CN110830149B

CN110830149B - Method and equipment for transmitting downlink common control channel for wireless communication

Info

Publication number: CN110830149B
Application number: CN201810889938.1A
Authority: CN
Inventors: 黎光洁; 王明威; 李春宏; 吴冶
Original assignee: Individual
Current assignee: Individual
Priority date: 2018-08-07
Filing date: 2018-08-07
Publication date: 2022-09-23
Anticipated expiration: 2038-08-07
Also published as: CN110830149A

Abstract

The invention discloses a downlink common control channel transmission method for wireless communication, and relates to the field of wireless communication. The method comprises the following steps: and preprocessing the data information based on a downlink common control channel (PD _ CCCH), mapping and loading the data information into data symbols according to a predefined data symbol format, and performing secondary scrambling processing for data transmission. The wireless communication channel transmission method provided by the invention inserts more pilot frequencies into the control channel in channel transmission, and the downlink PD-CCCH (common control channel) comprises PCP and PPS (pulse per second) for completing channel estimation together, thereby improving the channel estimation quality. Meanwhile, the downlink PD-CCCH (common control channel) bears fewer data bits, more coding redundancy is achieved, correct demodulation and decoding can be performed under very low conditions, the complexity is much smaller than that of other data channels, and the method and the device are suitable for communication data transmission under various low-power-consumption and ultra-low SNR scenes.

Description

Method and equipment for transmitting downlink common control channel for wireless communication

Technical Field

The present invention relates to the field of wireless communications, and in particular, to a downlink common control channel transmission method and transmission apparatus for wireless communications.

Background

The core of the technology in the wide-area internet of things is large coverage, low power consumption, a large number of connections and low cost. While the traditional communication protocols such as 3G, 4G and the like are designed for high performance, cost, power consumption and a large number of connections cannot be considered. In the prior art, the communication protocols such as Lora and the like achieve the aims of low cost and low power consumption to some extent at the cost of performance reduction. However, due to the adoption of the relatively backward spread spectrum technology (adopted in the third generation mobile communication before 20 years), the performance of the design is greatly reduced in complex environments, such as the coverage range is generally lower than 2km in urban environments. Whereas narrowband technologies such as SIGFOX do not have strong interference rejection. Especially, the use of the existing channel transmission technology in the wide area internet of things communication cannot meet the processing requirements of wide coverage area of the wide area internet of things, less communication data and limited system overhead, thereby causing resource waste and efficiency reduction in multi-carrier and multi-system communication.

In internet of things communication at ultra-low SNR (e.g., -30dB), a large amount of pilot overhead is required to receive data to complete channel estimation. And the optimized communication transmission based on the channel can effectively reduce the system overhead and reduce the resource consumption.

Disclosure of Invention

The invention aims to: in view of the above existing problems, in order to reduce the communication overhead, a downlink control channel transmission method implemented in a form of a control channel plus data is provided, which is also a method for wireless communication, and a corresponding transmission apparatus or transmission device, so as to achieve the effects of reducing the system overhead and reducing the resource consumption.

The technical scheme adopted by the invention is as follows:

a channel transmission method for wireless communication is characterized in that data information is preprocessed based on a downlink common control channel ((PD _ CCCH), mapped and loaded into data symbols according to a predefined data symbol format, and used for data transmission after secondary scrambling processing.

The data information is a source information character string; the data symbols represent a data transmission unit of wireless communication, and are composed of control and data.

The predefined DATA symbol format consists of a PCP control sequence, a PPS pilot sequence and a DATA DATA sequence; the PCP refers to a predefined variable-length variable cyclic prefix for resisting interference; the PPS pilot sequence refers to a predefined pilot sequence used for channel estimation together with the PCP control sequence.

The preprocessing of the data information refers to that the source information character string is sequentially subjected to CRC (cyclic redundancy check), channel coding, bit level scrambling and modulation processing to obtain a preprocessed data sequence.

