CN112995961A

CN112995961A - Terminal access method of terminal direct communication based on broadband technology

Info

Publication number: CN112995961A
Application number: CN202110252851.5A
Authority: CN
Inventors: 张永生; 郭梯云; 李建东; 王重阳
Original assignee: Beijing Guozhi Zhonghe Technology Co ltd
Current assignee: Anhui Rongzhao Intelligent Co ltd
Priority date: 2021-03-09
Filing date: 2021-03-09
Publication date: 2021-06-18
Anticipated expiration: 2041-03-09
Also published as: CN112995961B

Abstract

The invention provides a terminal access method of terminal direct communication based on broadband technology, which comprises the following steps: s20: the AC (access control layer) informs the MAC (medium access control layer) to search the cell; s21: the MAC sends the cell search result to the AC; s22: the AC confirms that the cell can be accessed; s23: the AC informs the MAC to initiate competition access and sends MSG3 carrying the ID number; s24: the MAC sends MSG4 carried in the transmission message to the AC; s25: the AC judges that an access request of the UE of the cell is received, selects whether to approve the access of the UE according to the link condition and sends the MSG4 carrying the unique identification number of the accessed UE to the MAC; s26: the MAC finishes the UE access, transmits a message MSG5 to the AC and informs the lower-level UE of successful access; s27: and the AC judges whether the access is successful, and if the access is successful, the MSG5 is sent to reply ACK to confirm that the cell access is successful.

Description

Terminal access method of terminal direct communication based on broadband technology

Technical Field

The invention relates to a terminal direct mode, in particular to a terminal access method of terminal direct communication D2D based on broadband technology.

Background

The description of the background of the invention pertaining to the related art to which this invention pertains is given for the purpose of illustration and understanding only of the summary of the invention and is not to be construed as an admission that the applicant is explicitly or implicitly admitted to be prior art to the date of filing this application as first filed with this invention.

In some application scenarios based on the LTE technology, for example, data acquisition of a smart grid of a power system, downlink transmission of acquisition instructions, and uplink transmission of acquired various types of data, some smart meters may be arranged in places with large path loss and weak coverage, and the signal-to-noise ratio of uplink reception is very low. In the existing general LTE network, in the border area of a cell or some special places, the transmission power of the existing cell is difficult to cover all users, and a user cannot access the existing place.

Terminal direct mode (D2D) refers to direct communication between two or more mobile stations without forwarding through a base station or network. Namely, the UE in the signal coverage is selected as the relay UE, and data transmission is performed between the relay UE and the UE outside the signal coverage, so that the UE outside the signal coverage accesses the network through the relay UE, and therefore, in an area where the network coverage cannot be reached, the D2D mode can support effective communication between mobile stations. To realize direct communication of terminals, a plurality of key technologies need to be broken through. For example, an inter-terminal synchronization technique, an inter-terminal discovery technique, an inter-terminal data transmission technique, an inter-terminal time domain and frequency domain resource coordination technique, and the like.

At present, the communication protocols of terminal direct connection include zigbee, lora, wifi and the like. Although Zigbee and lora have the characteristics of wide coverage and flexible networking, they are narrowband communication and have a low transmission rate. Wifi provides broadband communication, but is limited by the close range of communication.

4/5G broadband network is a network with base stations as the center, and terminals communicate with each other through the relay of the base stations (and core network). If the terminal cannot contact the base station, the terminal cannot communicate. Therefore, how to avoid the above-mentioned drawbacks and perform channel allocation reasonably so that UEs out of signal coverage can access the network through the relay UE becomes a problem to be solved urgently.

The invention combines the basic channel waveforms of PSS/SSS, PRACH, SC-OFDM and the like in 4G/5G communication, provides a novel broadband terminal direct connection protocol, and the terminal automatically establishes a chain network to carry out broadband direct connection communication and submits as a series of applications, comprising the following steps: the method comprises a channel configuration method, an inter-terminal synchronization method, a terminal access method, an inter-terminal data transmission method and an inter-terminal time domain and frequency domain resource coordination method. The method is expected to provide a long-distance high-reliability broadband terminal direct communication protocol.

The invention relates to a terminal access method of terminal direct communication D2D based on broadband technology, aiming at enabling UE outside signal coverage to access a network through relay UE based on the newly proposed terminal direct communication protocol technology, thereby being widely applied to terminal relay scenes and effectively expanding the coverage range of network access and remote data backhaul in a low-cost manner.

Disclosure of Invention

The invention provides a novel terminal direct communication D2D terminal access method based on broadband technology based on a novel terminal direct communication protocol proposed by the applicant.

Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

In one aspect of the present invention, a terminal access method for terminal direct communication based on broadband technology is provided, including:

s20: the AC informs the MAC to search the cell;

s21: the MAC sends the cell search result to the AC;

s22: the AC confirms that the cell can be accessed;

s23: the AC informs the MAC to initiate competition access and sends MSG3 carrying the ID number;

s24: the MAC sends MSG4 carried in the transmission message to the AC;

s25: the AC judges that an access request of the UE of the cell is received, selects whether to approve the access of the UE according to the link condition and sends the MSG4 carrying the unique identification number of the accessed UE to the MAC;

s26: the MAC finishes the UE access, transmits a message MSG5 to the AC and informs the lower-level UE of successful access;

s27: and the AC judges whether the access is successful, and if the access is successful, the MSG5 is sent to reply ACK to confirm that the cell access is successful.

According to another aspect of the present invention, there is provided a terminal access system for broadband technology-based terminal direct communication, the system comprising a memory and a processor, wherein the memory stores a computer program, and the computer program, when executed by the processor, causes the processor to execute any one of the above-mentioned terminal access methods for broadband technology-based terminal direct communication.

