CN105979603B - UAV Board Data link dispatching method based on TD-LTE technology towards letter flow QoS guarantee - Google Patents
UAV Board Data link dispatching method based on TD-LTE technology towards letter flow QoS guarantee Download PDFInfo
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Abstract
The invention discloses a kind of based on UAV Board Data link dispatching method of the TD-LTE technology towards letter flow QoS guarantee: being cooperated under the control of a variety of signalings realization by radio-resource-configuration module, channel status probe module and the information flow recovery module at the information flow generation module of UAV Communication terminal, classification map module, scheduler module and channel status probe module and eNodeB.The present invention uses 4G communication network TD-LTE, propose a kind of unmanned plane information flow classification map method and dispatching algorithm, the various information that control administrative center can be returned in flight course for unmanned plane provides differentiation and transmits service, provides effective link guarantee for the reliable acquisition information flown and obtain high quality of unmanned plane.
Description
Technical Field
The invention belongs to the technical field of unmanned aerial vehicles, relates to a scheduling method, and particularly relates to a small civil unmanned aerial vehicle uplink scheduling method for QoS guarantee of various signal flows based on a TD-LTE technology.
Background
The small civil unmanned aerial vehicle has the advantages of simple structure, small size and low cost; the flight and maintenance cost is low, and the severe environment is not feared; the unmanned aerial vehicle is flexible to use and convenient to carry, and does not need a special airport and large ground equipment, so that the small civil unmanned aerial vehicle can be applied to the fields of natural disaster prevention and treatment, urban and rural construction and planning, scientific observation, public security frontier defense and the like.
The unmanned aerial vehicle communication system is one of important subsystems, and is a key point for the unmanned aerial vehicle to communicate with a control management center in real time, feed back flight state and information and receive commands of the control management center. At present, an unmanned aerial vehicle system mainly adopts a wireless communication technology based on a satellite, Wi-Fi, Bluetooth or Zigbee (Zigbee), has the defects of limited transmission distance, low transmission rate, poor instantaneity and the like, and is difficult to meet the future development requirement of a civil unmanned aerial vehicle. With the development of 4G mobile communication technology and the rise of "internet +" thinking, some scholars and research institutions consider to adopt 4G network control to realize unmanned aerial vehicle communication, for example, md. arafauur Rahman adopts 4G WiMAX technology to design an unmanned aerial vehicle communication system for avalanche rescue; the American AT & T company announces that the performance of the unmanned aerial vehicle when being connected with a 4G LTE network is tested and optimized in cooperation with the Intel company; there are also manufacturers in China, such as China Mobile, which also start trying to control unmanned aerial vehicles using 4G networks. Taking TD-LTE technology with national proprietary intellectual property as an example, the method can support cell coverage with the radius of 100 km; the access service of more than 100km/s can be provided for high-speed mobile users lower than 350 km/h; the one-way transmission time delay in the user plane is lower than 5ms, the transition time of the control plane from the sleep state to the active state is lower than 50ms, and the transition time of the control plane from the residence state to the active state is lower than 100 ms; a variety of bandwidths from 1.25MHz to 20MHz can be flexibly configured. When the bandwidth is 20MHz, the TD-LTE system can achieve the frequency spectrum utilization rate of 10.8bit/Hz at the lower action and 5.4bit/Hz at the uplink, and can provide the standard peak rate of 100Mb/s at the lower action and 50Mb/s at the uplink, and the system peak rate of 200Mb/s at the lower action and 100Mb/s at the uplink. Meanwhile, the multi-antenna technology adopted by the TD-LTE system can improve the user performance at the edge of the cell through shaping, and improve the cell capacity and the anti-interference capability. Therefore, the 4G technology is introduced into a small civil unmanned aerial vehicle communication system, the transmission performance of the system is expected to be greatly optimized, and a good link foundation is provided for multimedia full-interactive communication between the unmanned aerial vehicle and a control management center.
