WO2017209570A1

WO2017209570A1 - Uplink data transmission method, random access method, and corresponding ue and base station thereof

Info

Publication number: WO2017209570A1
Application number: PCT/KR2017/005809
Authority: WO
Inventors: Chen QIAN; Chenxi HAO; Bin Yu; Qi XIONG; Jingxing Fu
Original assignee: Samsung Electronics Co., Ltd.
Priority date: 2016-06-03
Filing date: 2017-06-02
Publication date: 2017-12-07
Also published as: CN107466112A; CN107466112B

Abstract

The present disclosure relates to a pre-5^th-Generation (5G) or 5G communication system to be provided for supporting higher data rates Beyond 4^th-Generation (4G) communication system such as Long Term Evolution (LTE).The present disclosure discloses an uplink data transmission method, a random access method, and corresponding base station and user equipment (UE) thereof. The uplink data transmission method includes: transmitting, to a base station, a preamble through a random access channel, receiving, from the base station, a random access response (RAR), in which the RAR includes an identifier of the preamble, and transmitting, to the base station, data, in response to receiving the RAR including the identifier of the preamble.

Description

UPLINK DATA TRANSMISSION METHOD, RANDOM ACCESS METHOD, AND CORRESPONDING UE AND BASE STATION THEREOF

The present disclosure relates to radio communication technologies, and particularly to an uplink data transmission method and corresponding user equipment (UE) and base station thereof.

To meet the demand for wireless data traffic having increased since deployment of 4^th generation (4G) communication systems, efforts have been made to develop an improved 5^th generation (5G) or pre-5G communication system. Therefore, the 5G or pre-5G communication system is also called a 'Beyond 4G Network' or a 'Post Long Term Evolution (LTE) System'.

The 5G communication system is considered to be implemented in higher frequency (mmWave) bands, e.g., 28GHz or 60GHz bands, so as to accomplish higher data rates. To decrease propagation loss of the radio waves and increase the transmission distance, the beamforming, massive multiple-input multiple-output (MIMO), Full Dimensional MIMO (FD-MIMO), array antenna, an analog beam forming, large scale antenna techniques are discussed in 5G communication systems.

In addition, in 5G communication systems, development for system network improvement is under way based on advanced small cells, cloud Radio Access Networks (RANs), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, moving network, cooperative communication, Coordinated Multi-Points (CoMP), reception-end interference cancellation and the like.

In the 5G system, Hybrid frequency shift keying (FSK) and quadrature amplitude modulation (FQAM) and sliding window superposition coding (SWSC) as an advanced coding modulation (ACM), and filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) as an advanced access technology have been developed.

At present, rapid development of the information industry, especially demands for increase of mobile internets and internet of things (IoT), brings an unprecedented challenge to future mobile communication techniques. For example, according to a report of the international telecommunication union (ITU), ITU-R M.[IMT. BEYOND 2020. TRAFFIC], it is estimated that by year 2020, compared to that in year 2010 (4G), the number of mobile services will increase nearly 1000 times, and the number of user device connections will be more than 170 billion. As a massive number of IoT devices gradually penetrate into the mobile communication network, the number of connected devices will be even more astonishing. To meet the unprecedented challenge, the communication industry and academia have developed research on a wide fifth generation of mobile telecommunication (5G) technique for year 2020. At present, in a report of the ITU, ITU-R M. [IMT. VISION], the framework and overall objectives of the future 5G technique are discussed, in which a vision of demands, usage scenarios, and various important performance indicators of 5G are described in detail. Aiming at new demands in 5G, a report of the ITU, ITU-R M.[IMT.FUTURE TECHNOLOGY TRENDS], provides related information on trends of the 5G technique, intended to solve problems such as significantly improving system throughput, user experience consistency, and scalability to support IoT, delay, energy efficiency, costs, network flexibility, support for new merging services, and flexible spectrum usage.

In 5G technology, a demand for supporting massive machine-type communication (mMTC) services is proposed, and a connection density of an mMTC service may be up to millions of connections per square kilometer, which is far higher than a connection density supported by existing standards. A significant characteristic of this kind of data communication is bursts of data communications. That is, a user equipment (UE) is in a sleep state for a long period, and it is woken up for carrying out data communications only when there is a requirement for data transmission. This kind of service, e.g., intelligent meter reading will be ubiquitous in 5G. However, if a traditional technical scheme continues to be used, the access scheme of this kind of service will cause significant signaling overheads and decrease data communication efficiency of the system. Though some non-orthogonal multiple access methods, e.g., sparse code multiple access (SCMA), interleave-grid multiple access (IGMA)pattern division multiple access (PDMA), are able to improve spectral efficiency of data access, or use a Grant-free-based transmission scheme, the traditional Grant-free-based transmission scheme still requires uplink synchronization, i.e., requiring completion of a random access procedure, signaling overheads required are not decreased dramatically, and the signaling problem caused by uplink access and uplink data communications still lead to dramatic decrease of data communication efficiency.

In a traditional LTE-A technique, if a UE is in a sleep state, before transmitting data, the UE should establish uplink synchronization through a random access procedure. A contention-based random access procedure is shown in Fig.1, and it includes the following four steps:

Step 101: a UE randomly selects a preamble from a preamble resource pool, and transmits the preamble through a physical random access channel (PRACH).

Step 102: after a base station detects that the preamble is sent, it sends a random access response (RAR) which includes a random access preamble identifier, a timing advance instruction determined based on an estimation of latency between the UE and the base station, a temporary cell-radio network temporary identifier (C-RNTI), and time-frequency resource information allocated for next uplink transmission of the UE.

Step 103: the UE sends a third message (Msg3) to the base station based on information contained in the RAR. Msg3 includes information such as a UE identifier and a radio resource control (RRC) connection request, in which the UE identifier is unique for the UE, and it is used to resolve conflicts.

Step 104: the base station sends a conflict resolution identifier which includes a UE identifier of a UE which wins during conflict resolution to the UE. When the UE detects its UE identifier, it upgrades the temporal C-RNTI to a C-RNTI, sends an ACK signal to the base station to complete the random access procedure, and wait for scheduling by the base station. Or otherwise, the UE will start a new random access procedure after a period of delay.

After the random access procedure is completed, if the UE needs to transmit uplink data to the base station, it should further carry out a Grant-based uplink transmission procedure which includes the following steps:

Step 111: the UE sends a scheduling request (SR).

Step 112: after the base station receives the SR, it allocates a time-frequency resource for the UE, and sends grant information through a downlink control channel.

Step 113: after the UE receives grant information, it transmits uplink data on the specified time-frequency resource.

It can be seen from foregoing that in traditional art, even if the amount of data transmitted each time by the UE is very little, the UE needs to perform random access and Grant-based uplink data transmission when it carries out one uplink transmission after the sleep, the number of signaling overheads caused by which is huge compared to the amount of data transmitted.

In the case of massive connection communication in the 5G communications, especially in an internet of things scenario, when a large number of UEs perform transmission of burst small data packets, random access with Grant-based uplink transmission as described in the foregoing will incur a large number of signaling overheads, which decreases data transmission efficiency of the system.

In view of the foregoing, an object of the present disclosure is to provide an uplink data transmission method and corresponding base station and user equipment (UE), to reduce the number of signaling overheads of uplink transmission of the UE and improve efficiency of data transmission in a communication system.

The technical scheme of the present disclosure is realized as follows:

An uplink data transmission method, including:

selecting, by a UE, a preamble and transmitting the preamble through a random access channel;

detecting, by the UE, a random access response (RAR); in which the RAR includes a preamble identifier; and

performing, by the UE, uplink data transmission, in response to detecting that the RAR detected includes a preamble identifier of the transmitted preamble.

In a preferred embodiment of the uplink data transmission method, performing, by the UE, uplink data transmission includes: the UE determining a multiple access signature corresponding to the selected preamble based on a preamble and multiple access signature mapping relationship, and using the determined multiple access signature to perform uplink data transmission.

In a preferred embodiment of the uplink data transmission method, performing, by the UE, uplink data transmission includes:

the UE determining an uplink demodulation reference signal corresponding to the selected preamble based on a preamble and uplink demodulation reference signal mapping relationship, and inserting the determined uplink demodulation reference signal during uplink data transmission.

In a preferred embodiment of the uplink data transmission method, the method further includes:

the RAR further indicates a multiple access signature and an uplink demodulation reference signal allocated by the base station; and when using a non-orthogonal multiple access scheme, the UE uses the multiple access signature indicated by the RAR to perform uplink data transmission, and inserts the uplink demodulation reference signal; or

the RAR further indicates the uplink demodulation reference signal allocated by the base station; when using an orthogonal multiple access scheme, and when the UE performs uplink data transmission, the UE inserts the uplink demodulation reference signal indicated by the RAR; or

the RAR further indicates the multiple access signature allocated by the base station, and the UE determines an uplink demodulation reference signal corresponding to the selected preamble based on a preamble and uplink demodulation reference signal mapping relationship; and when using the non-orthogonal multiple access scheme, the UE performs uplink data transmission using the multiple access signature indicated by the RAR and inserts the uplink demodulation reference signal corresponding to the preamble.

In a preferred embodiment of the uplink data transmission method, when there is a mapping relationship between the preamble and an uplink demodulation reference signal, and there is a mapping relationship between the preamble and a multiple access signature, when the UE selects different preambles which are mapped to a same multiple access signature, corresponding uplink demodulation reference signals are different.

In a preferred embodiment of the uplink data transmission method, the method further includes: in response to the UE having not detected a RAR containing the preamble identifier of the preamble during a first period of time after the UE transmitting the preamble, or the UE detecting the RAR containing the preamble identifier of the preamble, but the RAR containing a negative acknowledgement (NACK) signal, the UE randomly re-selecting a preamble to perform random access after waiting for a pre-defined period of time.

