CN108632004B

CN108632004B - Method and device for data transmission by using multiple transmission time intervals

Info

Publication number: CN108632004B
Application number: CN201710294132.3A
Authority: CN
Inventors: 李迎阳; 张世昌; 王轶
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2017-03-24
Filing date: 2017-04-28
Publication date: 2022-08-12
Anticipated expiration: 2037-04-28
Also published as: CN108632004A

Abstract

The application provides a method for performing data transmission by using a plurality of transmission time intervals TTI, which is characterized by comprising the following steps: user Equipment (UE) detects Scheduling Authorization (SA) of other UE in a detection window on the basis of multiple TTI lengths on a resource pool, measures the receiving power of a scheduled data channel on the basis of the SA, and detects the receiving energy of each sub-channel of each sub-frame; the UE selects resources for data transmission based on the detected SA, the received power and the received energy; and the UE transmits the SA indication to the selected resource and performs data transmission through the resource. By adopting the method of the invention, the collision between the UE adopting the TTIs with different lengths is avoided as much as possible, the resource utilization rate is improved, and the transmission performance of the TTIs with different lengths is ensured.

Description

Method and device for data transmission by using multiple transmission time intervals

Technical Field

The present invention relates to wireless communication system technology, and in particular, to a method and apparatus for transmitting data using multiple Transmission Time Intervals (TTIs) of different lengths in a V2X system.

Background

In a Long Term Evolution (LTE) based V2X (Vehicle to Vehicle/legacy/Infrastructure/Network) system of the 3GPP standardization organization, there are two structures for configuring a PSCCH resource pool and a PSCCH resource pool. The PSCCH can be positioned in the same subframe with one PSSCH scheduled by the PSCCH; alternatively, the PSCCH may not be located in the same subframe as any PSCCH it schedules. The PSCCH resource pool and the PSCCH resource pool occupy the same set of subframes. One PSCCH is fixedly mapped to 2 PRBs (resource blocks). The allocation granularity of the frequency resources is sub-channels (sub-channels), one sub-channel comprises continuous PRBs, and the number of the PRBs is configured by high-layer signaling. The resources of a device may be occupying one or more contiguous subchannels. The PSCCH and PSCCH may be PRBs that occupy contiguous PRBs when they are located in the same subframe. In one or more consecutive sub-channels occupied by the resources of one device, two PRBs, e.g., the two PRBs with the lowest frequency, are used to carry the PSCCH, while the other PRBs are used to carry the PSCCH. The number of PRBs actually occupied by the psch also needs to be satisfied as a power of 2,3 and 5. The PRBs of the PSCCH and the PRBs of the PSCCH may also be discontinuous when the PSCCH and the PSCCH are located in the same subframe. In this case, the starting PRB positions of the PSCCH resource pool and the PSCCH resource pool may be configured separately. The psch resource pool still allocates resources at subchannel granularity. For a device, the index of the occupied PSCCH is equal to the minimum subchannel index of the occupied PSSCH.

In the V2X system, collision and in-band leakage problems can be solved based on detection (Sensing). A basic assumption here is that the occupation of resources by the device is semi-persistent scheduling (SPS), i.e. the resources occupied by the device are periodic over a period of time. As shown in fig. 1, the time when the device selects the PSCCH/PSCCH resource is considered as a subframe n, the device first detects the resource in its resource pool in the time period from the subframe n-a to the subframe n-b, and determines which time-frequency resources are occupied and which time-frequency resources are idle; then selecting PSCCH/PSSCH resources in a subframe n, recording that the PSCCH is transmitted in a subframe n + c, the PSSCH is transmitted in a subframe n + d, and the reserved resources are transmitted in a subframe n + e; next, PSCCH is transmitted at subframe n + c, PSCCH is transmitted at subframe n + d, and the next PSCCH is transmitted at subframe n + e where the reserved resources are. In particular, when c equals d, the PSCCH and PSCCH are located in the same subframe. The interval of the sub-frame n + e and the sub-frame n + d is equal to the reserved interval P. The reserved interval P is equal to P _step ·k，For example, P _step Equal to 100, i.e., supporting no more than about 100ms of delay, k may range from 1 to 10, which may be a set of all integers or a subset thereof, and k may be higher-level configured. When performing resource selection, the device may select K resources located in different subframes, that is, each data may be repeatedly transmitted K times, where K is greater than or equal to 1, for example, K is equal to 2, so as to avoid that some devices cannot receive the data due to the limitation of half-duplex operation. When K is greater than 1, each psch may indicate all K resources described above.

Fig. 2 is a flow chart illustrating the selection of resources based on detection. Assuming that resource selection is performed in subframe n, the reservation interval of the current reserved resources of the device is P _A And the number of cycles for which resources need to be reserved is C. The device may be in the selection window n + T ₁ ,n+T ₂ ]Internally selecting resources and in intervals P _A C cycles are reserved continuously. T is ₁ And T ₂ Dependent on the implementation of the UE, e.g. T ₁ ≤4，20≤T ₂ ≤100。T ₁ Depending on the effect of the processing delay, T, of the UE from selecting resources to the point where it can start transmitting scheduling assignment Signaling (SA) and data ₂ Mainly depending on the delay characteristics that the current traffic can tolerate. First, all resources in the selection window are set to be in the set S _A Middle (201). And then, according to the correctly received SA, assuming that the SA indicates that resources are continuously reserved after the subframe n, measuring the receiving power of a data channel scheduled by the SA, and excluding S when the receiving power exceeds a corresponding threshold _A A portion of the candidate resources (202). Specifically, the resource Y reserved after the subframe n according to the SA is not available when the received power exceeds a corresponding threshold, which is determined jointly according to the priority of the device performing the resource selection and the priority of the SA indication of correct reception. Note R _x,y Representative selection Window [ n + T ₁ ,n+T ₂ ]Within a single subframe resource, R _x,y Located in sub-frame y and containing one or more consecutive sub-channels starting from sub-channel x, then, when

