CN112713978B - Time-frequency control method based on Internet of vehicles - Google Patents

Time-frequency control method based on Internet of vehicles Download PDF

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CN112713978B
CN112713978B CN202011408629.1A CN202011408629A CN112713978B CN 112713978 B CN112713978 B CN 112713978B CN 202011408629 A CN202011408629 A CN 202011408629A CN 112713978 B CN112713978 B CN 112713978B
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scma
partition
signature
transmission
nodeb
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CN112713978A (en
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曾迎春
刘波
简和兵
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Chengdu Jinnuoxin High Tech Co Ltd
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/0001—Arrangements for dividing the transmission path
    • H04L5/0003—Two-dimensional division
    • H04L5/0005—Time-frequency
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/12—Arrangements for detecting or preventing errors in the information received by using return channel
    • H04L1/16—Arrangements for detecting or preventing errors in the information received by using return channel in which the return channel carries supervisory signals, e.g. repetition request signals
    • H04L1/18—Automatic repetition systems, e.g. Van Duuren systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0058—Allocation criteria
    • H04L5/006—Quality of the received signal, e.g. BER, SNR, water filling
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
    • H04L9/32—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols including means for verifying the identity or authority of a user of the system or for message authentication, e.g. authorization, entity authentication, data integrity or data verification, non-repudiation, key authentication or verification of credentials
    • H04L9/3247—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols including means for verifying the identity or authority of a user of the system or for message authentication, e.g. authorization, entity authentication, data integrity or data verification, non-repudiation, key authentication or verification of credentials involving digital signatures
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
    • H04W4/30—Services specially adapted for particular environments, situations or purposes
    • H04W4/40—Services specially adapted for particular environments, situations or purposes for vehicles, e.g. vehicle-to-pedestrians [V2P]
    • H04W4/44—Services specially adapted for particular environments, situations or purposes for vehicles, e.g. vehicle-to-pedestrians [V2P] for communication between vehicles and infrastructures, e.g. vehicle-to-cloud [V2C] or vehicle-to-home [V2H]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/04—Wireless resource allocation
    • H04W72/044—Wireless resource allocation based on the type of the allocated resource
    • H04W72/0446—Resources in time domain, e.g. slots or frames
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/04—Wireless resource allocation
    • H04W72/044—Wireless resource allocation based on the type of the allocated resource
    • H04W72/0453—Resources in frequency domain, e.g. a carrier in FDMA
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/50—Allocation or scheduling criteria for wireless resources
    • H04W72/54—Allocation or scheduling criteria for wireless resources based on quality criteria
    • H04W72/542—Allocation or scheduling criteria for wireless resources based on quality criteria using measured or perceived quality

Abstract

The invention provides a time-frequency control method based on Internet of vehicles, which comprises the following steps: receiving a set of SCMA resources, wherein the SCMA resources include a first SCMA partition and a second SCMA partition; wherein the first SCMA partition is associated with a first set of time-frequency resources and the second SCMA partition is associated with a second set of time-frequency resources; determining a plurality of parameters associated with an SCMA transmission, wherein the parameters include reliability, time delay, and signal-to-noise ratio; determining, based on the determined parameters, a SCMA partition associated with an SCMA transmission, the SCMA partition comprising a first SCMA partition or a second SCMA partition; receiving a SCMA signature set; determining a SCMA signature from the received SCMA signature set based on the determined SCMA partition; using the determined SCMA signature to send the SCMA transmission in the determined SCMA partition. The invention provides a time-frequency control method based on the Internet of vehicles, which carries out self-adaptive adjustment on a channel according to a V2X complex and changeable environment, thereby improving the reliability of the whole Internet of vehicles system while reducing the communication time delay.

Description

Time-frequency control method based on Internet of vehicles
Technical Field
The invention relates to a vehicle networking system, in particular to a time-frequency control method based on the vehicle networking system.