In a preferred embodiment of the uplink data transmission method, the method further includes: when the UE transmitting uplink data, the UE transmitting a unique UE identifier together with uplink data.

the UE detecting a control channel of a corresponding time-frequency resource after k subframes after the UE transmitting uplink data, and detecting an acknowledgement (ACK) or a NACK signal corresponding to the time-frequency resource and a multiple access signature and a UE identity (ID) allocated to the UE by the base station; where k is a preset value;

in response to the UE detecting the ACK signal and no further data needing to be transmitted, then the UE waiting for next data transmission; and

in response to the UE detecting the ACK signal, further data needing to be transmitted, and the UE ID allocated to the UE by the base station, then the base station performing uplink data transmission based on scheduling by the base station; and

in response to the UE detecting the NACK signal, the UE using a time-frequency resource and a multiple access signature same as those used for last uplink data transmission after m subframes, where m is a preset parameter; and in response to the number of times of detecting NACK signals exceeding a specified value, then the UE determining that access is failure, and increasing a priority of the preamble to perform random access.

when the UE attempting to perform random access for the first time, the UE selecting a preamble with an initial priority to transmit on the random access channel, where the initial priority is represented by the number of sub-sequences that constitute the preamble.

In a preferred embodiment of the uplink data transmission method, in response to access of the UE being failure, the UE waits for a preset interval, or waits for a random period of time, increases a priority of the preamble, and transmits the preamble with the priority increased on the random access channel.

In a preferred embodiment of the uplink data transmission method, in which the priority is represented by the number of sub-sequences that constitute the preamble, where when a first priority is higher than a second priority, the number of sub-sequences of a preamble having the first priority is more than the number of sub-sequences of a preamble having the second priority.

In a preferred embodiment of the uplink data transmission method, a length of a sub-sequence of the preamble is larger than a largest channel delay.

In a preferred embodiment of the uplink data transmission method, the method further includes: the UE transmitting the preamble in y^th subframe after the UE receiving an indication on a downlink transmission slot indicating that random access is able to be performed, where y is the preset number of subframes, and

indicating that the preamble is transmitted in a current subframe.

the UE transmitting uplink data on an uplink transmission part of x subframes after the UE detecting the RAR containing the preamble identifier corresponding to the transmitted preamble, where x is the preset number of subframes, and

indicating that uplink data is transmitted on an uplink transmission part of a current subframe.

the UE establishing downlink synchronization through a synchronization channel in a downlink transmission subframe, and obtaining random access channel information and preamble information by reading system information from a broadcast channel; and

after the UE obtaining random access channel information and preamble information, by reading a downlink time slot in an uplink transmission subframe, the UE determining whether the uplink transmission subframe can be used for transmitting the preamble.

In a preferred embodiment of the uplink data transmission method, when the UE sends the preamble, the UE determines a transmission power level according to an open-loop power control method.

In a preferred embodiment of the uplink data transmission method, selecting, by the UE, the preamble includes:

the UE selecting the preamble from preambles corresponding to a service type based on the service type.

A communication UE, includes:

a first module to select a preamble and transmit the preamble through a random access channel;

a second module to detect a random access response (RAR); in which the RAR includes a preamble identifier; and

a third module to perform uplink data transmission in response to detecting that the RAR detected includes a preamble identifier of the transmitted preamble.

A random access processing method, includes:

receiving, by a base station, a preamble transmitted by a UE;

performing a conflict detection for the transmitted preamble; and

in response to a result of the conflict detection being non-conflicting, transmitting, by the base station, a random access response (RAR) to the UE, where the RAR includes a preamble identifier of the transmitted preamble.

In a preferred embodiment of the random access processing method, performing the conflict detection for the preamble includes:

in response to a result of a correlation detection for the preamble being lower than a power threshold, then determining that the result of the conflict detection is non-conflicting; or otherwise, determining that the result of the conflict detection is conflicting.

In a preferred embodiment of the random access processing method, the power threshold is a power threshold determined by: determining a receiving power level of the base station according to an open-loop power control parameter of the UE, and determining the power threshold according to a specified tolerance of the receiving power level of the base station.

In a preferred embodiment of the random access processing method, the method further includes:

in response to determining that the result of the conflict detection is conflicting, then the base station not performing RAR processing for the preamble, or the base station inserting the preamble identifier and a NACK signal in the RAR.

In a preferred embodiment of the random access processing method, after transmitting the RAR to the UE, the method further includes:

receiving, by the base station, uplink data sent by the UE, and sending feedback information to the UE;

in which sending feedback information to the UE includes:

the base station transmitting an ACK or NACK signal of uplink data through a downlink control channel after k subframes after the UE sending uplink data, in which

in response to the base station receiving uplink data properly, and the base station determining that the UE has no demand for continuing to transmit data, then the base station sends the ACK signal to the UE;

in response to the base station receiving uplink data properly, and the base station determining that the UE needs to continue to transmit data, the UE allocates a UE ID for the UE and transmits the UE ID and the ACK signal to the UE through the downlink control channel; and

in response to the base station having not received uplink data properly, the base station sends the NACK signal.

In a preferred embodiment of the random access processing method,

the base station detects N preambles, priorities of which are different, using a detection window, where N is a positive integer larger than 1, and the N preambles, the priorities of which are different, have a same basic preamble,

in which a length of the detection window is decided by a length of a sub-sequence that constitutes the basic preamble, and

the base station detecting the N preambles, the priorities of which are different, using the detection window, includes:

when the base station performing a correlation detection, and detecting a basic preamble, then the base station moving the detection window to a neighbouring position; if the base station detecting a sub-sequence which is the same as the sub-sequence that constitutes the basic preamble detected in the detection window, then the base station moving the detection window to a neighbouring position; and if the base station being unable to detect a sub-sequence which is the same as the sub-sequence that constitutes the basic preamble detected in the detection window, then the base station determining that a preamble having a first priority is detected, or otherwise, the base station continuing to move the detection window to a neighbouring position; and if after the base station moving the detection window for j times, and the base station being unable to detect a sub-sequence which is the same as the sub-sequence that constitutes the basic preamble detected in the detection window, then the base station determining that the base station detects a preamble having a j^th priority, or otherwise, the base station continuing to move the detection window to a neighbouring position, where j is a positive integer not larger than a largest priority; and repeating the detection procedures until a position where a sub-sequence cannot be detected, or a preamble having the largest priority being detected.

In a preferred embodiment of the random access processing method, the method further includes: during a detection procedure using the detection window, in response to detecting a conflict according to a correlation detection for a sub-sequence of a first preamble, in case of a preamble which has a priority higher than that of the first preamble being not found, determining that there is a conflict between preambles; in case of a preamble which has a priority higher than that of the first preamble being found, determining whether there is a false conflict based on a delay of the preamble which has the priority higher than that of the first preamble and a cyclic shift between sub-sequences, in which the cyclic shift between the sub-sequences is a cyclic shift between the sub-sequence that constitutes the first preamble and a sub-sequence that constitutes the preamble which has the priority higher than that of the first preamble; and determining there is a false conflict when the following formula is met:

where N_S is the number of sampling points of the cyclic shift between a preamble having a lower priority and a preamble having a higher priority, and a cyclic shift towards right is positive; τ is a delay between the preamble having the lower priority and the preamble having the higher priority; γ is a preset threshold, and γ＞0.

in response to detecting preambles which have different priorities but have a same basic preamble, differentiating the different priorities by time division.

In a preferred embodiment of the random access processing method, differentiating the different priorities by time division includes: in response to a first priority being higher than a second priority, a time when data corresponding to the preamble of the first priority is transmitted and a current time being T1, and a time when data corresponding to the preamble of the second priority is transmitting and the current time being T2, then T1＜T2.

in case of a network load being smaller than a pre-defined threshold, the base station shortening the random access period, and notifying the UE to decrease a highest priority; and

in case of the network load being larger than the pre-defined threshold, the base station increasing the random access period, and notifying the UE to increase the highest priority.

A base station, includes:

a receiving module to receive a preamble transmitted by a UE;

a detecting module to perform a conflict detection for the transmitted preamble; and

a RAR module to send a RAR to the UE in response to a result of the conflict detection being non-conflicting, in which the RAR includes a preamble identifier of the transmitted preamble.

Compared to traditional art, the present disclosure provides a contention-based data transmission method to reduce the number of signaling overheads caused during an uplink access and data transmission procedure, and since an access and uplink data transmission procedure at the UE side is simplified in the present disclosure, the UE can perform uplink data transmission during a random access procedure, which simplifies the uplink access and data transmission procedure, better supports services such as a massive connection communication in 5G communication, reduces the number of signaling overheads during uplink transmission of the UE, and improves efficiency of data communication of the system.

In some embodiments, a method for operating a terminal in a wireless communication system comprises transmitting, to a base station, a preamble through a random access channel, receiving, from the base station, a RAR, wherein the RAR comprises an identifier of the preamble, and transmitting, to the base station, data in response to receiving the RAR comprising the identifier of the preamble.

In some embodiments, an apparatus for a terminal in a wireless communication system comprises a transceiver and at least one processor operatively coupled with the transceiver. The at least one processor is configured to control to transmit, to a base station, the preamble through a random access channel, receive, to the base station, a RAR, and transmit, to the base station, data in response to receiving the RAR comprising the identifier of the preamble. The RAR comprises an identifier of the preamble.

In some embodiments, a method for operating a base station in a wireless communication system comprises receiving, from a terminal, a preamble through a random access channel, performing a conflict detection for the preamble, and in response to a result of the conflict detection being non-conflicting, transmitting, to the terminal, a RAR, where the RAR comprises an identifier of the preamble.