Table 1 comparison of transmission performance of prior art communication technologies
| QoS | Satellite communication | Wi-Fi | Zigbee | 4G LTE/WiMAX |
| Data transmission rate>1Mbps | Is that | Is that | Whether or not | Is that |
| Distance of transmission between nodes>1km | Is that | Whether or not | Is that | Is that |
| Mobility | Is that | Is that | Is that | Is that |
| Low delay jitter | Is that | Is that | Whether or not | Is that |
| Price | Is expensive | Is cheap | Is cheap | Is moderate |
At present, some documents perform performance simulation evaluation on a 4G transmission link scheduling algorithm, however, research on an unmanned aerial vehicle communication system based on 4G is still in a starting stage, and a transmission link scheduling strategy is rarely researched specifically for the unmanned aerial vehicle communication system.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides an unmanned aerial vehicle uplink scheduling method facing to the QoS guarantee of the traffic flow based on the TD-LTE technology.
The purpose of the invention is realized by the following technical scheme:
the unmanned aerial vehicle uplink scheduling method facing to the signal flow QoS guarantee based on the TD-LTE technology is realized by the cooperation of an information flow generation module, a classification mapping module, a scheduling module and a channel state detection module at an unmanned aerial vehicle communication terminal, and a wireless resource configuration module, a channel state detection module and an information flow recovery module at an eNodeB under the control of various signaling, and comprises the following steps:
1) and (3) information flow classification mapping:
an information flow generation module at the unmanned aerial vehicle communication terminal submits the acquired application-level information flow to a classification mapping module for classification mapping;
2) uplink radio resource request:
at the scheduling moment, a scheduling module at an unmanned aerial vehicle communication terminal sends an uplink wireless resource request signaling to a wireless resource configuration module at an eNodeB, and the sending period of the uplink wireless resource request signaling and the position of the uplink wireless resource request signaling in a subframe are configured and determined by the wireless resource configuration module at the eNodeB;
3) detecting the quality of an uplink channel:
when an information flow packet needs to be scheduled, a scheduling module at an unmanned aerial vehicle communication terminal sends an uplink wireless resource request signaling to a channel state detection module of the unmanned aerial vehicle communication terminal, and triggers the channel state detection module of the unmanned aerial vehicle communication terminal to periodically send a channel detection signaling to a channel state detection module at an eNodeB, and the channel state detection module at the eNodeB compares a channel detection reference signal borne by the channel detection signaling with a known signal, so that the quality of a current uplink channel is known;
4) and (3) wireless resource allocation:
a wireless resource configuration module at an eNodeB performs wireless resource configuration on information flow to be scheduled at an unmanned aerial vehicle communication terminal according to a user identifier and data volume to be transmitted, and transmits a user-wireless resource configuration result to a scheduling module at the unmanned aerial vehicle communication terminal through a wireless resource configuration signaling, so that the scheduling module is informed of which carrier at which time the data can be transmitted, and the adopted modulation and coding scheme;
5) information flow HOL packet scheduling:
a scheduling module at the unmanned aerial vehicle communication terminal calculates a scheduling weight function psi when different information flows, users and wireless resources are configured according to a user-wireless resource configuration result, HOL groups in various information flow cache queues, QCI hierarchical weight and time delay performance weightl,n,k(t) taking a value to give a priority scheduling right to the HOL packet with the maximum function value;
6) and (3) information flow recovery:
and the scheduling module at the unmanned aerial vehicle communication terminal sequentially submits various information flow packets to be scheduled to the information flow recovery module at the eNodeB, and the information flow recovery module encapsulates and frames the received packets according to the information flow identifier and the user identifier bound to each packet and the radio resource configuration result carried on the radio resource configuration signaling, so that the transmission of various information flows is finally realized.
Further, the step 1) is specifically:
firstly, endowing packets in each type of information flow buffer queue with corresponding QCI hierarchical weight according to QCI grades in an LTE/SAE protocol framework;
secondly, according to the waiting time delay of the head group in the various information flow buffer queues in the buffer queues, giving corresponding time delay performance weight to the head group;
finally, a user identifier and an information flow identifier are bound for each information flow packet.
Further, in step 2), the scheduling module at the drone communication terminal needs to tell the radio resource configuration module at the eNodeB about the amount of data to be transmitted and the user identifier in the uplink radio resource request process.