When PRB of (2) overlaps with PRB of the above resource Y, R _x,y Not available to device A, i.e. from set S _A Excluding R _x,y J-0, 1.. C-1, C is the current requirement of device a according to period P _A The number of cycles for which resources are reserved. Next, S is judged _A If it reaches bit R of the total resource, e.g. 20% (203). If the ratio is less than R, raising the threshold by 3dB (204) and restarting from step 201; otherwise, execution continues with step 205. In step 205, S is estimated _A The resource with the minimum receiving energy is moved to the set S _B Up to S _B The ratio of resources of (a) is R. For a resource comprising a plurality of sub-channels, the received energy of the resource is the average of the received energy of the sub-channels. Next, from S _B Is selected (206) for data transmission and is used for data transmission (207). Here, when one data is transmitted twice, the UE first S _B Then, if there is available resource within the indicated range of SA while satisfying the delay requirement, the UE selects another resource for data transmission.

To enhance the performance of V2X systems, one direction is to use shorter Transmission Time Intervals (TTIs). The short TTI (sTTI) is beneficial to reducing the transmission delay, and the sTTI is beneficial to avoiding the problem that the data of other UEs cannot be received due to half duplex. How to effectively support data transmission of one UE on multiple carriers is an urgent problem to be solved.

Disclosure of Invention

The application provides a method and equipment for transmitting data by using various transmission time intervals, and provides a mapping structure of an sTTI, a resource pool configuration strategy, a resource allocation mechanism and a resource selection process, so that the transmission performance of UE is improved.

In order to achieve the purpose, the following technical scheme is adopted in the application:

a method for data transmission using multiple transmission time intervals, TTIs, comprising:

user Equipment (UE) detects Scheduling Authorization (SA) of other UE in a detection window on the basis of multiple TTI lengths on a resource pool, measures the receiving power of a scheduled data channel on the basis of the SA, and detects the receiving energy of each sub-channel of each sub-frame;

the UE selects resources for data transmission based on the detected SA, the received power and the received energy;

and the UE transmits the SA indication to the selected resource and performs data transmission through the resource.

Preferably, one long TTI (lTTI) is divided into a plurality of short TTIs (sTTIs), the automatic gain control AGC is arranged at the beginning part of each sTTI, an interval GAP is arranged at the end part, and the AGC and GAP of the sTTI are equal to the length of the lTTI; or the AGC of the first sTTI has the same length as the lTTI, the GAP of the last sTTI has the same length as the lTTI, and other AGC and/or GAP of the sTTI have shorter length than the lTTI.

Preferably, one lTTI divides a plurality of sTTIs, AGC is set at the beginning part of each sTTI, but GAP is set only at the ending part of the last sTTI, the GAP and the GAP of the lTTI have the same length, and the AGC of the sTTI and the lTTI have the same length; or the AGC of the first sTTI has the same length as the lTTI, and the AGC of other sTTI is shorter than the lTTI.

Preferably, one tti divides a plurality of ttis, the first tti sets AGC and is the same as the tti, the last tti sets GAP and is the same as the tti, and a shorter GAP and AGC are inserted between two adjacent ttis.

Preferably, one tti divides a plurality of sTTI, the first and last OFDM symbols of the sTTI each transmit data on one subcarrier every N subcarriers, and N is a constant.

Preferably, when data transmission is performed based on TTIs of various lengths, the resource pool is configured according to lTTI.

Preferably, when data transmission is performed based on TTIs of various lengths, the resource pool is configured for each TTI of various lengths.

Preferably, it is assumed that the SA of the sTTI occupies M times of the tti, and the SA of the qth sTTI occupies the SA resource q + [0, 1.. M-1], q ═ 0, 1.. M-1, M ═ N-M +1, and N is the number of tti data subchannels.

Preferably, assuming that the SA of the sttI occupies m times of the frequency resource of the ltTI, the SA of the qth sttI occupies the SA resource q m + [0, 1.. m-1] of the ltTI]+Δ ₁ ，q＝0,1,...,M-1，

The qth sTTI data subchannel occupies the lTTI data subchannel q · m + [0, 1.. m-1]]+Δ ₂ ，Δ ₁ And Δ ₂ Is a parameter of resource location, and N is the number of ttis data subchannels.

Preferably, when SA with different TTI lengths are received, the PSSCH-RSRP thresholds are different for different TTI lengths; or, recording the PSSCH-RSRP threshold as Th, comparing the PSSCH-RSRP with Th + delta to judge whether the resource is available, wherein delta is a power regulation parameter; or comparing PSSCH _ RSRP + delta with a threshold to judge whether the resource is available, wherein PSSCH _ RSRP is the received power of the data channel, and delta is the power adjusting parameter.

Preferably, when the received energy S-RSSI is measured according to the lTTI, the received energy of other symbols except the AGC and GAP symbols of the lTTI is measured; alternatively, the received energy of all symbols not used for GAP except the AGC and GAP symbols for the tti is measured; or, dividing one lTTI resource into a plurality of sTTI resources, firstly measuring the S-RSSI of each sTTI resource, and then obtaining the S-RSSI of the lTTI resource according to the S-RSSI of each sTTI resource.

Preferably, for one sTTI resource, if other sTTI with the same or overlapping frequency position are not available in the lti where the sTTI resource is located, the UE increases the probability of selecting the sTTI resource.

Preferably, when the UE supports the number of detected SAs less than the total number of SAs of a plurality of TTIs within one lTTI, the detected SA resources are determined according to the priority of different TTI lengths

(ii) a Or when the number of the SAs supported by the UE to be detected is less than the total number of the SAs in the plurality of TTIs in one lTTI, respectively determining the number of the SA resources of the lTTI and the number of the SA resources of the sTTI which are required to be detected by the UE.

Preferably, the number of PRBs with different detected TTI lengths is determined according to the priorities of the different TTI lengths; or respectively determining the PRB number of lTTI and the PRB number of sTTI which are required to be detected by the UE.

