CN105898873A - Data frame distribution method and device and data transmission method and device - Google Patents

Data frame distribution method and device and data transmission method and device Download PDF

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Publication number
CN105898873A
CN105898873A CN201610201874.2A CN201610201874A CN105898873A CN 105898873 A CN105898873 A CN 105898873A CN 201610201874 A CN201610201874 A CN 201610201874A CN 105898873 A CN105898873 A CN 105898873A
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frame
channel
lte
backoff
user terminal
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CN105898873B (en
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张奇勋
冯志勇
杨拓
郭春霞
赵思雯
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Beijing University of Posts and Telecommunications
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Beijing University of Posts and Telecommunications
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    • 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
    • H04W72/50—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
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W74/00—Wireless channel access
    • H04W74/08—Non-scheduled access, e.g. ALOHA
    • H04W74/0833—Random access procedures, e.g. with 4-step access
    • H04W74/0841—Random access procedures, e.g. with 4-step access with collision treatment
    • H04W74/085—Random access procedures, e.g. with 4-step access with collision treatment collision avoidance

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Quality & Reliability (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

The embodiments of the invention provide a data frame distribution method and device and a data transmission method and device. The data frame distribution method comprises the steps of: according to time slot lengths, calculated in the previous frame period, of a perception frame, transmission frame and a retreat frame of the current frame period, distributing the perception frame and the transmission frame of the current frame period to an LTE user terminal in the range covered by an LTE system base station; after detecting that the LTE user terminal successfully finish data transmission, distributing the retreat frame of the current frame period to the LTE user terminal, and enabling the LTE user terminal to retreat a channel according to the retreat frame. According to the invention, one retreat frame is added based on the frames of an existing LTE system, the channel occupancy of the LTE system is lowered, and the channel occupancy and the throughput capacity of a WLAN system are improved, so that the WLAN system and the LTE system can well coexist, and the utilization rate of unlicensed frequency bands is simultaneously improved.

Description

Data frame allocation method and device and data transmission method and device
Technical Field
The present invention relates to the field of wireless communication technologies, and in particular, to a method and an apparatus for allocating data frames and a method and an apparatus for transmitting data.
Background
With the explosive development of mobile internet and high-broadband data service, the mobile data traffic, the number of mobile terminals and the number of mechanical terminal connections increase in a blowout manner.
The prior art discloses a Licensed-Assisted Access (LAA) technology, which increases more available frequency spectrums by using a mode of an LTE system accessing an unlicensed frequency band in a Wireless Local Area Network (WLAN) system environment, and meets the requirements of users.
An access process of an unlicensed frequency band of an existing LTE (Long Term Evolution ) system is mainly performed in a listen-before-talk manner, generally, a frame of the LTE system includes two parts, namely a sensing frame and a transmission frame, the sensing frame is used for sensing whether a channel of a current unlicensed frequency band is in an idle state, and if the channel is in the idle state, the LTE system accesses the channel and transmits data through the transmission frame.
However, the WLAN system complies with a Media Access Control (MAC) layer protocol, which occupies a channel in a contention manner with collision backoff, while the LTE system does not have a collision backoff mechanism, and when the WLAN system and the LTE system coexist, the WLAN system may frequently backoff, and the LTE system may occupy the channel for a long time, which may greatly reduce the channel occupancy and throughput of the WLAN system, and reduce the channel utilization rate of the unlicensed frequency band.
Disclosure of Invention
Embodiments of the present invention provide a method and an apparatus for allocating a data frame and a method and an apparatus for transmitting data, so as to solve the problem of coexistence between a WLAN system and an LTE system and improve the utilization rate of an unlicensed frequency band.
In order to achieve the above object, an embodiment of the present invention provides a method for allocating a data frame, which is applied to a controller in a base station of an LTE system, and the method includes:
allocating the sensing frame and the transmission frame of the current frame period to an LTE user terminal in the coverage range of the LTE system base station according to the time slot lengths of the sensing frame, the transmission frame and the backoff frame of the current frame period calculated in the previous frame period; the sensing frame is used for detecting whether a channel at the current moment is in an idle state by an LTE user terminal; the transmission frame is used for data transmission of the LTE user terminal;
and when the LTE user terminal is detected to finish the data transmission successfully, allocating the backoff frame of the current frame period to the LTE user terminal, and enabling the LTE user terminal to backoff out of the channel according to the backoff frame.
Preferably, the slot lengths of the sensing frame, the transmission frame and the backoff frame of the current frame period are calculated by the following steps:
and calculating the time slot lengths of the sensing frame, the transmission frame and the backoff frame of the current frame period according to the channel occupation information of the unauthorized frequency band acquired within a first preset time before the current time and the historically stored channel occupation information.
Preferably, the channel occupancy information includes: the access times of the LTE system, the successful access times of the LTE system, the number of the WLAN system contention points and the throughput of the WLAN system contention points;
the calculating the time slot length of the backoff frame of the current frame period according to the channel occupation information of the unlicensed frequency band acquired within a first preset time before the current time and the historically stored channel occupation information includes:
calculating the successful access probability according to the acquired times of access attempts of the LTE system and the times of successful access of the LTE system in the unauthorized frequency band within a first preset time before the current time;
searching the number of WLAN system contention points matched with the successful access probability in the historically stored channel occupation information according to the successful access probability;
according to the number of the WLAN system contention points, the throughput of the WLAN system contention points with the number equal to that of the WLAN system contention points and the throughput of the WLAN system contention points with the number equal to that of the WLAN system contention points plus one are searched;
according to the formulaCalculating the time slot length of the backoff frame;
wherein T is the slot length of the frame period, PsucFor the successful access probability, n is the probability of successful access PsucThe number of the matched WLAN system contending for the points, n +1 is the probability P of successful accesssucThe number of the matched WLAN system contention points plus one, SnTo contend with the WLAN systemThroughput of WLAN system contention points under the same number of contention points n, Sn+1To the successful access probability PsucThe throughput of the WLAN system contention points under the same number of the matched WLAN system contention point number plus one number n + 1.
Preferably, the number of the WLAN system contention points and the throughput of the WLAN system contention points are information received in real time from the WLAN system base station.
Preferably, the calculating the time slot length of the sensing frame of the current frame period according to the channel occupancy information of the unlicensed frequency band acquired within a first predetermined time period before the current time and the historically stored channel occupancy information includes:
establishing a binary hypothesis model for the condition that a channel of an unauthorized frequency band is in an idle state and a non-idle state;
calculating the detection probability and the false alarm probability of the LTE user terminal according to the binary hypothesis model;
calculating the average throughput of the LTE system when the channel is in an idle state and the average throughput of the LTE system when the channel is in a non-idle state according to the detection probability and the false alarm probability;
according to the formulaAnd calculating the time slot length T of the sensing frame by a traversal algorithmsense；
Wherein, TbackIs the time slot length of the backoff frame of the current frame period, T is the time slot length of the frame period, R0Average throughput, R, of the LTE system with the channel in idle state1Average throughput, P, of the LTE system with the channel in a non-idle statedIn order to detect the probability of the occurrence,is a detection probability threshold.