Further, in the step 3), the channel state detection module at the eNodeB periodically sends the updated uplink channel quality identifier signaling to the radio resource configuration module, so as to inform the radio resource available during information flow scheduling to overcome the time-varying property of the radio channel.
Further, in the step 5), the scheduling module at the communication terminal of the unmanned aerial vehicle schedules the packets in the same information flow buffer queue according to a first-in first-out sequence.
Further, the scheduling weight function of the unmanned aerial vehicle communication terminal is determined according to the following steps:
weighting PF by a factorIntroducing a scheduling weight function psil,n,kIn (t), letSatisfies the formula (4):
wherein R isn,k(t) is time t the nth drone communication terminal information stream if the data transmission rate delivered to the eNodeB via the kth RB is expected,the information flow average data transmission rate of the nth unmanned aerial vehicle communication terminal at the last moment, namely the t-1 moment; wherein,given by:
wherein R isn(t) is the instantaneous data transmission rate of the nth drone communication terminal at time t, α being a scaling factor and given by:
wherein, TWA time window that affects user fairness;
weighting factor omega of CQIlIntroducing a scheduling weight function psil,n,kIn (t), let ω bel∈(0,1]Satisfies the following equation (7):
the formula (7) ensures that the scheduling module at the communication terminal of the unmanned aerial vehicle always allocates a larger CQI weight factor to the HOL packet with higher CQI priority in the classification mapping module, and allocates a smaller CQI weight factor to the HOL packet with lower CQI priority, so that the HOL packet with higher CQI weight factor is given the right of obtaining preferential scheduling, and preliminary QoS transmission guarantee is provided for information streams with different delay requirements and packet loss rate requirements;
for video service and audio service, the time delay is ensured by a factor omegal,n(t) introducing a scheduling weight function psil,n,kIn (t), let ω bel,n(t)∈(0,1]Satisfies the following equation (8):
in the formula (8), TlThe maximum waiting time delay requirement, tau, of the QCI information flow packets to be scheduled at the l level in a cache queue of a classification mapping module of the unmanned aerial vehicle communication terminall,n(t)∈(0,Tl]Waiting time, delta T, of HOL packets to be scheduled in a cache queue for scheduling time T nth level QCI information flow of unmanned aerial vehicle communication terminall∈(0,Tl]The guard time interval predetermined for the system is usually set as the frame length, i.e. the interval between two schedules; if Δ Tl≤Tl-τl,n(t), i.e. τl,n(t)∈(0,Tl-ΔTl]Then the waiting time of the HOL packet can meet the delay requirement; if Δ Tl＞Tl-τl,n(t), i.e. τl,n(t)∈(Tl-ΔTl,Tl]If the waiting time of the HOL packet is about to exceed the delay limit, the scheduling priority is the highest, and the scheduling module should give the right to obtain the priority scheduling;
scheduling weight function psi suitable for unmanned aerial vehicle communication terminall,n,k(t)∈(0,1]Can be given by formula (9):
at each scheduling moment, the scheduling module performs matching calculation among the available unmanned aerial vehicle communication terminal set, the wireless resource block set to be allocated and the HOL packet set to be scheduled according to the formula (9), and searches out a wireless resource matching identifier corresponding to the maximum scheduling weight function value, so that the specific information flow of the corresponding user is transmitted on the corresponding wireless resource block.
The invention has the following beneficial effects:
the invention provides a small civil unmanned aerial vehicle uplink scheduling method facing various information flow QoS guarantees by adopting a 4G communication network TD-LTE, provides an unmanned aerial vehicle information flow classification mapping method and a scheduling algorithm, can provide differentiated transmission service for various information returned to a control management center by an unmanned aerial vehicle in a flight process, and provides effective link guarantees for reliable flight of the unmanned aerial vehicle and acquisition of high-quality acquired information.
