CN110839228B - NB-IoT D2D communication method, terminal and system based on signaling monitoring - Google Patents

Abstract

The invention discloses a D2D communication method, a terminal and a system of NB-IoT based on signaling monitoring, wherein idle time-frequency domain resources required in the D2D communication process are obtained by monitoring an anchor carrier of a cell where an initiating terminal is located in an NB-IoT network; determining a target channel by using idle time frequency domain resources; sending the associated information of the D2D communication to a receiving terminal through a target channel, and receiving reply information of the receiving terminal aiming at the D2D communication through the target channel, so that the initiating terminal and the receiving terminal establish the D2D communication through the target channel; the association information includes a D2D communication request and a data service. The D2D communication between the NB-IoT terminals is realized without data forwarding by a base station, but direct communication is carried out in a D2D mode, and only one channel resource is occupied during communication, so that the pressure of the number of cell access terminals is effectively relieved, and the communication quality of the D2D terminals is improved.

Description

NB-IoT D2D communication method, terminal and system based on signaling monitoring

technical field

The present invention relates to the field of communication technology, in particular to a D2D communication method, terminal and system of NB-IoT based on signaling monitoring.

Background technique

NB-IoT (Narrow Band Internet of Things, Narrowband Internet of Things) is a technology that is naturally evolving to 5G. It has the characteristics of wide coverage, multiple connections, low speed, low cost, low power consumption, and excellent architecture. It is currently widely used in Smart cities, industrial Internet of Things, agriculture and the environment, wearable devices and other fields also have great room for development.

D2D (Device-to-Device, device-to-device) communication technology has been listed as one of the important wireless key technologies of the fifth generation mobile communication. D2D communication technology is applied to various application scenarios such as cellular network, Internet of Vehicles, AdHoc network, etc., so as to improve the throughput of users in the community and expand the network coverage.

As NB-IoT is integrated into the LTE standard and applied on a large scale, in the existing D2D communication mode, each D2D terminal must register with the base station, and the base station coordinates D2D terminal discovery and synchronization, and controls communication interference. When the network load is heavy, the load of the base station will be increased, so that the number of terminals accessing the cell is limited, and the communication quality of D2D terminals will be reduced.

Contents of the invention

In view of the above problems, the present invention provides an NB-IoT D2D communication method, terminal and system based on signaling monitoring, which relieves the pressure on the number of access terminals in a cell and improves the communication quality of D2D terminals.

In order to achieve the above object, the present invention provides the following technical solutions:

A D2D communication method of NB-IoT based on signaling monitoring, applied to an initiating terminal of a D2D communication system of NB-IoT, the system also includes a receiving terminal, and the method includes:

Obtain idle time-frequency domain resources required in the D2D communication process by monitoring the anchor carrier of the NB-IoT cell where the initiating terminal is located;

Using the idle time-frequency domain resources, determine a target channel;

Send the associated information of the D2D communication to the receiving terminal through the target channel, and receive the reply information of the receiving terminal for the D2D communication through the target channel, so that the initiating terminal and the receiving terminal pass through the receiving terminal. The target channel is used to establish D2D communication; the associated information includes D2D communication request and data service.

Optionally, the obtaining idle time-frequency domain resources required in the D2D communication process by monitoring the anchor carrier of the NB-IoT cell where the initiating terminal is located includes:

Monitor the anchor carrier of the NB-IoT cell where the initiating terminal is located, and obtain the associated information of the system information block;

Searching to obtain a search space according to the associated information of the system information block, the search space includes a public search space and a user-specific search space;

Decoding the search space to obtain base station resource allocation information;

Acquiring channel occupancy information of the cell from the resource allocation information of the base station;

Based on the channel occupancy situation information, idle time-frequency domain resources for the D2D communication process are obtained.

Optionally, the determining the target channel by using the idle time-frequency domain resources includes:

Acquiring downlink channel occupancy information of the anchor carrier according to the idle time-frequency domain resource;

Determining idle time-frequency domain resources in the downlink channel as a first channel according to the occupancy information of the downlink channel; the first channel is used for the initiating terminal to send a D2D communication request to the receiving terminal;

According to the idle time-frequency domain resource, obtain the uplink channel occupancy information of the D2D service communication carrier;

According to the uplink channel occupancy information, determine the idle time-frequency domain resource of the uplink channel in the D2D service communication carrier as the second channel, and determine the remaining idle time-frequency domain resource in the uplink channel except the second channel as the second channel. Three channels; the second channel is used for the receiving terminal to reply to the initiating terminal with the first reply information for the D2D communication request, and the third channel is used for the receiving terminal to reply to the initiating terminal for the received The second reply information of the data service.

Optionally, the method also includes

According to the idle time-frequency domain resource, obtain information about the downlink channel occupancy of the D2D service communication carrier;

According to the downlink channel occupancy information, determine the idle time-frequency domain resource of the downlink channel in the D2D service communication carrier as the fourth channel, and determine the remaining idle time-frequency domain resources in the downlink channels except the fourth channel for the fifth channel;

Wherein, the fourth channel is used for the initiating terminal to send service data to the receiving terminal; the fifth channel is used for the initiating terminal to send a communication frequency band switching instruction to the receiving terminal.

Optionally, the method also includes:

If the idle time-frequency domain resources of the downlink channel or uplink channel in each non-anchor carrier have been occupied, based on the occupancy information of the uplink and downlink channels in the anchor carrier and the time-frequency domain resources occupied during the D2D request communication process The situation information determines the candidate channel located in the anchor carrier, and the candidate channel represents the uplink and downlink idle time-frequency domain resources required in the D2D service communication process.