Background
The V2X is used as an important key technology for realizing environment perception, information interaction and cooperative control in the Internet of vehicles, so that the V2V, the V2R, the V2P and the V2I can be interactively communicated, and a series of traffic information such as real-time road conditions, road information, pedestrian information and the like is obtained, thereby improving driving safety, reducing congestion and improving traffic efficiency. With the continuous development of V2X technology, especially autonomous vehicles, higher requirements are placed on the communication delay of real-time data. Meanwhile, the requirements of ultra-low delay and high reliability in 5G scenes also put higher requirements on air interface delay of data transmission, and generally the requirement is controlled within 10 ms. However, in the existing LTE-based car networking solution, the implemented communication delay is generally more than 50 ms. This presents a significant challenge to the safe driving of autonomous vehicles in high-speed moving scenarios.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a time-frequency control method based on the Internet of vehicles, which comprises the following steps:
receiving a set of SCMA resources, wherein the SCMA resources include a first SCMA partition and a second SCMA partition; wherein the first SCMA partition is associated with a first set of time-frequency resources and the second SCMA partition is associated with a second set of time-frequency resources;
determining a plurality of parameters associated with an SCMA transmission, wherein the parameters include reliability, time delay, and signal-to-noise ratio;
determining, based on the determined parameters, a SCMA partition associated with an SCMA transmission, the SCMA partition comprising a first SCMA partition or a second SCMA partition;
receiving a SCMA signature set;
determining a SCMA signature from the received SCMA signature set based on the determined SCMA partition; and
using the determined SCMA signature to send the SCMA transmission in the determined SCMA partition.
Preferably, the first SCMA partition is associated with a high reliability level of the SCMA transmission and the second SCMA partition is associated with a low reliability level of the SCMA transmission.
Preferably, further comprising:
determining a plurality of layers associated with the SCMA transmission; and
transmitting the SCMA transmission in the determined SCMA partition using the determined plurality of layers associated with the SCMA transmission.
Preferably, further comprising:
determining the SCMA signature based on the SCMA partition using at least one of a communication type, RRC connection information, configuration information.
Preferably, further comprising:
adjusting the SCMA signature and the SCMA partition associated with the SCMA transmission based on an identifier received from a network; and
an SCMA retransmission is sent in the adjusted SCMA partition using the adjusted SCMA signature.
Compared with the prior art, the invention has the following advantages:
the invention provides a time-frequency control method based on the Internet of vehicles, which carries out self-adaptive adjustment on a channel according to a V2X complex and changeable environment, thereby improving the reliability of the whole Internet of vehicles system while reducing the communication time delay.
Drawings
Fig. 1 is a flowchart of a time-frequency control method based on a vehicle networking according to an embodiment of the present invention.
Detailed Description
A detailed description of one or more embodiments of the invention is provided below along with accompanying figures that illustrate the principles of the invention. The invention is described in connection with such embodiments, but the invention is not limited to any embodiment. The scope of the invention is limited only by the claims and the invention encompasses numerous alternatives, modifications and equivalents. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. These details are provided for the purpose of example and the invention may be practiced according to the claims without some or all of these specific details.
The invention provides a time-frequency control method based on the Internet of vehicles. Fig. 1 is a flowchart of a time-frequency control method based on a vehicle networking according to an embodiment of the invention.
To enable a network receiver to identify a NodeB or isolate SCMA transmissions from different nodebs, the present invention transmits SCMA transmissions in multiple SCMA partitions based on SCMA signatures. The NodeB receives a set of SCMA resources from the network. The set of SCMA resources includes a plurality of SCMA partitions. Such as a first SCMA partition and a second SCMA partition. A first SCMA partition is associated with a first set of time-frequency resources and a second SCMA partition may be associated with a second set of time-frequency resources.
The NodeB determines characteristics associated with SCMA transmissions. The characteristic includes a signal-to-noise ratio, or reliability or time delay associated with SCMA transmission. The NodeB determines, based on the characteristic, an SCMA partition associated with the SCMA transmission, e.g., a first SCMA partition or a second SCMA partition. Preferably, the first SCMA partition is associated with a high reliability level of SCMA transmissions. The second SCMA partition is associated with a low reliability level of the SCMA transmission.
