2), that is, 8<M<=15, the UE selects PRACH2 as the PRACH used during random access;

If R(1)+R(2)<M<=R(1)+R(2)+R(3), that is, 15<M<=21, the UE selects PRACH3 as the PRACH applied during random access;

R(1)+R(2)+R(3)<M<=R(1)+R(2)+R(3)+R(4), that is, 21<M<=24, UE selects PRACH4 as PRACH applied during random access;

R(1)+R(2)+R(3)+R(4)<M<=R(1)+R(2)+R(3)+R(4)+R(5), that is 24 <M<=26, the UE selects PRACH5 as the PRACH applied during random access;

R(1)+R(2)+R(3)+R(4)+R(5)<M<=R(1)+R(2)+R(3)+R(4)+R( 5)+R(6), that is, 26<M<=32, the UE selects PRACH6 as the PRACH used during random access.

Through the above implementation solution, it can be ensured that the UE can take into account the factors of PRACH utilization rate and time in the process of selecting the PRACH.

It can be seen from FIG. 4 and FIG. 5 that in the above implementation scheme, the probability of each PRACH being selected is basically the same, and the variation range of the corresponding time delay is small, and the average time delay is also small.

Specifically, in FIG. 4, when the starting point of the window is located in a different subframe in FIG. 3, the probability that each PRACH is selected, that is, the selection probability P(x) of each PRACH is given, and The probabilities of each choice are different. In Fig. 4, the last line of the corresponding table of P(x) is the average probability that each PRACH is selected (i.e. the average selection probability), and the average selection probability of each PRACH is basically the same, thus it can be seen that the utilization rate of each PRACH Already very close.

In Fig. 5, when the starting points of the windows are located in different subframes, the transmission delay D(x) of Msg1 when each PRACH is selected, and when the starting points of the windows are located in different subframes, The case of the average transmission delay D of Msg1; the integer number in Figure 5 indicates the number of the subframe where the corresponding PRACH is located when the starting point of the window is located in a different subframe; the last row in column D in Figure 5 indicates the average transmission delay of Msg1 , it can be seen that when the position of the starting point of the window is different from the position of the subframe, the variation range of the time delay of each selected PRACH is small, and at the same time, the overall average time delay is also small.

Embodiment two

In the second embodiment, specifically, the square of the number of each subframe is used as the corresponding R(x), and the calculation of the C value and the selection of the PRACH are performed according to the R(x).

Still taking Fig. 3 as an example, and taking the square of each subframe number in Embodiment 1 as R(x), when the starting point of the window is located in a different subframe, the corresponding probability P(x) is shown in Fig. 6, The average selection probability of each PRACH is still basically the same, thus it can be seen that the utilization ratio of each PRACH is still very close, but compared with Embodiment 1, the use fairness of PRACH has a little bit worse, this is due to the R( The difference between x) becomes larger, so the probability that the UE selects the PRACH with a smaller time delay increases.

Similarly, in this calculation method, when the starting points of the windows are located in different subframes, the transmission delay D(x) of Msg1 when each PRACH is selected, and when the starting points of the windows are located in different subframes, the transmission delay D(x) of Msg1 The average sending delay D can be represented as shown in FIG. 7 , it can be seen that when R(x) is the square of each subframe number, the average sending delay of Msg1 is smaller.

In a word, the second embodiment can also better realize the PRACH selection operation in the random access process of the UE.

The embodiment of the present invention also provides another implementation scheme for the UE to select the PRACH, and the second implementation scheme for the UE to select the PRACH will be described below.

In the second implementation scheme in which the UE selects the PRACH, the corresponding implementation process includes:

(1) The UE determines a PRACH window including 10 subframes, namely 10ms, according to the configuration of the PRACH. The 10ms PRACH window may not coincide with a radio frame. For example, the starting point of the 10ms PRACH window is in the radio frame #N, And the end point is within the wireless frame #N+1;

The process of determining the 10ms PRACH window may specifically include:

(1) Define the PRACH continuous block as a continuous PRACH in the time domain, and include PRACHs belonging to different frequency domains at the same time domain position, that is, it contains one or more PRACHs;

(2) Select a PRACH continuous block in 2 consecutive radio frames (20ms), the PRACH continuous block may specifically be the PRACH continuous block that contains the most PRACH in these two radio frames; if there is a PRACH continuous block in these 2 radio frames For two or more consecutive PRACH blocks that contain the most PRACHs, a continuous PRACH block that is farther away from the next consecutive block (the difference in the number of subframes) may be selected.