Optionally, the method also includes:

When the D2D communication request is sent to the receiving terminal through the first channel, if the first reply message of the receiving terminal for the D2D communication request is not received within a preset time period, the sending terminal’s switch its own frequency band to the anchor carrier frequency band, and resend the D2D communication request;

switch to the D2D service frequency band to receive the first reply message from the receiving terminal;

If the first reply message from the receiving terminal is not received within the preset number of times of resending requests, or the frequency domain resources are not enough to resend the D2D request information during the resending process, generate a report instruction, and send the The initiating terminal switches its own frequency band to the anchor carrier frequency band, and the reporting instruction indicates that the D2D communication with the receiving terminal fails.

Optionally, the method also includes:

In response to receiving the second reply message sent by the receiving terminal, send a communication frequency band switching instruction to the receiving terminal at a position in the time-frequency domain of the downlink channel of the D2D service communication carrier, and switch its own carrier frequency band to Anchor carrier end.

Optionally, the method also includes:

If the second reply message from the receiving terminal is not received within the preset times of resending the service data or the frequency domain resources are not enough to retransmit the service data when idle during the resending process, generate a report instruction, and send the The initiating terminal switches its own frequency band to the anchor carrier frequency band, and the reporting instruction indicates that the D2D communication with the receiving terminal fails.

A sending terminal, comprising:

The monitoring unit is configured to obtain the idle time-frequency domain resources required in the D2D communication process by monitoring the anchor carrier of the NB-IoT cell where the initiating terminal is located;

a determining unit, configured to determine a target channel by using the idle time-frequency domain resources;

a sending unit, configured to send D2D communication-related information to the receiving terminal through the target channel, and receive reply information from the receiving terminal for the D2D communication through the target channel, so that the initiating terminal and the The receiving terminal establishes D2D communication through the target channel; the associated information includes a D2D communication request and a data service.

A NB-IoT D2D communication system based on signaling monitoring, including an originating terminal and a receiving terminal, wherein,

The initiating terminal is used to execute the NB-IoT D2D communication method based on signaling monitoring as described in any one of the above;

The receiving terminal is configured to receive the associated information of the D2D communication sent by the initiating terminal, generate a reply message according to the associated information, and send the reply message to the initiating terminal.

Compared with the prior art, the present invention provides a NB-IoT D2D communication method, terminal and system based on signaling monitoring, by monitoring the anchor carrier of the NB-IoT cell where the initiating terminal is located, D2D Idle time-frequency domain resources required in the communication process; using the idle time-frequency domain resources to determine a target channel; sending the associated information of D2D communication to the receiving terminal through the target channel, and receiving the information through the target channel The receiving terminal responds to the D2D communication information, so that the initiating terminal and the receiving terminal establish D2D communication through the target channel; the associated information includes a D2D communication request and a data service. The D2D communication between NB-IoT terminals does not need to rely on the base station for data forwarding, but directly communicates through the D2D mode, and only occupies one channel resource during communication, thereby effectively alleviating the pressure on the number of access terminals in the cell and improving D2D terminal communication quality.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only It is an embodiment of the present invention, and those skilled in the art can also obtain other drawings according to the provided drawings without creative work.

FIG. 1 is a schematic flowchart of a D2D communication method for NB-IoT based on signaling monitoring provided by an embodiment of the present invention;

FIG. 2 is a schematic diagram of a D2D communication scenario between NB-IoT-D2D terminals provided by an embodiment of the present invention;

FIG. 3 is a diagram of a D2D communication area between NB-IoT-D2D terminals provided by an embodiment of the present invention;

FIG. 4 is a time-frequency domain resource diagram for D2D communication of NB-IoT provided by an embodiment of the present invention;

FIG. 5 is a flow chart of mutual communication between an initiating terminal and a receiving terminal for NB-IoT when requesting D2D communication according to an embodiment of the present invention;

FIG. 6 is a flowchart of mutual communication between an initiating terminal and a receiving terminal for NB-IoT during D2D service transmission according to an embodiment of the present invention;

FIG. 7 is a schematic structural diagram of an initiating terminal of an NB-IoT D2D communication system provided by an embodiment of the present invention.

Detailed ways

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

The terms "first" and "second" in the specification and claims of the present invention and the above drawings are used to distinguish different objects, rather than to describe a specific order. Furthermore, the terms "comprising" and "having", and any variations thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, system, product or apparatus comprising a series of steps or units is not defined by listed steps or units, but may include unlisted steps or units.

In order to facilitate the understanding of the embodiments provided by the present invention, the term information used in the present invention is now explained.

NB-IoT: Narrow Band Internet of Things, Narrow Band Internet of Things.

D2D: Device-to-Device, device to device.

SIM: Subscriber Identification Module, Subscriber Identification Module. It is a dedicated SIM card for NB-IoT.

NPBCH: Narrow-band Physical Broadcast Channel, Narrow-band Physical Broadcast Channel.

NPDSCH: Narrow-band Physical Downlink Shared Channel, Narrow-band Physical Downlink Shared Channel.

NPUSCH: Narrow-band Physical Uplink Shared Channel, Narrow-band Physical Uplink Shared Channel.

NPDCCH: Narrow-band Physical Downlink Control Channel, Narrow-band Physical Downlink Control Channel.

RAR: Random Access Response, random access reply.

CSS: Common Search Space, public search space. It is divided into a Type1-NPDCCH common search space (T1CSS) for paging reception and a Type2-NPDCCH common search space (T2CSS) related to RAR messages, Msg3 and Msg4.

USS: UE-specific Search Space, user-specific search space. It is used for UE in connected state to receive NPDCCH.

SIB-NB: System Information Block-Narrow Band, System Information Block-Narrow Band. It carries two CSS configuration parameters.

DCI: Downlink Control Information, downlink control information. The main function is to schedule the time-frequency domain positions and modulation and coding methods used by each channel. There are three formats of DCI supported by NB-IoT: Format N0 related to uplink NPUSCH scheduling; Format N1 related to downlink NPDSCH scheduling and random access triggered by PDCCH order; related to paging NPDSCH scheduling and directly related to system message update Indicates the relevant Format N2.