In some embodiments, an apparatus for a base station in a wireless communication system comprises a transceiver and at least one processor operatively coupled with the transceiver. The at least one processor is configured to control to receive, from a terminal, a preamble through a random access channel, perform a conflict detection for the preamble, and transmit, to the terminal, a RAR in response to a result of the conflict detection being non-conflicting. The RAR comprises an identifier of the preamble.

FIG.1 is a flowchart of a contention-based random access procedure in traditional long term evolution advanced (LTE-A) technology;

FIG.2a is a flowchart of an uplink data transmission method at a user equipment (UE) side according to the present disclosure;

FIG.2b is a flowchart of a processing method at a base station corresponding to the method of FIG.2a;

FIG.2c is a flowchart showing interactions between a UE and a base station during uplink data transmission provided according to the present disclosure;

FIG.3 is a schematic diagram of frequency band division for different services;

FIG.4 is a schematic diagram of random access channel time-frequency resources;

FIG.5 is a schematic diagram of a preamble structure in Embodiment 1;

FIG.6 is a schematic diagram showing a correlation detection threshold and power threshold relationship;

FIG.7 is a schematic diagram of preambles having different priorities;

FIG.8 is a schematic diagram of structures of preambles having different priorities, in which the number of sub-sequences that constitute a basic sequence of a preamble is larger than 1;

FIG.9 is a schematic diagram illustrating a situation where a conflict of different sub-sequences is caused due to delay;

FIG.10 is a schematic diagram of correlation detection and conflict detection processing of sub-sequences;

FIG.11 is a schematic diagram of structures of independent frames;

FIG.12 is a schematic diagram of a random access attempt;

FIG.13 is a schematic diagram of transmission schemes of UEs having different priorities;

FIG.14 is a schematic diagram of a structure of a channel frame in Embodiment 3;

FIG.15 is a schematic diagram of resource allocation;

FIG. 16 is an example configuration of a base station in a wireless communication system according to an exemplary embodiment of the present disclosure; and

FIG. 17 is an example configuration of a terminal in a wireless communication system according to an exemplary embodiment of the disclosure.

The present disclosure will be further described hereinafter in combination with the drawings and detailed embodiments.

An uplink access and data transmission procedure of the present disclosure includes processing procedures at a user equipment (UE) side and processing procedures at a corresponding base station side.

Fig.2a is a flowchart of an uplink data transmission method at a UE side according to the present disclosure. Referring to Fig.2a, uplink data transmission method at the UE side mainly includes:

Step 211, the UE selects a preamble and transmits the preamble through a random access channel, and before this, the UE should read random access information; before the UE sends the preamble, it determines a transmission power level through an open-loop power control method; the open-loop power control method refers to that the UE controls a transmission power level of the UE according to a measurement of downlink path loss, based on a given power level through which is a possible power level of the base station may be reached by the UE.

Step 212, the UE detects a random access response (RAR) sent from the base station; the RAR includes a preamble identifier of the related preamble; the RAR also includes time-frequency resource information allocated for the preamble by the base station.

Step 213, when the UE detects that the RAR includes a preamble identifier of the preamble, it performs uplink data transmission.

In a preferred embodiment, there is a mapping relationship between the preamble and a multiple access signature and an uplink demodulation reference signal, or there is a mapping relationship between the preamble and the uplink demodulation reference signal. These kinds of mapping relationships may be stored on the UE, and when the UE performs uplink data transmission on a time-frequency resource indicated by the RAR, it may perform uplink data transmission using the multiple access signature corresponding to the preamble and insert the uplink demodulation reference signal corresponding to the preamble; or the UE may perform uplink data transmission on the time-frequency resource indicated by the RAR and insert the uplink demodulation reference signal corresponding to the preamble.

That is, uplink data transmission of the UE may include: the UE determining the multiple access signature corresponding to the selected preamble according to the mapping relationship between the preamble and the multiple access signature, and using the determined multiple access signature to perform uplink data transmission.

Uplink data transmission of the UE may also include: the UE determining the uplink demodulation reference signal corresponding to the selected preamble according to the mapping relationship between the preamble and the uplink demodulation reference signal, and inserting the determined uplink demodulation reference signal when performing uplink data transmission.

To be more specific, when the non-orthogonal multiple access scheme is used, there is a mapping relationship between the preamble and the multiple access signature and the uplink demodulation reference signal, and the UE uses the multiple access signature and the uplink demodulation reference signal corresponding to the preamble to transmit uplink data on the time-frequency resource indicated by the RAR.

To be specific, when the orthogonal multiple access scheme is used, there is a mapping relationship between the preamble and the uplink demodulation reference signal, and the UE performs uplink data transmission using the uplink demodulation reference signal corresponding to the preamble on the time-frequency resource indicated by the RAR.

In another preferred embodiment, the multiple access signature and/or uplink demodulation reference signal used by the UE to perform uplink data transmission may also be allocated by the base station. In this case, there may be any of the following three situations:

The RAR also indicates a multiple access signature and an uplink demodulation reference signal allocated by the base station; and when the non-orthogonal multiple access scheme is used, the UE uses the multiple access signature indicated by the RAR to perform uplink data transmission, and inserts the uplink demodulation reference signal during uplink data transmission;

Or, the RAR also indicates the uplink demodulation reference signal allocated by the base station; and when the orthogonal multiple access scheme is used, and when the UE performs uplink data transmission, the UE inserts the uplink demodulation reference signal indicated by the RAR;

Or, the RAR also indicates the multiple access signature allocated by the base station, and the UE determines the uplink demodulation reference signal corresponding to the selected preamble according to the mapping relationship between the preamble and the uplink demodulation reference signal; and when the non-orthogonal multiple access scheme is used, the UE uses the multiple access signature indicated by the RAR to perform uplink data transmission, and inserts the uplink demodulation reference signal corresponding to the preamble.

Corresponding to the foregoing method, the present disclosure further discloses a communication UE, including:

a first module to select a preamble and transmit the preamble through a random access channel, and before this, read random access information; before the UE transmitting the preamble, determine a transmission power level through an open-loop power control method;

a second module to detect a random access response (RAR); the RAR includes a preamble identifier; and

a third module to perform uplink data transmission when it is detected that the RAR detected includes a preamble identifier of the preamble.

Fig.2b is a flowchart of a processing method at a base station corresponding to the method shown in Fig.2a. The processing method at the base station includes the following:

Step 221, the base station receives a preamble sent from a UE;

Step 222, the base station performs a conflict detection for the preamble; and

Step 223, the base station sends a RAR to the UE if a result of the conflict detection is non-conflicting, and the RAR contains a preamble identifier of the preamble.

A detailed processing procedure includes: determining that a preamble is received if a result of a correlation detection performed for the preamble exceeds a correlation detection threshold.

The procedure of performing the conflict detection for the preamble includes: determining that the result of the conflict detection is non-conflicting, if the result of the correlation detection for the preamble is lower than a power threshold; or otherwise, determining that the result of the conflict detection is conflicting.

If it is determined that the result of the conflict detection is non-conflicting, then the base station detects a timing advance for the preamble, and encapsulates and sends the random access response (RAR); the RAR includes timing advance information, the detected preamble identifier, and time-frequency resource information allocated for the UE corresponding to the preamble.

The base station may further receive and process uplink data transmitted from the UE and provide a corresponding response to the UE. The corresponding response may be an acknowledgement (ACK) response or a negative acknowledgement (NACK) response.

If a result of a correlation detection for a preamble exceeds the correlation detection threshold, and a result of the correlation detection for the preamble exceeds the power threshold, then it is determined that there is a conflict, and the base station will not perform RAR processing for the preamble, or the base station inserts a NACK signal in the RAR of the preamble to indicate that the preamble corresponding to the preamble identifier in the RAR will not be processed during this access.

Corresponding to the foregoing method, the present disclosure further provides a base station which includes:

a receiving module to receive a preamble sent from a UE;

a detection module to perform a conflict detection for the preamble; and

a RAR detection module to send a RAR to the UE if a result of the conflict detection is non-conflicting, the RAR containing a preamble identifier of the preamble.

The RAR module is specifically to: determine that a preamble is detected if a result of a correlation detection performed for the preamble exceeds a correlation detection threshold; and meanwhile, determine that there is no conflict and trigger the base station to detect a timing advance for the preamble, encapsulate and send the random access response (RAR), if the result of the correlation detection for the preamble is lower than a power threshold; the RAR includes timing advance information, the detected preamble identifier, and time-frequency resource information allocated for the UE corresponding to the preamble.

If a result of a correlation detection for a preamble exceeds the correlation detection threshold, and the result of the correlation detection for the preamble exceeds the power threshold, then it is determined that there is a conflict, and the base station will not perform subsequent RAR processing for the preamble, or the base station inserts a NACK signal in the subsequent RAR of the preamble to indicate that the preamble corresponding to the preamble identifier in the RAR will not be processed during this access.

The base station further includes a data receiving and processing module to receive and process uplink data transmitted from the UE and provide a corresponding response to the UE.

The multiple access signature of the present disclosure includes one or more of the following: a spread spectrum code sequence, an interleaving sequence, a scrambling code sequence, a codebook, etc.

The present disclosure can efficiently reduce the number of signalling overheads caused due to information interactions between the base station and the UE so as to improve system operation efficiency.

In the following, the technical scheme of the present disclosure will be introduced by way of combining the UE processing procedures and the base station processing procedures.