An apparatus for data transmission using multiple transmission time intervals, comprising a detection module, a resource selection module, and a transceiver module, wherein:

a detection module, configured to detect, by the UE, SAs of other UEs in a detection window based on multiple TTI lengths in one resource pool, measure a reception power of a scheduled data channel based on the SA, and detect a reception energy of each subchannel of each subframe;

a resource selection module, configured to select, by the UE, a resource for data transmission based on the detected SA, received power, and received energy;

By adopting the method of the invention, the collision between the UE adopting the TTIs with different lengths is avoided as much as possible, the resource utilization rate is improved, and the transmission performance of the TTIs with different lengths is ensured.

Drawings

FIG. 1 is a schematic illustration of resource selection based on detection;

FIG. 2 is a flow diagram of resource selection based on detection;

FIG. 3 is a flow chart of the present invention;

FIG. 4 is a schematic diagram of the structure of sTTI;

FIG. 5 is a diagram illustrating SA and data channel resources of an sTTI;

FIG. 6 is a diagram of SA and data channel resources of sTTI two;

FIG. 7 is a schematic view of resource selection according to the present invention;

FIG. 8 is a diagram of the apparatus of the present invention;

FIG. 9 is a diagram illustrating the use of half an OFDM symbol for AGC;

fig. 10 is a diagram illustrating the use of half an OFDM symbol as a GAP;

fig. 11 is a diagram illustrating a data channel mapping using half of an OFDM symbol as AGC and GAP.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and examples.

In the V2X communication, devices (UEs) participating in communication may be classified into various types, for example, a car (VUE), a Pedestrian (PUE), a roadside unit (RSU), and the like. It is assumed that the data transmission mechanism of the UE is that, first, the UE sends a control channel for indicating information such as time-frequency resources occupied by the data channel and a coding modulation scheme (MCS), which is hereinafter referred to as scheduling assignment Signaling (SA); next, the UE transmits data on the scheduled data channel. For the LTE D2D/V2X system, the SA is also called PSCCH, and the data channel is also called PSSCH. For a device, because its data is generated basically periodically for a period of time, the device can reserve resources periodically according to a certain reservation interval; and, each data may be repeatedly transmitted K times, and accordingly K resources need to be reserved, where K is greater than or equal to 1, so as to avoid that some devices cannot receive the data due to the limitation of half-duplex operation.

Assuming that a plurality of Transmission Time Interval (TTI) lengths are adopted, the longest TTI is denoted as lTTI, and other TTI lengths are collectively referred to as sTTI, and there may be one or more sTTI lengths. And a plurality of sTTIs divided in one lTTI. The adoption of the sTTI is beneficial to reducing the time delay of data transmission, and is particularly suitable for services with stricter time delay requirements. In a resource pool, only one kind of TTI length, lTTI or sTTI, can be used; or may be a data transmission allowing simultaneous presence of the tti and sTTI. Preferably, the a and data channels of one UE use TTIs of the same length.

FIG. 3 is a flowchart of a method for supporting multiple TTI lengths in accordance with the present invention, comprising the steps of:

step 301, the UE detects SAs of other UEs in a detection window based on multiple TTI lengths on one resource pool, measures the reception power of a scheduled data channel based on the SAs, and detects the reception energy of each subchannel of each subframe.

In the above measurement of the received power and the received energy, it is necessary to consider the influence of coexistence of a plurality of TTI lengths.

Step 302, the UE selects resources for data transmission based on the detected SA, received power and received energy.

In the resource selection process, the influence between the UEs with different TTI lengths can be avoided as much as possible, so that the coexistence performance is improved.

Step 303, the UE transmits the SA indication to the selected resource, and performs data transmission through the resource.

For a plurality of sttis divided within one tti, each sTTI includes an Automatic Gain Control (AGC) symbol, a DMRS, and a data symbol and a GAP (GAP) symbol. Wherein, the AGC symbol is used for the receiving end to adjust the operating point, and the AGC symbol can transmit data or not transmit data. The GAP symbol is a time interval for the UE's transceive transition time and avoids overlap between V2X signals and cellular signals and between V2X signals.

Further, the present invention provides several specific examples below to illustrate the method of the present invention supporting various TTI lengths in detail.

Example one

In actual communication, it is difficult to accurately predict the UE type and the distribution of traffic. For example, traffic operating according to the lTTI and traffic operating according to the sTTI are difficult to predict. It is considered that data transmission of the lTTI and the sTTI is simultaneously supported in the same resource pool.

As shown in fig. 4(a), the structure of the tti is that the first OFDM symbol of the tti is used for AGC, so it is likely that data on the first OFDM symbol cannot be used for decoding; the last OFDM symbol is left off as a GAP, which can be used to generate the UE transmit/receive switching time, and to avoid the V2X signal overlapping with the cellular network signal and the V2X signal of different UEs when multiplexing V2X with cellular network communication on one carrier. For example, the V2X subframe structure of LTE release 14 employs the ttii structure of fig. 4 (a).

One lTTI may be further divided into two or more sttis. The length of AGC and GAP required for a UE supporting sTTI may be the same as for a UE supporting only ttis. Or, because the delay requirement of the UE supporting sTTI is relatively strict, the processing capability of AGC and GAP is generally increased accordingly, so the length of AGC and GAP may be shortened. In addition, assuming that the cellular network transmission adopts lTTI, except the last sTTI, the problem of overlapping with the cellular network transmission does not exist.

As shown in fig. 4(b), AGC may be set at the beginning of each sTTI, and GAP may be set at the end. The AGC and GAP of the sTTI are equal to the sTTI length. Alternatively, the AGC of the first sTTI and the GAP of the last sTTI are the same, and the other AGCs and/or GAPs of the sTTI may be shorter than the tti length. For example, the AGC of the first sTTI and the GAP of the last sTTI may comprise a plurality of OFDM symbols, while the other AGCs and/or GAPs of the sTTI comprise only one OFDM symbol. The GAP may be used as a UE transmit-receive switching time and to avoid overlapping of V2X signals of different UEs. Due to the introduction of the GAP, the transceiving operation of the UE in one sTTI does not affect the transceiving operation in the next adjacent sTTI. The problem with this approach is that the overhead of AGC and GAP is large.