According to yet another aspect of the present invention, there is provided a storage medium having stored thereon computer program instructions executable by a processor to implement a terminal access method for terminal-through communication based on broadband technology as described above.

Under the condition of keeping the advantages of the cellular network, the D2D multi-hop self-organizing network is used for expanding the coverage range of network access with low cost, thereby supporting high-bandwidth flexible configuration of 1.4M-100M, high speed and video service, and simultaneously having longer communication distance, more flexible frequency band and higher safety compared with a WIFI communication mode.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

fig. 1 shows a first application scenario of the terminal access method of the terminal direct communication D2D based on the broadband technology according to the present invention;

fig. 2 shows a second application scenario of the terminal access method of the terminal-through communication D2D based on the broadband technology according to the present invention;

fig. 3 shows a chained networking manner between UEs adopted by the terminal access method of the broadband technology-based terminal direct communication D2D of the present invention;

fig. 4 is a system frame structure diagram of D2D adopted in the terminal access method of the broadband technology-based terminal direct communication D2D of the present invention;

FIG. 5 shows the sub-frame allocation map of a 40ms system superframe of D2D as employed by the present invention;

FIG. 6 is a diagram illustrating a 40ms superframe 5 user subframe allocation schedule of the synchronization channel of D2D according to the present invention;

fig. 7 shows a parameter configuration diagram of the PSS;

fig. 8 shows a parameter configuration diagram of SSS;

figure 9 shows a time-frequency location diagram of the PUCCH & USS channel;

fig. 10 shows a RE mapping diagram of PUCCH;

fig. 11 shows DMRS parameter configuration;

figure 12 shows a PRACH parameter configuration table;

fig. 13 shows determined reference symbol positions in a PUSCH channel;

fig. 14(a) shows a specific format of a header of a RAR packet, and fig. 14(B) and 14(C) show a specific format of a header of a non-RAR packet.

Fig. 15 shows a diagram of MAC scheduling information;

fig. 16 is a flow chart illustrating a terminal synchronization method of the broadband technology-based terminal-through communication according to the present technology;

fig. 17 is a schematic time-frequency location diagram of a synchronization channel in the terminal synchronization method for terminal direct communication based on broadband technology according to the present technology;

fig. 18 is a schematic diagram illustrating a terminal access method of the terminal direct communication D2D based on broadband technology according to the present application;

fig. 19(a) and 19(B) show parameters of messages MSG2 and MSG4, respectively.

Fig. 20 is a schematic structural diagram of an electronic device entity provided in an embodiment of the present invention.

Detailed Description

In order that the above objects, features and advantages of the present invention can be more clearly understood, a more particular description of the invention will be rendered by reference to the appended drawings. It should be noted that the embodiments and features of the embodiments of the present application may be combined with each other without conflict.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced in other ways than those specifically described herein, and therefore the scope of the present invention is not limited by the specific embodiments disclosed below.

The following discussion provides multiple embodiments of the invention. While each embodiment represents a single combination of the inventions, the various embodiments of the inventions can be combined in alternate, or combined, and thus the inventions can be considered to include all possible combinations of the same and/or different embodiments described. Thus, if one embodiment comprises A, B, C and another embodiment comprises a combination of B and D, then the invention should also be construed as comprising an embodiment that comprises A, B, C, D in all other possible combinations, although this embodiment may not be explicitly recited in the following text.

Fig. 1 shows a first application scenario of the terminal access method of the terminal direct communication D2D based on the broadband technology. As shown in fig. 1, a D2D multi-hop ad hoc network mode is added on the basis of a standard cellular network, and coverage extension is realized by using terminal relay. A terminal which is not in the coverage range of the base station network can communicate with other terminals through D2D, and is finally connected with a base station or a control console through multi-hop relay of a plurality of terminals, so that network access is realized. This effectively extends the coverage of network access in a cost-effective manner. The coverage area of the base station is used for communication between the terminal and the base station, and the coverage area of the base station is not used for direct communication between the terminal and the base station.

The communication terminals are denoted as T1, T2, T3, … … in the drawing. Within the coverage of the base station eNB1, e.g., terminal T1/T2, transmits data back directly over the wireless network. Within the coverage of base station eNB2, terminal T5 transmits data back directly over the wireless network. Outside the coverage of the base station, for example, T3 and T4 terminals pass through a D2D multi-hop network, and after multi-stage relaying, for example, data can be transmitted to other terminals, such as T1 through T2 relaying, and finally backhaul is implemented through the base station network.

Fig. 2 shows a second application scenario of the terminal access method of the terminal-through communication D2D based on the broadband technology. As shown in fig. 2, in the second application scenario of the present application, wireless access all employs a D2D multi-hop ad hoc network. The entire communication terminal is denoted as T1, T2, T3, … … in the drawing. T1 is connected to the router through wired Ethernet to realize external network connection. And a multi-hop self-organizing network is formed among the T1-T5 terminal nodes. The data of the T5 is relayed by terminal nodes such as T4, T3, T2, T1 and the like in sequence, and finally reaches a router, so that the connection of an external network is realized.

Thus, the wireless network is entirely composed of terminals with D2D functionality, and no base station is required. And realizing a high-availability network by terminal self-organization. Terminals within a certain distance can mutually discover to form an ad hoc network. When a certain terminal node fails, other nodes can be automatically adjusted to realize network self-healing to a certain degree. This results in a considerable increase in the availability and reliability of the network and, on the other hand, simplifies the maintenance work of the network.