Drawings
Fig. 1 is a schematic view of a communication system of a small civil unmanned aerial vehicle;
fig. 2 is a block diagram of the uplink scheduling of the drone of the present invention;
FIG. 3 is a wireless frame structure diagram of the TD-LTE system;
FIG. 4 is a graph of audio stream packet loss comparison;
FIG. 5 is a graph of a comparison of packet loss rates for video streams;
fig. 6 is a comparison diagram of fairness of communication terminals of the unmanned aerial vehicle.
Detailed Description
The invention is described in further detail below with reference to the accompanying drawings:
referring to fig. 1, when an unmanned aerial vehicle needs to return various collected information streams to an unmanned aerial vehicle control management center through a TD-LTE public network or private network, a method for scheduling an uplink of a small-sized civil unmanned aerial vehicle, which is guaranteed by various QoS information streams on an MAC layer, is shown in fig. 2, and the method is cooperatively realized by an information stream generation module, a classification mapping module, a scheduling module, and a channel state detection module at an unmanned aerial vehicle communication terminal, and a radio resource configuration module, a channel state detection module, and an information stream recovery module at an eNodeB under the control of various signaling, and mainly includes the following steps:
1) and (3) information flow classification mapping:
an information flow generation module at an unmanned aerial vehicle communication terminal submits various acquired application-level information flows to a classification mapping module for classification mapping, and firstly, corresponding QCI classification weights are given to packets in each type of information flow cache queues according to QCI grades in an LTE/SAE protocol framework (see table 2); secondly, according to the waiting time delay of head of queue (HOL) groups in various information flow buffer queues in the buffer queues, giving corresponding time delay performance weight to the head of queue (HOL) groups; finally, a user identifier and an information stream identifier are bound for each information stream packet.
TABLE 2 QCI hierarchical mapping of information gathered by small civil unmanned aerial vehicle
2) Uplink radio resource request:
at the scheduling time, a scheduling module at an unmanned aerial vehicle communication terminal sends an uplink wireless resource request signaling to a wireless resource configuration module at an eNodeB, the sending period of the signaling and the position of the signaling in a subframe are determined by upper layer configuration, and the scheduling module needs to tell the wireless resource configuration module at the eNodeB about the data volume to be transmitted and a user identifier in the uplink wireless resource request process.
3) Detecting the quality of an uplink channel:
when an information flow packet needs to be scheduled, a scheduling module at an unmanned aerial vehicle communication terminal sends an uplink wireless resource request signaling to a channel state detection module of the unmanned aerial vehicle communication terminal, and triggers the scheduling module to periodically send the channel detection signaling to a channel state detection module at an eNodeB, and the channel state detection module at the eNodeB compares a channel detection reference signal borne by the signaling with a known signal of the eNodeB, so that the quality of a current uplink channel is accurately known. In order to overcome the time-varying property of the wireless channel, the channel state detection module at the eNodeB periodically sends the updated uplink channel quality identifier signaling to the radio resource configuration module, thereby further informing the radio resource available for scheduling the information flow.
4) And (3) wireless resource allocation:
and the wireless resource configuration module at the eNodeB performs wireless resource configuration on the information flow to be scheduled at the unmanned aerial vehicle communication terminal according to the user identifier and the data volume to be transmitted, and sends the user-wireless resource configuration result to the scheduling module at the unmanned aerial vehicle communication terminal through a wireless resource configuration signaling, so that the scheduling module is informed of which carrier at which time the data can be transmitted, and the adopted modulation and coding scheme.
5) And (3) scheduling various information flow HOL packets:
the scheduling module at the communication terminal of the unmanned aerial vehicle calculates the value of the information flow-user-wireless resource scheduling configuration function according to the user-wireless resource configuration result, the QCI classification weight of the HOL packets in the various information flow cache queues and the time delay performance weight, and always gives the priority scheduling right to the HOL packet with the maximum function value.
6) And (3) information flow recovery:
and a scheduling module at the unmanned aerial vehicle communication terminal sequentially submits various information flow packets to be scheduled to an information flow recovery module at the eNodeB, and the module encapsulates and frames the received packets according to the information flow identifier and the user identifier bound to each packet and the radio resource configuration result carried on the radio resource configuration signaling, so that high-quality transmission of various information flows is finally realized.