As shown in fig. 4(c), AGC may be set at the beginning of each sTTI, but GAP may be set only at the end of the last sTTI, and this GAP has the same GAP length as the sTTI. The AGC of the sTTI is equal to the lTTI length. Alternatively, the AGC of the first sTTI has the same length as the tti, and the AGCs of the other sTTI may be shorter than the tti. For example, the AGC for the first sTTI may include multiple OFDM symbols, while the AGC for the other sTTI includes only one OFDM symbol. Since the end positions of other sTTI have no GAP, the transceiving operation on the next adjacent sTTI is affected. Assuming that the UE transmits a signal in one sTTI, the UE can complete the transmission-to-reception conversion using the previous part of the AGC symbol of the next sTTI, but this means that the UE can complete the AGC operation using only the remaining part of the AGC symbol; alternatively, the UE may not perform the receiving operation in the next sTTI. Assuming that the UE receives a signal in one sTTI, the UE can complete the conversion of the received transmission using the previous part of the AGC symbol of the next sTTI, but this means that the UE can only transmit valid signals or data for AGC in the remaining part of the AGC symbol; alternatively, the UE may not transmit in the next sTTI.

As shown in fig. 4(d), AGC may be set at the beginning of the first sTTI and is the same as the tti, GAP may be set at the end of the last sTTI and is the same as the tti, and a shorter GAP and AGC, i.e. a shorter segment than GAP and AGC of the tti, may be inserted between two adjacent sTTI. For example, one OFDM symbol is used to generate the GAP and AGC. Because the GAP and the AGC are introduced, the transceiving operation of the UE in one sTTI does not influence the transceiving operation in the next adjacent sTTI. Meanwhile, because the GAP and the AGC are relatively short, the expenses of the AGC and the GAP are reduced.

As shown in fig. 4(e), it is further assumed that the sTTI employs a larger subcarrier spacing (SCS) than the tti, such that the OFDM symbol length of the sTTI is shorter than the tti. The starting part of the first sTTI is set with AGC and is the same as the tti, e.g., an OFDM symbol occupying a plurality of sTTI; the ending part of the last sTTI is set up GAP and is the same as the tti, for example, an OFDM symbol occupying a plurality of sTTI; a shorter GAP and AGC is inserted between two adjacent sTTI, i.e. shorter than the GAP and AGC of an tti, e.g. an OFDM symbol occupying one sTTI each. Because the GAP and the AGC are introduced, the transceiving operation of the UE in one sTTI does not influence the transceiving operation in the next adjacent sTTI. Meanwhile, because the GAP and the AGC are relatively short, the expenses of the AGC and the GAP are reduced.

For the methods of fig. 4(b) -4 (e), within an OFDM symbol used for AGC, data may be transmitted occupying all subcarriers, e.g., within an AGC symbol at 15kHz subcarrier spacing; alternatively, data may be transmitted on every N subcarriers, for example, N equals 2. With the latter method, the signal on the OFDM symbol used for AGC has a repetitive structure in time. As shown in fig. 9, assuming that N is equal to 2, the AGC symbol may be equally divided into 2 parts, and all data may be received based on only the latter part. The receiving end may perform AGC operation using the previous part of the AGC symbol and receive data on the latter part of the AGC symbol, thereby reducing the overhead of AGC. Depending on the implementation of the receiving end device, the data may be received with the latter part of the AGC symbol, or may be received without the AGC symbol.

As shown in fig. 4(f), it is assumed that data is transmitted on one subcarrier every N subcarriers on the AGC symbol, thereby having the repeating structure shown in fig. 9, and that an OFDM symbol including GAPs is also transmitted on one subcarrier every N subcarriers, for example, N is equal to 2. As shown in fig. 10, assuming that N is equal to 2, the OFDM symbol may be equally divided into 2 parts and all data may be received based on only the previous part. The previous portion of this OFDM symbol may still transmit data, but the transmission is stopped on the latter portion to generate GAPs, thereby reducing the overhead of GAPs. The last symbol of the tti may be the GAP generated using the method shown in fig. 10, or no signal may be sent, so that the entire symbol is used for the GAP. Depending on the implementation of the receiving end device, the data may be received with the latter part of the AGC symbol, or may be received without the AGC symbol. Depending on the implementation of the receiving end device, the data may be received using a previous portion of the OFDM symbol including the GAP, or may also be received without using the OFDM symbol including the GAP.

For the sTTI structure shown in fig. 4(f), it is assumed that the first and last OFDM symbols of the sTTI both transmit data on one subcarrier every N subcarriers. As shown in fig. 11, assuming that N is equal to 2, the total amount of data transmitted in the first OFDM symbol and the last OFDM symbol is equivalent to the amount of data transmitted in an OFDM symbol spaced 15kHz apart by one subcarrier. In fig. 11(a), it is assumed that the subcarriers used for data transmission of the first and last OFDM symbols of sTTI are the same. In fig. 11(b), it is assumed that the subcarriers used for data transmission of the first and last OFDM symbols of the sTTI are different. For the mapping structure shown in fig. 11, rate matching may be handled according to time-frequency resources where the data channel contains an integer number of OFDM symbols. For example, in fig. 11, assuming that two OFDM symbols are used to carry the DMRS, the number of OFDM symbols available for actually transmitting data is equivalent to 4. That is, the rate matching may be performed for data transmission in 4 OFDM symbols, but actually the modulation symbols of the data are mapped to 5 OFDM symbols for data transmission.