Fig.2c is a flowchart showing interactions between a UE and a base station during uplink data transmission provided according to the present disclosure. Referring to Fig.2c, after the UE is woken up, first it performs downlink synchronization, and read configuration information including system information and random access information. Configuration information is sent to the UE in advance by the base station through a physical broadcast channel (PBCH), and configuration information includes information such as a random access channel position, a cell size, and a multiple access signature.

In step 201, the UE obtains information on a preamble resource pool based on foregoing configuration information, randomly selects a preamble from the preamble resource pool, and sends the preamble to the base station through a random access channel.

In step 202, the base station performs a correlation detection for the preamble to determine whether the preamble is detected, and determine whether there is a conflict. If there is no conflict or a conflict of the preamble can be resolved, the base station calculates a timing advance of the preamble and transmits the timing advance through a RAR to the UE. The RAR includes a preamble identifier and a corresponding timing advance.

In step 203, the UE sends required uplink data according to information in the RAR.

There is a mapping relationship between the preamble and a multiple access signature and an uplink demodulation reference signal/uplink demodulation reference signals, i.e., one preamble corresponding to one or more demodulation reference signals and corresponding to one multiple access signature. The multiple access signature includes an orthogonal multiple access signature, e.g., an orthogonal code sequence; or the multiple access signature also includes a non-orthogonal multiple access signature, e.g., a codebook of sparse code multiple access (SCMA), a codebook of pattern division multiple access (PDMA), an interleaving pattern of interleave division multiple access (IDMA), and a grid mapping pattern and an interleaving pattern of a grid-mapping-based multiple access scheme. Once the UE selects a preamble, it means that the UE selects a corresponding multiple access signature. In this way, the bases station may select a proper time resource for the UE to perform uplink data transmission according to conflicts of multiple access signatures.

The UE uses open-loop power control to ensure that a power value of the preamble received by the base station is in a threshold range after a correlation detection is performed, and if the power value exceeds the threshold range, then it is determined that there is a conflict. By changing lengths of preambles, priorities of the UEs can be controlled. A UE having a higher priority uses a longer preamble, and has a larger probability to be accessed.

In the following, the scheme of the present disclosure will be described through detailed embodiments.

a. Embodiments of the present disclosure

Embodiment 1

In embodiment 1, a contention-based uplink data transmission flow applicable to the mMTC will be described in combination with detailed system configurations. A system may divide frequency resources into enhanced mobile broadband (eMBB), ultra-reliable low-latency communication (URLLC), and massive machine-type communication (mMTC) frequency resources according to service scenarios, as shown in Fig.3. Among them, a frequency band allocated to the mMTC may be further divided into a frequency band that supports a fast-access mMTC service and a frequency band that supports a scheduling-based mMTC service.

It is to be specified that in Fig.3, the fast-access mMTC and the scheduling-based mMTC are differentiated by time division scheme. However, the fast-access mMTC and the scheduling-based mMTC may be differentiated by frequency division scheme. In addition, these two types of services may be differentiated by a mixed mode of timing division+frequency division, or time-frequency resources are not differentiated for the two types of services, but the two types of services are differentiated based on preambles. The base station determines a type of a service by detecting a preamble, and allocates a suitable access resource (including a time-frequency resource and a multiple access signature) for the scheduling-based mMTC.

Take the way of dividing frequency bands in Fig.3 as an example. After the UE is woken up because there is a requirement for data transmission, first the UE carries out downlink synchronization according to a synchronization channel, and reads system information in a broadcast channel to obtain information such as how frequency domains of different services are divided, how resources that support the fast-access mMTC service and the scheduling-based mMTC service are allocated, a time-frequency resource position of a random access channel, a structure of a preamble resource pool for random access. Take the way of dividing frequency bands in Fig.3 as an example. Assume that a random access channel for the mMTC service is located in the middle of a sub-frequency band allocated for the mMTC service, as shown in Fig.4. The fast-access mMTC service and the scheduling-based mMTC service share a same random access channel resource, and the service types are differentiated according to preambles.

The method of the present disclosure may further configure preamble resource pools corresponding to different service types; and the procedure of the UE selecting the preamble includes: selecting the preamble from a preamble resource pool corresponding to a current service type. For example, the fast-access mMTC service and the scheduling-based mMTC service correspond to different preamble resource pools respectively.

For example, for a UE that supports the fast-access mMTC service, after the UE reads system information, the UE randomly selects a preamble from a preamble resource pool corresponding to the fast-access mMTC service. To be specific, available contention-based random access preambles are divided into a set of fast-access preambles and a set of scheduling-based preambles, in which the fast-access preambles are one-to-one mapping to available multiple access signatures. For example, in the interleave division multiple access scheme where users are differentiated according to interleavers, the number of available interleavers is far larger than the number of available preambles. In this case, a part of interleavers that meet a certain condition may be selected from the available interleavers to establish a one-to-one mapping relationship with the preambles. If the number of available multiple access signatures is relatively few, and it is less than the number of available preambles, then a multiple-to-one mapping relationship may be established between the preambles and the multiple access signatures. For example, in SCMA, the number of available codebooks is relatively few, and a mapping relationship may be established between multiple codebooks and one preamble.

Meanwhile, for reference signals used for channel estimation during uplink access, a one-to-one mapping relationship or a one-to-many mapping relationship may be established between the reference signals and the preambles. When there is a mapping relationship between the preambles and the uplink demodulation reference signals, and there is a mapping relationship between the preambles and the multiple access signatures (in a special example, when there is a many-to-one mapping relationship between the preambles and the uplink demodulation reference signals, and there is a many-to-one mapping relationship between the preambles and the multiple access signatures), it is necessary to ensure that when preambles selected by UEs are different but they are mapped to a same multiple access signature, uplink demodulation reference signal sequences corresponding to the preambles are different. One possible mapping scheme is shown in Table 1.

As is shown by the example of Table 1, the number of available preambles is 12, the number of available multiple access signatures (e.g., available codebooks or available interleavers) is 3, and the number of available reference sequences is 4. When the mapping scheme shown in the example of Table 1 is used, even if preambles selected by UEs correspond to a same multiple access signature, e.g., two UEs selecting a preamble 1 and a preamble 3 respectively, and the two preambles corresponding to a same multiple access signature 1, in which case, reference signal resources selected by the two UEs are different, respectively reference signal 1 and reference signal 3. This mapping scheme is able to reduce the probability of conflict to some extent. That is, the two UEs still can be served on a same time-frequency resource.

Fig.5 is a schematic diagram of a preamble structure used in Embodiment 1. A preamble consists of multiple same sub-sequences, in which a cyclic premix (CP) is added before the preamble, and a guard interval is added after the preamble. A sub-sequence may be generated using a technique similar to LTE, i.e., using a Zadoff-Chu (ZC) sequence with a relatively good correlation character as a root sequence to generate different sub-sequences using cyclic shift. The length of a sub-sequence and the number of duplications of a sub-sequence in the basic sequence may be determined according to information such as a cell radius and channel conditions, and they are notified to the UEs by way of system information through a broadcast channel.

A UE selects a preamble, i.e., selecting a corresponding reference signal sequence and a multiple access signature for subsequent uplink data transmission. After the UE selects the preamble, the UE sends the preamble in a random access channel. Before the UE sends the preamble, it determines a transmission power level through an open-loop power control method so that a power level received at the base station is in a certain range. Fig.6 is a schematic diagram showing a correlation detection threshold and power threshold relationship. Referring to Fig.6, the base station performs a correlation detection for the preamble, and determines whether there is a conflict according to a pre-defined power threshold. That is, the base station determines a receiving power level of the base station according to an open-loop power control parameter of the UE and determines a power threshold according to a specified tolerance degree of the receiving power level, in which the specified tolerance degree can ensure that a fading of a small degree would not affect the detection accuracy; and if a result of a correlation detection for a certain preamble exceeds a correlation detection threshold, it indicates that the preamble is detected; and meanwhile, if the result of the correlation detection for the preamble is lower than the power threshold, it indicates that there is not a conflict, and in this case, the base station detects a timing advance for the preamble, and encapsulates a random access response (RAR). The RAR includes timing advance information, a preamble identifier of the detected preamble, and optional time-frequency resource information allocated for the UE, and it is transmitted through a downlink control channel or a downlink shared channel.

The UE detects the downlink control channel or the downlink shared channel, and if the UE detects a preamble identifier of the preamble that it has transmitted in the RAR, then the UE uses a reference signal and a multiple access signature corresponding to the preamble to perform uplink data transmission on a time-frequency resource specified in the RAR.

When the base station detects preambles and finds that a result of a correlation detection for a certain preamble exceeds a correlation detection threshold, and that it also exceeds the determined power threshold, then this indicates that there is a conflict during transmission of the preamble. After the base station detects the conflict of the preamble, it may perform the following processes:

Approach 1: the base station does not perform subsequent RAR processing for the preamble. A UE which sent the preamble will still detect a downlink control channel or a downlink shared channel, but will not be able to detect a preamble identifier corresponding to the preamble that it sent. After detecting several symbols, the UE considers that the access of this time is failure, and after it waits for a specified period of time, the UE randomly re-selects a preamble and starts a new access and uplink data transmission procedure. The specified period of time may be randomly selected, or may be pre-defined, or may be generated according to a certain rule.

Approach 2: the base station inserts a NACK signal in the RAR of the preamble to indicate that the preamble corresponding to the preamble identifier in the RAR will not be processed during this access. After the UE detects the NACK signal in the RAR signal, it re-selects a preamble to perform a new access and uplink data transmission procedure. In this approach, a new field, i.e., an ACK/NACK signal of 1 bit corresponding to the preamble identifier needs to be added in the RAR. If it is detected properly, and there is not a conflict, then the base station sends an ACK signal, and if there is a conflict, the base station sends a NACK signal.