The scheduling weight function determination of the unmanned aerial vehicle communication terminal of the present invention is described in detail below:
the radio frame structure of the TD-LTE system is shown in fig. 3. In the TD-LTE system, 1 radio frame comprises 10 subframes for 10ms, each subframe is divided into 2 slots in the time domain, each slot comprises 7 SC-FDMA symbols, and the frequency domain comprises a plurality of subcarriers. In one subframe, a resource block in the unit of 12 subcarriers in the frequency domain at every 7 SC-FDMA symbols in the time domain is referred to as one RB. The total number of RBs in a subframe is determined by the system uplink bandwidth. The uplink scheduling is actually a radio resource allocation process, and aims to allocate the RBs in one subframe to multiple information streams of multiple unmanned aerial vehicle communication terminals according to a scheduling algorithm, and the RBs obtained by each unmanned aerial vehicle communication terminal is continuously distributed in a frequency domain. At the scheduling moment, a scheduling module at an unmanned aerial vehicle communication terminal needs to search the best matching result for the RB, the unmanned aerial vehicle terminal and various information flows, so that the system can ensure user fairness while obtaining the maximum throughput, and the QoS requirements of various information flows are met.
Suppose that the system has N UAV communication terminals and K RBs at the scheduling time can carry various information streams, so that the radio resource matches the identifier Cl,n,k(t) satisfies:
(3) formula shows that at the scheduling time, each RB can be allocated to only 1 information stream on 1 drone communication terminal.
Scheduling time t', if:
then there are:
Cl′,n′,k′(t′)＝1 (3)
wherein, at the scheduling time t, if an HOL packet with a CQI level of l at the nth unmanned aerial vehicle communication terminal classification mapping module is sent to an eNodeB via a kth RB, the scheduling weight function corresponding to the HOL packet is ψl,n,k(t) of (d). When the value of the radio resource matching identifier satisfies the formula (3), it indicates that the scheduling module at the scheduling time t 'nth' unmanned aerial vehicle communication terminal uploads the l 'information stream to the eNodeB on the k' RB.
TABLE 3 Performance comparison of three exemplary scheduling algorithms
| Scheduling algorithm | User fairness | Channel adaptation | Time delay guarantee | System throughput | Complexity of |
| MAX C/I | Difference (D) | Good taste | Difference (D) | Highest point of the design | Is smaller |
| RR | Good taste | Difference (D) | Difference (D) | Lowest level of | Small |
| PF | Is preferably used | Is preferably used | Good taste | Is higher than | Is larger |
The typical scheduling algorithms suitable for the TD-LTE mobile communication network are three, namely a Round Robin (RR) algorithm, a maximum carrier-to-interference ratio (MAX C/I) algorithm and a Proportional Fair (PF) algorithm, and the performance comparison thereof is shown in table 3Introducing a scheduling weight function psil,n,kIn (t), letSatisfies the formula (4):
wherein R isn,k(t) if the nth UAV communication terminal information flow at time tData transmission rate expectations delivered to the eNodeB over the kth RB,the information flow average data transmission rate of the nth unmanned aerial vehicle communication terminal at the last moment, namely the t-1 moment. Rn,kThe greater the value of (t), orThe smaller the value, theThe larger the value, the more likely it is that the nth drone terminal acquires the kth RB, wherein,given by:
wherein R isn(t) is the instantaneous data transmission rate of the nth drone communication terminal at time t, α being a scaling factor and given by:
wherein, TWA time window that impacts user fairness.
Typical information returned to a control management center by a small civil unmanned aerial vehicle through a TD-LTE mobile communication network mainly comprises three types of services: flight status data information, audio information, and video information. Table 2 lists the hierarchical mapping of the system to these three types of typical traffic, where the flight status data information is closely related to the safe and smooth flight of the drone, and thus has the highest QCI rating, i.e., l ═ 1, and the audio information and video information are the current drone creditThe information acquisition process needs real-time transmission of the main service types, which correspond to l 2 and l 4, respectively, and other QCI grades are reserved grades and used for the hierarchical mapping of other newly added special services. Weighting factor omega of CQIlIntroducing a scheduling weight function psil,n,kIn (t), let ω bel∈(0,1]Satisfies the following equation (7):
the formula (7) can ensure that the scheduling module at the communication terminal of the unmanned aerial vehicle always allocates a larger CQI weight factor to the HOL packets with higher CQI priority in the classification mapping module, and allocates a smaller CQI weight factor to the HOL packets with lower CQI priority, so that the HOL packets with higher CQI weight factors are given the right to obtain preferential scheduling, and preliminary QoS transmission guarantee is provided for information streams with different delay requirements and packet loss rate requirements.