IDLE: In NB-IoT, the NB-IoT terminal is in an idle state. In this state, NB-IoT terminals can monitor NPDCCH and NPBCH, obtain system information, etc.

IDLE DRX: Idle Discontinuous Reception, idle state discontinuous reception. It is a state when the NB-IoT terminal is in IDLE, and can monitor NPDCCH and NPBCH discontinuously.

NB-IoT-D2D terminal: In NB-IoT, an NB-IoT terminal that has successfully registered and can perform D2D communication.

Cellular communication mode: A communication mode in which NB-IoT-D2D terminals communicate with base stations.

D2D communication mode: a communication mode for direct communication between NB-IoT-D2D terminals.

IDLE listening state: When each NB-IoT-D2D terminal is in cellular communication mode or D2D communication mode, this state refers to the state in which each terminal can receive and send messages.

Initiating terminal: When the NB-IoT terminal needs to upload data, it requests the NB-IoT-D2D terminal for D2D communication.

Receiving terminal: the NB-IoT-D2D terminal that accepts the D2D communication request of the initiating terminal and can perform D2D communication with the initiating terminal.

Q-ACK: A confirmation message returned by the receiving terminal after receiving the D2D communication request from the initiating terminal.

D-ACK: A confirmation message returned by the receiving terminal after receiving the data service uploaded by the initiating terminal.

D2D request communication process: a communication process in which the initiating terminal requests D2D communication from the receiving terminal.

D2D service communication process: including the process of the receiving terminal replying Q-ACK to the initiating terminal, the process of transmitting data services from the initiating terminal to the receiving terminal, the process of replying D-ACK from the receiving terminal to the initiating terminal, and the initiating terminal sending frequency band switching instructions to the receiving terminal communication process.

Anchor carrier: In an NB-IoT multi-carrier cell, a carrier that can carry all uplink and downlink transmission services, and each NB-IoT terminal resides on this carrier when it is in IDLE. This carrier is used to bear the D2D request communication process.

Non-anchor carrier: In the NB-IoT multi-carrier cell, the carrier that does not carry NPSS/NSSS/NPBCH/SIB-NB.

D2D service communication carrier: By analyzing the channel idle time and frequency domain resources of the cell where the NB-IoT-D2D terminal is located, an optimal non-anchor carrier for carrying the D2D service communication process is preferentially selected from various non-anchor carriers. If the idle time-frequency domain resources in each non-anchor carrier have been occupied, the anchor carrier is selected as the D2D service communication carrier.

D2D service frequency band: During the D2D service communication process, the frequency band of the D2D service communication carrier.

In the wireless communication mode integrating NB-IoT and D2D, it is stipulated that NB-IoT-D2D terminals can support both cellular communication and D2D communication modes at the same time. According to communication requirements, NB-IoT-D2D terminals can realize traditional cellular communication through the base station, and can also communicate directly with other NB-IoT-D2D terminals in D2D communication mode. The details are as follows: When the NB-IoT-D2D terminal performs cellular communication, its processing flow is consistent with the traditional NB-IoT communication flow. When the NB-IoT-D2D terminal needs to perform D2D communication, it first switches to the IDLE monitoring state, and obtains the channel occupancy information of the current cell by monitoring the SIB information and NPDCCH in the base station signaling. Based on this information, select idle spectrum resources that can be used for D2D communication, use the anchor carrier of the cellular network as the request communication carrier, and use the original channel as the information carrier, initiate a D2D communication request to the receiving terminal, and prepare to complete the transmission of the service packet. At this time, if the D2D service is a unicast service, the number of receiving terminals is 1; if the D2D service is a multicast or broadcast service, the number of receiving terminals is greater than 1.

In the present invention, the NB-IoT-D2D terminal can directly communicate through the D2D mode without relying on the base station for data forwarding. When communicating between NB-IoT-D2D terminals, only one channel resource is occupied, which can effectively relieve the pressure on the number of access terminals in the cell. At the same time, NB-IoT-D2D terminals use the idle spectrum resources of the cellular network for D2D communication by monitoring base station signaling, which can effectively avoid the impact of D2D communication on the cellular communication mode, reduce channel conflicts, and improve spectrum utilization. In addition, the coverage area of the base station can be effectively expanded through D2D communication between nodes.

The D2D communication method of NB-IoT based on signaling monitoring provided by the present invention is applied to the initiating terminal of the D2D communication system of NB-IoT. The D2D communication system also includes a receiving terminal, see FIG. 1, the method includes:

S101. Obtain idle time-frequency domain resources required in the D2D communication process by monitoring the anchor carrier of the NB-IoT cell where the initiating terminal is located.

The process of obtaining idle time-frequency domain resources required in the D2D communication process specifically includes:

Monitor the anchor carrier of the NB-IoT cell where the initiating terminal is located, and obtain the associated information of the system information block;

Searching to obtain a search space according to the associated information of the system information block, the search space includes a public search space and a user-specific search space;

Decoding the search space to obtain base station resource allocation information;

Acquiring channel occupancy information of the cell from the resource allocation information of the base station;

Based on the channel occupancy situation information, idle time-frequency domain resources for the D2D communication process are obtained.

S102. Determine a target channel by using the idle time-frequency domain resource.

The process includes:

Acquiring downlink channel occupancy information of the anchor carrier according to the idle time-frequency domain resource;

Determining idle time-frequency domain resources in the downlink channel as a first channel according to the occupancy information of the downlink channel; the first channel is used for the initiating terminal to send a D2D communication request to the receiving terminal;

According to the idle time-frequency domain resource, obtain the uplink channel occupancy information of the D2D service communication carrier;

According to the uplink channel occupancy information, determine the idle time-frequency domain resource of the uplink channel in the D2D service communication carrier as the second channel, and determine the remaining idle time-frequency domain resource in the uplink channel except the second channel as the second channel. Three channels; the second channel is used for the receiving terminal to reply to the initiating terminal with the first reply information for the D2D communication request, and the third channel is used for the receiving terminal to reply to the initiating terminal for the received The second reply information of the data service.