That is, for a UE, if the UE has not detected a RAR that contains the preamble identifier of the preamble, a first period of time after the UE sends the preamble, or if the UE detects a RAR that contains the preamble identifier of the preamble, but the RAR includes a NACK signal, then the UE will re-select a preamble randomly to perform access after waiting for a pre-defined period of time.

Since the UE has not completed the traditional random access procedure when it transmits uplink data, a UE ID is not allocated to the UE. To facilitate the base station to know UE information, when the UE sends uplink data, it needs to show its identity in uplink data, i.e., transmitting a unique UE identifier together with uplink data.

In addition, if the UE is unable to complete transmission of data during one transmission, it needs to add a request for continuing to transmit data in the data, and optionally it adds a size of data to be transmitted. This kind of indication is similar to the buffer status report (BSR) in LTE-A.

After the UE detects a corresponding RAR and completes uplink data transmission, it needs to wait for a feedback from the base station.

For the base station side,

After the base station sends a RAR to a UE, the method further includes:

the base station receiving uplink data sent from the UE and transmitting feedback information to the UE;

in which, transmitting feedback information to the UE includes:

after k subframes after the UE transmitting uplink data, the base station transmitting an ACK or NACK signal of uplink data through a downlink control channel; in which:

if the base station receives uplink data properly, and the base station determines that the UE has no requirement for further transmitting data, then the base station sends a ACK signal to the UE; and the UE knows by itself whether it needs to further transmit data, and the UE will notify the base station whether the UE will further transmit data;

if the base station receives uplink data properly, and the base station determines that the UE needs to further transmit data, then the base station will allocate a UE ID for the UE, and transmits the UE ID and an ACK signal to the UE through a downlink control channel; and

if the base station has not received uplink data properly, then the base station will send a NACK signal.

For a UE side,

the UE detects a control channel corresponding to a time-frequency resource after K subframes after the UE sends uplink data, and detects an ACK/NACK signal corresponding to a time-frequency resource and a multiple access signature and a UE ID allocated by the base station for the UE. Specifically:

if the UE detects an ACK signal and there is no further data that needs to be transmitted, then the UE will wait for next data transmission;

if the UE detects an ACK signal and there is further data that needs to be transmitted, and the UE detects a UE ID allocated by the base station for the UE, then the UE performs uplink data transmission based on scheduling by the base station;

if the UE detects a NACK signal, then after m subframes, the UE retransmits uplink data using a same time-frequency resource and a same multiple access signature as those used for the last uplink data transmission, where m is a preset parameter; the UE sets a counter, and if the number of NACK signals that it detects exceeds a specified value t, i.e., uplink data transmission procedure having been repeated for t times and the UE still having not properly transmitted uplink data, then the UE determines that the access is failure, the UE increases its priority, and re-selects a preamble to perform access.

It should be specified that the present disclosure is not only applicable to non-orthogonal multiple access schemes, but also applicable to orthogonal multiple access schemes. To be specific, when the system uses an orthogonal multiple access scheme to differentiate UEs, preambles will be independent of multiple access signatures, but only have corresponding relationships with demodulation reference signals used. When the base station allocates uplink resources, it only allocates orthogonal time-frequency resources to different UEs.

It should be further specified that, preambles may be independent of multiple access signatures and reference signals. In this case, it is the base station that allocates a multiple access signature and a reference signal for a preamble where there is no conflict and indicates these to the UE through a RAR. In this case, besides a preamble identifier, the RAR further includes time-frequency resource information, multiple access signature information and reference signal information. Compared to the scheme where preambles correspond to multiple access signatures and reference signal resources, this scheme needs to add more signalling in a RAR, and the number of signalling overheads is larger than that in the foregoing scheme. In this scheme, after the UE detects a RAR of a corresponding preamble, the UE sends uplink data according to time-frequency resource allocation, multiple access signature allocation and reference signal resource allocation.

In addition, the number of signalling overheads during the resource allocation may be reduced by a mapping between reference signals and multiple access signatures, or a mapping between reference signals and preambles, or a mapping between reference signals and multiple access signatures.

Embodiment 2

In this embodiment 2, how to process and determine the priority of a UE in the scheme of the present disclosure will be introduced in combination with a detailed system configuration. In this embodiment 2, the system configuration and resource allocation are the same as those in Embodiment 1. Different services are differentiated by frequency division, and the fast-access mMTC and the scheduling-based mMTC are differentiated by time division. A preamble structure is as shown in Fig.5, in which a preamble consists of one or more sub-sequences.

The priority of the UE is represented by the number of sub-sequences that constitute a preamble, and it is decided by the number of access attempts. When the first priority is higher than the second priority, the number of sub-sequences of a preamble having the first priority is more than the number of sub-sequences of a preamble having the second priority. Define that a basic preamble consists of N₀ same sub-sequences, representing the lowest priority (priority 0); a preamble having a higher priority is obtained by concatenating an increased number of sub-sequences, i.e., the preamble having the higher priority being obtained by concatenating more sub-sequences. For example, a preamble having a first level of priority consists of N₀+1 same sub-sequences, and a preamble having a j^th level of priority consists of N₀+j same sub-sequences. A preamble identifier may be obtained by adding additional bits before or after a basic preamble identifier. For example, when the additional bits are added before the basic preamble identifier, if the number of available basic preambles is N_B, then the basic preamble identifier needs to be represented by a bit sequence having a length of [log₂N_B], where [ ] represents a ceiling operation. If there are K levels of priorities, then additional bits having a length of [log₂K] should be added before the basic preamble identifier to indicate a priority over that of the basic preamble.

Fig.7 is a schematic diagram of preambles having different priorities. As shown by the example in Fig.7, a basic preamble consists of one sub-sequence, and since there are four priorities, then additional two bits should be added as priority indications.

When a UE attempts to perform random access for the first time, it will randomly select an initial priority, i.e., selecting a preamble having a basic priority, and transmit the preamble having the basic priority through a random access channel, where the basic priority is represented by the number of sub-sequences that constitute the preamble. If the base station detects that there is a conflict for the preamble having the basic priority, then the base station notifies the UE through a RAR or does not notify the UE.

After the UE knows that access of this time fails, it will wait for a preset time interval or a random period of time, increase the priority of the preamble, i.e., using a lengthened preamble, and transmit the preamble which has the increased priority through the random access channel again, to enter into a next access and data transmission procedure. If the next access and data transmission procedure is still not successful, then the UE will wait for the preset time interval or the random period of time, continue to increase the priority of preamble, i.e., continuing to lengthen the preamble, and transmit the preamble which has the increased priority through the random access channel, to carry out a next access and data transmission procedure until access is successful or the largest level of priority is achieved.

The base station carries out a detection of preambles having multiple priorities at the same time through a detection window. A detailed way of detection is as shown in Fig.7. The base station detects N preambles having different priorities through the detection window, where N is a positive integer larger than 1, and the N preambles having the different priorities have a same basic preamble, in which the length of the detection window is decided by the length of the sub-sequences that constitute the basic preamble, and the base station detects the N preambles having different priorities through the detection window. In the example shown in Fig.7, since the basic preamble consists of one sub-sequence, the length of the detection window is the same as the length of the sub-sequence.

When the base station performs a correlation detection and detects a basic preamble, then the base station moves the detection window to a neighbouring position; if the base station can detect a sub-sequence same as the sub-sequence that constitutes the basic preamble detected in the detection window, then the base station continues to move the detection window to a neighbouring position; and if the base station cannot detect a sub-sequence same as the sub-sequence that constitutes the basic preamble detected in the detection window, then the base station determines that a preamble having the first priority is detected, or otherwise, the base station continues to move the detection window to a neighbouring position; and if after the base station moves the detection window for j times, and it cannot detect a sub-sequence same as the sub-sequence that constitutes the basic preamble detected in the detection window, then the base station determines that it detects a preamble having the j^th priority, or otherwise, the base station continues to move the detection window to a neighbouring position, where j is a positive integer not larger than the largest priority; and the detection procedures are repeated until a sub-sequence position cannot be detected, or a preamble having the largest priority is detected. The observation window shown in Fig.7 is the length of the preamble having the largest priority.

Through the foregoing detection procedures, preambles which have different priorities but have the same basic preamble can be detected. Take Fig.7 as an example, if the preamble having the highest priority and the preamble having the basic priority are transmitted at the same time, a correlation detection result which is about two times of the power threshold will be detected in the first detection window, but in the subsequent detection windows, only one sub-sequence can be detected. According to this result, transmission of the basic preamble and transmission of the preamble having the highest priority can be determined, but since they correspond to the same basic preamble, they use the same reference signal and multiple access signature, and they need to be served on different time-frequency resources.

Fig.8 is a schematic diagram of structures of preambles having different priorities and detection methods, in which the number of sub-sequences that constitute a basic preamble is larger than 1. In Fig.8, if a basic preamble consists of two sub-sequences, then a basic detection window (for detection) consists of two neighbouring component detection windows, and through summing correlation detection results of the two component detection windows, a detection result of the basic preamble will be obtained. When a preamble having a higher priority is detected, the length of the component detection window is still the length of the sub-sequence, while the length of the observation window (a detection widow of a preamble having the highest priority) will be the same as the length of the preamble having the highest priority.

It is to be specified that since the basic preamble consists of sub-sequences, therefore, when a preamble is designed, a condition that the largest channel delay should not exceed the length of the sub-sequence. That is, if the length of the sub-sequence of the preamble is larger than the largest channel delay, there will be a conflict.