The NodeB receives a SCMA signature set from which it is determined based on the SCMA partition. For example, the NodeB determines the SCMA signature based on the SCMA partition using one of: communication type, RRC connection information, or configuration information. The node b determines a plurality of layers associated with an SCMA transmission, uses an SCMA signature associated with the SCMA transmission or the determined plurality of layers to send the SCMA transmission in the determined SCMA partition.
The NodeB receives a representation from the network associated with the SCMA transmission, and if the SCMA transmission is successful, the NodeB receives an acknowledgement representation. If the SCMA transmission is unsuccessful, the NodeB receives a rejection response. Adjusting an SCMA partition or SCMA signature associated with the SCMA transmission if the NodeB receives a rejection response indication from the network. For example, the NodeB may adjust the SCMA signature by adjusting a sequence index, length, or cyclic phase shift associated with the SCMA signature. The NodeB uses the adjusted SCMA signature to send SCMA retransmissions in the SCMA partition. The SCMA signature may be derived from one of: codeword, sequence, interleaver, resource component mapping, SRS, preamble, or spatial dimension or power.
Preferably, SCMA signature features are also provided, such as providing SCMA signature pool definitions or configurations. For example, an independent representation of transmission by SRS or transmission based on a scheduling request may be provided. Optionally, SCMA transmission without SCMA signature representation, or SCMA representation based on physical uplink control channel, or SCMA layer identifier may also be provided.
In unlicensed SCMA operation, the NodeB may initiate transmissions without prior coordination. If the receiver cannot determine the identifier of active V2X in the system, the NodeB attempts to decode multiple V2X, regardless of the actual activity of V2X. To reduce receiver processing complexity, the NodeB sends a respective representation with an SCMA transmission to declare the NodeB's identifier, identify the SCMA signature, or allow the receiver to make adjustments.
The resources are associated with a corresponding SCMA signature transmission in addition to the resources required for the data transmission. SCMA signature selection is performed, for example, based on a number of parameters. The plurality of parameters may include orthogonality, length, service, for dividing SCMA signature pool resources into a plurality of groups.
The set of resources for SCMA signature may be represented by index set P ═ { … Pi… description, index piA set of other parameters representing a variety of available configuration options that define SCMA signature resources. And the NodeB determines an SCMA signature resource pool through the parameter combination. SCMA signature selection may be based on various forms of specific identification attributes including base station ID, group ID, cell ID, service ID. The SCMA signature resource set may also be defined by a number of values of sequence index, length, seed, cyclic phase shift, etc.
The NodeB may determine the SCMA signature based on the signal-to-noise ratio measurements, and may also consider the path loss, interference, size of the data payload, or quality of service to determine the SCMA signature. For example, the NodeB determines the SCMA signature based on the beam indicated by the downlink control information of the scheduling request identifier field. The SCMA signature is identified, for example, based on the RRC connected state of the NodeB, e.g., whether the NodeB is in connected, idle, or inactive mode.
Preferably, the NodeB may be configured with periodic access to a particular SCMA signature resource set or group of SCMA signature resource sets. The SCMA signature resource set may be valid for a duration configured by the timer. The NodeB may use an SCMA signature resource set shared with multiple other nodebs and select an SCMA signature from the set of configuration values without coordination with the gNB.
In an SCMA system with multiple retransmissions, the set of SCMA signature resources used for retransmission may be based on the following associated parameters: load conditions, service type, path loss, downlink beam, base station ID, NodeB group ID, cell ID, etc. For example, the NodeB may use a different set of SCMA signature resources for HARQ transmissions. If K HARQ retransmissions are used, the indexes are divided into M groups, M ≦ K. The subset of resources allocated to the retransmission may be orthogonal to other defined sets, and the index of the retransmission is determined by detecting the use of SCMA signature resources. And may use multiple sets of resources to define the resources for SCMA signature or SRS, or may set two different sets of resources to define the resources for HARQ transmission. Based on the operating conditions, the NodeB may select an additional resource set or switch to another resource set. The NodeB determines the resource set definition for the retransmission step, e.g. based on the NodeB's ID, group ID or cell ID configuration. The NodeB may use a resource set with SCMA signatures or SRS resources available for initial transmission by the NodeB to reduce the collision probability for the first transmission by the NodeB.