Correspondingly, when analyzing idle time-frequency domain resources, it also includes:

According to the idle time-frequency domain resource, obtain information about the downlink channel occupancy of the D2D service communication carrier;

According to the downlink channel occupancy information, determine the idle time-frequency domain resource of the downlink channel in the D2D service communication carrier as the fourth channel, and determine the remaining idle time-frequency domain resources in the downlink channels except the fourth channel as the fourth channel. Five channels; the fourth channel is used for the initiating terminal to send service data to the receiving terminal; the fifth channel is used for the initiating terminal to send communication frequency band switching instructions to the receiving terminal.

S103. Send the associated information of the D2D communication to the receiving terminal through the target channel, and receive the reply information of the receiving terminal for the D2D communication through the target channel, so that the initiating terminal and the receiving terminal D2D communication is established through the target channel; the associated information includes a D2D communication request and a data service.

The above-mentioned embodiments will be described in detail below.

In the NB-IoT network, the initiating terminal monitors the anchor carrier of the cell where it is located, and obtains SIB information from NPBCH and NPDSCH, finds all CSS and USS according to the SIB information, and then decodes all DCI carried by NPDCCH from all search spaces Base station resource allocation information in the format. Then first analyze the downlink channel occupancy of Format N1 and N2 obtained by decoding the USS and CSS, and select the free time-frequency domain resources of the downlink channel located in the anchor carrier for the originating terminal to request the receiving terminal during the D2D request communication process. D2D communication: select the idle time-frequency domain resource of the downlink channel in the D2D service communication carrier, which is used for transmitting data services from the initiating terminal to the receiving terminal and sending communication frequency band switching instructions during the D2D service communication process. Then analyze the uplink channel occupancy of Format N0 obtained by decoding the USS and T2CSS, and select the idle time-frequency domain resource of the uplink channel located in the D2D service communication carrier for the receiving terminal to reply to the initiating terminal with a Q-ACK that can perform D2D communication And the receiving terminal replies a D-ACK indicating that the data service has been received to the initiating terminal. If the idle time-frequency domain resources of the downlink channel or uplink channel in each non-anchor carrier have been occupied, it may be considered to select the idle time-frequency domain resources of the uplink and downlink channels located in the anchor carrier for D2D communication.

After the initiating terminal completes the analysis of the idle time-frequency domain resources for D2D communication, it carries its own location, ID numbers of the two terminals, information about the D2D service communication carrier, and information about each component in the D2D communication on the time-frequency domain position of the downlink channel in the anchor carrier. The information such as the size and location of the idle frequency domain resources occupied by the step requests D2D communication from the receiving terminal, and at the same time, the initiating terminal starts a timer waiting for the reply from the receiving terminal, switches its own carrier frequency band to the D2D service frequency band, and waits for the receiving terminal to reply and confirm information.

After receiving the request information of the initiating terminal in the downlink channel of the anchor carrier, the receiving terminal switches from the anchor carrier frequency band to the D2D service frequency band, and then at the time-frequency domain position in the uplink channel of the D2D service communication carrier, Reply to the initiating terminal with Q-ACK to inform that D2D communication can be performed; at the same time, the receiving terminal starts a timer for waiting for the initiating terminal to transmit data services, and waits for the initiating terminal to upload data.

After the initiating terminal receives the Q-ACK replied by the receiving terminal on the D2D service communication carrier, it carries the data to be transmitted and sends it to the receiving terminal at the time-frequency domain position in the downlink channel of the D2D service communication carrier, and starts waiting again at the same time. The timer for the receiving terminal to reply, waiting for the receiving terminal to reply D-ACK. If the timer waiting for the reply from the receiving terminal becomes 0 for the first time, and the initiating terminal has not received the Q-ACK replied by the receiving terminal on the D2D service communication carrier, it proves that the service transmission has failed, and the initiating terminal will switch its own frequency band to The anchor carrier frequency band, (the purpose of frequency band switching: here is for the abnormal communication situation that occurs - 'due to resource interference or sudden resource occupation on the anchor carrier, the receiving terminal cannot receive the D2D request message from the sending terminal , so that the initiating terminal cannot receive the Q-ACK.' The countermeasures. At this time, the initiating terminal needs to return to the anchor carrier frequency band to resend the D2D request. In addition, due to the large number of services on the anchor carrier, resource interference or The probability of resources being suddenly occupied is relatively high, so the probability of this abnormal situation is relatively high.) Retransmit the D2D communication request, and then switch to the D2D service frequency band to wait for the reply message from the receiving terminal. If the initiating terminal retransmits N times and still does not receive the Q-ACK from the receiving terminal on the D2D service communication carrier, it will abandon the D2D communication, report the D2D communication failure, and switch its own carrier to the anchor carrier frequency band. If the initiating terminal retransmits for the Kth time (K≤N), and the analyzed idle time-frequency domain resources are not enough to retransmit the D2D communication request, it will abandon the D2D communication, report the D2D communication failure, and switch its own carrier to the anchor carrier band.

After receiving the data transmitted by the initiating terminal, the receiving terminal replies with a D-ACK at the position in the time-frequency domain of the uplink channel of the D2D service communication carrier to notify the completion of the D2D communication. At the same time, the receiving terminal starts a carrier switching waiting timer, and waits for a communication frequency band switching instruction from the initiating terminal. If the timer for the receiving terminal to wait for the initiating terminal to transmit the data service becomes 0 and has not received the data service sent by the initiating terminal, it proves that the service transmission has failed. The receiving terminal retransmits the Q-ACK in the D2D service communication carrier and waits for Initiate the data service transmission of the terminal. If the receiving terminal retransmits M times and still does not receive the data service sent by the initiating terminal, it will abandon the D2D communication, report the failure of the D2D communication, and switch its own carrier to the anchor carrier frequency band. If the receiving terminal retransmits for the Lth time (L≤M), and the analyzed idle time-frequency domain resources are not enough to retransmit Q-ACK, it will give up the D2D communication, report the D2D communication failure, and switch its own carrier to the anchor carrier band.