In the prior art, resource scheduling of an LTE system is a fast time-frequency resource allocation, an eNodeB allocates radio resources every 1ms, and a time-frequency resource diagram of the LTE system is shown in the figure. This way it is possible for D2D to use unallocated time-frequency resources or to partially multiplex already allocated resources.

In the LTE system, as shown in fig. 4, the basic unit of the time domain radio resource is TTI (transmission time interval), and each TTI value is 1 ms. Each TTI, in turn, consists of 2 slots of 0.5ms, i.e., 14 OFDM symbols in a typical configuration. The 10 TTIs constitute one LTE radio frame.

In the frequency domain, the whole bandwidth is divided into 20khz sub-channels, which correspond to 12 consecutive 15khz sub-carriers. The size of the sub-channel is fixed, and the number of sub-channels corresponding to different bandwidths is different.

In the time-frequency domain, the time domain corresponds to 0.5ms, and the unit corresponding to 1 subchannel in the frequency domain is called rb (resourceblock).

D2D communication typically has 4 modes: an uplink multiplexing mode, a downlink multiplexing mode, a dedicated resource mode, and a relay mode.

The multiplexing mode D2D user multiplexes the cellular user resource to generate co-channel interference, the base station adopts reasonable resource allocation and power control, multi-antenna technology and advanced coding technology to control the interference between links.

Dedicated resource mode D2D users occupy a portion of the independent resources for end-to-end direct communication and the remaining resources are used for cellular communication. Because the resources of the parts are mutually orthogonal, no interference is generated between the D2D communication and the cellular communication.

Relay mode (conceptually the same as conventional cellular mode) D2D users relay communications through the base station, and all communication links allocate independent orthogonal channel resources without interfering with each other.

The selection of the mode depends on a variety of factors and also determines the different data synchronization and transmission modes.

The D2D mode selection strategy depends not only on the link quality between D2D devices and between D2D devices and the base station, but also on the specific interference environment and location information. For example, the mode selection based on path loss is simple and easy but has poor performance, and only considers the channel condition between D2D devices. For another example, when the D2D device is far away from the base station, the effect of using the uplink frequency band is better than that of the downlink frequency band; when the D2D device is closer to the base station, it is better to use the downlink frequency band than the uplink frequency band. However, good mode selection algorithms need to take into account a number of factors and have higher requirements for channel measurements.

The application selects a downlink frequency band.

Fig. 5 shows a system frame structure diagram of D2D adopted by the terminal UE downlink synchronization method of the broadband technology-based terminal direct communication D2D of the present invention. Fig. 5 is a schematic diagram of a system frame structure of D2D adopted in the terminal UE downlink synchronization method of the broadband technology-based terminal direct communication D2D according to the present invention. The system frame structure of D2D of the present invention is composed of a system superframe, a system half frame, a system subframe (synchronization subframe/scheduling measurement subframe), and a data subframe. As described in turn below.

1) System superframe

The system superframe length is N, the system superframe is composed of two system half-frames with the same length, and the length of each system half-frame is N/2. Wherein the system superframe length N can be configured to be 4, 8, 16, i.e. corresponding to 40ms/80ms/160 ms.

2) System half-frame

A system superframe is composed of two system fields.

The system half frame is composed of a system subframe (synchronous subframe/scheduling measurement subframe) and a data subframe, and the length of the system half frame is N/2. When the system superframe N is configured to be 4, 8, 16(40ms/80ms/160ms), the system field length corresponds to 2, 4, 8(20ms/40ms/80 ms).

In order to solve the problem of data frame resource preemption, a first system half frame (also called a system first half frame) starts to schedule and preempt data subframe resources in a scheduling subframe from a first node of a user, and a second system half frame (also called a system second half frame) starts to schedule and preempt the data subframe resources in the scheduling subframe from a last node of the user.

Fig. 6 shows the subframe allocation map of a 40ms system superframe of D2D employed by the present invention. Assume that users corresponding to the communication terminals T1-T5 of fig. 1-2 are UEs 1-5. As shown in fig. 6, a 40ms system superframe is a scheduling diagram for allocating subframes to 5 users UE 1-UE 5. The system has 5 users, the system frame is set as 40ms, wherein, the first half frame of users arranges the scheduling subframes from UE1 to UE5 in sequence, so that the data subframes are preempted from the sequence of users UE1 to UE5, and the second half frame of the system is opposite, and the scheduling subframes and the data subframe resources are preempted from the sequence of users UE5 to UE 1.

3) System subframe

The system subframe includes: a synchronization subframe, a scheduling measurement subframe, and a data subframe.

3.1) synchronization subframes

The synchronization subframe contains 2 symbols, which are PSS and SSS, respectively. Transmission is performed at regular intervals starting at one subframe 0 of the system superframe. When the system superframe length is 40ms, 80ms and 160ms respectively, the fixed period corresponding to the synchronous subframe is 20ms, 40ms and 80 ms. And transmitting a PSS sequence of one symbol and an SSS sequence of one symbol after 624Ts at the boundary of the synchronous subframe.

And the tail node transmits the synchronization subframe for synchronizing other surrounding nodes only when the system is networked.

3.2) scheduling measurement subframes

The scheduling measurement subframe uses 1 subframe as a unit, and finds the corresponding position of the user system measurement subframe in the system superframe according to the current node number obtained after user synchronization, and the scheduling measurement subframe in the first system field carries out time domain resource allocation in the system field in sequence from the head node (as shown in fig. 6, UE1- > UE 5). For example, subframe 2 of user UE2 is a scheduled measurement subframe sent to user UE1, subframe 3 is a scheduled measurement subframe sent to user UE3, and so on. The scheduled measurement sub-frames in the second system half-frame are allocated resources sequentially from the end node (e.g., UE5- > UE 1).