Example two

When data transmission of the ltri and the sTTI is simultaneously supported within one resource pool, the resource pool may still be configured or preconfigured according to the lTTI. In LTE release 14, after removing some subframes that are not available for V2X, e.g., subframes for synchronization channel (SLSS), TDD downlink subframes, and reserved resources, all remaining subframes are reordered, and then a bitmap is periodically applied on the basis of the reordered logical subframe indices to define a resource pool. A '1' in the bitmap indicates that the subframe belongs to the resource pool, and a '0' indicates that the subframe does not belong to the resource pool.

For the lTTI transmission, the resource pool may be configured on the basis of the physical subframe index, or may be defined on the basis of the logical subframe index according to the method of LTE release 14. For sTTI transmissions, its resource pool is still defined in terms of tti, so that no additional signaling or configuration information is needed. Note that one lTTI is divided into M sttis, then the index of the mth sTTI within the lTTI with the index K is K · M + M, K is 0, 1. By adopting the method, for one service, the reserved interval when the lTTI transmission is adopted is recorded as P _rsvp ＝k·P _step ，P _step Is a basic reservation interval, for example, 100, k is a coefficient, the value range of k may be configured in a higher layer, and in LTE release 14, the maximum set of the value ranges of k is [1/5,1/2,1,2,3,4,5,6,7,8,9,10 ]]With a reserved interval of sTTI of

Alternatively, sTTI is represented by a two-dimensional index (k, m), where k is an index of an lTTI in which sTTI is located, and m is an index of the sTTI in the lTTI. With this method, the reserved intervals of sTTI and lTTI are equal, i.e. P _rsvp ＝k·P _step However, the influence of the two-dimensional index (k, m) needs to be taken into account when handling resource selection and indicating resources in the SA.

Or, for one resource pool, after removing some Time Units (TUs) that are not available for V2X, the TU may be a subframe, a timeslot or a mini-slot (mini-slot), where one timeslot is divided into a plurality of mini-slots, the UE using the tti reorders the ttis of all remaining TUs, and then defines a first resource pool based on the reordered logical subframe index; and the UE adopting the sTTI reorders the sTTI of all the rest TUs, and then defines a second resource pool on the basis of the reordered logical subframe indexes. The first resource pool and the second resource pool may or may not completely overlap from the perspective of time resources.

EXAMPLE III

Under the condition of a certain amount of transmission data, along with the shortening of TTI, the number of frequency resources occupied by UE is correspondingly increased, thereby ensuring certain transmission performance. For example, when the SA is mapped to an lTTI transmission, 2 PRBs are occupied, and assuming that an lTTI is divided into 2 sTTI, about 4 PRBs need to be occupied when the SA is transmitted within one sTTI. In addition, taking fig. 4(b) as an example, 8 OFDM symbols in the tti carry data; because of the overhead of the additional AGC and GAP, the OFDM symbols carrying DMRS and data within sTTI are only 5, and assuming two OFDM symbols as DMRS, only 3 OFDM symbols carry data. Thus, the required number of PRBs is 16/3, while ensuring that the coding rate of the SA is unchanged. By reducing the number of bits of the SA of the sTTI, the number of PRBs required can be reduced.

For a resource pool, according to lTTI, the data channel is divided into N sub-channels, and the resources are allocated by the sub-channels. Accordingly, the SA resource pool is also divided into N SA resources, so as to correspond to N data subchannels one to one. Because of the variation of the TTI length, the number of divided data subchannels of the sTTI may be the same as or more than the number of divided data subchannels of the TTI.

The number of PRBs of the data subchannel of the sTTI is assumed to be the same as that of the lTTI, and the SA of one sTTI is assumed to occupy m times of the frequency resource of the lTTI. As shown in fig. 5, the SA of the qth sTTI may be SA resource q + [0, 1.. M-1], q ═ 0, 1.. M-1, M ═ N-M +1, which occupy the lti. The SA for the qth sTTI may be to allocate data subchannels with a granularity of n consecutive subchannels starting from a data subchannel q. For example, n may be 1 or m, and n may be higher layer signaling configured or preconfigured. The use of n greater than 1 is advantageous for reducing the overhead of indicating subchannel resources in the SA.

Or, it is assumed that the frequency resource occupied by the SA of one sTTI is m times of the tti, and the number of PRBs of one sTTI data subchannel is also m times of the tti. As shown in FIG. 6, the SA of the qth sTTI can be the SA resource q.m + [0, 1.. m-1] occupying the lTTI]+Δ ₁ ，q＝0,1,...,M-1，

The qth sTTI data subchannel may be the occupied ltri data subchannel q · m + [0, 1.. m-1]]+Δ ₂ . When m cannot divide N exactly, the above-mentioned Δ ₁ And Δ ₂ The position of the SA resource occupied by the SA of the sTTI in the SA resource pool and the position of the subchannel occupied by the sTTI data subchannel in the data resource pool can be adjusted. Delta ₁ And Δ ₂ May be equal or unequal. E.g. Δ ₁ And Δ ₂ Are all equal to 0. Thus, for sTTI, SA resources correspond one-to-one to data subchannels. The SA of the qth sTTI may schedule one or more consecutive sTTI data subchannels starting from the sTTI data subchannel q. This approach is advantageous to reduce the overhead of indicating subchannel resources in the SA.

Example four

When data transmission of the lTTI and the sTTI is simultaneously supported in one resource pool, the resource selection of the UE needs to consider the influence of the data transmission of the lTTI and the data transmission of the sTTI.