After the initiating terminal receives the D-ACK replied by the receiving terminal, the initiating terminal sends a communication frequency band switching instruction to the receiving terminal at the time-frequency domain position in the downlink channel of the D2D service frequency band, and switches its own carrier frequency band to the anchor carrier frequency band. If the timer waiting for the reply from the receiving terminal becomes 0 for the second time, and the initiating terminal has not received the D-ACK sent by the receiving terminal, it proves that the service transmission has failed, and the initiating terminal retransmits the D2D data service in the D2D service frequency band. Wait for the D-ACK from the receiving terminal. If the initiating terminal retransmits X times and still does not receive the D-ACK, it will abandon the D2D communication, report the failure of the D2D communication, and switch its own carrier to the anchor carrier frequency band. If the initiating terminal retransmits for the Zth time (Z≤X), and the analyzed idle time-frequency domain resources are not enough to retransmit the D2D data service, it will abandon the D2D communication, report the D2D communication failure, and switch its own carrier to the anchor carrier band.

The receiving terminal receives the communication frequency band switching instruction, switches its own frequency band to the anchor carrier frequency band, and ends the D2D communication. If the carrier switching waiting timer becomes 0 and the receiving terminal has not received the communication frequency band switching instruction, it will automatically switch to the anchor carrier frequency band and end the D2D communication.

In the D2D communication system based on NB-IoT, the present invention does not rely on the base station to coordinate D2D communication, but adopts a direct D2D communication mode based on signaling monitoring, which aims to alleviate the pressure on the number of access terminals in the cell and improve Spectrum utilization and network capacity.

In the D2D communication system based on NB-IoT, the current D2D communication mode between two NB-IoT-D2D terminals with SIM cards and successful registration is mainly studied. The communication scene is shown in Figure 2.

Scenario 1: Communication between NB-IoT-D2D terminals within the coverage of the same base station.

Scenario 2: Communication between NB-IoT-D2D terminals without cellular network coverage.

Scenario 3: Communication between NB-IoT-D2D terminals within the coverage of different base stations.

The specific process of D2D communication between NB-IoT-D2D terminals is as follows:

S201. The initiating terminal analyzes the idle spectrum resources required in the D2D communication process, and requests the receiving terminal for D2D communication with corresponding information:

The initiating terminal first monitors the anchor carrier of the NB-IoT cell where it is located, obtains SIB information from NPBCH and NPDSCH, finds all CSS and USS according to the SIB information, and then decodes all DCI formats carried by NPDCCH from all search spaces. Base station resource allocation information, and then obtain the channel occupancy information of the current cell from the analyzed base station resource allocation information, based on this information, select idle time-frequency domain resources for D2D communication:

S2011, D2D requests resources required for the communication process:

When the NB-IoT terminal is in the IDLE state and resides on the anchor carrier, the D2D request communication process between the initiating terminal and the receiving terminal needs to be performed on the anchor carrier.

The initiating terminal analyzes the downlink channel occupancy of the anchor carriers of Format N1 and N2 obtained by decoding the USS and CSS, and selects idle time-frequency domain resources in the downlink channel for the initiating terminal to request D2D communication from the receiving terminal during the D2D request communication process .

S2012, resources required for the D2D business communication process:

In the NB-IoT mechanism, the initial synchronization of each NB-IoT terminal is located on the anchor carrier, which has a lot of traffic, so in order to reduce the pressure on the anchor carrier, the idle resources on the non-anchor carrier are preferentially selected for use. D2D service communication process.

The initiating terminal analyzes the uplink channel occupancy of the D2D service communication carrier under Format N0 obtained by decoding the USS and T2CSS, and first selects the idle time-frequency domain resources of the uplink channel in the D2D service communication carrier for the D2D service communication process. The initiating terminal replies with a Q-ACK indicating that D2D communication is possible; and then selects the remaining idle time-frequency domain resources in the uplink channel for the receiving terminal to reply to the initiating terminal with a D-ACK indicating that the data service has been received.

The initiating terminal analyzes the downlink channel occupancy of the D2D service carrier under Format N1 and N2 obtained by decoding the USS and CSS, and first selects the idle time-frequency domain resources of the downlink channel in the D2D service communication carrier for initiating during the D2D service communication process. The terminal transmits data services to the receiving terminal, and then selects the remaining idle time-frequency domain resources in the downlink channel for the initiating terminal to send a communication frequency band switching instruction to the receiving terminal.

The D2D communication area diagram between NB-IoT-D2D terminals in the above process is shown in Figure 3, and the time-frequency domain resource diagram is shown in Figure 4.

If the idle time-frequency domain resources of the downlink channel or uplink channel in each non-anchor carrier have been occupied, then based on the occupancy information of the uplink and downlink channels in the anchor carrier, and the time-frequency domain occupied by the D2D request communication process In terms of resources, analyze and select the uplink and downlink idle time-frequency domain resources in the anchor carrier for the D2D service communication process.

After the initiating terminal completes the analysis of the idle time-frequency domain resources for D2D communication, it carries its own location, ID numbers of the two terminals, information about the D2D service communication carrier, and information about each component in the D2D communication on the time-frequency domain position of the downlink channel in the anchor carrier. The information such as the size and location of the idle frequency domain resources occupied by the step requests D2D communication from the receiving terminal, and at the same time, the initiating terminal starts a timer waiting for the reply from the receiving terminal, switches its own carrier frequency band to the D2D service frequency band, and waits for the receiving terminal to reply Q -ACK.