Because video service and audio service have more severe real-time transmission requirements, the time delay is guaranteed to be factor omegal,n(t) introducing a scheduling weight function psil,n,kIn (t), let ω bel,n(t)∈(0,1]Satisfies the following equation (8):
in the formula (8), TlThe maximum waiting time delay requirement, tau, of the QCI information flow packets to be scheduled at the l level in a cache queue of a classification mapping module of the unmanned aerial vehicle communication terminall,n(t)∈(0,Tl]Waiting time, delta T, of HOL packets to be scheduled in a cache queue for scheduling time T nth level QCI information flow of unmanned aerial vehicle communication terminall∈(0,Tl]The guard interval, which is predetermined for the system, is typically set to the frame length, i.e. the interval between two schedules. If Δ Tl≤Tl-τl,n(t), i.e. τl,n(t)∈(0,Tl-ΔTl]Then the HOL packet is sentCan meet the delay requirement, and taul,n(t) the shorter the scheduling priority is, the lower it is; if Δ Tl＞Tl-τl,n(t), i.e. τl,n(t)∈(Tl-ΔTl,Tl]Then the waiting time of the HOL packet is about to exceed the delay limit, and its scheduling priority is the highest, and the scheduling module should give it the right to obtain the priority scheduling. Therefore, ωl,n(t) will further provide better real-time transmission guarantees for information streams with different latency requirements.
In summary, the scheduling weight function psi suitable for the unmanned aerial vehicle communication terminall,n,k(t)∈(0,1]Can be given by formula (9):
at each scheduling moment, the scheduling module performs matching calculation among the available unmanned aerial vehicle communication terminal set, the wireless resource block set to be allocated and the HOL packet set to be scheduled according to the formula (9), and searches out a wireless resource matching identifier corresponding to the maximum scheduling weight function value, so that the specific information flow of the corresponding user is transmitted on the corresponding wireless resource block.
Test verification:
and (3) carrying out simulation verification on the uplink scheduling strategy of the small civil unmanned aerial vehicle facing to various information flow QoS guarantees based on the TD-LTE technology by adopting an LTE-Sim simulation platform. The simulation scenario is shown in fig. 2: the cell radius is 1km, and the cell comprises 1 eNodeB and 5 to 10 unmanned aerial vehicle communication terminals. The eNodeB is located at the center of a cell, the flight mode of the unmanned aerial vehicle is set to be a Way-Point model, and the driving speed is set to be 30 km/h. Besides flight state data information for ensuring stable flight of the unmanned aerial vehicle, each unmanned aerial vehicle communication terminal uploads two types of information streams, audio information and video information at the same time. The VoIP flow is simulated using an on/off markov model and the video flow is simulated using a video test sequence "highway. The simulation time is set to 100s, each simulation process is carried out at least 10 times, and the final result is averaged.