Before a user establishes a connection after synchronization, the first system half frame is used for access and system information transmission, and after the access, the whole system rearranges the position of the user scheduling measurement subframe corresponding to the second half system half frame, for example, once the user UE6 wants to access the system, subframe 1 of the second half system half frame becomes the scheduling measurement subframe sent by the user 6 to the user 1.

The scheduling measurement subframe configures the USS channel and the PUCCH channel or the RACH channel.

The USS channel: for the UE to perform channel time domain resource idle measurement, such as the subframe indicated in fig. 6. If the USS signals in the measurement scheduling subframes transmitted by user UE1 and user UE2 are not measured by user UE4, user UE4 may consider subframe 123 of frame 0 as available for reception, informing user UE5 that user UE5 may borrow these subframes to transmit data information to user UE 4. The same applies to subframes in the dark gray frame, taking the latter half system half frame user UE1 as an example, the user UE1 does not detect the USS signal in the measurement scheduling subframe from the user UE5, although the data subframes are already occupied by the data transmitted by the user UE5, the user UE1 may notify the user UE2 that there is no collision on the subframes, and the user UE2 determines according to the own data subframe occupancy, and may transmit data to the user UE1 on the subframes.

A PUCCH channel:

for the transmission of system information at access (MSG2/MSG3/MSG4/MSG5 …);

for indicating time-frequency scheduling information and corresponding MCS of data subframes, length of target UE data, etc. during connection, for example, in fig. 3, UE1 applies for data subframes 0-3 from UE2 for data transmission;

time-frequency domain scheduling information (the next system superframe takes effect) that indicates other users to schedule the measurement subframe as a data subframe when connected. For example, user 5 utilizes the scheduled measurement subframe time domain resources of

users

1 and 2 for transmitting data to user 4. But this is limited to the case where user 4 does not detect the USS signals of user 1 and user 2 at the corresponding time domain locations during the channel idle measurement.

For feeding back ACK information in HARQ;

the relevant measurements for UE measurements include time frequency offset, link quality.

RACH channel:

the method is used for the lower node to initiate a random access signal to the upper node for uplink synchronization. And the time domain resource of the RACH is transmitted in the first symbol of the scheduling measurement subframe corresponding to the user.

3.3) data subframes

The data sub-frame is used for transmitting data among users, and the scheduling coding information of the data sub-frame is indicated by the scheduling measurement sub-frame. If the data subframe occupies time domain resources except the scheduling measurement subframe, the information in the scheduling subframe takes effect in the current half frame; and if the data subframe occupies the time domain resource of the scheduling subframe of other users, the information in the scheduling subframe takes effect in the next system superframe. The last sub-frame of the continuously transmitted data sub-frame should be reserved with GAP of N symbols on the scheduling, and the number of N is determined by the measurement result of USS between users.

The channel adopted by the transmission protocol of the terminal direct communication based on the broadband technology comprises the following steps: 1) synchronization channel, PSS channel and SSS channel; 2) control channels, PUCCH channels and USS channels; 3) a random access channel, PRACH channel; 4) data channel: a PUSCH channel.

1) Synchronization channel, PSS channel and SSS channel

The synchronization channel consists of a PSS channel and a SSS channel, occupying the middle 6 RBs of the entire transmission bandwidth. When the superframe length of the system is 40ms, the fixed period corresponding to the synchronization subframe is 20ms, and the period of the synchronization channel is 20 ms. One SSS symbol sequence and one SSS sequence are transmitted at the subframe boundary back 624 Ts. As shown in fig. 6, the time-frequency location of the synchronization channel is shown. The PSS channel consists of a PSS sequence of one symbol. The PSS sequence occupies the first 0FDM signal of the synchronization subframe. The PSS sequence was generated using the PSS sequence in 4 GLTE. See standard [ 3GPPTS36.2116.11.1 ] for details, generated using Rootindexu ═ 38.

The SSS channel is composed of SSS sequences of one symbol, and the SSS sequences occupy the second 0FDM symbol, occupying the middle 6 RBs of the entire transmission bandwidth. The SSS sequence is generated by adopting the SSS sequence in the 4 GLTE. Please refer to standard [ 3GPPTS36.2116.11.2 ], which is the prior art and will not be described in detail.

The SSS sequence 0bit represents the front and back system field, the first system field SSS sequence minimum bit is 0, the second system field SSS sequence minimum is 1, 1-6bit represents the node number when accessing.

And the tail node transmits the synchronization information used for synchronizing other surrounding nodes and acquiring the order of the chain in the system to calculate the corresponding user information subframe resource only when the system is networked.

The parameter configuration of the PSS is shown as fig. 7.

Fig. 8 shows parameter configuration of the SSS.

2) Control channel, PUCCH & USS channel

Fig. 9 is a time-frequency position of the PUCCH & USS channel. The PUCCH and USS channels are transmitted in the first two symbols in the scheduling measurement subframe, and the PUCCH occupies the middle 6 RBs occupied by the USS in the whole system of the first two symbols.

Fig. 10 is RE mapping of PUCCH. The PUCCH channel is composed of data and reference symbols, where the reference signals occupy fixed positions in one RB, i.e., positions of

REs

1, 5, 9, i.e., 1/4 intervals, as shown in the dark squares of fig. 10. Data occupies the remaining REs in 1 RB.

The DMRS sequences are generated using the uplink DMRS sequences in 4 GLTE. See [ 3GPPTS36.2115.5.2.1 ], for prior art and will not be described in detail. Wherein n is_csFor MOD (N,12)And N is a node index corresponding to the current user from the root node. Fig. 11 shows DMRS parameter configuration.