The mapping and loading into the DATA symbols according to the predefined DATA symbol format means that the preprocessed DATA sequence, PCP (pulse train control) sequence and PPS (pulse train control) parameter DATA are respectively mapped to the position of a DATA DATA sequence, the position of a PCP control sequence and the position of a PPS pilot sequence in the DATA symbols to obtain loaded DATA symbols;

the length and value of the PCP and PPS parameter data are determined according to the communication equipment and the physical layer channel of the current wireless communication.

The secondary scrambling processing means that the loaded data symbols are scrambled again at the symbol level, and corresponding filtering processing is carried out according to the scrambling result to obtain data finally used for sending and transmitting. The scrambling at the symbol level comprises sequentially multiplying the sample data in the loaded data symbols with random sequence flow data, wherein the random sequence is generated by a random sequence generator.

The filtering process includes the steps of: firstly, sign data after phase modulation are processed by unwrapping, then interpolation and Gaussian filtering are carried out, and then the phase is restored to be within 0-2 pi.

In another aspect, the present invention further provides a channel transmission apparatus for wireless communication, which includes a processor configured to pre-process data information based on a downlink common control channel ((PD _ CCCH), map and load the data information into data symbols according to a predefined data symbol format, and perform secondary scrambling for a data transmission basis.

In summary, due to the adoption of the technical scheme, the invention has the beneficial effects that:

1. according to the embodiments provided by the invention, more pilot frequencies are inserted into the control channel in channel transmission, and the downlink PD-CCCH (common control channel) and PPS are used for completing channel estimation together except PCP, thereby improving the channel estimation quality.

2. According to the embodiments provided by the invention, the downlink PD-CCCH (common control channel) bears less data bits, more coding redundancy is provided, correct demodulation and decoding can be carried out under very low conditions, meanwhile, the complexity is much smaller than that of a shared data channel, and the method and the device are suitable for communication data transmission under various low-power consumption and ultra-low SNR scenes.

Drawings

The invention will now be described, by way of example, with reference to the accompanying drawings, in which:

fig. 1 is a schematic diagram of a basic communication frame structure according to an embodiment of the present invention.

Fig. 2 is a flowchart of an information sending method of a downlink common control channel PD _ CCCH according to an embodiment of the present invention.

Fig. 3 is a schematic diagram of a data PDU format of a downlink common control channel PD-CCCH according to an embodiment of the present invention.

Fig. 4 is a schematic diagram of a resource mapping relationship on a data symbol according to an embodiment of the present invention.

FIG. 5 is a flow chart illustrating a phase filter process according to an embodiment of the present invention.

Fig. 6 is a schematic diagram of a phase filtering result obtained by the phase filtering process according to the embodiment of the present invention.

Detailed Description

Various embodiments will be described and illustrated in detail below with reference to the accompanying drawings,

any feature disclosed in this specification (including any accompanying claims, abstract) may be replaced by alternative features serving equivalent or similar purposes, unless expressly stated otherwise. That is, unless expressly stated otherwise, each feature is only an example of a generic series of equivalent or similar features.

The following embodiments describe Wide-area internet Of Things communicAtion based on the WIoTa (Wide-range internet Of Things communicAtion protocol) protocol. It should be noted that, in a mobile communication system, a user equipment may receive information from a base station in a downlink and transmit information to the base station in an uplink. The information transmitted or received by the user equipment may include data and various control information. And various types of physical channels may exist according to the type and use of information transmitted or received by the user equipment.

In addition, the configuration method and embodiments of the present invention may also be applied to various wireless access systems, including CDMA (code division multiple access), FDMA (frequency division multiple access), TDMA (time division multiple access), OFDMA (orthogonal frequency division multiple access), SC-FDMA (single carrier frequency division multiple access), and the like.

The meaning of the individual parameters which are to be found in the following examples is first explained:

data symbol: the data symbol represents a communication data transmission unit, consists of PCP control and data, and the number of Ts points is the power of 2;

frame: a frame consisting of 16 subframes, each subframe starting with a broadcast channel broadcast frame number;

subframe: a subframe, which may be uplink or downlink;

burst: one Burst is the smallest transmission unit, and can occupy one or more subframes according to the difference of the BOOST Level, and one basic transmission unit is fixedly composed of 8 slots (slots);

slot: and one time slot is a unit occupied by the PD-CCCH and PU-CCCH physical layer channels.