Since the system always provides the scheduling service having the CQI level of level 1 and the constant transmission rate for the data information closely related to the flight status, and the amount of such information is not large, the best scheduling transmission service is always obtained, and thus, only the audio information having the QCI level of level 2 and the video information having the QCI level of level 4 are subjected to the performance evaluation. Fig. 4 and 5 show the packet loss rate performance histograms of the audio and video information streams, respectively. It can be seen that as the number of cell unmanned aerial vehicle communication terminals increases, the uplink load of the system becomes larger and larger, and the packet loss rates of the two algorithms increase accordingly. As the QCI level of the audio information flow is higher than that of the video information flow and the transmission rate is lower than that of the video information flow, the packet loss rate of the audio information flow of the two algorithms is very low and is within 1 percent, and the packet loss rate of the audio information flow is greatly lower than that of the video information flow. Because the recommendation algorithm can give priority scheduling rights to the HOL packets which are about to exceed the waiting time interval, when the HOL packets are about to exceed the delay limit, the packets can obtain the RB preferentially and upload the RB, and therefore, for the audio information stream and the video information stream, the recommendation algorithm can obtain the packet loss rate performance which is superior to that of the PF algorithm, and better real-time guarantee is provided for acquisition of uplink communication information of the unmanned aerial vehicle. Fig. 6 shows a comparison of fairness indexes of two proposed algorithms, where the fairness index is closer to 1, which indicates that fairness of system users is better, and it can be known that the proposed algorithm is slightly lower than a proportional fairness algorithm, which is necessary overhead for providing real-time transmission guarantee for information flows by the proposed algorithm, but can still ensure that the system users have better fairness in terms of wireless resource acquisition.
Claims (5)
1. An unmanned aerial vehicle uplink scheduling method facing to signal flow QoS guarantee based on TD-LTE technology is characterized in that an information flow generation module, a classification mapping module, a scheduling module and a channel state detection module at an unmanned aerial vehicle communication terminal, and a wireless resource configuration module, a channel state detection module and an information flow recovery module at an eNodeB are cooperatively realized under the control of various signaling, and the method comprises the following steps:
1) and (3) information flow classification mapping:
an information flow generation module at the unmanned aerial vehicle communication terminal submits the acquired application-level information flow to a classification mapping module for classification mapping;
2) uplink radio resource request:
at the scheduling moment, a scheduling module at an unmanned aerial vehicle communication terminal sends an uplink wireless resource request signaling to a wireless resource configuration module at an eNodeB, and the sending period of the uplink wireless resource request signaling and the position of the uplink wireless resource request signaling in a subframe are configured and determined by the wireless resource configuration module at the eNodeB;
3) detecting the quality of an uplink channel:
when an information flow packet needs to be scheduled, a scheduling module at an unmanned aerial vehicle communication terminal sends an uplink wireless resource request signaling to a channel state detection module of the unmanned aerial vehicle communication terminal, and triggers the channel state detection module of the unmanned aerial vehicle communication terminal to periodically send a channel detection signaling to a channel state detection module at an eNodeB, and the channel state detection module at the eNodeB compares a channel detection reference signal borne by the channel detection signaling with a known signal, so that the quality of a current uplink channel is known;
4) and (3) wireless resource allocation:
a wireless resource configuration module at an eNodeB performs wireless resource configuration on information flow to be scheduled at an unmanned aerial vehicle communication terminal according to a user identifier and data volume to be transmitted, and transmits a user-wireless resource configuration result to a scheduling module at the unmanned aerial vehicle communication terminal through a wireless resource configuration signaling, so that the scheduling module is informed of which carrier at which time the data can be transmitted, and the adopted modulation and coding scheme;
5) information flow HOL packet scheduling:
a scheduling module at the unmanned aerial vehicle communication terminal calculates a scheduling weight function psi when different information flows, users and wireless resources are configured according to a user-wireless resource configuration result, HOL groups in various information flow cache queues, QCI hierarchical weight and time delay performance weightl,n,k(t) taking a value to give a priority scheduling right to the HOL packet with the maximum function value;
the scheduling weight function of the unmanned aerial vehicle communication terminal is determined according to the following steps:
weighting PF by a factorIntroducing a scheduling weight function psil,n,kIn (t), letSatisfies the formula (4):
wherein R isn,k(t) is time t the nth drone communication terminal information stream if the data transmission rate delivered to the eNodeB via the kth RB is expected,the information flow average data transmission rate of the nth unmanned aerial vehicle communication terminal at the last moment, namely the t-1 moment; wherein,given by:
wherein R isn(t) is the instantaneous data transmission rate of the nth drone communication terminal at time t, α being a scaling factor and given by:
wherein, TWA time window that affects user fairness;
weighting factor omega of CQIlIntroducing a scheduling weight function psil,n,kIn (t), let ω bel∈(0,1]Satisfies the following equation (7):
the formula (7) ensures that the scheduling module at the communication terminal of the unmanned aerial vehicle always allocates a larger CQI weight factor to the HOL packet with higher CQI priority in the classification mapping module, and allocates a smaller CQI weight factor to the HOL packet with lower CQI priority, so that the HOL packet with higher CQI weight factor is given the right of obtaining preferential scheduling, and preliminary QoS transmission guarantee is provided for information streams with different delay requirements and packet loss rate requirements;
for video service and audio service, the time delay is ensured by a factor omegal,n(t) introducing a scheduling weight function psil,n,kIn (t), let ω bel,n(t)∈(0,1]Satisfies the following equation (8):
in the formula (8), TlThe maximum waiting time delay requirement, tau, of the QCI information flow packets to be scheduled at the l level in a cache queue of a classification mapping module of the unmanned aerial vehicle communication terminall,n(t)∈(0,Tl]Waiting time, delta T, of HOL packets to be scheduled in a cache queue for scheduling time T nth level QCI information flow of unmanned aerial vehicle communication terminall∈(0,Tl]The guard time interval predetermined for the system is usually set as the frame length, i.e. the interval between two schedules; if Δ Tl≤Tl-τl,n(t), i.e. τl,n(t)∈(0,Tl-ΔTl]Then the waiting time of the HOL packet can meet the delay requirement; if Δ Tl＞Tl-τl,n(t), i.e. τl,n(t)∈(Tl-ΔTl,Tl]If the waiting time of the HOL packet is about to exceed the delay limit, the scheduling priority is the highest, and the scheduling module should give the right to obtain the priority scheduling;
scheduling weight function psi suitable for unmanned aerial vehicle communication terminall,n,k(t)∈(0,1]Can be given by formula (9):
at each scheduling moment, the scheduling module performs matching calculation among the available unmanned aerial vehicle communication terminal set, the wireless resource block set to be allocated and the HOL packet set to be scheduled according to the formula (9), and searches out a wireless resource matching identifier corresponding to the maximum scheduling weight function value, so that the specific information flow of the corresponding user is transmitted on the corresponding wireless resource block;
6) and (3) information flow recovery:
and the scheduling module at the unmanned aerial vehicle communication terminal sequentially submits various information flow packets to be scheduled to the information flow recovery module at the eNodeB, and the information flow recovery module encapsulates and frames the received packets according to the information flow identifier and the user identifier bound to each packet and the radio resource configuration result carried on the radio resource configuration signaling, so that the transmission of various information flows is finally realized.
2. The TD-LTE technology-based UAV uplink scheduling method for QoS guarantee of signal flow, according to claim 1, wherein the step 1) is specifically as follows:
firstly, endowing packets in each type of information flow buffer queue with corresponding QCI hierarchical weight according to QCI grades in an LTE/SAE protocol framework;
secondly, according to the waiting time delay of the head group in the various information flow buffer queues in the buffer queues, giving corresponding time delay performance weight to the head group;
finally, a user identifier and an information flow identifier are bound for each information flow packet.
3. The TD-LTE technology-based UAV uplink scheduling method for QoS guarantee of traffic flow is according to claim 1, wherein in step 2), the scheduling module at the UAV communication terminal needs to tell the radio resource configuration module at the eNodeB the amount of data to be transmitted and the user identifier during the uplink radio resource request.
4. The TD-LTE technology-based UAV uplink scheduling method for QoS guarantee of traffic flow according to claim 1, wherein in step 3), the channel status detection module at the eNodeB periodically sends updated uplink channel quality identification signaling to the radio resource configuration module, so as to inform the radio resource available during scheduling of the traffic flow to overcome the time-varying property of the radio channel.
5. The TD-LTE technology-based uplink scheduling method for UAVs (unmanned aerial vehicles) facing to QoS (quality of service) guarantee of signal streams is according to claim 1, wherein in the step 5), the scheduling module at the UAV communication terminal schedules the packets in the same information stream buffer queue according to the order of first-in first-out.
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