(3) determining that the first subframe after the PRACH continuous block is the window starting point;

Referring to FIG. 8 , the corresponding window starting point determined under different PRACH distribution conditions, and the corresponding window length may be, but not limited to, 10 ms.

(2) Determine the corresponding relationship between the subframe position in the window and the PRACH; when the initial subframe is located in a different subframe position in the window, select the PRACH corresponding to the subframe.

After the 10ms window for a certain PRACH configuration is determined, each subframe in the window will be explicitly assigned one PRACH or two PRACHs it uses, where the case of two PRACHs is that the number of PRACHs cannot be divisible by 10 For example, when the number of PRACHs is N=3, there are 2 subframes and two PRACHs need to be considered.

Assuming that the number of PRACHs included in the window is N, specifically, the subframes in the window can be divided into N groups starting from the starting point of the window, and the N groups of subframes correspond to N PRACHs in turn.

Through the above allocation method, the UE can also take into account both delay control and fairness in the process of selecting the PRACH, thereby providing a better implementation scheme for random access time-frequency resource selection of the user equipment.

The implementation scheme of the second UE selecting the PRACH will be further described below in conjunction with specific application embodiments.

Embodiment Three

In the third embodiment, as shown in FIG. 9A, the corresponding PRACH structure includes two adjacent PRACH#1 and PRACH#2; based on FIG. 9A, the corresponding PRACH selection process may include:

First, since a PRACH continuous block is included in the determined window, the window is the first subframe after the PRACH continuous block;

Secondly, the number of subframes corresponding to each PRACH is calculated as: 10/N=10/2, the subframes within the first 5ms in the window are all corresponding to PRACH#1; the subframes within the second 5ms are all corresponding to PRACH #2.

Finally, after the above allocation operation is completed, the PRACH selection operation in the random access process can be performed according to the subframe position of the initial subframe in the window;

Still referring to Figure 9A, assuming that A, B, C, and D are four initial subframe positions, according to the above configuration, PRACH#1 needs to be selected to initiate RA at A and B subframe positions, while C, B, and C The D subframe position needs to select PRACH#2 to initiate RA.

Among them, for a subframe in which two PRACHs can be selected, if the two PRACHs belong to different frequency bands, the UE can select a PRACH in a frequency band with good quality as the PRACH of the subframe according to the current air interface quality of different frequency bands, and the corresponding air interface quality is good The characteristics may include but are not limited to: low path loss in this frequency band, or high RSRP (reference signal strength)/RSRQ (reference signal quality), and so on.

It can be seen that, through the implementation of the third embodiment above, a balance between the utilization rate of the PRACH and the random access delay can also be achieved.

Embodiment Four

In the fourth embodiment, as shown in FIG. 9B, the corresponding PRACH structure includes three adjacent PRACH#1, PRACH#2 and PRACH#3; based on FIG. 9B, the corresponding PRACH selection process may include:

First, since the determined window has only one PRACH continuous block, the window is the first subframe after the PRACH continuous block.

Secondly, calculate the number of subframes corresponding to each PRACH: 10/N=10/3={3+(1/3)}, for the convenience of description, (1/3) can be simplified and replaced by 3.33; so the window The subframes within the first 3.33ms in length all correspond to PRACH#1; the subframes within the second 3.33ms all correspond to PRACH#2; the subframes within the third 3.33ms all correspond to PRACH#3.

Finally, after the above allocation operation is completed, the PRACH selection operation in the random access process can be performed according to the subframe position of the initial subframe in the window;

Referring to FIG. 9B , assuming that there are four initial subframe positions, namely: A, B, C and D, according to the above configuration, if RA is initiated at point A, select PRACH#1 as the access point of RA, if Initiating RA at point B, there is a 1/3 chance (selection probability) to select PRACH#1 as the access point of RA, and there is a 2/3 chance (selection probability) to select PRACH#2 as the access point of RA. Point C initiates RA, there is a 2/3 chance (selection probability) to select PRACH#2 as the access point of RA, there is a 1/3 chance (selection probability) to select PRACH#3 as the access point of RA, if in D The point initiates RA, and selects PRACH#3 as the access point of RA.

That is, when a subframe in the window corresponds to two PRACHs, and the UE chooses to send a message for random access in the subframe, the UE can use t1/(t1+t2) as the first PRACH of the two PRACHs The selection probability of t2/(t1+t2) is used as the selection probability of the second PRACH in the two PRACHs, where t1 is the duration occupied by the first PRACH in the subframe length, and t2 is the second PRACH in the subframe length. 2. The duration occupied by PRACH allocation.