Since generally preambles, inter-correlation between which is zero, are generated by performing cyclic shifts for a root sequence, but in Embodiment 2, the preambles having the different priorities are obtained by concatenating same sub-sequences. Since distances between the UEs and the base station are different, multi-paths that are gone through are different, and therefore, delays when preambles sent by the different UEs arriving at the base station are different too. In this situation, there may be a conflict as shown in Fig.9. Fig.9 is a schematic diagram illustrating a situation where a conflict of different sub-sequences is caused due to delay.

In Fig.9, a sub-sequence 1 and a sub-sequence 2 are sequences that are generated from a root sequence by cyclic shifts and that they have inter-correlation of 0. Since the first preamble is formed by concatenating the sub-sequences 1, and when a delay of the second preamble is the same as the cyclic shift between the sub-sequence 1 and the sub-sequence 2, the detection window of the sub-sequence 2 can detect transmission of the two sub-sequences 2, which causes the base station to consider that there is a conflict in transmission of the second preamble. However, in fact, this kind of conflict caused due to delay and the preamble structure is a false alarm generated during the detection procedure, and in fact, the first preamble and the second preamble in Fig.9 do not conflict.

To solve the above conflict issue of the detection, the detection procedures should be slightly modified. Since delays between different preambles may be obtained by determining correlation detection peak values, the delays may be involved into detection of the preambles, to determine a false conflict between the sub-sequences caused due to delay. To be specific, if a conflict is found by performing a correlation detection for the sub-sequences of the first preamble, then if a preamble, a priority of which is higher than that of the first preamble, is not found, it is determined that there is an inter-preamble conflict; and if a preamble, a priority of which is higher than that of the first preamble, is found, whether there is a false conflict is determined according to a delay of the preamble, the priority of which is higher than that of the first preamble, and the cyclic shift between the sub-sequences, in which the cyclic shift between the sub-sequences is a cyclic shift between the sub-sequences that form the first preamble and the sub-sequences that form the preamble, the priority of which is higher than that of the first preamble; and when the following formula is met, it is determined that there is a false conflict:

In the foregoing formula, N_S is the number of sampling points of a cyclic shift of a sub-sequence having a lower priority and a sub-sequence having a higher priority, assuming that the cyclic shift towards right is positive (the cyclic shift of the sub-sequence 2 relative to the sub-sequence 1 in Fig.9 is positive, and of course, the cyclic shift towards left may be positive); τ is a delay of a sub-sequence having a lower priority relative to a sub-sequence having a higher priority, the unit of delay is the number of sampling points; γ is a preset threshold, and γ＞0.

Fig.10 is a schematic diagram of correlation detection and conflict detection processing of sub-sequences. The foregoing detection procedures may be described by Fig.10.

Embodiment 3

In Embodiment 3, a self-contained frame structure access and uplink transmission procedure will be introduced in combination with a detailed system configuration. The system configuration and resource division may be as those in Embodiment 1, in which different services are divided by frequency division, and the fast-access mMTC and the scheduling-based mMTC are differentiated by time division. A preamble structure is as shown in Fig.5, where a preamble consists of one or more sub-sequences.

In Embodiment 3, a system frame structure uses the self-contained frame structure shown in Fig.11. Fig.11 (a) shows a structure of an uplink transmission frame, and before uplink data is transmitted, downlink data is transmitted by time division first. This part of downlink data includes control information, scheduling information, etc. of the uplink transmission frame. Fig.11 (b) shows a structure of a downlink transmission frame. After downlink data is transmitted, uplink data is transmitted by time division. This part of uplink data includes information such as an ACK/NACK signal of downlink transmission data of the downlink transmission frame and a possible uplink scheduling request. This kind of flexible frame structure design can meet a forward compatibility requirement of 5G communications.

To be specific, in Embodiment 3, before the UE attempts to perform random access, it has established downlink synchronization, and therefore, by reading downlink data in the uplink transmission frame, the UE determines whether the uplink transmission frame can be used for transmitting a preamble. To be specific, the UE establishes downlink synchronization through a synchronization channel in a downlink transmission subframe, and reads system information in a broadcast channel to know random access channel information and preamble information.

After the UE knows random access channel information and preamble information, by reading a downlink time slot in the uplink transmission subframe, the UE may determine whether the uplink transmission subframe can be used for transmitting a preamble. That is, a new field is added in the downlink time slot to indicate whether a corresponding frequency band in the uplink transmission subframe can be used for transmitting a preamble (i.e., whether it can transmit a random access channel) and indicate a time-frequency resource of the random access channel. A simple way is estimating the frequency resource of the random access channel, and using a downlink data transmission part to indicate whether an uplink data transmission part of the uplink transmission subframe can be used for transmitting the random access channel, a procedure of which is as shown in Fig.12. Fig.12 is a schematic diagram of a random access attempt. In Fig.12, the UE reads indication information in the downlink transmission part, and finds that the first two subframes cannot be used for transmitting a random access preamble, but in the third subframe, in the downlink transmission part, the UE finds that the uplink transmission subframe can be used for transmitting a random access channel, and then a random access preamble is transmitted in the uplink transmission part of the uplink transmission subframe.

Or, the number of subframes may be preset to

, and the UE transmits a preamble on a y^th subframe after the UE knows random access channel information and preamble information, where y=0 is to indicate that current subframe can be used for transmitting a preamble.

After the base station detects a preamble, it needs to send a RAR to the UE to notify the UE of time-frequency resource allocation for uplink data transmission and a timing advance of the UE, so as to provide uplink synchronization for the UE. The self-contained frame structure shown in Fig.11 is able to simplify contents that need to be transmitted in the RAR and enables different UEs to be served according to their priorities. To be specific, on a sub-frequency band allocated for mMTC UEs, a frequency band for fast-access mMTC UEs is fixed, e.g., a number of PRBs located in the middle of the sub-frequency band are allocated for the fast-access mMTC UEs. In this way, the base station may complete resource allocation for uplink data by notifying the UE to transmit uplink data on which subframe by the RAR, which simplifies the design of the RAR and meanwhile division of the resources for the mMTC UEs is more flexible.

Fig.13 is a schematic diagram of transmission schemes of UEs having different priorities. When the base station detects transmission of preambles having different priorities, it will indicate the priorities of the UEs by RARs. The procedure is as shown in Fig.13. If the base station detects preambles which have different priorities but have a same basic preamble, it differentiates the priorities by time division. To be specific, a RAR corresponding to a preamble having a higher priority is transmitted using a subframe closer to a current time, and a RAR corresponding to a preamble having a lower priority is transmitted using a subframe farer from the current time; that is, when a first priority is higher than a second priority, a time difference between a time when data corresponding to a preamble having the first priority is transmitted and the current time is T1, and a time difference between a time when data corresponding to a preamble having the second priority is transmitted and the current time is T2, then T1<T2. In Fig.13, it is assumed that M preambles which consist of a same basic preamble but have different priorities are received. The base station first transmits a RAR for a preamble having the highest priority during downlink data transmission of a subframe closest to the current time, i.e., subframe 1. After the UE that has transmitted the preamble having the highest priority detects the RAR, on an uplink transmission time-frequency resource of this subframe, i.e., the subframe 1, the UE uses a reference signal and a multiple access signature corresponding to the basic preamble to perform uplink data transmission, and since the other UEs have not detected their corresponding preamble identifiers, they will wait. The procedures will repeat until a UE having the lowest priority has complete data transmission.

Fig.14 is a schematic diagram of a structure of a channel frame in Embodiment 3. As shown in Fig.14, in Embodiment 3, to prevent a conflict between a UE that attempts to perform random access this time and a UE that attempts to perform random access next time from happening, an interval between two neighbouring subframes for transmitting preambles should be not less than the largest priority. A period between two random access subframes is a random access channel period. The random access channel period is represented by the number of subframes, and it should be larger than the number of the largest priority. The random access channel period indicates that if the base station has not notified a UE that a certain preamble has a conflict, then the UE will attempt to detect a RAR in a downlink transmission part of subframes within the period, and if after the period, the UE has not detected a corresponding RAR, and has detected an indication of transmitting a preamble in a downlink transmission part of a random access subframe transmitted during a next period, then the UE considers that this access is failure, and will increase the priority to perform retransmission. If the base station notifies the UE of a conflict of a certain preamble through a RAR, then the UE will increase the priority and wait for a next chance for transmitting a preamble, and perform an access procedure again.

In case of the network load being relatively light, for example, a case where the network load is smaller than a pre-defined threshold, i.e., the number of fast-access mMTC UEs served by the base station being relatively small and there being a lower probability of a conflict. In this case, the UE may use a lower priority to complete access, and the base station may shorten the random access channel period, and notify the UE to decrease the highest priority. Setting the highest priority and shortening the random access channel period may be notified to the user through a broadcast channel or through a downlink control channel.

In case of the network load being relatively heavy, for example, the network load being larger than the pre-defined threshold, i.e., the number of fast-access mMTC UEs served by the base station being relatively large, therefore, there is a higher probability of a conflict, and the UE needs to wait for a longer period of time to complete access, and even if the UE uses the current highest priority, there is still a certain probability of a conflict. In this case, the base station should increase the random access channel period, and notify the UE to increase the highest priority. Setting the highest priority and increasing the random access channel period may be notified to the user through a broadcast channel or through a downlink control channel.

The scheme shown in Embodiment 3 can schedule resources more flexibly. For example, if the number of fast-access mMTC UEs served by the base station is relative small, a random access channel period does not need to be very large; but if the number of scheduling-based mMTC UEs is relatively large, they will cause a relatively large load to the network. In this case, the base station selects to decrease or keep the current random access channel period according to the total load, the load of the fast-access mMTC UEs and the load of the scheduling-based mMTC UEs. By keeping the random access channel period unchanged, the base station may use a free frequency band for fast-access mMTC UEs to serve some scheduling-based mMTC UEs to alleviate the pressure caused to the network by the scheduling-based mMTC UEs; by decreasing the random access channel period, a waiting time of a fast-access mMTC UE may be decreased to improve the user experience of this kind of UE. It can be seen that, by adjusting the random access channel period, a compromise between the system utilization rate and user experience can be achieved.