The level of the coverage capacity is increased, the higher the level is, the more occupied air interface resources (the more data repetition) is, and the stronger the coverage capacity (BOOST) is;

AP is access point;

DL/UL ratio: the uplink and downlink ratio, when the DL/UL ratio is 1, the frame structure is a basic frame, otherwise, the frame structure is an extended frame;

cyclic-redundancy check (CRC);

PCP (primary phenol treatment): variable predefined CP refers to a cyclic prefix of a predefined variable length.

PPS: predefined pilot sequence refers to a predefined pilot sequence.

Repetition group: the RG parameter refers to a basic symbol to be occupied by information bits (bits), and if a basic transmission unit includes more symbols, the RG parameter is repeated. The common control channel fixed uses RG of 1, while the data channel may use a large RG.

In the embodiment, the wide area internet of things communication based on the WIoTa adopts a TDD time division duplex mode, for example, one frame is fixed to 34.133/2ms, one subframe includes one Rx and one Tx (equal in time), and 8 subframes are one frame.

As fig. 1 is a basic communication frame structure used in the wide area communication internet of things (WIoTa), the explanation of the frame structure can help to explain the physical layer channel structure.

Fig. 1 shows a basic frame structure under the condition that the bandwidth of 1.25MHz (1.92MHz sampling rate, and the sampling interval of 0.5208us) and the coverage capability parameter BOOST are configured to be 0.

In fig. 1, one frame (frame) is 273.0668 ms, and includes 16 subframes (subframes), and the uplink/downlink ratio DL/UL ratio is 1: 1, the uplink and downlink subframes are arranged in a staggered manner. The basic/minimum transmission unit of user data is one basic transmission unit. A basic transmission unit is fixed to contain 8 slots. As shown in fig. 1, when the BOOST configuration is 0, a slot includes 8 data symbols, one data symbol is a basic transmission unit, and includes control and data therein, and 8 slots constitute a basic transmission unit. Here, one downlink data symbol is 512Ts, and the number of sampling points of the uplink data symbol may be configured accordingly according to specific network requirements (512 points, 256 points, 128 points, 64 points).

In this embodiment, the uplink and downlink behaviors are arranged in a staggered manner, each uplink basic transmission unit and each downlink basic transmission unit respectively correspond to one uplink subframe and one downlink subframe, the IoT terminal device is accessed into the internet of things communication network under the configuration condition of the coverage capability parameter BOOST, and the corresponding access point also performs data transmission with each terminal device under the same BOOST configuration condition. Further, the uplink/downlink ratio DL/UL ratio and the coverage capability parameter BOOST are set, and different values of the coverage capability parameter BOOST are used for configuring the number of data symbols contained in the basic transmission unit, so that the modulation coding and the repetition times of the control channel and the data channel are controlled by the coverage capability parameter BOOST at the same time.

In the WIoTa-based wide area Internet of things communication, the WIoTa-based wide area Internet of things communication comprises five basic physical layer channels, wherein two channels are a Common Control Channel (CCCH), namely an uplink common control channel (PU _ CCCH) and a downlink common control channel (PD _ CCCH), the common control channel bears short message indication information, ACK information, information such as request access and Data PDU (Protocol Data Unit ) request sending. The data PDU is a data bit (bit) in the physical layer channel.

As shown in fig. 2, a flow chart of an information sending method of a downlink common control channel (PD _ CCCH) in wide area internet of things wireless communication is provided, where, as shown in the flow chart, an initial information string (bits) is sequentially subjected to CRC check, channel coding, bit level scrambling and modulation, then loaded into a data symbol (data symbol) together with a PCP and a PPS through resource mapping (RE), then subjected to symbol level repetition and symbol level scrambling, and finally subjected to phase filtering for data sending.

Wherein, the PCP (variable predefined Cyclic-prefix) refers to a Cyclic prefix with a predefined length, and unlike the CP in LTE, the PCP improves the efficiency of the whole system by predefining sequence prefixes with different lengths on different channels. In one embodiment, the length of the PCP in the downlink common control channel PD-CCH is generated and determined by a system PCP parameter generator and is in the form of a random constellation modulation sequence, facilitating estimation and transmission delay.