Referring to Figure 9, at point B, the specific process of selecting PRACH can be as follows: UE can select a random number (0~1), and when the random number is within 0~1/3, select PRACH#1 as the access point of RA Access point, when the random number belongs to the range of 1/3~1, select PRACH#2 as the access point of RA. In the same way, point C can also be treated similarly.

Through this fourth embodiment, in the process of selecting the PRACH for random access by the UE, the parameters of the utilization rate of the PRACH and the time delay of the random access can be well balanced, so as to obtain a better selection of random access. Implementation scheme of time-frequency resources.

It should be noted that, in the fourth embodiment, for a subframe that can correspond to two PRACHs in the window, specifically, it can be allowed to correspond to a PRACH earlier in time; if the two PRACHs are the same in time (that is, two PRACHs Different frequency bands belonging to a subframe) are still allocated according to two PRACHs, for example, the subframe can be made to correspond between two PRACHs according to a certain selection probability.

Alternatively, for subframes that can correspond to two PRACHs, all of them may select the PRACH that is higher in numbering order as the corresponding PRACH. At this point, determine the correspondence between the subframe position in the window and the PRACH as follows:

(1) If there are N PRACHs in a window containing M subframes, the PRACHs are numbered sequentially in the frequency domain first and then the time domain, that is, the PRACH numbers are from 0 to (N-1).

All subframes are numbered sequentially within the window, and the subframes are numbered from 0 to (M-1).

Determine the corresponding relationship as:

If the PRACH corresponding to subframe x is y, then y=Floor(x/(M/N)), 0<=x<M.

Embodiment five

The configuration of the PRACH and the configuration of the PRACH selection window in this embodiment are the same as those in the fourth embodiment. The PRACH number and subframe number in the window are shown in FIG. 9C .

Referring to Figure 9C, it is assumed that there are 4 initial subframe positions, namely: A, B, C and D. According to the above configuration, if RA is initiated at point A, select PRACH#0 as the access point of RA. To initiate RA at point C, select PRACH#1 as the access point of RA. If RA is initiated at points C and D, select PRACH#2 as the access point of RA.

In addition, in Embodiment 3 to Embodiment 5, the starting point of the window can also be determined in other ways:

(1) Determine the PRACH farthest away from the next PRACH (subframe number difference) in 2 consecutive radio frames (20 ms).

(2) determining that the first subframe after the PRACH is the window starting point;

or:

(1) In a radio frame (10 ms), determine the half frame (5 ms, the first half frame or the second half frame) that contains the most PRACH.

(2) determine that the first subframe after the last PRACH in the half frame is the window starting point;

Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be implemented through computer programs to instruct related hardware, and the programs can be stored in a computer-readable storage medium. During execution, it may include the processes of the embodiments of the above-mentioned methods. Wherein, the storage medium may be a magnetic disk, an optical disk, a read-only memory (Read-Only Memory, ROM) or a random access memory (Random Access Memory, RAM), etc.

The embodiment of the present invention also provides a device for selecting a PRACH, and its specific implementation structure is shown in Figure 10A and Figure B, which may include:

A window setting unit 101, configured to set a PRACH selection window;

The selection unit 102 is configured to select a PRACH for random access within the PRACH selection window set by the window setting unit 101 .

The device for selecting the PRACH provided in the embodiment of the present invention can be specifically implemented through the following two schemes, which can be specifically:

Referring to FIG. 10A, in a first implementation solution, the device may further include:

A position determining unit 103, configured to determine the initial subframe position of the user equipment;

The window setting unit 101 is specifically configured to set the PRACH selection window starting from the initial subframe position determined by the position determination unit 103, and the PRACH selection window includes M subframes.

And in the first implementation scheme, the corresponding selection unit 102 is specifically configured to determine the selection coefficient R(x) of the xth PRACH in the PRACH selection window, where the R(x) is the selection coefficient R(x) from the window Starting from the starting point and numbered in descending order, the number in the time domain of the subframe where the xth PRACH is located or the kth power of the number, k is greater than 1;

According to the selection coefficient R(x) of the xth PRACH, the selection probability of the xth PRACH is calculated as: $P\left(x\right)=\frac{R\left(x\right)}{\underset{i=1}{\overset{\mathrm{no}}{\mathrm{\&Sigma;}}}R\left(i\right)},$ It is also used to select the corresponding PRACH according to the selection probability corresponding to each PRACH, where N is the number of PRACHs included in the PRACH selection window, and R(i) represents the selection coefficient of the i-th PRACH.