For PUCCH coding using POLAR coding scheme of 5GNR, see [ 3GPPTS38.2125.3.1 ], which is not described in detail for the prior art. After CRC is cancelled, 16 bits of mask to RNTI is adjusted by QPSK. Wherein Cellid used for generating scrambling codes is the node index of the user, and CRNTI is distributed by the upper node.

The sequence generation of the USS is the same as the PSS sequence generation formula generated by the PSS channel, and is generated using Root indexu 25.

3) Random access channel, PRACH channel

Fig. 12 shows a PRACH parameter configuration table. The PRACH channel is sent on a scheduling measurement subframe of a first half system frame sent to a superior node by a user, and is used for accessing the same superior node after downlink synchronization of the user. The PRACH starts transmission from the first symbol of the scheduled measurement subframe, occupying the middle 6 RBs of the system bandwidth. The RACH sequence formula [ 3GPPTS36.2116.11.2 ] of LTE is applied, which is not described in detail for the prior art.

4) Data channel: PUSCH channel

Fig. 13 shows the determined reference symbol position in the PUSCH channel, which is determined according to the length of the transmission symbol and DMRS-add-pos (DMRS-additive position) configured in the scheduling information, as shown in fig. 13. The PUSCH channel is transmitted on a data subframe, consisting of data and reference symbols. And scheduling the time-frequency domain position and MCS of the PUSCH in the data subframe by the MAC information in the scheduling measurement subframe. The PUSCH channel may start to be transmitted at any position of 14 symbols of one subframe, with a transmitted symbol length of 1-14. The position of the reference symbol of the PUSCH is determined according to the length of the transmission symbol and the DMRS-add-pos configured in the scheduling information, as shown in FIG. 13, wherein l0 is the DMRS symbol of the first symbol of the PUSCH, and the reference symbol occupies the whole PUSCH scheduled RB. The DMRS sequence generation formula is referred to as [ 3GPPTS36.2116.11.2 ], which is the prior art and is not described in detail.

And the channel coding of the PUSCH data adopts the LDPC coding standard of 5G. See [ 3GPPTS38.2125.3.2 ] for prior art, and will not be described in detail. Wherein Cellid used for generating scrambling codes is the node index of the user, and CRNTI is distributed by the upper node.

The protocol high layer of the invention consists of an Access Control (AC), a data delivery layer (IPrealy) and an L2 layer. The following are described separately:

1) access control model layer (AC)

The access control mode layer (AC) is used to process system related information, as well as the establishment of RBs.

The access control mode (AC) layer is divided into two parts, transmission and reception. And sending a function mainly processing the cell established by the UE, and receiving a function mainly processing the cell to be accessed.

1.1) function of the transmitting part

Establishing a cell, namely reading NV content, acquiring basic information (superframe length, system frequency point, system bandwidth and the like) of the cell, and determining a cell ID number to be established according to whether the current UE has access to a certain cell and the accessed cell ID.

And establishing new RBs, namely three RBs are required to be established, one for communication between the UE and the UE at the upper stage, one for communication between the UE and the UE at the lower stage, and one for receiving downlink data sent to the UE.

1.2) function of the receiving part

Terminal access

Processing received system information

2) IPrealay layer

The IPrealay layer is responsible for delivering data between an upper layer and a lower layer; the setting mode is as follows:

2.1) configuring the native IP Address

According to the node position of the UE in the chain, the fixed front IP address is 192.168.13, and the last 8 bits is the current node position. For example, if the UE is the 5 th UE in the chain, the IP address is 192.168.13.5;

the last digit of the destination address IP of the data to be transmitted is regarded as the IP of the machine which transmits the data to the chain in the uplink direction, and so on,

2.2) establishment of bearers

The sending end at least establishes a bearer without a bearer ID and only has a direction;

the receiving end establishes a bearer and processes the IP data sent to the local machine;

the last byte value of the destination IP is passed to L2.

3) Layer L2

The L2 layer is responsible for handling non-signaling data. The L2 layer is divided into a PDCP layer, an RLC layer, and a MAC layer. An uplink buffer function is added, newly added cells of D2D can be processed, and a part of random access functions are added, wherein L1C is merged into L2 to be responsible for processing flows related to physical layer resource scheduling and time sequence, and a part of random access functions are added.

3.1) transmitting part

And (4) respectively grouping the uplink RB and the downlink RB, having no logical channel, and replacing the last byte value of the IP address in the MAC subheader.

There are three types of data: A) service data from IPRELAY (data delivery layer), B) signaling data from AC, C) data generated by L2 itself (system information, MACCE, etc.).

3.2) receiving part

If the data is the data for the UE, the data is unpacked and then delivered to an upper layer;

if the data is forwarded, after the uplink and the downlink are judged, the data is put into a corresponding bearing cache, and the sending part carries out subsequent processing;

and if the system information is the system information, performing subsequent scheduling according to the content.

In the protocol, the MAC mainly includes RAR packets and non-RAR packets according to the packet format. Fig. 14(a) shows a specific format of a header of a RAR packet, and fig. 14(B) and 14(C) show a specific format of a header of a non-RAR packet.

As shown in fig. 14(a), the RAR packet is transmitted and received with a fixed timing, and the RAPID in the header is preambeindex in msg1, and is a generated random number.

As shown in fig. 14(B), the non-RAR packet is distinguished by the LCID. In the non-RAR message header, E: 1, followed by at least one prefix; e: 0, which is the last header.

Fig. 14(C) shows a specific definition of the non-RAR packet LCID.