Preferably, the calculating the time slot length of the transmission frame of the current frame period according to the channel occupation information of the unlicensed frequency band acquired within a first predetermined time period before the current time and the historically stored channel occupation information includes:
according to the formula Ttrans＝T-Tback-TsenseCalculating the time slot length T of the transmission frametrans；
Wherein, TsenseIs the time slot length, T, of the sensing frame of the current frame periodbackAnd T is the time slot length of the backoff frame of the current frame period.
Preferably, the method further comprises:
and when detecting that the LTE user terminal does not successfully finish data transmission, allocating a sensing frame and a transmission frame of the next frame period to the LTE user terminal.
The embodiment of the invention also provides a data transmission method, which is applied to an LTE user terminal and comprises the following steps:
acquiring a sensing frame and a transmission frame distributed by a controller in an LTE system base station; the sensing frame and the transmission frame are allocated to the LTE user terminal when the controller calculates the time slot lengths of the sensing frame, the transmission frame and the backoff frame of the current frame period;
detecting whether the channel is in an idle state according to the sensing frame;
when detecting that a channel is in an idle state according to a sensing frame distributed by a controller in an LTE system base station, accessing the channel, and transmitting data according to a transmission frame distributed by the controller;
and after the data transmission is successfully completed, receiving a backoff frame distributed by the controller, and backoff out the channel according to the backoff frame.
The embodiment of the invention also provides a data frame distribution device, which is applied to a controller in a base station of an LTE system, and the device comprises:
the first sensing frame and transmission frame distribution module is used for distributing the sensing frame and the transmission frame of the current frame period to the LTE user terminal in the coverage range of the LTE system base station according to the time slot lengths of the sensing frame, the transmission frame and the backoff frame of the current frame period calculated in the previous frame period; the sensing frame is used for detecting whether a channel at the current moment is in an idle state by an LTE user terminal; the transmission frame is used for data transmission of the LTE user terminal;
and the backoff frame allocation module is used for allocating the backoff frame of the current frame period to the LTE user terminal to enable the LTE user terminal to backoff out the channel according to the backoff frame after detecting that the LTE user terminal successfully completes data transmission.
The embodiment of the invention also provides a data transmission device, which is applied to an LTE user terminal and comprises the following components:
the sensing frame and transmission frame acquisition module is used for acquiring the sensing frame and the transmission frame distributed by the controller in the LTE system base station; the sensing frame and the transmission frame are allocated to the LTE user terminal when the controller calculates the time slot lengths of the sensing frame, the transmission frame and the backoff frame of the current frame period;
the channel detection module is used for detecting whether the channel is in an idle state or not according to the sensing frame;
the data transmission module is used for accessing the channel when detecting that the channel is in an idle state according to a sensing frame distributed by a controller in an LTE system base station, and transmitting data according to a transmission frame distributed by the controller;
and the channel backoff module is used for receiving a backoff frame distributed by the controller after the data transmission is successfully completed, and backoff the channel according to the backoff frame.
The data frame distribution method and device and the data transmission method and device provided by the embodiment of the invention have the advantages that a backoff frame is added on the basis of the frame of the existing LTE system, the channel occupancy rate and the throughput of the WLAN system are improved by reducing the channel occupancy rate of the LTE system, the WLAN system and the LTE system can well coexist, and the utilization rate of an unauthorized frequency band is improved. Of course, it is not necessary for any product or method of practicing the invention to achieve all of the above-described advantages at the same time.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a first flowchart of a method for allocating data frames according to an embodiment of the present invention;
fig. 2 is a schematic diagram of a coexistence time frame of a WLAN system and an LTE system according to an embodiment of the present invention;
fig. 3 is a second flowchart of a method for allocating data frames according to an embodiment of the present invention;
fig. 4 is a flowchart of a time slot length calculation method of a backoff frame in the data frame allocation method according to an embodiment of the present invention;
fig. 5 is a flowchart of a time slot length calculation method of a sensing frame in an allocation method of a data frame according to an embodiment of the present invention;
fig. 6 is a flowchart of a data transmission method according to an embodiment of the present invention;
fig. 7 is a schematic structural diagram of a data frame distribution device according to an embodiment of the present invention;
fig. 8 is a schematic structural diagram of a second apparatus for distributing data frames according to an embodiment of the present invention;
fig. 9 is a schematic structural diagram of a back-off frame timeslot length calculating unit in the data frame allocating apparatus according to the embodiment of the present invention;
fig. 10 is a schematic structural diagram of a sensing frame timeslot length calculating unit in a data frame allocating apparatus according to an embodiment of the present invention;
fig. 11 is a schematic structural diagram of a data transmission device according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example one
As shown in fig. 1, a first flowchart of a method for allocating a data frame according to an embodiment of the present invention is applied to a controller in a base station of an LTE system, and the principle of the method is as follows: by adding a backoff frame in the frame of the existing LTE system, when the LTE system and the WLAN system coexist, the channel is backed off after one-time data transmission is finished, so that the opportunity that the WLAN system occupies the channel to transmit data is increased, and the utilization rate of the channel is integrally improved. The data frame allocation method comprises the following steps:
s110, distributing the sensing frame and the transmission frame of the current frame period to the LTE user terminal in the coverage range of the LTE system base station according to the time slot lengths of the sensing frame, the transmission frame and the backoff frame of the current frame period calculated in the previous frame period; the sensing frame is used for detecting whether a channel at the current moment is in an idle state by an LTE user terminal; and the transmission frame is used for data transmission of the LTE user terminal.
Specifically, the frame period of the LTE system is a slot length (denoted by T) of a complete frame, and the slot length T of the frame period may be set according to different protocol version specifications (such as MAC layer protocol), or may be set by itself, such as 20 ms. The frame period of the LTE system is sequentially divided into a sensing frame, a transmission frame and a backoff frame, wherein the sensing frame is used for the LTE user terminal to detect whether a current channel of an unauthorized frequency band is in an idle state, the transmission frame is used for the LTE user terminal to transmit data, and the backoff frame is used for the LTE user terminal to backoff out of the channel. Time slot length of sensing frame, transmission frame and back-off frame (defining time slot length of sensing frame as T)senseThe time slot length of the transmission frame is TtransAnd the length of the time slot of the back-off frame is Tback) The setting can be fixed, and the specific setting can be calculated according to different conditions. For example, the slot length T of the perceptual framesense1 millisecond, slot length of transmission frame TtransIs 10 ms and the slot length T of the backoff framebackIs 9 milliseconds. Preferably, before allocating the sensing frame, the transmission frame and the backoff frame in the current frame period, the controller in the LTE system base station calculates the specific lengths of the three frames, and each frame period needs to be calculated, so that the calculation process of the current frame period needs to be completed in the last frame period.