Further, depending on network congestion conditions, the NodeB may adjust the SCMA signature representation and the power of SRS transmissions, and the NodeB may be set for a duration. For example, if the NodeB has not received uplink control information to refresh its buffer after reaching the configured duration of t1, the NodeB interprets the transmission condition as potential SRS congestion. If the NodeB has not received uplink control information to refresh the NodeB's buffer after the configured duration t2, the NodeB may interpret the transmission condition as potential SCMA signature congestion.
Optionally, the SCMA signature representation may be based on a scheduling request. For example, the scheduling request is for access signature transmission by SCMA. Multiple scheduling requests may be used to represent the signature subset. For example, two scheduling requests SR may be used. SR1For representing the access signature subset a. SR2For representing the access signature subset B. For example, different scheduling requests are associated with different access signature subsets, such that by sending the scheduling request, the gNB can determine from which access signature subset the NodeB can select a signature of the NodeB, or transmit the selected access signature. SRkMay be associated with the access signature subset K, where K is 1,2,3, …, K. K is a design parameter. In one embodiment, K depends on the number of subsets available after accessing the signature pool.
And after selecting the access signature subset, the NodeB selects a scheduling request according to the selected access signature subset. The NodeB transmits the selected SR, and the gNB detects a scheduling request transmitted from the NodeB. The gNB determines an access signature subset based on the transmitted SR. The gNB detects data from the determined access signature subset.
The NodeB may also determine the SCMA transmission partition based on certain time-frequency resources. The SCMA partition may include time-frequency resources for data transmission. The transmission of the SCMA signature identifier may be performed in the same time slot as the SCMA payload transmission. The transmission of the SCMA signature identifier is separate from SRS transmission or independent of SCMA payload. The SCMA signature identifier may be transmitted in a different partition than the SRS transmission or SCMA payload. The transmission of the SCMA signature identifier may be based on short orthogonal or pseudo-orthogonal multiple sequences, or embedded SRS transmission or SCMA payload. The transmission of the SCMA signature identifier may be based on an orthogonal transmission protocol. And the NodeB may autonomously select the SCMA signature identifier mapping. The NodeB may use the same resource component set location for transmission of the SCMA signature identifier.
The transmission of the SCMA signature identifier may be embedded with the SRS transmission or the SCMA payload. The transmission of the SCMA signature identifier may be based on the transmission of multiple pseudo-orthogonal sequences, e.g., for use as SRS or SCMA signature representation.
The NodeB may determine to use a separate SCMA signature representation or a combination of SCMA signature representations based on the SRS based on the resource allocation size. If the resource allocation is small, the NodeB may not configure SRS for SCMA signature representation. The reduced density SRS is used to represent the SCMA signature at this time; or a short sequence may be used to represent the SCMA signature. For example, in the SRS first configuration, the NodeB uses a plurality of third subcarriers. In a second configuration of SRS, the NodeB may use 2 subcarriers in the resource block and use a short sequence to represent the SCMA signature.
On transmission of the SCMA payload, the NodeB may transmit a SCMA identifier, which includes a plurality of parameters used in the SCMA transmission. The identifier may be transmitted in a separate resource independent of the SCMA signature, or embedded with multiple components of the SCMA transmission. The identifier may be sent in a different NR partition, e.g., in a NR slot or SCMA partition, and before or after the SCMA partition that includes the SCMA transmission.
The NodeB may transmit an SCMA identifier, which may include a plurality of characteristics related to SCMA transmissions by the NodeB, including the NodeB identifier; an SRS index; or SCMA signature index. After transmitting the NodeB identifier, the NodeB identifier allows the gNB to assign the decoded transmission to the correct NodeB. After transmitting the SRS index, the SRS index allows the gNB to identify the SRS used or to estimate the channel for the NodeB for coding. After transmitting the SCMA signature index, the SCMA signature index allows the gNB to identify the SCMA signature characteristics used, e.g., scrambling sequence or interleaving pattern, and to separate the NodeB from other nodebs.