In order to overcome intersymbol interference ISI (inter-symbol interference) specific to an OFDM (orthogonal frequency division multiplexing) system, the LTE introduces a cyclic prefix concept, adopts initial synchronization based on CP (cyclic content provider), and has an algorithm which is only based on a differential method and can work only when the signal-to-noise ratio of a received signal is required to be higher than about-10 dB. The PCP scheme provided by the embodiment of the invention can adopt a differential algorithm and a related algorithm, so that the signal-to-noise ratio of a received signal can be as low as-30 dB, and thus, the WIoTa-based terminal for the wide area Internet of things communication can still normally work in severe environments or extreme situations, and meanwhile, a base station can also cover a large range, thereby reducing the deployment and maintenance cost of the system.

Under ultra-low SNR (such as-30 dB), a large amount of pilot overhead is needed to complete data reception, and in order to reduce overhead, data transmission in WIoTa-based wide area internet of things communication is in the form of control channels plus data, and more pilots are inserted into the control channels. Besides the PCP, the downlink common control channel PD-CCCH is also provided with a parameter PPS (predefined pilot sequence), namely a predefined pilot sequence, which is used for finishing channel estimation together with the PCP and improving the channel estimation quality. Meanwhile, the downlink common control channel PD-CCCH bears less data bits, has more coding redundancy, can carry out correct demodulation and decoding under a very low condition, and has much less complexity compared with a shared data channel. In the embodiment, more accurate downlink common control channel PD-CCCH channel estimation can be completed together with PCP and PPS according to the correctly demodulated control channel data. In one embodiment, the length of the PPS in the downlink common control channel PD-CCH is generated and determined by a system PPS parameter generator and takes the form of a random constellation modulation sequence.

The downlink common control channel PD-CCCH only occupies one time slot in one basic transmission unit, and the load number of the common control channel is determined by a system load bit parameter (PD-CCCH _ PAYLOAD).

Specifically, the bit number (including CRC, etc.) of the data PDU of the downlink common control channel PD-CCCH is determined by a system load bit parameter (PD-CCCH _ PAYLOAD). In one embodiment, the format of the DATA PDU of the downlink common control channel PD-CCCH is shown in fig. 3 below, and consists of TYPE field + DATA field + CRC field. Wherein the length of the "TYPE" field is 3 bits, which is used to indicate the loaded logical channel, and the CRC TYPE used is determined by the system CRC parameter generator. The sum of the number of TYPE field bits + the number of DATA field bits + the number of CRC field bits cannot be larger than the number of DATA bits determined by the system load bit parameter. For example, if the number of bits determined by the system load bit parameter is 14 bits, TYPE is 3 bits, and CRC is 5 bits, DATA is 6 bits, and if the number of bits of the service DATA unit of the carried logical channel is smaller than the number of bits of the DATA field, 0 to 6 bits are filled in the following to process.

In one embodiment, the value for the system load bit parameter (PD-CCCH _ PAYLOAD) is set as follows:

the system load bit parameter is 0, and the corresponding digit is 8;

the system load bit parameter is 1, and the corresponding digit is 12;

the system load bit parameter is 2, and the corresponding digit is 16;

the system load bit parameter is 3, and the corresponding bit number is 20.

In one embodiment, the logical channel indicated by the "TYPE" field of 3 bits specifically includes the parameters shown in table 1 below.

TABLE 1 evaluation of "TYPE" fields and corresponding logical channel tables

TYPE domain value	Logical channel
		000	LD-BROADCAST-CH
001	LD-SM-CONTROL-CH
		002	LD-REQUEST-CH
003	LD-ACK-CH
		004	LD-PAGING-CH
005	LD-GROUP-DRX-SM-CH
		006	Reserved
007	Reserved

In the downlink common control channel PD-CCCH, the repetition group parameter RG is fixed to 1, and thus the resource mapping relationship on one DATA symbol is as shown in fig. 4, and one DATA symbol is composed of a PCP bit, a PPS bit, and a DATA bit. Therefore, the data generated after encoding needs to be padded with resources of TS (symbol length-PPS length-PCP length), and since the data is fixedly mapped to 1/4Pi QPSK modulation, the number of bits required for encoding is 2 × (symbol length-PPS length-PCP length).