Further, after the LTE user terminal enters the coverage area of the LTE system base station, the LTE system base station may allocate a sensing frame and a transmission frame in a frame period of the LTE user terminal, and the LTE user terminal detects whether a current channel of the unlicensed frequency band is in an idle state according to the sensing frame, and if the current channel is in the idle state, the LTE user terminal accesses the channel and performs data transmission, and if the current channel is detected to be in the non-idle state, the LTE user terminal does not transmit data on the transmission frame.
It should be noted that when the LTE ue detects the channel state according to the sensing frame, there is a certain false alarm probability, that is, whether the detection result of the LTE ue is correct. For example, if the LTE user terminal detects that the current channel is in an idle state, and actually the channel is in a non-idle state, the detection result is an error result, and the LTE user terminal does not perform data transmission on the transmission frame. In this embodiment, the false alarm probability is negative correlation according to the time slot length of the sensing frame, and the longer the time slot length of the sensing frame, the smaller the false alarm probability.
And S120, when the LTE user terminal is detected to finish the data transmission successfully, allocating the backoff frame of the current frame period to the LTE user terminal, and enabling the LTE user terminal to backoff out of the channel according to the backoff frame.
Specifically, the successful completion of data transmission refers to that the LTE user terminal successfully completes data transmission of the slot length of the transmission frame, and when the LTE user terminal senses that the current channel is in a non-idle state or senses that the current channel is in an idle state but is actually in a non-idle state (i.e., false alarm), the LTE user terminal cannot successfully complete data transmission.
When a controller in an LTE system base station detects that an LTE user terminal successfully completes data transmission, the controller allocates a backoff frame in a current frame period of the LTE user terminal, the LTE user terminal backs out a channel according to the backoff frame, and a WLAN user terminal can carry out detection and data transmission in the time slot length of the backoff frame, so that the opportunity that the WLAN system occupies the channel is increased, and the WLAN system and the LTE system can well coexist.
Fig. 2 is a schematic diagram of a coexistence time frame of a WLAN system and an LTE system according to an embodiment of the present invention. The upper diagram is a frame structure of the WLAN system, the lower diagram is a frame structure of the LTE system, and the horizontal axis is time. The LTE system base station perceives different modes to be allocated to the perception frame (the time slot length of which is T) in the user terminal frame period (the time slot length of which is T) according to the success or failure of the detection of the user terminal channel statesense) Transmission frame (with time slot length of T)trans) And a backoff frame (the slot length of which is T)back)。
When the LTE user terminal detects that the current channel is idle through the sensing frame, the channel is accessed, data transmission is carried out through the transmission frame, and after the transmission frame is finished, the LTE user terminal backs off the channel according to the backoff frame (the detection is successful). The WLAN user terminal can perform normal detection and data transmission within the backoff time, and when the backoff frame time of the LTE system is finished and the user terminal performs the detection of the next frame period, if the current channel is detected to be non-idle (the WLAN user terminal accesses the channel) or the false alarm detection is detected, the LTE user terminal cannot perform the data transmission until the transmission frame is finished and enters another frame period (the detection is failed).
According to the data frame distribution method provided by the embodiment of the invention, a backoff frame is added on the basis of the frame of the existing LTE system, and the channel occupancy and the throughput of the WLAN system are improved by reducing the channel occupancy of the LTE system, so that the WLAN system and the LTE system can well coexist, and the channel utilization rate of an unlicensed frequency band channel is also improved.
Example two
As shown in fig. 3, a second flowchart of a method for allocating data frames according to an embodiment of the present invention is considered as an extension of the method shown in fig. 1, where the method includes:
s310, calculating the time slot lengths of the sensing frame, the transmission frame and the backoff frame of the current frame period according to the channel occupation information of the unlicensed frequency band collected within a first preset time before the current time and the historically stored channel occupation information.
Specifically, the first predetermined time period is a preset time interval for acquiring channel occupancy information of the unlicensed frequency band, and can be freely set. E.g. a slot length of ten frame periods or a slot length of twenty frame periods, etc.
In this embodiment, the channel occupancy information includes the number of times of access attempts of the LTE system, the number of times of successful access of the LTE system, the number of contention points of the WLAN system, the throughput of contention points of the WLAN system, and the like.
The access times of the LTE system are the times of detecting the channel by the LTE user terminal, and the access times comprise the total times of detecting that the current channel is in an idle state and a non-idle state by the LTE user terminal; the successful access times of the LTE system are the times that the LTE user terminal detects that the current channel is in an idle state and data transmission is successful after the channel is accessed; the number of the WLAN system contention points is the number of the WLAN user terminals in the coverage range of the LTE system base station within a first preset time, namely the number of the WLAN user terminals contending for a channel with the LIT user terminals; the throughput of the WLAN system contention point is the throughput of the WLAN user terminal in the coverage range of the LTE system base station within the first preset time.
It should be noted that, because within the first predetermined time period, there may be WLAN user terminals coming in and going out of the coverage of the LTE system base station, and at the same time, throughput may also be changed, in this embodiment, the number of WLAN system contention points and the throughput of the WLAN system contention points are actually two average values, so as to represent an average change condition of the number of WLAN system contention points and the throughput information of the LAN system contention points within the first predetermined time period.
Further, the number of contention points of the WLAN system and the throughput of contention points of the WLAN system are information received in real time from the base station of the WLAN system. Because the controller in the LTE system base station cannot directly acquire data information in the WLAN system, the controller in the LTE system base station needs to send an instruction to the controller in the WLAN system base station to acquire the data, and the controller in the WLAN system base station sends the number of contention points of the WLAN system and the throughput of the contention points of the WLAN system to the controller in the LTE system base station in real time through the WLAN system base station, so as to meet the requirements of the controller in the LTE system base station.
Specifically, the historically stored channel occupation information is the channel occupation information stored in the controller in the LTE system base station (the number of times the LTE system attempts to access, the number of times the LTE system successfully accesses, the number of WLAN system contention points, and the throughput of the WLAN system contention points), and the storage mode may be fixed storage, such as storage of channel occupation information for a certain two months; the storage mode may also be real-time storage, for example, the number of times of LTE system attempted access and the number of times of LTE system successful access, which are acquired in real time by the controller in the LTE system base station, the number of WLAN system contention points and the throughput of WLAN system contention points, which are received in real time by the controller in the LTE system base station from the WLAN system base station.