The content of the SCMA identifier may be determined by the NodeB by the relation between the parameters sent to the gNB. If there is a one-to-one mapping between the multiple parameters, the parameters are sent to the gNB for indicating that the multiple parameters can be implicitly derived. If there is a one-to-many or many-to-many mapping between the parameters, each parameter is sent to the gNB. The SCMA identifier may include a plurality of parameters if there is a one-to-one mapping between the NodeB identifier, the SRS index, and the SCMA signature. If there is a one-to-many mapping between the NodeB identifier and the SRS index, and a one-to-one mapping between the SRS and the SCMA signature, the SCMA identifier includes more than two elements. For example, the SCMA identifier includes one of an SRS or NodeB identifier or the used SCMA signature. If there is a many-to-many mapping between the NodeB identifier, SRS index, and SCMA signature, the SCMA identifier may include more than three elements. For example, the NodeB may include the identifier, the SRS index, or the SCMA signature.
Preferably, the SCMA identifier is configured by the gNB. For example, if the gNB supports multiple SCMA schemes with different SCMA signatures, the gNB may configure the SCMA access signature contents during the establishment of the SCMA schemes. To transmit the SCMA identifier in an SCMA identifier resource, an identifier from a NodeB may be transmitted in a non-orthogonal manner to identifiers of a plurality of other nodebs.
The NodeB performs SCMA transmission based on a plurality of load characteristics. For example, the NodeB may have an SCMA payload with characteristics that may use modifications to SCMA transmissions based on which to optimize SCMA transmissions. Examples of characteristics or parameters include reliability level, block error rate, delay requirement, signal-to-noise ratio, or geographical location of the STA. For example, a near NodeB may be associated with a first SCMA zone, while a far NodeB may be associated with a second SCMA zone.
The characteristic may be associated with an SCMA load service type. For example, the NodeB selects a technology complementary to the gbb configuration or if the NodeB covers the gbb configuration, the NodeB may indicate the change of the configuration to the eNB in the SCMA identifier.
The NodeB adjusts the reliability of SCMA signature/data payload transmission by one of the following. Since the repetition rates of the SCMA signatures or data payloads are different, the NodeB selects the repetition rate for transmitting the SCMA signatures or data payloads, selects the data coding rate or rate matching for transmission of the data payloads, and then adjusts the SRS transmission parameters for channel estimation. For example, for orthogonal SRS used in SCMA transmission, the reliability is improved because of the increased density of SRS in time and frequency. For non-orthogonal SRS used in SCMA transmission, a reduction in the number of non-orthogonal SRS may increase reliability.
The NodeB may be configured by the gNB with multiple SCMA partitions, where the SCMA partitions are mapped to multiple service types. When data arrives at a NodeB for transmission to a gNB, the NodeB may identify a plurality of transmission characteristics and select a plurality of SCMA partitions based on the characteristics. The NodeB selects a plurality of characteristics for SCMA transmission based on the selected SCMA partition, including an SRS index, an SCMA signature, or an SCMA signature identifier, and transmits an uplink SCMA payload to the gNB in the determined SCMA partition using a plurality of SCMA parameters. The NodeB may listen for downlink transmissions from the gNB to indicate whether the transmission was successful, unsuccessful, or unknown.
In a preferred example, the NodeB initiates SCMA transmission at any time in a SCMA time slot or SCMA partition, or at a fixed time, such as a fixed time slot or fixed SCMA partition. The fixed time may be configured by the gNB. Furthermore, transmission may be delayed until the NodeB is synchronized with the allowed transmission resources when the SCMA payload arrives.