The base station decides whether to adjust the random access channel period according to a measurement of the network load. A possible way of determining this is that if the load of the scheduling-based mMTC UEs is larger than a first threshold, and meanwhile thee load of the fast-access mMTC UEs is smaller than a second threshold, then the base station may decrease the random access channel period so as to improve the resource utilization rate of the whole system.

If the base station selects to keep the current random access channel, or only slightly decreases the random access channel period, but it still can complete data transmission of the fast-access mMTC UEs using a time shorter than the random access channel period, then more time-frequency resources may be allocated to the scheduling-based mMTC UEs.

Fig.15 shows a schematic diagram of possible resource allocation. Referring to Fig.15, a sub-band allocated to the mMTC UE service consists of 18 sub-carriers, in which 6 sub-carries in the middle are allocated to fast-access mMTC UEs, but sub-carries at the two sides are allocated to scheduling-based mMTC UEs. Each subframe consists of 14 consecutive multi-carrier symbols, in which the first two multi-carrier symbols are used for downlink transmission; the third and the fourth multi-carrier symbols are used as a guard interval between uplink and downlink transmission; and the remaining multi-carrier symbols are used for uplink data transmission. The 6 sub-carries in the middle of the multi-carrier symbols for uplink data transmission in the first subframe are used for transmitting a random access channel.

In Fig.15, during a random access channel period, data transmission of all fast-access mMTC UEs can be completed, and in this case, there is no data to be transmitted by the resources for uplink data transmission of fast-access mMTCs in the last subframe of the last random access channel. In this case, the base station may allocate the resources to scheduling-based mMTC UEs by resource allocation so as to improve the resource utilization rate of the system.

In other situations, not all multiple access signatures of some time-frequency resources for uplink data transmission of fast-access mMTC UEs are used. This situation may occur when the load of fast-access mMTC UEs is light, the last several subframes in a random access channel period cannot fully use the multiple access signatures so as to cause the utilization rate of the resources is low. In this case, the base station may serve some scheduling-based mMTC UEs on the frequency band for fast-access mMTCs so as to improve the utilization rate of the multiple access signatures.

It is to be further specified that in the transmission scheme of the self-contained frame structure shown in Fig.13, control signalling transmitted by a downlink data transmission part of a current subframe controls an uplink data transmission part of the current subframe. However, in a practical system, due to a processing ability of a UE, control signalling transmitted by the downlink data transmission part of the current subframe cannot be fully processed before uplink data transmission part of the current subframe starts to be transmitted. In this case, a preset time (e.g., the preset time may use the number of subframes as the unit) may be specified , when the UE detects RAR data in control signalling of the downlink transmission part, it performs uplink data transmission on an uplink transmission part of a subframe after a preset interval. Or the UE transmits a preamble on y^th subframe after the UE receives an indication on a downlink transmission timeslot indicating that random access can be performed, where y is the preset number of subframes and

indicating that the current subframe can be used to transmit a preamble.

Embodiment 4:

In Embodiment 4, a self-contained frame structure access and uplink transmission procedure will be introduced in combination with a detailed system configuration. The system configuration and resource division are as shown in Embodiment 1, in which different services are divided by frequency division, and the fast-access mMTC and the scheduling-based mMTC are differentiated by time division. A preamble structure is as shown in Fig.5, in which a preamble consists of one or more sub-sequences.

After a UE is woken up because there is a requirement for data transmission, it reads system information and random access information from a broadcast channel. In Embodiment 4, a random access channel uses a frame structure similar to that in LTE-A, i.e., uplink transmission and downlink transmission being differentiated by time division or by frequency division. Meanwhile, a fixed frequency resource (sub-band) is allocated to fast-access mMTC UEs, and subframes on the sub-band use the self-contained subframe structure shown in Embodiment 3. That is, before uplink data transmission, first downlink data including downlink control signalling will be transmitted by time division, and then a sub-band resource allocated to the UE will be notified to the UE through system information in the broadcast channel.

The UE uses a frame structure similar to that in LTE-A, transmits a preamble on a random access channel, and searches for a RAR in the sub-band resource allocated for the fast-access mMTC UEs. When a preamble identifier corresponding to the preamble transmitted is found, the UE transmits uplink data on an uplink transmission part of a corresponding subframe according to a time-sequence rule. To be specific, assuming that the preset number of subframes x≥0, the UE transmits uplink data on an uplink transmission part of x subframes after the UE detects the preamble identifier corresponding to the preamble transmitted, where x is the preset number of subframes and

The present disclosure simplifies the uplink random access procedure and the uplink scheduling-based data transmission procedure, and combines the random access procedure and the uplink data transmission procedure together, so as to simplify the uplink data transmission procedure of the UE, and reduce the number of signalling overheads during transmission of burst small packets of a traditional uplink data transmission procedure, which improves spectral efficiency of the system. The present disclosure provides different priorities for different preambles by changing lengths of the preambles, so as to enable conflict detection through preambles. By combining the self-contained frame structure, the scheme of the present disclosure can perform resource allocation and priority processing more flexibly, which improves operation efficiency of the system and reduces the number of signalling overheads of transmission of burst small packets.

In addition, the respective function modules in the embodiments of the present disclosure may be integrated into one processing unit, or may physically exist as respective separate modules. Alternatively, two or more modules may be integrated into one unit. The above integrated unit may be implemented not only with hardware, but also with software function units. The function modules in the embodiments may be located at one UE or network scheme, or may be distributed to multiple UEs or network nodes.

Further, each embodiment of the present disclosure may be implemented by data processing applications executed by a data processing device, such as a computer. Apparently, the data processing applications constitute the present disclosure. Further, a data processing application stored in a storage medium generally may be executed by reading the data processing application out from the storage medium, or the data processing application may be installed or copied to a storage device (such as a hard disk or a memory) of the data processing device to execute. Therefore, the storage medium also constitutes the present disclosure. Any recording scheme may be used for the storage medium, e.g., a paper storage medium (such as a paper tape), a magnetic storage medium (such as, floppy, disk and flash), an optical storage medium (such as, a compact disc read-only memory (CD-ROM)), and a magneto-optical storage medium (such as magneto-optical (MO)).

Therefore, embodiments of the present disclosure further disclose a storage medium which may store a data processing application. The data processing application may be used to execute any of the foregoing embodiments of the methods of the present disclosure.

Further, the method steps in above embodiments of the present disclosure not only may be implemented via the data processing application, but also may be implemented via hardware, such as a logic gate, a switch, an application-specific integrated circuit (ASIC), a programmable logic controller (PLC) and an embedded microcontroller. Therefore, hardware, which may implement the methods of the present disclosure, may constitute the embodiments of the present disclosure.

FIG. 16 is an example configuration of a base station in a wireless communication system according to an exemplary embodiment of the present disclosure. FIG. 16 illustrates an example of a configuration of the base station. Hereinafter, the term "unit" or the term ending with the suffix "-er" or "-or" refer to a unit for processing at least one function or operation and these terms may be implemented by using hardware or software or a combination of hardware and software.

Referring to FIG. 16, the base station includes a wireless communication interface 1610, a backhaul communication interface 1620, a storage 1630, and a controller 1640.

The wireless communication interface 1610 performs functions for transmitting and receiving signals via a radio channel. For example, the wireless communication interface 1610 performs a function of converting between a baseband signal and a bit string according to a physical layer standard of a system. For example, when transmitting data, the wireless communication interface 1610 generates complex symbols by encoding and modulating a transmission bit string. In addition, when receiving data, the wireless communication interface 1610 restores a reception bit string by demodulating and decoding a baseband signal. In addition, the wireless communication interface 1610 up-converts a baseband signal into a radio frequency (RF) band signal and then transmit the RF band signal through an antenna, and down-converts an RF band signal received through the antenna into a baseband signal.

For example, the wireless communication interface 1610 may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a digital to analog converter (DAC), an analog-to-digital converter (ADC), or the like. In addition, the wireless communication interface 1610 may include at least one antenna array configured by a plurality of antenna elements. In view of hardware, the wireless communication interface 1610 may be configured by a digital unit and an analog unit, and the analog unit may be configured by a plurality of sub-units according to operation power and operation frequency.

The wireless communication interface 1610 transmits and receives signals as described above. Accordingly, the wireless communication interface 1610 may be referred to as a transmission interface, a reception interface, a transmission and reception interface, a transmitter, a receiver or a transceiver. In addition, in the following description, transmitting and receiving performed through a radio channel may include processing by the wireless communication interface 1610 as described above.

The backhaul communication interface 1610 provides an interface for communication with other nodes in a network. That is, the backhaul communication interface 1610 converts a bit string to be transmitted from the base station to another node, for example, another access node, another base station, a core network, or the like into a physical signal, and converts a physical signal received from another node into a bit string.

The storage 1630 stores data such as a basic program, an application program, setting information, or the like for the operation of the base station. The storage 1630 may be configured by a volatile memory, a nonvolatile memory, or a combination of a volatile memory and a nonvolatile memory. The storage 1630 provides the stored data according to a request of the storage 1630 and the controller 1640.

The controller 1640 controls overall operations of the base station. For example, the controller 1640 transmits and receives signals through the wireless communication interface 1610 or the backhaul communication interface 1620. In addition, the controller 1640 records and reads data on and from the storage 1630. The controller 1640 may perform functions of a protocol stack which a communication standard requires. To achieve this, the controller 1640 may include at least one processor.