S202. The receiving terminal receives the request information from the initiating terminal, and informs the initiating terminal that the D2D communication can be confirmed:

When the receiving terminal is in the IDLE monitoring state in the cellular mode, it needs to first receive the message requesting D2D communication from the initiating terminal, and then enter the D2D communication mode to communicate with the initiating terminal after completing the DRX state specified by the base station;

When the receiving terminal is in the IDLE monitoring state in the D2D communication mode and has no other tasks, it receives the request information from the initiating terminal and directly communicates with the initiating terminal.

After the receiving terminal receives the request information of the initiating terminal in the downlink channel of the anchor carrier, it switches from the anchor carrier frequency band to the D2D service frequency band, and then at the time-frequency domain position in the uplink channel of the D2D service communication carrier, Reply to the initiating terminal with Q-ACK to inform that D2D communication can be performed; at the same time, the receiving terminal starts a timer for waiting for the initiating terminal to transmit data services, and waits for the initiating terminal to upload data. At this time, the flow chart of mutual communication between the initiating terminal and the receiving terminal is shown in FIG. 5 .

S203. After receiving the message confirming the D2D communication from the receiving terminal, the initiating terminal uploads the data service to the receiving terminal:

The initiating terminal sends the data to be transmitted to the receiving terminal at the time-frequency domain position in the downlink channel of the D2D service communication carrier, and at the same time restarts the timer waiting for the receiving terminal to reply, and waits for the receiving terminal to reply D-ACK.

If the timer waiting for the reply from the receiving terminal becomes 0 for the first time, and the initiating terminal has not received the Q-ACK message from the receiving terminal on the D2D service communication carrier, it proves that the service transmission has failed, and the initiating terminal will switch its own frequency band Go to the anchor carrier frequency band, retransmit the D2D communication request, and then switch to the D2D service frequency band to wait for the reply message from the receiving terminal. If the initiating terminal retransmits N times and still does not receive the Q-ACK message from the receiving terminal on the D2D service communication carrier, it will abandon the D2D communication, report the D2D communication failure, and switch its own carrier to the anchor carrier frequency band . If the initiating terminal retransmits for the Kth time (K≤N), and the analyzed idle time-frequency domain resources are not enough to retransmit the D2D communication request, it will abandon the D2D communication, report the D2D communication failure, and switch its own carrier to the anchor carrier band.

S204. After receiving the data transmitted by the initiating terminal, the receiving terminal replies to the initiating terminal D-ACK:

The receiving terminal replies to the initiating terminal D-ACK at the position in the time-frequency domain of the uplink channel of the D2D service communication carrier to inform the completion of the D2D communication. At the same time, the receiving terminal starts a carrier switching waiting timer, and waits for a communication frequency band switching instruction from the initiating terminal. At this time, the flow chart of mutual communication between the initiating terminal and the receiving terminal is shown in FIG. 6 .

If the timer for the receiving terminal to wait for the initiating terminal to transmit the data service becomes 0 and has not received the data service sent by the initiating terminal, it proves that the service transmission has failed. The receiving terminal retransmits the Q-ACK in the D2D service communication carrier and waits for Initiate the data service transmission of the terminal. If the receiving terminal retransmits M times and still does not receive the data service sent by the initiating terminal in the D2D service communication carrier, it will abandon the D2D communication, report the D2D communication failure, and switch its own carrier to the anchor carrier frequency band. If the receiving terminal retransmits for the Lth time (L≤M), and the analyzed idle time-frequency domain resources are not enough to retransmit Q-ACK, it will give up the D2D communication, report the D2D communication failure, and switch its own carrier to the anchor carrier band.

S205. The initiating terminal sends a frequency band switching instruction to the receiving terminal:

After the initiating terminal receives the D-ACK replied by the receiving terminal, the initiating terminal sends a communication frequency band switching instruction to the receiving terminal at the time-frequency domain position in the downlink channel of the D2D service communication carrier, and switches its own carrier frequency band to the anchor carrier frequency band .

If the timer waiting for the reply from the receiving terminal becomes 0 for the second time, and the initiating terminal has not received the D-ACK sent by the receiving terminal, it proves that the service transmission failed, and the initiating terminal retransmits the D2D data service in the D2D service communication carrier , waiting for the D-ACK of the receiving terminal. If the initiating terminal retransmits X times and still does not receive the D-ACK, it will abandon the D2D communication, report the failure of the D2D communication, and switch its own carrier to the anchor carrier frequency band. If the initiating terminal retransmits for the Zth time (Z≤X), and the analyzed idle time-frequency domain resources are not enough to retransmit the D2D data service, it will abandon the D2D communication, report the D2D communication failure, and switch its own carrier to the anchor carrier band.

S206. The receiving terminal switches frequency bands:

The receiving terminal receives the communication frequency band switching instruction, switches its own frequency band to the anchor carrier frequency band, and ends the D2D communication.

If the carrier switching waiting timer becomes 0 and the receiving terminal has not received the communication frequency band switching instruction, it will automatically switch to the anchor carrier frequency band and end the D2D communication.

In the present invention, the communication between each NB-IoT-D2D terminal does not need to rely on the base station for data forwarding, but directly communicates through the D2D mode, and only occupies one channel resource during communication, thereby effectively alleviating the pressure on the number of access terminals in the cell , Improve network capacity. The NB-IoT-D2D terminal uses the idle spectrum resources of the cellular network to conduct D2D communication by monitoring base station signaling, which can effectively avoid the impact of D2D communication on the cellular communication mode, reduce channel conflicts, and improve spectrum utilization. The NB-IoT-D2D terminal directly performs D2D communication between nodes through the D2D mode, which can effectively expand the coverage area of the base station. Because the communication between NB-IoT-D2D terminals does not generate traffic fees, this method only needs to spend a certain amount of communication costs between NB-IoT-D2D terminals and base stations, thereby saving a lot of traffic overhead caused by D2D communication and improving user service experience.