Based on the allowed class of service for the NodeB, the NodeB starts transmitting in the initial partition for SCMA transmission. If the NodeB has communications from multiple service types to send, the NodeB may send the information in the corresponding zone. After transmitting the uplink SCMA payload to the gNB in the SCMA partition, the NodeB monitors the downlink transmission from the gNB. If the transmission is successful, the SCMA transmission ends. If the transmission is unsuccessful, the information is retransmitted in the next SCMA partition. For example, upon completion of a predefined number of transmissions, the NodeB may receive a gbb grant that identifies dedicated resources for transmitting this information. This is useful for high reliability service types that may have failed.
Additionally, in an uplink SCMA transmission system, the overload of the system may be controlled by the gNB by adjusting the number of available SCMA signatures. The gNB controls the complexity of the receiver processing by changing the multiplexing of the SCMA signature. The NodeB further comprises an identifiable field for representing an identifier of the NodeB. The identifiable field may include RNTI type information, e.g., to indicate an identifier of a transmission source of the NodeB. For the actual load, the NodeB may combine the actual load with the identifiable field. The CRC check bits for the payload are calculated and calculated based on the identifiable field, or the NodeB may append the CRC check bits to the identifiable field prior to encoding.
In a preferred embodiment where SCMA signatures are used for SCMA transmission in multiple SCMA partitions, the gNB may configure a set of SCMA signatures or a set of SCMA resources to the NodeB. The NodeB determines a subset of SCMA resources, a plurality of SCMA partitions, and then determines a plurality of SCMA partitions based on the signal-to-noise ratio measurement. Next, an SCMA signature subset is determined for the SCMA resource subset based on the communication type, reliability, time delay, or the like, and a transmission parameter, such as an index, number of layers, or retransmission index, is determined. The NodeB may transmit uplink data using the SCMA signature or SCMA resources.
The conventional SCMA channel estimation scheme is easily affected by a high noise power level, which may result in poor NodeB performance and high detection error, and cannot apply a time-frequency domain denoising process. Thus in another aspect of the invention, the SCMA channel estimation is performed using a time-frequency local spreading and noise reduction process.
The gNB sends spread symbols, localized in the time-frequency domain, to the NodeB for SCMA channel estimation. The NodeB receives the spread symbols and performs a time-frequency analysis to convert the received spread symbols to the time-frequency domain. The NodeB applies a noise reduction procedure to separate the spread symbols from the embedded noise in the time-frequency domain. The NodeB performs time-frequency compounding to generate a noise-reduced spread spectrum signal in the time domain. The noise remaining after noise reduction is only a portion overlapping with spread spectrum symbols in the time-frequency domain. The NodeB then performs SCMA channel estimation over the de-noised spread spectrum symbols.
According to the invention, the transmission of the gNB is limited to a spreading sequence in the time-frequency domain, and the NodeB performs a time-frequency analysis and a noise reduction in the time-frequency domain to reduce the noise prior to the SCMA channel estimation. By performing noise reduction prior to SCMA channel estimation, a significant amount of noise can be filtered out of the received spreading sequence, and thus the signal-to-noise ratio prior to SCMA channel estimation is significantly increased.
Preferably, the spreading sequence is configured to:
Figure BDA0002817791940000111
wherein N is the length of the spreading sequence, q is the adjustment coefficient, and r is 1 or-1.
A demultiplexer in the gNB demultiplexes the data symbols and the spread symbols. The spread symbols may be transmitted continuously. The data symbols and the spread spectrum symbols after the multi-path addressing are modulated by a modulator of the gNB, and the modulated data symbols and the spread spectrum symbols are transmitted through a channel.
The NodeB comprises a demultiplexer, a denoising module, a channel estimator and a demodulator. The demultiplexer separates received data symbols and received spread spectrum symbols from the received data. The received spread symbols are sent to a de-noising module. The de-noising module performs time-frequency domain processing to filter noise from the received spread spectrum symbols. The denoised spread symbols are then sent to an SCMA channel estimator to perform SCMA channel estimation based on the denoised spread symbols. The received data symbols are sent to a demodulator. A demodulator detects and demodulates the transmitted data symbols based on the channel estimates generated by the channel estimator.