According to exemplary embodiments of the present disclosure, the controller 1640 may transmit the RAR comprising the identifier of the preamble. For example, the controller 1640 may control the base station to perform operations according to the exemplary embodiments of the present disclosure.

FIG. 17 is an example configuration of a terminal in a wireless communication system according to an exemplary embodiment of the disclosure. FIG. 17 illustrates an example of a configuration of the terminal. Hereinafter, the term "unit" or the term ending with the suffix "-er" or "-or" refer to a unit for processing at least one function or operation and these terms may be implemented by using hardware or software or a combination of hardware and software.

Referring to FIG. 17, the terminal includes a communication interface 1710, a storage 1720, and a controller 1730.

The communication interface 1710 performs functions for transmitting and receiving signals via a radio channel. For example, the communication interface 1710 performs a function of converting between a baseband signal and a bit string according to a physical layer standard of a system. For example, when transmitting data, the communication interface 1710 generates complex symbols by encoding and modulating a transmission bit string. In addition, when receiving data, the communication interface 1710 restores a reception bit string by demodulating and decoding a baseband signal. In addition, the communication interface 1710 up-converts a baseband signal into an RF band signal and then transmit the RF band signal through an antenna, and down-converts an RF band signal received through the antenna into a baseband signal. For example, the communication interface 1710 may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, or the like.

The communication interface 1710 may include a plurality of transmission/reception paths. The communication interface 1710 may include at least one antenna array configured by a plurality of antenna elements. In view of hardware, the communication interface 1710 may be configured by a digital circuitry and an analog circuitry (e.g., radio frequency integrated circuit (RFIC)). Here, the digital circuitry and analog circuitry may be implemented as one package. Also, the communication interface 1710 may include a plurality of RF chain. The communication interface 1710 may perform beamforming.

Also, the communication interface 1710 may include different communication modules for processing signals of different frequency band. The communication interface 1710 may include a plurality of communication modules for supporting a plurality of different wireless access technologies. For example, the plurality of different wireless access technologies may include Bluetooth low energy (BLE), wireless fidelity (Wi-Fi), Wi-Fi gigabyte (WiGig), cellular network (e.g., long term evolution (LTE)), or the like. Also, different frequency bands may include super high frequency (SHF)(e.g., 2.5 GHz, 5 GHz) band and millimeter wave(e.g., 60 GHz).

The wireless communication interface 1710 transmits and receives signals as described above. Accordingly, the communication interface 1710 may be referred to as a transmission interface, a reception interface, a transmission and reception interface, a transmitter, a receiver or a transceiver. In addition, in the following description, transmitting and receiving performed through a radio channel may include processing by the communication interface 1710 as described above.

The storage 1720 stores data such as a basic program for the operation of the terminal, an application program, setting information, or the like. The storage 1710 may be configured by a volatile memory, a nonvolatile memory, or a combination of a volatile memory and a nonvolatile memory. In addition, the storage 1720 provides stored data in response to a request of the controller 1730.

The controller 1730 controls overall operations of the terminal. For example, the controller 1730 transmits and receives signals through the communication interface 1710. In addition, the controller 1730 records and reads data on and from the storage 1720. The controller 1730 may perform functions of a protocol stack which the communication standard requires. To achieve this, the controller 1730 may include at least one processor or microprocessor or may be a part of the processor. In addition, a part of the communication interface 1710 and the controller 1730 may be referred to as a communication processor (CP).

According to exemplary embodiments of the present disclosure, the controller 1730 may transmit the data in response to receiving the RSR comprising the identifier of the preamble. For example, the controller 1730 may control the terminal to perform operations according to the exemplary embodiments of the present disclosure.

What is described in the foregoing are only embodiments of the present disclosure, and should not be construed as limitations to the present disclosure. Any changes, equivalent replacements, modifications made without departing from the scope and spirit of the present disclosure are intended to be included within the protecting scope of the present disclosure.

Claims

A method for operating a terminal in a wireless communication system, the method comprising:

transmitting, to a base station, a preamble through a random access channel;

receiving, from the base station, a random access response (RAR), wherein the RAR comprises an identifier of the preamble; and

transmitting, to the base station, data in response to receiving the RAR comprising the identifier of the preamble.
The method of claim 1, wherein the transmitting the data comprises:

determining a multiple access signature corresponding to the preamble based on a preamble and multiple access signature mapping relationship; and

transmitting, to the base station, the data using the determined multiple access signature.
The method of claim 1, wherein the transmitting the data comprises:

determining an uplink demodulation reference signal corresponding to the preamble based on a preamble and uplink demodulation reference signal mapping relationship; and

inserting the determined uplink demodulation reference signal during transmission of the data.
The method of claim 1, further comprising:

if the RAR indicates a multiple access signature and an uplink demodulation reference signal is allocated by the base station, in response to using a non-orthogonal multiple access scheme, transmitting, to the base station, the data using the multiple access signature indicated by the RAR, and inserting the uplink demodulation reference signal;

if RAR indicates the uplink demodulation reference signal allocated by the base station, in response to using an orthogonal multiple access scheme, transmitting, to the base station, the data, and inserting the uplink demodulation reference signal indicated by the RAR; and

if RAR indicates the multiple access signature allocated by the base station, determining an uplink demodulation reference signal corresponding to the selected preamble based on a preamble and uplink demodulation reference signal mapping relationship, in response to using the non-orthogonal multiple access scheme, transmitting, to the base station, the data using the multiple access signature indicated by the RAR, and inserting the uplink demodulation reference signal corresponding to the preamble.
The method of claim 1, wherein there is a mapping relationship between the preamble and an uplink demodulation reference signal, and there is a mapping relationship between the preamble and a multiple access signature, in response to selecting different preambles which are mapped to a same multiple access signature, corresponding uplink demodulation reference signals are different.
The method of claim 1, further comprising:

in response to having not detected a RAR containing the preamble identifier of the preamble during a first period of time after transmitting the preamble, or detecting the RAR containing the preamble identifier of the preamble, and the RAR containing a NACK signal, randomly re-selecting a preamble to perform random access after waiting for a pre-defined period of time.
The method of claim 1, further comprising: if the terminal transmits the data, transmitting a unique identifier of the terminal together with the data.
The method of claim 1, further comprising:

detecting a control channel of a corresponding time-frequency resource after k subframes after the terminal transmits the data, and detecting an acknowledgement (ACK) or a negative acknowledgement (NACK) signal corresponding to the time-frequency resource and a multiple access signature and an identity (ID) allocated to the terminal by the base station; where k is a preset value;

in response to detecting the ACK signal and no further data needing to be transmitted, waiting for next data transmission; and

in response to detecting the ACK signal, further data needing to be transmitted, and the ID allocated to the terminal by the base station, transmitting the data based on scheduling by the base station; and

in response to detecting the NACK signal, using a time-frequency resource and a multiple access signature same as those used for last uplink data transmission after m subframes, where m is a preset parameter; and in response to the number of times of detecting NACK signals exceeding a specified value, determining that access is failure, and increasing a priority of the preamble to perform random access.
An apparatus for a terminal in a wireless communication system, the apparatus comprising:

a transceiver; and

at least one processor operatively coupled with the transceiver,

wherein the at least one processor is configured to control to:

transmit, to a base station, the preamble through a random access channel;

receive, to the base station, a random access response (RAR), wherein the RAR comprises an identifier of the preamble; and

transmit, to the base station, data in response to receiving the RAR comprising the identifier of the preamble.
A method for operating a base station in a wireless communication system, the method comprising:

receiving, from a terminal, a preamble through a random access channel;

performing a conflict detection for the preamble; and

in response to a result of the conflict detection being non-conflicting, transmitting, to the terminal, a random access response (RAR), where the RAR comprises an identifier of the preamble.
The method of claim 10, wherein the performing the conflict detection for the preamble comprises:

in response to a result of a correlation detection for the preamble being lower than a power threshold, then determining that the result of the conflict detection is non-conflicting; or otherwise, determining that the result of the conflict detection is conflicting.
The method of claim 11, wherein the power threshold is a power threshold determined by: determining a receiving power level of the base station according to an open-loop power control parameter of the terminal, and determining the power threshold according to a specified tolerance of the receiving power level of the base station.
The method of claim 10, further comprising:

in response to determining that the result of the conflict detection is conflicting, not performing RAR processing for the preamble, or inserting the identifier and a negative acknowledgement (NACK) signal in the RAR.
The method of claim 10, wherein after transmitting the RAR to the terminal, further comprises:

receiving, from the terminal, data; and

transmitting, to the terminal, feedback information;

wherein the transmitting the feedback information comprises:

transmitting an acknowledgement (ACK) or negative acknowledgement (NACK) signal of uplink data through a downlink control channel after k subframes after the data are transmitted, wherein

in response to receiving the data properly, determining that the terminal has no demand for continuing to transmit the data, and transmitting the ACK signal to the terminal; or

in response to receiving the data properly, determining that the terminal needs to continue to transmit the data, allocating an identifier (ID) for the terminal and transmitting the ID and the ACK signal to the terminal through the downlink control channel; or

in response to having not received uplink data properly, transmitting the NACK signal.
An apparatus for a base station in a wireless communication system, the apparatus comprising:

a transceiver; and

at least one processor operatively coupled with the transceiver,

wherein the at least one processor is configured to control to:

receive, from a terminal, a preamble through a random access channel;

perform a conflict detection for the preamble; and

transmit, to the terminal, a random access response (RAR) in response to a result of the conflict detection being non-conflicting, and

wherein the RAR comprises an identifier of the preamble.