In this embodiment, the step is a step of calculating the time slot lengths of the sensing frame, the transmission frame and the backoff frame of the current frame period in the above step S110.
Specifically, the current time is defined as the time for calculating the current frame period, and the current time must be a certain time in the previous frame period according to the deduction of time. In this embodiment, the acquired channel occupancy information within the first predetermined time period before the current time may be compared with the historically stored channel occupancy information, the state of the current channel is determined by using a big data statistical method (such as a neural network algorithm, a linear regression algorithm, or a clustering algorithm), the time slot lengths of the sensing frame, the transmission frame, and the backoff frame of the new frame period are calculated, and the new frame period is used as the current period.
S320, distributing the sensing frame and the transmission frame of the current frame period to the LTE user terminal in the coverage range of the LTE system base station according to the time slot lengths of the sensing frame, the transmission frame and the backoff frame of the current frame period calculated in the previous frame period; the sensing frame is used for detecting whether a channel at the current moment is in an idle state by an LTE user terminal; and the transmission frame is used for data transmission of the LTE user terminal.
In the present embodiment, the step S320 is the same as the above S110.
And S330, when the LTE user terminal is detected to finish the data transmission successfully, allocating the backoff frame of the current frame period to the LTE user terminal, and enabling the LTE user terminal to backoff out of the channel according to the backoff frame.
In this embodiment, the step S330 is the same as the step S120.
S340, when detecting that the LTE user terminal does not complete the data transmission successfully, allocating a sensing frame and a transmission frame of the next frame period to the LTE user terminal.
As shown in fig. 2, if the controller in the LTE system base station detects that the LTE user terminal does not complete data transmission successfully, the controller is not allocated to the backoff frame of the current frame period of the LTE user terminal, but directly allocated to the sensing frame and the transmission frame of the next frame period of the LTE user terminal, so that the LTE user terminal can directly enter the next frame period after the transmission frame of the current frame period is finished, and thus, a channel corresponding to the time slot length of the backoff frame can be saved.
According to the data frame distribution method provided by the embodiment of the invention, the acquired channel occupation information in the first preset time before the calculation time of the current frame period is compared with the historically stored channel occupation information, and the sensing frame, the transmission frame and the backoff frame of the current frame period are calculated, so that the coexistence problem of a WLAN system and an LTE system is solved, the real-time change channel state is adapted, and the channel utilization rate is further improved.
EXAMPLE III
As shown in fig. 4, a flowchart of a method for calculating a time slot length of a backoff frame in a method for allocating a data frame according to an embodiment of the present invention may be regarded as a specific implementation manner of the method for calculating a backoff frame in S310, where the method includes:
s410, calculating the successful access probability according to the acquired times of the LTE system attempted access and the times of the LTE system successful access of the unauthorized frequency band within a first preset time before the current time.
Specifically, let LTE of the unlicensed frequency band within a first predetermined time before the current timeThe number of times of access attempts of the system is NattemptThe successful access times of the LTE system are NsucThen probability of successful accessIs calculated by the formula
For example, if the LTE system attempts to access the cell for a number of times Nattempt10, the number of successful accesses N of the LTE systemsucSuccessful access probability, 8
And S420, searching the number of the WLAN system contention points matched with the successful access probability in the historically stored channel occupation information according to the successful access probability.
In this embodiment, because the data amount in the historically stored channel occupancy information is huge, the number of contention points of different WLAN systems corresponds to a certain successful access probability, the successful access probability fluctuates in a certain data range, and the successful access probability can be regarded as the average value of the data range. For example, if the number n of contention points of the WLAN system is 9, the probability of successful accessBetween 79% and 81%, can be considered asSimilarly, assume a probability of successful accessSearching and in historically stored channel occupancy informationThe number n of the matched WLAN system contention points is 9. The matching method canA clustering algorithm, a neural network algorithm, or a linear regression algorithm in statistics, etc.
In the present embodiment, if the LTE system attempts access for the number of times NattemptNumber of successful accesses N for LTE system, 5sucSuccessful access probability 4The number n of contention points for the WLAN system is also 9.
S430, according to the number of the WLAN system contention points, the throughput of the WLAN system contention points with the same number as the number of the WLAN system contention points and the throughput of the WLAN system contention points with the same number as the number of the WLAN system contention points plus one are searched.
Specifically, because the number of the WLAN system contention points within the coverage area of the LTE system base station changes with time, the throughput of the WLAN system contention points will also change continuously, a fixed number of the WLAN system contention points will correspond to the throughput of one WLAN system contention point, and the throughput of the WLAN system contention points will fluctuate within a certain range.
In this embodiment, the throughput S of the WLAN system contention points matching the WLAN system contention point number n is searched in the historically stored channel occupancy informationnAnd the throughput S of WLAN system contention points with the same number of WLAN system contention points plus one number n +1n+1. Generally, as the number of contention points of the WLAN system increases, the throughput of contention points of the WLAN system decreases, i.e., Sn+1＜Sn。
S440, according to the formulaCalculating the time slot length T of the back-off frameback。
In particular, assume that the probability of a successful access transmission isThe probability of a failed access attempt isAnd the duration of the failed access attempt is T-TbackIn a successful access attempt, assuming that the slot length of the sensing frame is much smaller than the slot length of the transmission frame and the slot length of the backoff frame, the slot length T of the transmission frametrans≈T-Tback. The channel occupancy rate of the unlicensed frequency band LTE system can be calculated as follows:
Φ = P ^ s u c ( T - T b a c k ) P ^ s u c T + ( 1 - P ^ s u c ) ( T - T b a c k ) .
in this embodiment, in order to ensure that the channel occupancy of the WLAN system cannot be too low, the channel occupancy of the LTE system needs to have an upper limit, and is selected according to the following formula:
Φ · S n n ≤ S n n - S n + 1 n + 1
left side of the above formulaThe method comprises the steps that after an LTE user terminal enters the coverage range of an LTE system base station, the average throughput of original n WLAN contention nodes is reduced; formula rightAfter 1 WLAN contention node is added, the throughput of the original n WLAN contention nodes is reduced. The expression of the formula means that the decrease degree of average throughput caused by adding one LTE user terminal to the original n WLAN contention nodes is lower than that caused by adding one WLAN contention node.
Obtained by solving the two formulas
Wherein T is the slot length of the frame period, PsucFor the successful access probability, n is the probability of successful access PsucThe number of the matched WLAN system contending for the points, n +1 is the probability P of successful accesssucThe number of the matched WLAN system contention points plus one, SnFor the throughput of WLAN system contention points of the same number n as the number of WLAN system contention points, Sn+1To the successful access probability PsucThe throughput of the WLAN system contention points under the same number of the matched WLAN system contention point number plus one number n + 1.