The denoising module comprises a time-frequency analysis unit, a denoising unit and a time-frequency composite unit. The time-frequency analysis unit performs a joint time-frequency analysis to convert the received spread spectrum symbols to the time-frequency domain. The time-frequency analysis unit may perform a time-frequency analysis method. The noise reduction unit applies a noise reduction process to separate the spread symbols from the embedded noise in the time-frequency domain. The masking operation is performed in the time-frequency domain. The output of the time-frequency analysis unit is a matrix whose elements represent how the energy of the input signal is concentrated in the time-frequency domain. The masking operation multiplies the matrix output of the time-frequency analysis unit by a preset matrix, where the elements of the matrix are unity around the partition in the input signal energy set and 0 in the other partitions. Since the transmitted spread symbols are localized to the time-frequency domain plane, the spread symbols can be separated from the embedded noise in the time-frequency domain.
The time-frequency domain composition unit performs a time-frequency domain composition operation to generate denoised spread spectrum symbols in the time domain. The output of the time-frequency compounding unit contains the least noise. Preferably, the spread symbol based estimation can be expressed as follows:
y[n]＝∑mp[m]h[n-m]+w[n]
where p is the transmitted spread spectrum signal, h is the impulse response of the channel, w is the additive white noise, and y is the received signal. The SCMA channel estimation described above is used to find h [ n ] given the received signal y [ n ].
When performing the SCMA channel estimation scheme in a MIMO system, time-frequency analysis is first employed, and then noise reduction is performed in the NodeB to reduce noise and cancel interference from other antennas from the spread-spectrum signal prior to SCMA channel estimation. By employing a noise reduction process, a significant amount of noise as well as spread spectrum interference can be filtered out from the received spread spectrum signal prior to SCMA channel estimation.
Preferably, the gNB further includes a precoding unit, a plurality of adders, and a plurality of V2X transmit antennas. The input data is precoded by a precoding unit. Spreading sequence p1…pMAnd adding the precoded data. Where the spreading sequence is not precoded, the NodeB can estimate the original MIMO channel by receiving the spreading for each antenna. Spreading and data symbol passingThe V2X transmit antenna transmits.
For MIMO transmission, a plurality of NodeB receiving antennas, a plurality of denoising modules and a plurality of channel estimators are arranged in a NodeB. The data and spreading symbols received by each NodeB receive antenna are separated from each other. The separated spread symbols are sent to respective denoising modules. The de-noising module performs time-frequency domain processing to filter noise from the received spread spectrum symbols. The time-frequency analysis unit performs joint time-frequency analysis to convert the spread symbols to the time-frequency domain. The time-frequency analysis unit of the denoising module can execute the joint time-frequency analysis method. The noise reduction unit then applies a noise reduction process to separate the spread symbols in the time-frequency domain from the embedded noise and interfering spread spectrum from other antennas. Since the transmitted spread symbols are localized in the time-frequency plane, the spread symbols can be separated from the embedded noise in the time-frequency domain. The time-frequency composition unit performs time-frequency composition to generate a denoised spread spectrum symbol in the time domain. The output of the time-frequency complex unit contains the least noise because the spreading is chosen to be non-overlapping in the time-frequency domain. The denoised spread symbols are then sent to a channel estimator, which performs channel estimation based on the denoised spread symbols.
To effectively filter out noise, the spreading sequences must be very well localized into the time-frequency domain, and the spreading sequences for different antennas cannot overlap each other after passing through the multipath channels. The first condition ensures successful noise filtering by masking, while the second condition allows interference to be cancelled from other spreads only by masking.
To satisfy the above conditions, the q values can be selected by the following rule, and the spreading sequences of different antennas are selected from the same sequence family by different q values. I.e. for antenna M e 1, ·, M, q ═ M-1) N/M, where N is the length of the spreading sequence. A MIMO system with 4V 2X transmit antennas is assumed. Q is selected to be 0, 64, 128 and 192 for antennas, 2,3 and 4, respectively, according to the above rules. Signal r received at a NodeB receiving antenna during transmission of a spreading sequence1(t) is expressed as follows:
r1(t)＝p1(t)*h11(t)+p2(t)*h12(t)+p3(t)*h13(t)+p4(t)*h14(t)+n(t)
wherein p isi(t) (i ═ 1.., 4.) is the spreading sequence assigned to antenna i, and h is the spreading sequence assigned to antenna i1i(t) (i ═ 1.., 4.) is the channel impulse response between the V2X transmit antenna i and the NodeB receive antenna, and n (t) is additive noise.