On the basis of the RAR packet and the non-RAR packet shown in fig. 14(a) (B) (C), the predetermined rule of the MAC layer packet is as follows:

(1) the head is front and the data is back, the head may comprise more than one header;

(2) system information is before (if any), data is after;

(3) if the length of the packed packet does not reach the maximum length allowed by the MAC PDU, adding a Padding sub-header at the end of the MAC header;

(4) the last subhead has no length;

(5) if the length of the packed packet +2 is the maximum length allowed by the MAC PDU, the MAC PDU starts two bytes filled with 0xff and then is the subheader;

(6) if the length of the packet +1 is the maximum length allowed by the MAC PDU, the MAC PDU starts a byte filled with 0xff and then is the subheader;

(7) if the length of the packed packet is the maximum length allowed by the mac pdu, the mac pdu does not contain 0xff, and is directly the subheader.

The preset rule of the MAC layer unpacking is as follows:

when the data packet to be sent is very large and is larger than the sending length provided by the MAC, the IP packet needs to be split, which needs to add one byte of information to complete the function, and this byte is called an unpacking information byte. The MAC packs the packet by placing the unpack information byte in front of the data, i.e., as part of the data. The unpacking information byte consists of two parts: the rightmost 6bits represent the node number, the purpose is to tell the destination node to whom the ip packet is destined, and the leftmost two bits represent the position where the fragment sits in the ip packet:

00: no subpackage is carried out;

01: the beginning of an IP packet;

10: a middle packet of the IP packet;

11: the last part of the IP packet.

There may be three cases depending on the size of the IP packet: A) this IP packet is not split; B) this IP packet is split into two parts: a beginning and a last portion; C) this IP packet is split into three parts: beginning, middle and last portions.

The generation of the MAC scheduling information, namely the MAC is responsible for the generation of the scheduling information in the system measurement subframe, and the functions comprise:

(1) and the system is responsible for generating data subframe time-frequency information of the user to the upper node and the lower node according to the occupation condition of the current data subframe and the result of channel idle measurement.

(2) And the data subframe occupation condition of the whole superframe is updated.

(3) And the MCS is responsible for generating the data sub-frame according to the reported channel quality of the L1 layer.

(4) Responsible for the lower node TA value measured according to layer L1.

Specifically, fig. 15 shows a diagram of MAC scheduling information.

Based on the above definitions, the terminal synchronization method of terminal direct communication according to the present application searches for the PSS synchronization channel, then searches for the SSS synchronization channel, and finally performs RSRP calculation according to the DMRS to confirm the final synchronization through the downlink synchronization flow UE.

Fig. 16 is a flow chart illustrating a terminal synchronization method for terminal direct communication based on broadband technology according to the present invention.

As shown in fig. 16, the method for downlink synchronization of the terminal UE in the terminal direct communication according to the present application includes the following steps:

s10: the UE searches for the PSS synchronization channel, including in particular,

s101: the UE carries out PSS search in a period corresponding to the system superframe configuration length;

as described above, the system superframe is composed of N subframes (e.g., subframes having a length of 1 ms), and the length of the system superframe is denoted as N. A system superframe is divided into two system fields. The length of each system field is N/2. Where N may be configured to be 4, 8, 16, i.e., the system superframe corresponding period is 40ms/80ms/160 ms.

In this step, the UE performs PSS search at a period corresponding to the system superframe configuration length, i.e., 40ms/80ms/160 ms.

In the invention technology related to the protocol, except that synchronous information is triggered and sent according to a command, the UE initially searches for a synchronous state for the PSS.

S102: the PSS synchronization channel is transmitted with said period starting at subframe 0 of the first frame of the system half frame, followed by a fixed period T2 (e.g., 624Ts) at the subframe boundary, one symbol PSS sequence and one symbol SSS sequence.

As shown in fig. 6, a 40ms system superframe, 5 user subframe allocation map. In order to solve the problem of data frame resource preemption, a first system field starts to schedule and preempt data subframe resources from a first node of a user in a scheduling frame, and a second system field starts to schedule and preempt the data subframe resources from a last node of the user in the scheduling frame. As shown in fig. 3, the system consists of 5 users, the system frame is set to 40ms, wherein the first half frame of users arranges the scheduling subframes from 1 to 5 in sequence, so that the data subframes are preempted from the sequence of users 1 to 5, and the second half frame of systems occupies the scheduling subframes and preempts the data subframe resources from the sequence of users 5 to 1.

Furthermore, the tail node transmits the PSS subframe only when the system is networked. In this manner, to synchronize with other surrounding nodes.

S11: it is determined whether the peak value of the PSS exceeds the threshold, and if so, step S12 is performed.

S12: the UE searches for the SSS synchronization channel.

S13: and judging whether the peak value of the SSS exceeds a threshold, if so, executing the step S14.

S14: and the UE acquires an SSS sequence corresponding to the SSS exceeding a judgment threshold, sets the current user node of the first system field to be 0bit and the current user node of the SSS sequence of the second system field to be 1bit, and determines a system information subframe in a scheduling measurement subframe occupied by the UE.

As described above, before the user establishes a connection after synchronization, the first system half frame (i.e. the first system half frame) is used for access and system information transmission, and after the access, the whole system rearranges the position of the user scheduled measurement subframe corresponding to the second half frame, for example, once the user UE6 wants to access the system, subframe 1 of the second half frame becomes the scheduled measurement subframe sent by the user 6 to the user 1.