In one embodiment, the LENGTH value of the parameter PCP is determined by a corresponding downlink PCP LENGTH parameter (DL _ PCP _ LENGTH), and the LENGTH value of the PPS is determined by a corresponding downlink PPS LENGTH parameter (DL _ PPS _ LENGTH), for example, when the downlink PCP LENGTH parameter is 0, the LENGTH value of the PCP is 4; when the downlink PPS length parameter is 0, the length of the PPS is also 4. The specific value relationship is shown in the following table 2:

TABLE 2 length values of PCP and PPS

The coding rate of the downlink common control channel PD-CCCH is determined by the parameters of the coding rate of the system, and if the bit number generated by the coder exceeds the required bit number, interception processing is carried out; if the number of bits generated is less than the required number of bits, it is repeated in sequence until it is filled. After the coded bits are generated, the coded bits are scrambled at the bit (bit) level, then mapped into modulation symbols according to the 1/4Pi QPSK constellation, and generate data symbols together with PCP and PPS. After the data symbols are generated by mapping, the data is subjected to symbol level (symbol) repetition and secondary scrambling, and the data of the control channel of the last time slot is obtained for sending.

The secondary scrambling processing refers to scrambling the data symbols loaded with specific data at symbol level, and performing corresponding filtering processing according to the scrambling result to obtain data finally used for sending and transmitting.

In one embodiment, the symbol level scrambling method is as follows: firstly, generating a random character string, for example, the random character string can be generated by a Golden sequence generator, and obtaining a random sequence with the bit number being the number of all data symbols in a frame; then, the sampling point data in all data symbols in the processed frame is multiplied by the random sequence stream data after bit modulation in sequence.

Scrambling for bit (bit) or QAM level is generally used in the existing communication system, while scrambling for bit and symbol level is used in the embodiment of the present invention, which can not only resist interference of same frequency system, but also increase of complexity of receiver is small.

The values of the PCP and PPS parameters are generated and determined by corresponding parameter generators. In one embodiment, since both the PCP and the PPS are 1/2Pi BPSK modulation, to ensure phase continuity at the junction of the PCP and the PPS, if the number of samples of the PCP is not an integer multiple of 16, a constellation rotation of the first sample of the PPS is required to join the last sample of the PCP. And the DATA part will do the same if the sum of PCP and PPS is not an integral multiple of 16.

Before data is sent, filtering processing is needed, and the design of a general shaping filter such as a root cosine filter brings signal amplitude fluctuation, so that the setting of the constant amplitude of the whole internet of things communication system is damaged. Although the GMSK modulation also performs gaussian filtering in the phase domain and then performs operations such as MSK phase accumulation, the GMSK can obtain very good out-of-band rejection capability, but the GMSK modulation can only work under the signal modulation of BPSK, and the spectrum efficiency cannot be effectively improved.

For this reason, the present embodiment also provides a new phase filter, which operates simultaneously with 1/2Pi BPSK, 1/4Pi QPSK, 1/8Pi 8 PSK. The phase filter provided by the embodiment is performed in the phase domain, without destroying the constant modulus characteristic, but because the phase has the problem of 2pi inversion, it is difficult to directly perform phase filtering, so the processing flow of the phase filter is provided as shown in fig. 5 below:

firstly, unwrap processing is carried out on a symbol after phase modulation, the unwrap processing is mainly used for processing the 2pi inversion problem of a phase, a symbol range in a range of 0-2 pi is converted into a linear range through unwrap unwrapping operation, and the phase is more continuous. And then, after interpolation (interpolation) and Gaussian filter (Gaussian filter) processing, converting the phase range of 0-2 pi through Wrap-around Wrap processing, and finally pushing a voltage-controlled oscillation circuit at a radio frequency end.