The UE detects SAs of other UEs and measures PSSCH-RSRP of a received SA-scheduled data channel, thereby processing resource selection according to the PSSCH-RSRP. The UE needs to detect the SA of the lTTI and the SA of the sTTI. When the currently detected PSSCH-RSRP exceeds a threshold, the corresponding data channel resources are unavailable. The threshold for the psch-RSRP may be different for different TTI lengths. The thresholds for PSSCH-RSRP may be configured or preconfigured, respectively, for different TTI lengths. Or respectively configuring or pre-configuring a PSSCH-RSRP threshold for the detected other UEs and the UE performing detection, wherein the TTI lengths of the other UEs are the same or different. Or, recording PSSCH-RSRP threshold as Th, and comparing PSSCH _ RSRP with threshold Th to judge whether the resource is available when one UE detects SA for scheduling TTI with the same length; when one UE detects SA scheduling different length TTI, comparing PSSCH-RSRP with Th + Delta to judge whether resources are available, wherein Delta is a power adjusting parameter and Delta is a constant or is related to the priority of the detected other UE and/or the UE performing detection. For example, the PSSCH-RSRP threshold corresponding to the SA scheduling for the TTI of different length may be smaller than the PSSCH-RSRP threshold corresponding to the SA scheduling for the TTI of the same length, so as to preferentially remove resources occupied by other UEs employing different TTI lengths, and avoid collisions between UEs employing different TTI lengths as much as possible. Or, recording PSSCH-RSRP threshold as Th, and when one UE detects SA for scheduling TTI with the same length, comparing PSSCH _ RSRP with threshold Th to judge whether the resource is available; when a UE detects an SA scheduling different TTIs, the psch-RSRP measured according to the SA may be modified, i.e. PSSCH _ RSRP + Δ is compared with a threshold Th to determine whether resources are available, where Δ is a power adjustment parameter and Δ is a constant, or is related to the priority of the other detected UEs and/or the UE performing the detection. For example, Δ may be negative, thereby preferentially removing resources occupied by other UEs employing the same TTI length, thereby allowing more collisions between UEs employing different TTI lengths. Under the condition of transmitting equivalent data, the sTTI is adopted to occupy more frequency resources, the lTTI can occupy more time resources, and the UE adopting the two transmission methods can not collide by 100 percent, so that the partial overlapping of the resources occupied by the UE adopting different TTI lengths has relatively small influence on data reception to a certain extent. The method for removing resources according to PSSCH-RSRP may be only used when the UE performing detection employs an tti; alternatively, it may be used only when the UE performing detection employs sTTI; alternatively, the TTI length of the UE performing detection may not be distinguished, and the TTI length may be used for the UE performing detection.

The UE may also measure the S-RSSI of the resources and select a number of resources with the smallest S-RSSI to obtain a set S _B . The TTI length of the resources is the same as the TTI length occupied by the UE. To obtain the S-RSSI for an tti resource, assuming that the S-RSSI is measured according to the tti, for an tti, the UE may measure other symbols except for the AGC and GAP symbols of the tti to obtain the S-RSSI. Alternatively, for an lTTI, the UE may measure S-RSSI on all symbols not used for GAP except for AGC and GAP symbols of the lTTI, considering that the lTTI is divided into multiple sTTIs, each of which may have its own GAP symbol. For example, for the party of FIG. 4(b) except for AGC and GAP symbols for lTTIThe GAP symbol of the first sTTI is not used for measuring S-RSSI; for the method of fig. 4(d), GAP in the front of the second sTTI is not used to measure S-RSSI; for fig. 4(e), the GAP symbols of the first sTTI are not used for measuring S-RSSI. The UE may also measure S-RSSI on only a subset of the time resources determined according to the above rules. By adopting the method, because the GAP symbol of the sTTI is not used for measuring the S-RSSI, the strength of the interference signal can be estimated more accurately, thereby reducing the collision. To obtain the S-RSSI for an sTTI resource, assuming that S-RSSI is measured according to sTTI, for an sTTI, the UE may measure other symbols besides AGC and GAP symbols of said sTTI to obtain S-RSSI. For a resource of one lTTI, it is assumed that it is divided in time into N sTTI resources s _n ，n＝0,1...N-1，s _n The frequency resources are the same as the lTTI resources, and in order to obtain the S-RSSI of the lTTI resources, the UE may first measure each sTTI resource S _n S-RSSI, then according to the respective sTTI resource S _n The S-RSSI of the lTTI resource is obtained. For example, the S-RSSI of the lTTI resource may be the S-TTI resource _n The maximum, average, weighted average, etc. of S-RSSI. The method for measuring S-RSSI may be only used when the UE performing detection employs an lTTI; alternatively, it may be used only when the UE performing detection employs sTTI; alternatively, the TTI length of the UE performing detection may not be distinguished, and the TTI length may be used for the UE performing detection.

The UE is then in set S _B A resource is selected. The UE may be in set S _B The resources are randomly selected. Or for UE adopting sTTI, for S _B If the sTTI resource is located in an lti, other sTTI with the same frequency position or overlapping are not available, the UE may select such sTTI resource with a higher probability. By adopting the method, the UE of the sTTI uses the same or adjacent PRB in one lTTI as much as possible, so that more lTTI resources are possibly reserved for the UE of the lTTI, and further the collision among the UE with different TTI lengths is avoided. As shown in FIG. 7, assuming that

resources

702 and 711 are not available, the other four

resources

701, 712, 703, 713 are all available because

resources

703 and 713 are located in the same PRB, making them generally selected by the UE of the sTTIThe rate is lower than

resources

701 and 712, thereby facilitating the lpi resources composed of

resources

703 and 713 to be selected by UEs of other lpis.

For one resource pool, the SA resources of N lTTIs are divided in one lTTI, the SA resources of M sTTIs are divided in one sTTI, the total number of SAs which need to be detected by the UE in one lTTI period is L ═ N + M · M, and M is the number of the divided sTTIs in one lTTI. The number of SAs that the UE can detect within one tti period depends on the capability of the UE. For a UE with particularly high capability, that is, the number of detectable SAs is greater than or equal to L, the UE may detect each possible SA resource. Assuming that the UE has limited capability, that is, the number of detectable SAs is equal to or less than L, the UE may define a rule for selecting the detected SAs. One possible rule is to define different detection priorities for different TTI lengths. For example, the UE first guarantees to detect SA resources for all ttis, and then the remaining capability is used to detect SA resources for sTTI. For example, it is assumed that the safety-related V2X message is transmitted through the tti, and therefore, it is necessary to preferentially detect the SA resource of the tti. Or, another rule is to determine the number L of SA resources of the L ttis that the UE needs to detect respectively _L And number L of SA resources of sTTI _S . The above parameter L _L And L _S May be base station configured, pre-configured, or predefined in a standard for one UE capability. Or, the maximum number of the SAs supported and detected by the UE in one lTTI is recorded as L _max Another rule is to determine the number L of SA resources of lTTI that the UE needs to detect _L Then SA detection capability, i.e., L, remains _max -L _L SA resources for handling sTTI. The above parameter L _L May be base station configured, pre-configured, or predefined in a standard for one UE capability.