Referring to FIG. 10B , correspondingly in the second implementation scheme, the corresponding window setting unit 101 is specifically used to select a preferred PRACH continuous block in M consecutive subframes, and the preferred PRACH continuous block is the M In subframes, the most continuous blocks of PRACH are included, and the preferred PRACH continuous blocks are continuous PRACHs in the time domain, and include PRACHs belonging to different frequency domains at the same time domain position; or, if there are many PRACH continuous blocks that contain the most PRACHs select a PRACH continuous block with a large number of subframes different from the next PRACH continuous block as the preferred PRACH continuous block, and set the PRACH selection window with the first subframe after the preferred PRACH continuous block as the starting point , the window contains M subframes.

Optionally, the device provided by the second implementation scheme may also include a numbering unit 104, configured to sequentially number the N PRACHs contained in the PRACH selection window in the order of the frequency domain first and then the time domain, and also use Within the PRACH selection window, all subframes are numbered sequentially from small to large.

Optionally, the device provided in the second implementation scheme may further include a correspondence determining unit 105, configured to determine the correspondence between the subframe position and the PRACH according to method one; wherein, the method one may specifically be: Subframe x corresponds to PRACH y, where y=Floor(x/(M/N)), 0<=x<M.

The corresponding correspondence determining unit 105 may further be configured to select corresponding M/N subframes for each PRACH, and set the average value of the time delay between each subframe and its corresponding PRACH to be minimum. Specifically can include:

When a subframe corresponds to two PRACHs, select a PRACH corresponding to a subframe earlier in time;

or,

If the two PRACHs are the same in time, randomly select a PRACH as the corresponding PRACH of the subframe;

or,

If the two PRACHs belong to different frequency bands, the PRACH in the frequency band with better air interface quality is selected as the corresponding PRACH of the subframe.

or,

The user equipment takes t1/(t1+t2) as the selection probability of the first PRACH among the two PRACHs, takes t2/(t1+t2) as the selection probability of the second PRACH among the two PRACHs, and selects the PRACH with a higher probability as The PRACH corresponding to the subframe, where t1 is the duration occupied by the first PRACH in the subframe length, and t2 is the duration occupied by the second PRACH in the subframe length.

An embodiment of the present invention also provides a user equipment, which may include the above apparatus for selecting a PRACH.

To sum up, the implementation of the embodiment of the present invention can make each PRACH can be effectively used, and can ensure a small random access delay as much as possible, so that each PRACH can be reasonably used in the random access process of the UE. PRACH resources.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed in the present invention can easily think of changes or Replacement should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (15)

1. A method for selecting PRACH, characterized in that, comprising: Set the PRACH selection window; selecting a physical random access channel PRACH for random access within the PRACH selection window; The setting of the PRACH selection window specifically includes: Determine the initial subframe position of the user equipment, and the user equipment selects a subframe after the initial subframe position to send a random access preamble; setting the PRACH selection window starting from the initial subframe position; The selecting a PRACH for random access within the PRACH selection window includes: determining the selection probability corresponding to each PRACH according to the time delay of each PRACH in the PRACH selection window, and selecting a corresponding PRACH according to the selection probability corresponding to each PRACH; The step of determining the selection probability of each PRACH in the window includes: Determine the selection coefficient R(x) of the xth PRACH in the PRACH selection window, where the R(x) is where the xth PRACH obtained by numbering in descending order is from the starting point of the window The number of the subframe in the time domain or the kth power of the number, where k is greater than 1; According to the selection coefficient R(x) of the xth PRACH, the selection probability of the xth PRACH is calculated as:

Wherein, N is the number of PRACHs included in the PRACH selection window, and R(i) represents the selection coefficient of the i-th PRACH. 2. The method according to claim 1, wherein if there are multiple PRACHs in one subframe, the selection coefficients R(x) of the multiple PRACHs are the same. 3. method according to claim 1, is characterized in that, described setting PRACH selection window specifically comprises: Select a preferred PRACH continuous block in M consecutive subframes, the preferred PRACH continuous block is the continuous block containing the most PRACH in the M subframes, the preferred PRACH continuous block is the continuous PRACH in the time domain, and includes PRACHs belonging to different frequency domains in the domain position; or, if there are multiple PRACH continuous blocks containing the most PRACH, select the PRACH continuous block with a larger number of subframes from the next PRACH continuous block as the preferred PRACH continuous block; The PRACH selection window is set with the first subframe after the preferred PRACH continuous block as the starting point, and the window includes M subframes. 4. The method according to claim 3, characterized in that, the method also comprises PRACH and subframe numbers in the PRACH selection window: Numbering the N PRACHs included in the PRACH selection window in sequence in the frequency domain first and then the time domain; All the subframes in the PRACH selection window are numbered sequentially from small to large. 5. The method according to claim 4, characterized in that the method further comprises determining the correspondence between the subframe position and the PRACH according to method one; Described method one is specifically: The xth subframe corresponds to the yth PRACH, where y=Floor(x/(M/N)), 0<=x<M. 6. The method according to claim 5, wherein said method one further comprises: Each PRACH corresponds to M/N subframes, and the average value of time delay between each subframe and its corresponding PRACH is set to be minimum. 7. The method according to claim 6, wherein if one subframe corresponds to two PRACHs, the method further comprises: The subframe corresponds to a PRACH earlier in time; or, If the two PRACHs are the same in time, arbitrarily select a PRACH as the corresponding PRAGH of the subframe; or, If the two PRACHs belong to different frequency bands, select the PRACH in the frequency band with good air interface quality as the corresponding PRACH of the subframe; or, The user equipment takes t1/(t1+t2) as the selection probability of the first PRACH among the two PRACHs, takes t2/(t1+t2) as the selection probability of the second PRACH among the two PRACHs, and selects the PRACH with a higher probability as The PRACH corresponding to the subframe, where t1 is the duration occupied by the first PRACH in the subframe length, and t2 is the duration occupied by the second PRACH in the subframe length. 8. The method according to any one of claims 1-7, wherein the method for selecting the PRACH comprises: When the initial subframe of the user equipment is located at a different subframe position in the window, the PRACH corresponding to the subframe is selected. 9. A device for selecting PRACH, comprising: The window setting unit is used to set the PRACH selection window; a selection unit, configured to select a PRACH for random access within the PRACH selection window; a location determining unit, configured to determine an initial subframe location of the user equipment; The window setting unit is specifically configured to set the PRACH selection window starting from the initial subframe position, and the PRACH selection window includes M subframes; The selection unit is specifically configured to determine the selection coefficient R(x) of the xth PRACH in the PRACH selection window, where the R(x) is numbered in descending order from the starting point of the window The obtained number of the subframe where the xth PRACH is located in the time domain or the kth power of the number, where k is greater than 1; Calculate the selection probability of the xth PRACH according to the selection coefficient R (x) of the xth PRACH as:

It is also used to select the corresponding PRACH according to the selection probability corresponding to each PRACH, where N is the number of PRACHs included in the PRACH selection window, and R(i) represents the selection coefficient of the i-th PRACH. 10. The apparatus of claim 9, wherein The window setting unit is specifically used to select a preferred PRACH continuous block in M consecutive subframes, the preferred PRACH continuous block is the continuous block containing the most PRACH in the M subframes, and the preferred PRACH continuous block is a time domain Consecutive PRACH, including PRACH belonging to different frequency domains in the same time domain position; or, if there are multiple PRACH continuous blocks containing the most PRACH, select the PRACH with a larger number of subframes than the next PRACH continuous block The continuous block is a preferred PRACH continuous block, and the PRACH selection window is set with the first subframe after the preferred PRACH continuous block as a starting point, and the window includes M subframes. 11. The device according to claim 10, further comprising a numbering unit, configured to number the N PRACHs included in the PRACH selection window sequentially in the order of the frequency domain first and then the time domain, and use Within the PRACH selection window, all subframes are numbered sequentially from small to large. 12. The device according to claim 11, further comprising a correspondence determining unit, configured to determine the correspondence between the subframe position and the PRACH according to method one; Described method one is specifically: The xth subframe corresponds to the yth PRACH, where y=Floor(x/(M/N)), 0<=x<M. 13. The device according to claim 11, wherein the correspondence determining unit is further configured to select corresponding M/N subframes for each PRACH, and set the delay between each subframe and its corresponding PRACH The average value is the smallest. 14. The device of claim 13, comprising: When a subframe corresponds to two PRACHs, select a PRACH corresponding to a subframe earlier in time; or, If the two PRACHs are the same in time, randomly select a PRACH as the corresponding PRACH of the subframe; or, If the two PRACHs belong to different frequency bands, select the PRACH in the frequency band with good air interface quality as the corresponding PRACH of the subframe; or, The user equipment takes t1/(t1+t2) as the selection probability of the first PRACH among the two PRACHs, takes t2/(t1+t2) as the selection probability of the second PRACH among the two PRACHs, and selects the PRACH with a higher probability as The PRACH corresponding to the subframe, where t1 is the duration occupied by the first PRACH in the subframe length, and t2 is the duration occupied by the second PRACH in the subframe length. 15. A user equipment, characterized in that the user equipment comprises the apparatus according to any one of claims 9-13. the

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