According to the time slot length calculation method of the backoff frame in the data frame allocation method provided by the embodiment of the invention, according to the successful access probability in the first preset time, the WLAN system contention point number information is searched in the historically stored channel occupation information, and then the WLAN system contention point throughput under the same number of the WLAN system contention points and the WLAN system contention point throughput under the same number of the WLAN system contention points plus one number of the WLAN system contention points are searched, and the time slot length of the backoff frame in the current frame period is calculated according to the information, so that the channel occupancy rate of the WLAN system is improved, and the channel utilization rate is improved.
Example four
As shown in fig. 5, a flowchart of a method for calculating a time slot length of a sensing frame in a method for allocating a data frame according to an embodiment of the present invention is considered as a specific implementation manner of the method for calculating a sensing frame in S310, where the method includes:
s510, a binary hypothesis model is established for the situation that the channel of the unlicensed frequency band is in an idle state and a non-idle state.
Specifically, assume s (n), u (n) represent WLAN system signals and additive white gaussian noise, respectively. When a WLAN system signal uses a channel for data transmission, the signal is detected by an LTE user terminal and is sampled at a frequency fsSampling is performed so that the time slot length T of the sensing framesenseThe number of the samples sampled is Tsensefs。
For an LTE ue in the sensing frame, its received signal y (n) obeys a binary hypothesis testing model (this is a prior art), as follows:
y ( n ) = u ( n ) : H 0 s ( n ) + u ( n ) : H 1
wherein H0For WLAN systems to be in idle state, H1For WLAN system in non-idle state, assume u (n) is an independent and identically distributed Gaussian random variable with mean 0 and varianceObedience distributionThe same assumption is madeAnd independently of u (n).
And S520, calculating the detection probability and the false alarm probability of the LTE user terminal according to the binary hypothesis model.
Specifically, the meaning of the detection probability is to determine whether the LTE user terminal performs detection. Since the channel WLAN system is in an idle state or a non-idle state (in this embodiment, only the WLAN system and the LTE system are considered, and therefore the WLAN system is in the idle state or the non-idle state, that is, the channel is in the idle state or the non-idle state), the LTE user terminal can perform channel detection, and therefore when the WLAN system is in the idle state, the LTE user terminal has a certain probability of performing channel detection.
In this embodiment, according to the formula of the binary hypothesis test model, the detection probability of the LTE ue when the WLAN system is in a non-idle state and the threshold value is greater than the threshold value (this is prior art) can be calculated
P d = Pr ( T ( y ) > ϵ | H 1 ) = Q ( ( ϵ σ u 2 - γ - 1 ) 1 γ + 1 T s e n s e f s 2 ) ;
Where Q (x) is a Q function, which is a threshold value, and γ is a signal-to-noise ratio.
Meanwhile, the false alarm probability of the LTE user terminal is obtained when the WLAN system is in an idle state and the threshold value is larger than the threshold value (the prior art)
P f = Pr ( T ( y ) > ϵ | H 0 ) = Q ( ( ϵ σ u 2 - 1 ) T s e n s e f s 2 ) .
S530, calculating the average throughput of the LTE system when the channel is in the idle state and the average throughput of the LTE system when the channel is in the non-idle state according to the detection probability and the false alarm probability.
In particular, assume C0For the throughput of the LTE system with the channel in idle state, the occurrence probability is (1-P)f)P(H0)。C1The throughput of the LTE system with the channel in the non-idle state is shown, and the occurrence probability is (1-P)d)P(H1) (ii) a Wherein, P (H)0) And P (H)1) Can be obtained by the following formula (this is prior art)
Wherein,and the transmission probability of each station in a time slot is represented by p, the collision probability is represented by W, the minimum contention window of the WLAN system is represented by n, the number of contention points of the WLAN system is represented by m, and the maximum backoff order is represented by m.
Finally, the average throughput R of the LTE system under the idle state of the channel is obtained through calculation0＝C0(1-PfPH0, average throughput of LTE system with WLAN system in non-idle state R1 — C11-PdPH 1.
S540, according to the formulaAnd calculating the time slot length T of the sensing frame by a traversal algorithmsense。
In this embodiment, the average throughput R of the LTE system when the channel is in the non-idle state1＝C1(1-Pd)P(H1) It can be known that the detection probability PdAverage throughput R of LTE system when it is too small1The probability P is checked to be large in order to avoid an excessive throughput of the LTE systemdNeed to be greater than a certain detection probability thresholdNamely, it is
Meanwhile, in order to ensure that the LTE user terminal achieves a smaller false alarm probability when detecting the channel, the sensing frame needs to be increased as much as possibleTime slot length TsenseTherefore, the calculation formula of the average perceived throughput for the objective function LTE systemT in (1)senseThe value of (c) is maximized as much as possible.
From the above formula, the objective function is relative to TsenseFor convex functions, there is at least one maximum on the curve of the target function, at TsenseThe maximum value can be calculated by a traversal algorithm in the range and is taken as the optimal Tsense；
Wherein, TbackIs the time slot length of the backoff frame of the current frame period (which can be obtained by solving according to the above embodiment), T is the time slot length of the frame period, R0Average throughput, R, of the LTE system with the channel in idle state1Average throughput, P, of the LTE system with the channel in a non-idle statedIn order to detect the probability of the occurrence,is a detection probability threshold.
The method for calculating the time slot length of the sensing frame in the data frame allocation method provided by the embodiment of the invention is characterized in that a binary hypothesis model is established for the channel state in an idle state or a non-idle state, the detection probability, the false alarm probability, the average throughput of the LTE system when the channel is in the idle state and the average throughput of the LTE system when the channel is in the non-idle state are calculated, an objective function of the average sensing throughput of the LTE system is determined, and the time slot length of the optimal sensing frame in the objective function is calculated by using a traversal method according to the lower limit of the predefined detection probability. The method searches the optimal time slot length of the sensing frame on the premise of ensuring the detection probability of the LTE user terminal, and reduces the false alarm probability.
Further, the calculating the time slot length of the transmission frame of the current frame period according to the channel occupation information of the unlicensed frequency band acquired within the first predetermined time before the current time and the historically stored channel occupation information includes:
according to the formula Ttrans＝T-Tback-TsenseCalculating the time slot length T of the transmission frametrans；
Wherein, TsensrIs the time slot length, T, of the sensing frame of the current frame periodbackAnd T is the time slot length of the backoff frame of the current frame period.