In addition, the total number of PRBs that the UE can decode is also dependent on the capability of the UE. The total number of PRBs may be the total number of PRBs of the data channel exclusively, or may be the total number of PRBs including the SA and the data channel. The capability of defining the number of PRBs that the UE can detect in terms of only one TTI length, e.g., ltri, may be possible, and may translate into the capability of other TTI lengths. Alternatively, the capability of defining the number of PRBs that can be detected by the UE for each TTI length may be used. Push buttonThe ability to define the number of PRBs that a UE can detect as a TTI length may be for PRBs that can only be used to detect this TTI length; or, the capability of defining the number of PRBs that the UE can detect according to one TTI length may also be converted into PRBs for detecting other TTI lengths. For example, the total number of PRBs that can be detected by the UE in an lTTI is N, and correspondingly, the number of PRBs that can be detected by the UE in an sTTI may be defined as c · N, where c is a coefficient and may be related to the relative length of the sTTI and the lTTI, and for example, c is equal to 2. Assuming that the UE has limited capabilities, it may be defined a rule that the UE determines the number of PRBs detected according to different TTI lengths. One possible rule is to define different detection priorities for different TTI lengths. For example, the UE first guarantees to detect all PRBs of the tti, and then the remaining capability is used to detect the PRBs of the sTTI. For example, it is assumed that the safety-related V2X message is transmitted through the tti, and therefore it is necessary to preferentially detect the PRB of the tti. Or, another rule is to determine the number L of PRB sources for the lTTI that the UE needs to detect respectively _L And number L of PRBs of sTTI _S . The above parameter L _L And L _S May be base station configured, pre-configured, or predefined in a standard for one UE capability. Or, suppose that the maximum number of PRBs that the UE supports detection in the tti is L _max Another rule is to determine the number L of PRBs of lTTI that the UE needs to detect _L Then the remaining detection capability is used to process the PRBs of the sTTI, i.e. corresponding to L _max -L _L The detection capability of the PRBs of one tti is used to process the PRBs of the sTTI. The above parameter L _L May be base station configured, preconfigured, or predefined in a standard for one UE capability.

Corresponding to the above method, the present application also discloses an apparatus, which may be configured to implement the above method, as shown in fig. 8, the apparatus includes a detecting module, a resource selecting module, and a transceiver module, where:

and the receiving and sending module is used for transmitting the SA indication to the selected resource by the UE and carrying out data transmission through the resource.

It will be understood by those skilled in the art that all or part of the steps carried by the method for implementing the above embodiments may be implemented by hardware related to instructions of a program, which may be stored in a computer readable storage medium, and when the program is executed, the program includes one or a combination of the steps of the method embodiments.

In addition, functional units in the embodiments of the present application may be integrated into one processing module, or each unit may exist alone physically, or two or more units are integrated into one module. The integrated module can be realized in a hardware mode, and can also be realized in a software functional module mode. The integrated module, if implemented in the form of a software functional module and sold or used as a stand-alone product, may also be stored in a computer readable storage medium.

The storage medium mentioned above may be a read-only memory, a magnetic or optical disk, etc.

The above description is only exemplary of the present application and should not be taken as limiting the present application, as any modification, equivalent replacement, or improvement made within the spirit and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A method performed by a user equipment, UE, in a communication system, comprising:

receiving control information on a PSCCH, wherein the control information comprises information of resources scheduled by the PSCCH for the PSSCH;

determining Reference Signal Received Power (RSRP) of PSSCH;

determining a set of resources for data transmission based on the RSRP and a threshold;

transmitting data through the resource set;

wherein the threshold is determined based on a length of a TTI of the PSSCH.

2. The method of claim 1, further comprising:

one long tti (ltti) divides a plurality of short ttis (stti);

setting Automatic Gain Control (AGC) at the beginning part of each sTTI; and

setting a GAP at the ending part;

the length of AGC of each sTTI is equal to that of AGC of the lTTI, and the length of GAP of each sTTI is equal to that of GAP of the lTTI; or,

the length of AGC of the first sTTI is the same as that of AGC of the l TTI, the length of GAP of the last sTTI is the same as that of GAP of the l TTI, and the lengths of AGC or GAP of other sTTI are shorter than that of AGC or GAP of the l TTI; or

The length of AGC and GAP for each other sTTI is shorter than the length of AGC and GAP for the tti, respectively.

3. The method of claim 1, wherein the data is transmitted on a subset of the set of resources, wherein the subset is identified based on a length of a TTI used for data transmission.

4. The method of claim 1, wherein one tti divides a plurality of ttis, the first sTTI is configured with AGC and same as the tti, the last sTTI is configured with GAP and same as the tti, and a shorter GAP and AGC are inserted between two adjacent sTTI.

5. The method of claim 1, wherein an tti divides a plurality of sTTI, wherein the first and last OFDM symbols of the sTTI are each transmitted on one subcarrier every N subcarriers, and wherein N is a constant.

6. The method of claim 1, wherein when data transmission is performed based on TTIs of various lengths, the resource pool is configured according to lTTI; alternatively, the resource pool is configured for each TTI of length.

7. The method according to claim 1, wherein the scheduling assignment signaling SA of the sTTI is assumed to occupy M times of frequency resources of the tti, and the SA of the qth sTTI occupies SA resources q + [0, 1.. M-1], q ═ 0, 1.. M-1, M ═ N-M +1, and N is the number of tti data subchannels.