In S14, when the SSS exceeds the judgment threshold, the current user node number of the first system half frame of the corresponding SSS sequence is 0bit, and the current user node number of the SSS sequence of the second system half frame is 1 bit;

the corresponding SSS sequence 0bit represents the front and back system field, the first system field SSS sequence minimum bit is 0, the second system field SSS sequence minimum 1, wherein, 1-6 represents the current user node number.

See fig. 17 for a schematic time-frequency location diagram of the synchronization channel. As shown in fig. 17, the SSS is at the latter symbol position of the PSS.

S15: according to PSS and SSS synchronous channels, calculating TCA and FCA of frequency domain, adjusting time sequence and AFC to correct time frequency offset;

s16: calculating RSRP according to the PSS and SSS synchronous signals which are periodically grabbed, determining whether to access the UE according to the strength of PRSP, and if so, executing a step S15;

s17: and synchronously adjusting DL _ Timing according to the PSS and the SSS to perform downlink synchronization, and calculating the starting position of the superframe of the system and the current subframe position.

After the RSRP is judged to decide to access the UE, DL _ Timing is synchronously adjusted according to the PSS and the SSS to carry out downlink synchronization, and the starting position of a superframe and the position of a subframe where the superframe is located at present are calculated.

Therefore, the terminal synchronization method of the terminal direct communication searches the PSS synchronization channel and the SSS synchronization channel through the downlink synchronization process UE, and finally calculates the RSRP according to the DMRS to confirm the final synchronization position and complete synchronization. In this way, the UE completes synchronization with other user nodes around.

The broadband technology-based terminal direct communication technology of the present invention can perform the step of UE access after the UE synchronization, and the technology adopts a random access process, and the following description is continued.

Fig. 18 is a schematic diagram illustrating a terminal access method of the terminal direct communication D2D based on the broadband technology according to the present application.

As mentioned above, the protocol higher layer of the present invention is composed of an Access Control (AC), a data delivery layer (IPrealy), and an L2 layer. The terminal access method of the terminal direct communication D2D based on the broadband technology is completed by the protocol high layer.

MSG1

After synchronization, the MSG1 is sent on the scheduling measurement subframe of the user calculated by the node index before the point in the first half frame, the information of the MSG1 such as preambleFormat, NCS, U and High-speed-flag are all defined by initialization, and the sent frequency domain position is 6 RBs in the middle.

S20: the AC (access control layer) informs the MAC (medium access control layer) to search the cell;

s21: the MAC sends the cell search result to the AC;

MAC sends terminal access request, the request message carries detected lead code, concretely, MAC calculates frame structure according to information (upper and lower half frame indication, existing node number) in SSS, and sends information in SSS to AC;

optionally, in step S211, when the MAC sends the cell search result to the AC, if multiple cells are searched, the MAC selects one cell according to a predetermined rule to report, so as to avoid performing cell search again when camping (camp on).

S22: the AC confirms that the cell can be accessed;

specifically, the AC selects which terminal's RACH request message to receive and informs the MAC to reply to MSG 2.

And (3) contention access, namely after the access node sends the PRACH, the access node judges that the PRACH is the same as the Preamble-idx of the access node after receiving the MSG2, and sends MSG3 to perform a contention access process in the nearest corresponding information subframe. If contention access is not considered, MSG3 completes for random access. And after receiving the access completion, the root node stops sending the synchronization information and sends MSG4 to inform the next node of completing the establishment. And the established node starts to send the synchronous signal.

The parameters of the MSG2 and MSG4 are shown in fig. 19(a) and 19(B), respectively.

MSG2

The sending node of the synchronization information searches RACH in corresponding resources, selects a nearest UE from the RACH, and receives MSG2 containing TA, Preamble-idx, RNTI and other system information on a scheduling subframe of a receiving upper node corresponding to the user in a first system half frame of a next system super frame.

S24: the MAC reports the MSG4 carried in the transmission message.

The parameter settings of MSG4 are shown in fig. 19 (B).

S25: and the AC judges that the access request of the UE of the cell is received, selects whether to approve the access of the UE according to the link condition and sends the MSG4 carrying the unique identification number of the accessed UE to the MAC.

Optionally, the step S25 further includes:

s251: judging whether the UE to be accessed is an initial node;

s252: if yes, executing the following access steps;

s253: if not, determine whether the UE initial state is a synchronization state?

S254: if yes, a random access process is carried out.

Optionally, the terminal access method for terminal direct communication based on the broadband technology further includes the following steps, so as to facilitate subsequent data communication.

S28: the AC informs the MAC to establish a new RB;

as described above, establish RBs — there are three RBs to establish: one for communication between the UE and the UE of the previous stage, one for communication between the UE and the UE of the next stage, and one for receiving downlink data sent to the UE.

Optionally, the AC notifies L1C to stop sending the synchronization signal;

s29: MAC indicates that the new RB is established successfully;

s30: the AC reports the current access status to the ATMT and IPRELAY (data delivery layer).

As mentioned above, IPRELAY (data delivery layer) is part of the protocol upper layer.

Optionally, the terminal access method for terminal direct communication based on broadband technology further includes the following steps,

s31: the AC judges whether the current UE is the first node in the link or not, if so, the AC informs the DHCP to configure the IP;

s32: the AC judges whether the current UE is the last node in the link, if not, the AC informs L1C to establish a new cell.

As described above, the specific way for the AC to establish a new cell is to read NV content, obtain basic cell information (superframe length, system frequency point, system bandwidth, etc.), and determine a cell ID number to be established according to whether the current UE has accessed a certain cell and the accessed cell ID.