In this embodiment, since the time slot length of the frame period is a fixed value, and the frame period is sequentially divided into the sensing frame, the transmission frame, and the backoff frame, the time slot length of the transmission frame can be determined according to the time slot length of the sensing frame and the time slot length of the backoff frame obtained in the above embodiments.
EXAMPLE five
As shown in fig. 6, a flowchart of a data transmission method provided in an embodiment of the present invention is applied to an LTE user terminal, and the method includes:
s610, acquiring a sensing frame and a transmission frame distributed by a controller in an LTE system base station; the sensing frame and the transmission frame are allocated to the LTE user terminal when the controller calculates the time slot lengths of the sensing frame, the transmission frame and the backoff frame of the current frame period.
Specifically, after the LTE user terminal enters the coverage area of the LTE system base station, the controller in the LTE system base station may allocate the sensing frame and the transmission frame to the LTE user terminal according to the calculated time slot lengths of the sensing frame, the transmission frame, and the backoff frame in the frame period (the calculation method of each frame is the same as that in the above-mentioned embodiment, and is not described here again).
And S620, detecting whether the channel is in an idle state according to the sensing frame.
Specifically, the LTE user terminal detects whether the channel is in an idle state according to the time slot length of the sensing frame. In this embodiment, the longer the detection time of the LTE user terminal is, the lower the false alarm probability is.
S630, when detecting that the channel is in an idle state according to the sensing frame distributed by the controller in the LTE system base station, accessing the channel, and transmitting data according to the transmission frame distributed by the controller.
Specifically, if the current channel is detected to be in an idle state, the LTE user terminal accesses the channel and performs data transmission according to a transmission frame; and if the current channel is detected to be in a non-idle state, the user terminal does not transmit data until the end of the transmission frame.
And S640, after the data transmission is successfully completed, receiving a backoff frame distributed by the controller, and backoff out the channel according to the backoff frame.
Specifically, after the LTE system base station controller detects that the LTE user terminal successfully completes data transmission, a backoff frame of a current frame period is allocated to the LTE user terminal, the LTE user terminal backs out a channel according to the backoff frame until the backoff frame is finished and then enters a next frame period, and the WLAN user terminal can perform normal detection and data transmission within a time slot length of the backoff frame of the LTE system, so that the backoff frame of the LTE system provides the WLAN user terminal with a chance of occupying the channel.
Further, if the LTE system base station controller detects that the LTE user terminal does not successfully complete data transmission, after the transmission frame of the current frame period is finished, the backoff frame of the current frame period of the LTE user terminal is not allocated, but directly allocated to the sensing frame and the transmission frame of the next frame period of the LTE user terminal.
According to the data transmission method provided by the embodiment of the invention, the LTE user terminal can actively retreat from the channel after the data transmission is finished, and the time slot length of the retreat frame is vacated for the WLAN user terminal to carry out detection and data transmission, so that the channel occupancy rate of the WLAN system is increased, the coexistence problem of the WLAN system and the LTE system is solved, and the channel utilization rate of the unauthorized frequency band is improved.
EXAMPLE six
As shown in fig. 7, a first structural diagram of an apparatus for allocating a data frame according to an embodiment of the present invention is applied to a controller in a base station of an LTE system, and is configured to execute the method shown in fig. 1, where the apparatus includes a first sensing frame and transmission frame allocating module 7100 and a backoff frame allocating module 7200.
A first sensing frame and transmission frame allocation module 7100, configured to allocate, according to the time slot lengths of the sensing frame, the transmission frame, and the backoff frame of the current frame period calculated in the previous frame period, the sensing frame and the transmission frame of the current frame period to an LTE user terminal in the coverage area of the LTE system base station; the sensing frame is used for detecting whether a channel at the current moment is in an idle state by an LTE user terminal; and the transmission frame is used for data transmission of the LTE user terminal.
A backoff frame allocation module 7200, configured to allocate the backoff frame of the current frame period to the LTE user terminal after detecting that the LTE user terminal successfully completes data transmission, so that the LTE user terminal backs out the channel according to the backoff frame.
The data frame distribution device provided by the embodiment of the invention adds a backoff frame on the basis of the frame of the existing LTE system, improves the channel occupancy and the throughput of the WLAN system by reducing the channel occupancy of the LTE system, enables the WLAN system and the LTE system to well coexist, and simultaneously improves the channel utilization rate of an unlicensed frequency band channel.
EXAMPLE seven
As shown in fig. 8, a second structure diagram of an apparatus for allocating a data frame according to an embodiment of the present invention is used to execute the method shown in fig. 3, and the apparatus includes a first sensing frame and transmission frame allocating module 7100, a backoff frame allocating module 7200, a time slot length calculating module 7300, and a second sensing frame and transmission frame allocating module 7400.
The time slot length calculating module 7300 is configured to calculate the time slot lengths of the sensing frame, the transmission frame, and the backoff frame of the current frame period according to the channel occupancy information of the unlicensed frequency band acquired within a first predetermined time period before the current time and the historically stored channel occupancy information.
Specifically, the channel occupancy information includes: the number of times of access attempts of the LTE system, the number of times of successful access of the LTE system, the number of contention points of the WLAN system and the throughput of the contention points of the WLAN system. The number of the WLAN system contention points and the throughput of the WLAN system contention points are information sent by the WLAN system base station and received in real time.
A first sensing frame and transmission frame allocation module 7100, configured to allocate, according to the time slot lengths of the sensing frame, the transmission frame, and the backoff frame of the current frame period calculated in the previous frame period, the sensing frame and the transmission frame of the current frame period to an LTE user terminal in the coverage area of the LTE system base station; the sensing frame is used for detecting whether a channel at the current moment is in an idle state by an LTE user terminal; and the transmission frame is used for data transmission of the LTE user terminal.
A backoff frame allocation module 7200, configured to allocate the backoff frame of the current frame period to the LTE user terminal after detecting that the LTE user terminal successfully completes data transmission, so that the LTE user terminal backs out the channel according to the backoff frame.
A second sensing frame and transmission frame allocation module 7400, configured to allocate the sensing frame and the transmission frame of the next frame period to the LTE user terminal after detecting that the LTE user terminal does not complete data transmission successfully.
Specifically, the timeslot length calculation module 7300 includes: a sensing frame slot length calculation unit 7310, a transmission frame slot length calculation unit 7320, and a backoff frame slot length calculation unit 7330.
The sensing frame time slot length calculating unit 7310 is configured to calculate the time slot length of the sensing frame of the current frame period according to the channel occupancy information of the unlicensed frequency band collected within a first predetermined time period before the current time and the historically stored channel occupancy information.