On the other hand, an initiating terminal is also provided in an embodiment of the present invention, and the initiating terminal is a terminal initiating communication in the NB-IoT D2D communication system. Referring to FIG. 7 , the initiating terminal includes:

The monitoring unit 10 is configured to monitor the anchor carrier of the NB-IoT cell where the initiating terminal is located, to obtain idle time-frequency domain resources required in the D2D communication process;

A determining unit 20, configured to determine a target channel by using the idle time-frequency domain resource;

The sending unit 30 is configured to send the associated information of the D2D communication to the receiving terminal through the target channel, and receive the reply information of the receiving terminal for the D2D communication through the target channel, so that the initiating terminal and The receiving terminal establishes D2D communication through the target channel; the associated information includes a D2D communication request and a data service.

On the basis of the above embodiments, the monitoring unit includes:

The space search subspace is used to find a search space according to the associated information of the system information block, and the search space includes a public search space and a user-specific search space;

a decoding subunit, configured to perform decoding processing on the search space to obtain base station resource allocation information;

A first obtaining subunit, configured to obtain channel occupancy information of the cell from the resource allocation information of the base station;

The second obtaining subunit is configured to obtain idle time-frequency domain resources for the D2D communication process based on the channel occupancy information.

On the basis of the above embodiments, the determining unit includes:

The third acquiring subunit is configured to acquire downlink channel occupancy information of the anchor carrier according to the idle time-frequency domain resources;

The first determining subunit is configured to determine the idle time-frequency domain resource in the downlink channel as the first channel according to the downlink channel occupancy information; the first channel is used by the initiating terminal to combine the D2D communication request with the service sending data to the receiving terminal;

The fourth obtaining subunit is used to obtain the uplink channel occupancy information of the D2D service communication carrier according to the idle time-frequency domain resources;

The second determining subunit is configured to determine the idle time-frequency domain resource of the uplink channel in the D2D service communication carrier as the second channel according to the uplink channel occupancy information, and determine the remaining resources in the uplink channel except the second channel The free time-frequency domain resource is determined as a third channel; the second channel is used for the receiving terminal to reply to the initiating terminal with the first reply information for the D2D communication request, and the third channel is used for the receiving terminal to reply to the initiating terminal The initiating terminal replies with second reply information for the received data service.

On the basis of the above embodiments, the sending terminal also includes

The fifth obtaining subunit is to obtain the downlink channel occupancy information of the D2D service communication carrier according to the idle time-frequency domain resource;

The third determination subunit determines the idle time-frequency domain resource of the downlink channel in the D2D service communication carrier as the fourth channel according to the downlink channel occupancy information, and determines the remaining idle time in the downlink channels except the fourth channel The frequency domain resource is determined as the fifth channel; the fourth channel is used for the initiating terminal to send service data to the receiving terminal; the fifth channel is used for the initiating terminal to send communication frequency band switching instructions to the receiving terminal .

On the basis of the foregoing embodiments, the sending terminal further includes:

The fourth determining subunit is used for if the downlink channel or uplink channel in each non-anchor carrier is idle and the frequency domain resources are occupied, based on the occupancy information of the uplink and downlink channels in the anchor carrier and the D2D request communication process The situation information of the time-frequency domain resources occupied by the network determines the candidate channel located in the anchor carrier, and the candidate channel represents the uplink and downlink idle time-frequency domain resources required in the D2D service communication process.

On the basis of the foregoing embodiments, the sending terminal further includes:

The first judging subunit is configured to: when the D2D communication request is sent to the receiving terminal through the first channel, if the receiving terminal does not receive a first reply message for the D2D communication request within a preset time period , then switch the self-frequency band of the initiating terminal to the anchor carrier frequency band, and resend the D2D communication request;

The first switching subunit is configured to switch to the D2D service frequency band to receive the first reply message from the receiving terminal;

The first instruction generation unit is configured to retransmit the D2D request information if the first reply message of the receiving terminal is not received within the preset number of times of resending requests or the frequency domain resources are not enough when the resending process is idle, A report instruction is generated, and the self-frequency band of the initiating terminal is switched to an anchor carrier frequency band, the report instruction indicates that the D2D communication with the receiving terminal fails.

On the basis of the foregoing embodiments, the sending terminal further includes:

a sending subunit, configured to, in response to receiving the second reply message sent by the receiving terminal, send a communication frequency band switching instruction to the receiving terminal at a time-frequency domain position in the downlink channel of the D2D service communication carrier, and Switch its own carrier frequency band to the anchor carrier.

On the basis of the foregoing embodiments, the sending terminal further includes:

The second instruction generation unit is configured to retransmit the service data if the second reply message from the receiving terminal is not received within the preset number of times of resending the service data or the frequency domain resources are not enough during the retransmission process when idle, A report instruction is generated, and the self-frequency band of the initiating terminal is switched to an anchor carrier frequency band, the report instruction indicates that the D2D communication with the receiving terminal fails.

Each embodiment in this specification is described in a progressive manner, each embodiment focuses on the difference from other embodiments, and the same and similar parts of each embodiment can be referred to each other. As for the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and for the related information, please refer to the description of the method part.

The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (8)