Fig. 3 shows a chained networking manner among UEs adopted by the terminal access method of the broadband technology-based terminal direct communication D2D of the present invention. As shown in fig. 3, after receiving the link establishment request from the head node UE1, the head node UE1 starts sending synchronization signals, the surrounding nodes search for synchronization signals and request access to the UE1, the UE1 selects a UE2 with the closest distance from the received requests for access connection, after the access is successful, the UE1 and the UE2 establish a communication link, the UE1 stops sending synchronization signals, the UE2 starts sending synchronization signals, the surrounding nodes receive signals and request connection to the UE2, the UE2 selects the closest UE3 to establish a communication link, and so on. The head node communicates only with the lower node, the tail node communicates only with the upper node, and the middle node communicates with the upper and lower UEs.

The invention relates to a terminal access method of terminal direct communication D2D based on broadband technology, aiming at enabling UE outside signal coverage to access a network through relay UE based on the newly proposed terminal direct communication protocol technology, thereby being widely applied to terminal relay scenes and effectively expanding the coverage range of network access and remote data backhaul in a low-cost manner. The greatest difference between the D2D communication technology is that it uses the licensed band of the telecom operator, the interference environment is controllable, and the data transmission has higher reliability.

In addition, bluetooth requires manual pairing when transferring files, and also requires user configuration when accessing a WLAN connection point, and D2D communication can be automatically connected; meanwhile, the similar technologies work in an unlicensed frequency band, and compared with the D2D communication connection working in the licensed frequency band, the communication connection is not stable and reliable enough. In addition, the direct communication in the short distance can also effectively reduce the burden of the base station, reduce the transmitting power of the terminal equipment and reduce the transmission time delay.

Fig. 20 is a schematic structural diagram of an electronic device entity of a terminal access system for terminal direct communication based on broadband technology according to an embodiment of the present invention, and as shown in fig. 20, the electronic system includes: a processor (processor)101, a memory (memory)102, and a bus 103; the processor 101 and the memory 102 complete communication with each other through the bus 103. The processor 101 is configured to call program instructions in the memory 102 to perform the methods provided by the above-described method embodiments.

The present embodiments disclose a computer program product comprising a computer program stored on a non-transitory computer readable storage medium, the computer program comprising program instructions which, when executed by a computer, enable the computer to perform the methods provided by the above-described method embodiments. The present embodiments provide a non-transitory computer-readable storage medium storing computer instructions that cause the computer to perform the methods provided by the method embodiments described above. Those of ordinary skill in the art will understand that: all or part of the steps for implementing the method embodiments may be implemented by hardware related to program instructions, and the program may be stored in a computer readable storage medium, and when executed, the program performs the steps including the method embodiments; and the aforementioned storage medium includes: various media that can store program codes, such as ROM, RAM, magnetic or optical disks. The above-described embodiments of the electronic device and the like are merely illustrative, where the units described as separate parts may or may not be physically separate, and the parts displayed as units may or may not be physical units, may be located in one place, or may also be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.

Finally, it should be noted that: the above embodiments are only used for illustrating the technical solutions of the embodiments of the present invention, and are not limited thereto; although embodiments of the present invention have been described in detail with reference to the foregoing embodiments, those skilled in the art will understand that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A terminal access method of terminal direct communication based on broadband technology comprises the following steps:

s20: the AC informs the MAC to search the cell;

s21: the MAC sends the cell search result to the AC;

s22: the AC confirms that the cell can be accessed;

s24: the MAC sends MSG4 carried in the transmission message to the AC;

2. The terminal access method of broadband-based terminal direct communication according to claim 1, wherein in step S21, when the MAC sends the cell search result to the AC, if multiple cells are searched, the MAC selects one cell according to a predetermined rule to report, so as to avoid cell search again when camping.

3. The terminal access method for broadband technology-based terminal direct communication according to claim 1, wherein in step S23, the AC selects which terminal of the cell to receive the RACH request message, and notifies the MAC to reply to the MSG 2.

4. The terminal access method of the broadband technology-based terminal direct communication according to claim 3, wherein the access node UE receives MSG2 after sending PRACH, determines that it is the same as its Preamble-idx, and sends MSG3 in the nearest corresponding information subframe for contention access.

5. The terminal access method of terminal through communication based on broadband technology as claimed in claim 4, wherein the node sending synchronization information performs RACH search on corresponding resources, selects a nearest UE from the RACH, and receives MSG2 on a scheduling subframe of a node on the receiving side corresponding to the user in a first system half frame of a next system super frame, where the scheduling subframe includes system information such as TA, Preamble-idx, and RNTI.

6. The terminal access method for terminal-through communication based on broadband technology as claimed in claim 1, wherein the step S25 further comprises:

s251: the AC determines whether the current UE is the first node in the link,

s252: if yes, informing DHCP to configure IP;

s253: if not, judging whether the initial state of the UE is a synchronous state;

s254: if yes, a random access process is carried out.

7. The terminal access method for broadband technology-based terminal direct communication according to claim 1, further comprising:

s28: the AC informs the MAC to establish an RB used for the communication between the UE and the UE at the upper stage and a new RB used for receiving downlink data sent to the UE;

s29: MAC indicates that the new RB is established successfully;

s30: and the AC reports the current access state of ATMT and IPRELAY.

8. The terminal access method for broadband technology-based terminal direct communication according to claim 1, further comprising:

9. A terminal access system for broadband technology based terminal direct communication, the system comprising a memory and a processor, the memory storing a computer program, the computer program when executed by the processor causing the processor to perform the terminal access method for broadband technology based terminal direct communication according to any one of claims 1 to 8.

10. A storage medium having stored thereon computer program instructions executable by a processor to implement a terminal access method for broadband technology based terminal direct communication as claimed in claims 1-8.