8. The method of claim 1, wherein the SA of the qth sTTI occupies m times of frequency resources of the tti and the SA of the qth sTTI occupies q · m + [0, 1.. m-1] of SA resources of the tti]+Δ ₁ ，q＝0,1,...,M-1，

9. The method of claim 1, wherein the PSSCH-RSRP thresholds are different for different TTI lengths when SAs of different TTI lengths are received; or, recording the PSSCH-RSRP threshold as Th, comparing the PSSCH-RSRP with Th + delta to judge whether the resource is available, wherein delta is a power regulation parameter; or comparing PSSCH-RSRP + delta with a threshold to judge whether the resource is available, wherein PSSCH-RSRP is the received power of the data channel, and delta is the power adjusting parameter.

10. The method of claim 9, wherein RSRP of the PSSCH is less than or equal to the threshold, and wherein the set of resources for data transmission includes resources for the PSSCH; the RSRP of the PSSCH is greater than the threshold, and the set of resources for data transmission does not include resources for the PSSCH.

11. The method of claim 1, the determining a set of resources for data transmission comprising:

for one sTTI resource, if other sTTI with the same frequency position or overlapping frequency position is unavailable in the lTTI where the sTTI resource is located, the UE increases the probability of selecting the sTTI resource.

12. The method of claim 1, the determining resources for data transmission comprising:

when the number of the SAs supported by the UE to be detected is less than the total number of the SAs of various TTIs with different lengths in the lTTI, determining the detected SA resources according to the priority of the TTIs with different lengths; or,

and when the number of the SAs supported and detected by the UE is less than the total number of the SAs of the plurality of TTIs with different lengths in the lTTI, respectively determining the number of the SA resources of the lTTI and the number of the SA resources of the sTTI which need to be detected by the UE.

13. The method of claim 1, the determining a set of resources for data transmission comprising:

determining the number of detected resource blocks PRB of the TTIs with different lengths according to the priorities of the TTIs with different lengths; or respectively determining the PRB number of lTTI and the PRB number of sTTI which are required to be detected by the UE.

14. The method of claim 1, the control information is received based on a length of a plurality of TTIs.

15. An apparatus performed by a User Equipment (UE) in a communication system, comprising a detection module, a resource selection module, and a transceiving module, wherein:

a detection module, configured to receive control information on a PSCCH, where the control information includes information of resources for the PSCCH scheduled by the PSCCH; determining Reference Signal Received Power (RSRP) of PSSCH;

a resource selection module to determine a set of resources for data transmission based on the RSRP and a threshold;

the transceiving module is used for carrying out data transmission through the resource set;

wherein the threshold is determined based on a length of a TTI of the PSSCH.

16. The apparatus of claim 15, wherein:

one long tti (ltti) divides a plurality of short ttis (stti);

setting automatic gain control AGC at the beginning part of each sTTI; and

setting a GAP at the ending part;

the length of AGC of each sTTI is equal to that of AGC of the l TTI, and the length of GAP of each sTTI is equal to that of GAP of the l TTI; or,

17. The apparatus of claim 15, wherein the data is transmitted on a subset of the set of resources, wherein the subset is identified based on a length of a TTI used for data transmission.

18. The apparatus of claim 15, wherein an tti divides a plurality of sTTI, a first sTTI is configured with AGC and same as the tti, a last sTTI is configured with GAP and same as the tti, and a shorter GAP and AGC are inserted between two adjacent sTTI.

19. The apparatus of claim 15, wherein an tti divides a plurality of sTTI, wherein the first and last OFDM symbols of the sTTI are each to transmit data on one subcarrier every N subcarriers, and wherein N is a constant.

20. The apparatus of claim 15, wherein when data transmission is performed based on TTIs of various lengths, the resource pool is configured according to lTTI; alternatively, the resource pool is configured for each TTI of length.

21. The apparatus according to claim 15, wherein the SA of sTTI occupies M times of frequency resources of lti, the SA of qth sTTI occupies q + [0, 1.. M-1], q ═ 0, 1.. M-1, M ═ N-M +1, and N is the number of lti data subchannels.

22. The apparatus of claim 15, wherein the SA of the qth sTTI occupies m times of frequency resources of the tti and the SA of the qth sTTI occupies q · m + [0, 1.. m-1] of SA resources of the tti]+Δ ₁ ，q＝0,1,...,M-1，

The qth sTTI data sub-channel occupies the lttti data sub-channel q · m + [0, 1.. m-1]]+Δ ₂ ，Δ ₁ And Δ ₂ Is a parameter of resource location, and N is the number of ttis data subchannels.

23. The apparatus of claim 15, wherein when SA of different length TTIs are received, the PSSCH-RSRP thresholds are different for different TTI lengths; or, recording the PSSCH-RSRP threshold as Th, comparing the PSSCH-RSRP with Th + delta to judge whether the resource is available, wherein delta is a power regulation parameter; or comparing PSSCH-RSRP + delta with a threshold to judge whether the resource is available, wherein PSSCH-RSRP is the received power of the data channel, and delta is the power adjusting parameter.

24. The device of claim 23, wherein RSRP of the PSSCH is less than or equal to the threshold, and wherein the set of resources for data transmission comprises resources for the PSSCH; the RSRP of the PSSCH is greater than the threshold, and the set of resources for data transmission does not include resources for the PSSCH.

25. The apparatus of claim 15, the determining a set of resources for data transmission comprising:

26. The device of claim 15, the resource selection module to determine resources for data transmission comprises:

27. The device of claim 15, the resource selection module to determine the set of resources for data transmission comprises:

determining the number of PRBs of TTIs with different lengths according to the priorities of the TTIs with different lengths; or respectively determining the PRB number of lTTI and the PRB number of sTTI which are required to be detected by the UE.

28. The apparatus of claim 15, the control information is received based on a length of a plurality of TTIs.

29. A user device, comprising:

a transceiver; and

a processor coupled to the transceiver and configured to perform the method of any of claims 1-14.