1. A D2D communication method of NB-IoT based on signaling monitoring, characterized in that it is applied to an initiating terminal of a D2D communication system of NB-IoT, and the system also includes a receiving terminal, the method comprising: Obtain idle time-frequency domain resources required in the D2D communication process by monitoring the anchor carrier of the NB-IoT cell where the initiating terminal is located; Using the idle time-frequency domain resources, determine a target channel; Send the associated information of the D2D communication to the receiving terminal through the target channel, and receive the reply information of the receiving terminal for the D2D communication through the target channel, so that the initiating terminal and the receiving terminal pass through the receiving terminal. Establish D2D communication on the target channel; the associated information includes D2D communication request and data service; Wherein, the use of the idle time-frequency domain resource to determine the target channel: Acquiring downlink channel occupancy information of the anchor carrier according to the idle time-frequency domain resources; Determining idle time-frequency domain resources in the downlink channel as a first channel according to the occupancy information of the downlink channel; the first channel is used for the initiating terminal to send a D2D communication request to the receiving terminal; According to the idle time-frequency domain resource, obtain the uplink channel occupancy information of the D2D service communication carrier; According to the uplink channel occupancy information, determine the idle time-frequency domain resource of the uplink channel in the D2D service communication carrier as the second channel, and determine the remaining idle time-frequency domain resource in the uplink channel except the second channel as the second channel. Three channels; the second channel is used for the receiving terminal to reply to the initiating terminal with the first reply information for the D2D communication request, and the third channel is used for the receiving terminal to reply to the initiating terminal for the received The second reply information of the data service; According to the idle time-frequency domain resource, obtain information about the downlink channel occupancy of the D2D service communication carrier; According to the downlink channel occupancy information, determine the idle time-frequency domain resource of the downlink channel in the D2D service communication carrier as the fourth channel, and determine the remaining idle time-frequency domain resources in the downlink channels except the fourth channel It is a fifth channel; wherein, the fourth channel is used for the initiating terminal to send service data to the receiving terminal; the fifth channel is used for the initiating terminal to send a communication frequency band switching instruction to the receiving terminal. 2. The method according to claim 1, wherein the idle time-frequency domain resources required in the D2D communication process are obtained by monitoring the anchor carrier of the NB-IoT cell where the initiating terminal is located, including : Monitor the anchor carrier of the NB-IoT cell where the initiating terminal is located, and obtain the associated information of the system information block; Searching to obtain a search space according to the associated information of the system information block, the search space includes a public search space and a user-specific search space; Decoding the search space to obtain base station resource allocation information; Acquiring channel occupancy information of the cell from the resource allocation information of the base station; Based on the channel occupancy situation information, idle time-frequency domain resources for the D2D communication process are obtained. 3. The method according to claim 1, characterized in that the method further comprises: If the idle time-frequency domain resources of the downlink channel or uplink channel in each non-anchor carrier have been occupied, based on the occupancy information of the uplink and downlink channels in the anchor carrier and the time-frequency domain resources occupied during the D2D request communication process The situation information determines the candidate channel located in the anchor carrier, and the candidate channel represents the uplink and downlink idle time-frequency domain resources required in the D2D service communication process. 4. The method according to claim 1, characterized in that the method further comprises: When the D2D communication request is sent to the receiving terminal through the first channel, if the first reply message of the receiving terminal for the D2D communication request is not received within a preset time period, the sending terminal’s switch its own frequency band to the anchor carrier frequency band, and resend the D2D communication request; switch to the D2D service frequency band to receive the first reply message from the receiving terminal; If the first reply message from the receiving terminal is not received within the preset number of times of resending requests, or the frequency domain resources are not enough to resend the D2D request information during the resending process, generate a report instruction, and send the The initiating terminal switches its own frequency band to the anchor carrier frequency band, and the reporting instruction indicates that the D2D communication with the receiving terminal fails. 5. The method according to claim 1, characterized in that the method further comprises: In response to receiving the second reply message sent by the receiving terminal, at the position in the time-frequency domain of the downlink channel of the D2D service communication carrier, send a communication frequency band switching instruction to the receiving terminal, and switch its own carrier frequency band to the anchor Fixed carrier terminal. 6. The method according to claim 1, characterized in that the method further comprises: If the second reply message from the receiving terminal is not received within the preset times of resending the service data or the frequency domain resources are not enough to retransmit the service data when idle during the resending process, generate a report instruction, and send the The initiating terminal switches its own frequency band to the anchor carrier frequency band, and the reporting instruction indicates that the D2D communication with the receiving terminal fails. 7. An initiating terminal, characterized in that, comprising: The monitoring unit is configured to obtain the idle time-frequency domain resources required in the D2D communication process by monitoring the anchor carrier of the NB-IoT cell where the initiating terminal is located; a determining unit, configured to determine a target channel by using the idle time-frequency domain resource; a sending unit, configured to send the associated information of the D2D communication to the receiving terminal through the target channel, and receive the reply information of the receiving terminal for the D2D communication through the target channel, so that the initiating terminal communicates with the receiving terminal The terminal establishes D2D communication through the target channel; the associated information includes D2D communication request and data service; Wherein, the determining unit is specifically used for: Acquiring downlink channel occupancy information of the anchor carrier according to the idle time-frequency domain resources; Determining idle time-frequency domain resources in the downlink channel as a first channel according to the occupancy information of the downlink channel; the first channel is used for the initiating terminal to send a D2D communication request to the receiving terminal; According to the idle time-frequency domain resource, obtain the uplink channel occupancy information of the D2D service communication carrier; According to the uplink channel occupancy information, determine the idle time-frequency domain resource of the uplink channel in the D2D service communication carrier as the second channel, and determine the remaining idle time-frequency domain resource in the uplink channel except the second channel as the second channel. Three channels; the second channel is used for the receiving terminal to reply to the initiating terminal with the first reply information for the D2D communication request, and the third channel is used for the receiving terminal to reply to the initiating terminal for the received The second reply information of the data service; According to the idle time-frequency domain resource, obtain information about the downlink channel occupancy of the D2D service communication carrier; According to the downlink channel occupancy information, determine the idle time-frequency domain resource of the downlink channel in the D2D service communication carrier as the fourth channel, and determine the remaining idle time-frequency domain resources in the downlink channels except the fourth channel It is a fifth channel; wherein, the fourth channel is used for the initiating terminal to send service data to the receiving terminal; the fifth channel is used for the initiating terminal to send a communication frequency band switching instruction to the receiving terminal. 8. A NB-IoT D2D communication system based on signaling monitoring, characterized in that it includes an initiating terminal and a receiving terminal, wherein, The initiating terminal is configured to execute the D2D communication method of NB-IoT based on signaling monitoring according to any one of claims 1-6; The receiving terminal is configured to receive the associated information of the D2D communication sent by the initiating terminal, generate a reply message according to the associated information, and send the reply message to the initiating terminal.

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