The transmission frame time slot length calculating unit 7320 is configured to calculate the time slot length of the transmission frame of the current frame period according to the channel occupancy information of the unlicensed frequency band collected within a first predetermined time period before the current time and the historically stored channel occupancy information.
The backoff frame time slot length calculating unit 7330 is configured to calculate the time slot length of the backoff frame of the current frame period according to the channel occupancy information of the unlicensed frequency band collected within a first predetermined time period before the current time and the historically stored channel occupancy information.
The data frame distribution device provided by the embodiment of the invention compares the acquired channel occupation information within the first preset time before the calculation time of the current frame period with the historically stored channel occupation information to calculate the sensing frame, the transmission frame and the backoff frame of the current frame period, solves the coexistence problem of the WLAN system and the LTE system, adapts to the real-time changing channel state and further improves the utilization rate of the channel.
Example eight
Fig. 9 is a schematic structural diagram of a back-off frame slot length calculating unit in a data frame allocating apparatus according to an embodiment of the present invention, where the back-off frame slot length calculating unit is configured to execute the method shown in fig. 4.
The backoff frame slot length calculation unit 7330 includes: a successful access probability generating sub-unit 7331, a WLAN system contention point number generating sub-unit 7332, a WLAN system contention point throughput generating sub-unit 7333, and a backoff frame slot length generating sub-unit 7334.
A successful access probability generating subunit 7331, configured to calculate a successful access probability according to the number of times of access attempts of the LTE system and the number of times of successful access of the LTE system in the unlicensed frequency band within the first predetermined time before the current time that are acquired.
A WLAN system contention point number generating subunit 7332, configured to search, according to the successful access probability, the number of contention points of the WLAN system, which is matched with the successful access probability, in the historically stored channel occupancy information.
A WLAN system contention point throughput generating subunit 7333, configured to search, according to the number of the WLAN system contention points, the throughput of the WLAN system contention points in the number equal to the number of the WLAN system contention points, and the throughput of the WLAN system contention points in the number equal to the number of the WLAN system contention points plus one.
A back-off frame slot length generation subunit 7334 for generating the slot length according to the formulaCalculating the time slot length T of the back-off frameback。
Wherein T is the slot length of the frame period, PsucFor the successful access probability, n is the probability of successful access PsucThe number of the matched WLAN system contending for the points, n +1 is the probability P of successful accesssucThe number of the matched WLAN system contention points plus one, SnFor the throughput of WLAN system contention points of the same number n as the number of WLAN system contention points, Sn+1To the successful access probability PsucThe throughput of the WLAN system contention points under the same number of the matched WLAN system contention point number plus one number n + 1.
The backoff frame time slot length calculating unit in the data frame distributing device provided by the embodiment of the invention searches the WLAN system contention point number information in the historical stored channel occupation information according to the successful access probability in the first preset time, further searches the WLAN system contention point throughput under the same number of the WLAN system contention points and the WLAN system contention point throughput under the same number of the WLAN system contention points plus one, and calculates the time slot length of the backoff frame of the current frame period according to the information, thereby improving the channel occupancy rate of the WLAN system and the channel utilization rate.
Example nine
Fig. 10 is a schematic structural diagram of a perceptual frame slot length calculating unit in an apparatus for allocating data frames according to an embodiment of the present invention, where the unit is configured to execute the method shown in fig. 5.
The perceptual frame slot length calculation unit 7310 includes: a binary hypothesis model generation sub-unit 7311, a detection probability and false alarm probability generation sub-unit 7312, an LTE system average throughput generation sub-unit 7313, and a perceptual frame slot length generation sub-unit 7314.
A binary hypothesis model generating subunit 7311, configured to establish a binary hypothesis model for a situation where a channel in the unlicensed frequency band is in an idle state and a non-idle state.
A detection probability and false alarm probability generating subunit 7312, configured to calculate the detection probability and false alarm probability of the LTE user terminal according to the binary hypothesis model.
An LTE system average throughput generating subunit 7313, configured to calculate, according to the detection probability and the false alarm probability, an average throughput of the LTE system when the channel is in an idle state and an average throughput of the LTE system when the channel is in a non-idle state.
A perceptual frame slot length generation subunit 7314 for generating a perceptual frame slot length according to a formula And calculating said by a traversal algorithmTime slot length T of sensing framesense。
Wherein, TbackIs the time slot length of the backoff frame of the current frame period, T is the time slot length of the frame period, R0Average throughput, R, of the LTE system with the channel in idle state1Average throughput, P, of the LTE system with the channel in a non-idle statedIn order to detect the probability of the occurrence,is a detection probability threshold.
The sensing frame time slot length calculating unit in the data frame distributing device provided by the embodiment of the invention establishes a binary hypothesis model for the channel state in an idle state or a non-idle state, calculates the detection probability, the false alarm probability, the average throughput of the LTE system with the channel in the idle state and the average throughput of the LTE system with the channel in the non-idle state, determines an objective function of the average sensing throughput of the LTE system, and calculates the time slot length of the optimal sensing frame in the objective function by using a traversal method according to the lower limit of the predefined detection probability. The method searches the optimal time slot length of the sensing frame on the premise of ensuring the detection probability of the LTE user terminal, and reduces the false alarm probability.
Example ten
Fig. 11 is a schematic structural diagram of a data transmission apparatus according to an embodiment of the present invention, which is applied to an LTE user terminal and configured to execute the method shown in fig. 6. The data transmission device includes: a perceptual frame and transport frame acquisition module 1110, a channel detection module 1120, a data transmission module 1130, and a channel backoff module 1140.
A sensing frame and transmission frame acquiring module 1110, configured to acquire a sensing frame and a transmission frame allocated by a controller in an LTE base station; the sensing frame and the transmission frame are allocated to the LTE user terminal when the controller calculates the time slot lengths of the sensing frame, the transmission frame and the backoff frame of the current frame period;
a channel detection module 1120 for detecting whether the channel is in an idle state according to the sensing frame
A data transmission module 1130, configured to access a channel when it is detected that the channel is in an idle state according to a sensing frame allocated by a controller in a base station of an LTE system, and perform data transmission according to a transmission frame allocated by the controller.
And a channel backoff module 1140, configured to receive a backoff frame allocated from the controller after data transmission is successfully completed, and backoff the channel according to the backoff frame.
According to the data transmission device provided by the embodiment of the invention, the LTE user terminal can actively retreat from the channel after the data transmission is finished, and the time slot length of the retreat frame is vacated for the WLAN user terminal to carry out detection and data transmission, so that the channel occupancy rate of the WLAN system is increased, the coexistence problem of the WLAN system and the LTE system is solved, and the channel utilization rate of the unauthorized frequency band is improved.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
All the embodiments in the present specification are described in a related manner, and the same and similar parts among the embodiments may be referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, for the system embodiment, since it is substantially similar to the method embodiment, the description is simple, and for the relevant points, reference may be made to the partial description of the method embodiment.