By employing a noise reduction process, a significant amount of noise as well as spread spectrum interference can be filtered out from the received spread spectrum signal prior to SCMA channel estimation. In another embodiment, the gNB includes an FFT unit, a subcarrier mapping unit, an inverse FFT unit, a plurality of adders, and a plurality of V2X transmit antennas. The input data in the time domain is processed by the FFT unit to be converted into frequency domain data. The frequency domain data is mapped to subcarriers by a subcarrier mapping unit. Then, the subcarrier mapping data is converted into time domain data by the IFFT unit. Spreading sequence p1..pMAnd added to the time domain data. Where the spreading sequence is not precoded, the NodeB can estimate the original MIMO channel by receiving the spreading for each antenna. The spread and data symbols are transmitted via the V2X transmit antenna.
To achieve better SCMA channel estimation performance, the spreading sequences transmitted by the multiple antennas are preferably orthogonal to each other. Frequency division multiple access is used to achieve orthogonality between the spreading of different V2X transmit antennas in the same cell. I.e., different V2X transmit antennas of the same cell use different subcarriers for the spread symbols. Orthogonality between spread symbols of different cells belonging to the same Node-B is achieved using code division multiple access.
In conclusion, the invention provides a time-frequency control method based on the internet of vehicles, which performs adaptive adjustment on channels according to the complicated and changeable environment of V2X, thereby improving the reliability of the whole internet of vehicles system while reducing the communication delay.
It will be apparent to those skilled in the art that the modules or steps of the invention described above may be implemented in a general purpose computing system, centralized on a single computing system, or distributed across a network of multiple computing systems, and optionally implemented in program code that is executable by a computing system, such that the program code is stored in a storage system and executed by a computing system. Thus, the present invention is not limited to any specific combination of hardware and software.
It is to be understood that the above-described embodiments of the present invention are merely illustrative of or explaining the principles of the invention and are not to be construed as limiting the invention. Therefore, any modification, equivalent replacement, improvement and the like made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. Further, it is intended that the appended claims cover all such variations and modifications as fall within the scope and boundaries of the appended claims or the equivalents of such scope and boundaries.

Claims (5)

1. A time-frequency control method based on the Internet of vehicles is characterized by comprising the following steps:
receiving a set of SCMA resources, wherein the SCMA resources include a first SCMA partition and a second SCMA partition; wherein the first SCMA partition is associated with a first set of time-frequency resources and the second SCMA partition is associated with a second set of time-frequency resources;
determining a plurality of parameters associated with an SCMA transmission, wherein the parameters include reliability, time delay, and signal-to-noise ratio;
determining, based on the determined parameters, a SCMA partition associated with an SCMA transmission, the SCMA partition comprising a first SCMA partition or a second SCMA partition;
receiving a SCMA signature set;
determining a SCMA signature from the received SCMA signature set based on the determined SCMA partition; and
using the determined SCMA signature to send the SCMA transmission in the determined SCMA partition.
2. The method of claim 1, wherein the first SCMA partition is associated with a high reliability level of the SCMA transmission and a second SCMA partition is associated with a low reliability level of the SCMA transmission.
3. The method of claim 1, further comprising:
determining a plurality of layers associated with the SCMA transmission; and
transmitting the SCMA transmission in the determined SCMA partition using the determined plurality of layers associated with the SCMA transmission.
4. The method of claim 1, further comprising:
determining the SCMA signature based on the SCMA partition using at least one of a communication type, RRC connection information, configuration information.
5. The method of claim 1, further comprising:
adjusting the SCMA signature and the SCMA partition associated with the SCMA transmission based on an identifier received from a network; and
an SCMA retransmission is sent in the adjusted SCMA partition using the adjusted SCMA signature.
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