As shown in fig. 6 below, the input phase, unwrap unwrapped phase, interpolated filtered phase, and wrap-around recovered phase filtering result are shown after the phase filtering process.

In another embodiment, an apparatus for wireless communication is further provided, and the apparatus includes a processor configured to pre-process data information based on a downlink common control channel (PD _ CCCH), load the pre-processed data information into data symbols according to a predefined data symbol format mapping, and perform secondary scrambling for data transmission.

In summary, embodiments of the present invention provide an information sending method and a corresponding wireless communication device through a downlink common control channel (PD _ CCCH) in wide area internet of things communication. Based on the information sending method and the communication device in the embodiment, efficient, stable and low-power-consumption data communication of the internet of things can be completed in wide-area wireless internet of things communication.

All of the features disclosed in this specification, or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations of features and/or steps that are mutually exclusive.

The invention is not limited to the foregoing embodiments. The invention extends to any novel feature or any novel combination of features disclosed in this specification and any novel method or process steps or any novel combination of features disclosed.

Claims

1. A channel transmission method for wireless communication is characterized in that data information is preprocessed based on a downlink common control channel (PD _ CCCH), then is mapped and loaded into data symbols according to a predefined data symbol format, and the loaded data symbols are used for data transmission after secondary scrambling processing at a symbol level is carried out;

the data symbol represents a data transmission unit of wireless communication and consists of control and data;

the predefined DATA symbol format consists of a PCP control sequence, a PPS pilot sequence and a DATA sequence; the PCP refers to a predefined variable-length variable cyclic prefix for resisting interference; the PPS pilot sequence refers to a predefined pilot sequence and is used for finishing channel estimation together with a PCP control sequence;

the mapping and loading into the DATA symbols according to the predefined DATA symbol format means that the preprocessed DATA sequence, the PCP parameter DATA and the PPS parameter DATA are respectively mapped to the position of a DATA DATA sequence, the position of a PCP control sequence and the position of a PPS pilot sequence in the DATA symbols to obtain the loaded DATA symbols.

2. The method for channel transmission of wireless communication of claim 1, wherein the data information is a source information string.

3. The method as claimed in claim 1, wherein the preprocessing the data information comprises sequentially performing CRC check, channel coding, bit level scrambling and modulation on the source information string to obtain a preprocessed data sequence.

4. The channel transmission method for wireless communication of claim 3, wherein the length and value of the PCP and PPS parameter data are determined according to a communication device and a physical layer channel of current wireless communication.

5. The method as claimed in claim 1, wherein the performing of the secondary scrambling process is to perform symbol-level scrambling again on the loaded data symbols, and perform corresponding filtering process according to the scrambling result to obtain the data finally used for transmission and transmission.

6. The channel transmission method for wireless communication of claim 5, wherein the symbol-level scrambling comprises sequentially multiplying sample data within the loaded data symbols with stream data of a random sequence, the random sequence being generated by a random sequence generator.

7. The channel transmission method for wireless communication according to claim 6, wherein the filtering process comprises the steps of: firstly, sign data after phase modulation is subjected to unwrapping processing, then interpolation and Gaussian filtering are carried out, and then the phase is restored to be within the phase range of 0-2 pi.

8. A channel transmission apparatus for wireless communication, the apparatus comprising a processor, the processor being configured to pre-process data information based on a downlink common control channel (PD _ CCCH), map and load the data information into data symbols according to a predefined data symbol format, and perform secondary scrambling for data transmission;

the predefined DATA symbol format consists of a PCP control sequence, a PPS pilot sequence and a DATA sequence; the PCP refers to a predefined variable-length variable cyclic prefix for anti-interference; the PPS pilot sequence refers to a predefined pilot sequence and is used for finishing channel estimation together with a PCP control sequence;

the mapping and loading into the DATA symbols according to the predefined DATA symbol format means that the preprocessed DATA sequence and the PCP and PPS parameter DATA are respectively mapped to the position of a DATA DATA sequence, the position of a PCP control sequence and the position of a PPS pilot sequence in the DATA symbols to obtain the loaded DATA symbols.