The above description is only for the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall fall within the protection scope of the present invention.

Claims (10)

1. A method for allocating data frames is applied to a controller in a base station of an LTE system, and comprises the following steps:
allocating the sensing frame and the transmission frame of the current frame period to an LTE user terminal in the coverage range of the LTE system base station according to the time slot lengths of the sensing frame, the transmission frame and the backoff frame of the current frame period calculated in the previous frame period; the sensing frame is used for detecting whether a channel at the current moment is in an idle state by an LTE user terminal; the transmission frame is used for data transmission of the LTE user terminal;
and when the LTE user terminal is detected to finish the data transmission successfully, allocating the backoff frame of the current frame period to the LTE user terminal, and enabling the LTE user terminal to backoff out of the channel according to the backoff frame.
2. The method of claim 1, wherein the slot lengths of the sensing frame, the transmission frame and the backoff frame of the current frame period are calculated by:
and calculating the time slot lengths of the sensing frame, the transmission frame and the backoff frame of the current frame period according to the channel occupation information of the unauthorized frequency band acquired within a first preset time before the current time and the historically stored channel occupation information.
3. The method of claim 2, wherein the channel occupancy information comprises: the access times of the LTE system, the successful access times of the LTE system, the number of the WLAN system contention points and the throughput of the WLAN system contention points;
the calculating the time slot length of the backoff frame of the current frame period according to the channel occupation information of the unlicensed frequency band acquired within a first preset time before the current time and the historically stored channel occupation information includes:
calculating the successful access probability according to the acquired times of access attempts of the LTE system and the times of successful access of the LTE system in the unauthorized frequency band within a first preset time before the current time;
searching the number of WLAN system contention points matched with the successful access probability in the historically stored channel occupation information according to the successful access probability;
according to the number of the WLAN system contention points, the throughput of the WLAN system contention points with the number equal to that of the WLAN system contention points and the throughput of the WLAN system contention points with the number equal to that of the WLAN system contention points plus one are searched;
according to the formulaCalculating the time slot length of the backoff frame;
wherein T is the slot length of the frame period, PsucFor the successful access probability, n is the probability of successful access PsucThe number of the matched WLAN system contending for the points, n +1 is the probability P of successful accesssucThe number of the matched WLAN system contention points plus one, SnFor the throughput of WLAN system contention points of the same number n as the number of WLAN system contention points, Sn+1To the successful access probability PsucThe throughput of the WLAN system contention points under the same number of the matched WLAN system contention point number plus one number n + 1.
4. The method of claim 3 wherein the number of WLAN system contention points and the throughput of the WLAN system contention points are information received in real time from a WLAN system base station.
5. The method according to claim 3, wherein the calculating a time slot length of a sensing frame of the current frame period according to the channel occupancy information of the unlicensed frequency band collected within a first predetermined time period before the current time and the historically stored channel occupancy information includes:
establishing a binary hypothesis model for the condition that a channel of an unauthorized frequency band is in an idle state and a non-idle state;
calculating the detection probability and the false alarm probability of the LTE user terminal according to the binary hypothesis model;
calculating the average throughput of the LTE system when the channel is in an idle state and the average throughput of the LTE system when the channel is in a non-idle state according to the detection probability and the false alarm probability;
according to the formula And calculating the time slot length T of the sensing frame by a traversal algorithmsense；
Wherein, TbackIs the time slot length of the backoff frame of the current frame period, T is the time slot length of the frame period, R0Average throughput, R, of the LTE system with the channel in idle state1Average throughput, P, of the LTE system with the channel in a non-idle statedIn order to detect the probability of the occurrence,is a detection probability threshold.
6. The method according to claim 4, wherein the calculating a time slot length of a transmission frame of the current frame period according to the channel occupancy information of the unlicensed frequency band collected within a first predetermined time period before the current time and the historically stored channel occupancy information includes:
according to the formula Ttrans＝T-Tback-TsenseCalculating the time slot length T of the transmission frametrans；
Wherein, TsenseIs the time slot length, T, of the sensing frame of the current frame periodbackAnd T is the time slot length of the backoff frame of the current frame period.
7. The method according to any one of claims 1-6, further comprising:
and when detecting that the LTE user terminal does not successfully finish data transmission, allocating a sensing frame and a transmission frame of the next frame period to the LTE user terminal.
8. A data transmission method is applied to an LTE user terminal, and comprises the following steps:
acquiring a sensing frame and a transmission frame distributed by a controller in an LTE system base station; the sensing frame and the transmission frame are allocated to the LTE user terminal when the controller calculates the time slot lengths of the sensing frame, the transmission frame and the backoff frame of the current frame period;
detecting whether the channel is in an idle state according to the sensing frame;
when detecting that a channel is in an idle state according to a sensing frame distributed by a controller in an LTE system base station, accessing the channel, and transmitting data according to a transmission frame distributed by the controller;
and after the data transmission is successfully completed, receiving a backoff frame distributed by the controller, and backoff out the channel according to the backoff frame.
9. An apparatus for allocating data frames, applied to a controller in a base station of an LTE system, the apparatus comprising:
the first sensing frame and transmission frame distribution module is used for distributing the sensing frame and the transmission frame of the current frame period to the LTE user terminal in the coverage range of the LTE system base station according to the time slot lengths of the sensing frame, the transmission frame and the backoff frame of the current frame period calculated in the previous frame period; the sensing frame is used for detecting whether a channel at the current moment is in an idle state by an LTE user terminal; the transmission frame is used for data transmission of the LTE user terminal;
and the backoff frame allocation module is used for allocating the backoff frame of the current frame period to the LTE user terminal to enable the LTE user terminal to backoff out the channel according to the backoff frame after detecting that the LTE user terminal successfully completes data transmission.
10. A data transmission device, applied to an LTE user terminal, the device comprising:
the sensing frame and transmission frame acquisition module is used for acquiring the sensing frame and the transmission frame distributed by the controller in the LTE system base station; the sensing frame and the transmission frame are allocated to the LTE user terminal when the controller calculates the time slot lengths of the sensing frame, the transmission frame and the backoff frame of the current frame period;
the channel detection module is used for detecting whether the channel is in an idle state or not according to the sensing frame;
the data transmission module is used for accessing the channel when detecting that the channel is in an idle state according to a sensing frame distributed by a controller in an LTE system base station, and transmitting data according to a transmission frame distributed by the controller;
and the channel backoff module is used for receiving a backoff frame distributed by the controller after the data transmission is successfully completed, and backoff the channel according to the backoff frame.
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