CN106714323A - Priority distinguishing and dispatching method of heterogeneous flow in 4G network - Google Patents

Abstract

The invention discloses a scheduling method for priority distinction of heterogeneous streams in a 4G network, which includes first obtaining the user's time delay and packet loss rate and calculating the weighting coefficient according to the CQI fed back by the user, and then according to the actual situation of 4G transmission, Considering the four factors of packet header delay, queue length, rate, and throughput, a mathematical model is established. Finally, according to the flow priority, the weight coefficient is set respectively, and the scheduling priority factor is calculated. The invention distinguishes different scheduling priorities according to the importance of business flows, and can also consider QoS indicators such as time delay, throughput, packet loss rate, etc., and ensures the fairness of scheduling. In the LTE-Sim simulation environment, the MP-MLWDF algorithm is compared with the existing SQPS. The simulation results show that the performance of the MP-MLWDF algorithm has been significantly improved.

Description

A priority-based scheduling method for heterogeneous flows in 4G networks

technical field

The invention belongs to the technical field of computer wireless communication networks, and in particular relates to a priority-discriminating scheduling method for heterogeneous flows in a 4G network.

Background technique

With the development of the LTE (Long Term Evolution) network, its high-speed, low-latency and other characteristics have effectively improved the user's mobile service experience and can better meet the user's business needs. As the leading technology of the new generation of broadband wireless mobile communications, LTE has been rapidly commercialized around the world. At the same time, with the diversified development of various multimedia services such as high-definition voice, web pages, and videos, it has become a new trend to differentiate the priorities of different services to provide QoS (Quality of Service) guarantees.

Although the performance of the 4G system has been greatly improved, it still requires a lot of precious frequency resources. How to use limited frequency resources to meet user demands and increasing data traffic has become a problem that mobile device manufacturers and mobile network operators must face. Therefore, for 4G mobile communications, the performance of the system largely depends on the efficiency of resource scheduling. There are three common scheduling algorithms at present: RR (round robin algorithm), MAX C/I (maximum load-to-interference ratio) scheduling algorithm and PF (proportional fair) scheduling algorithm. Different scheduling algorithms have different emphasis on throughput, packet loss rate, queuing delay and fairness.

However, these scheduling algorithms mentioned above belong to system-level scheduling and are not suitable for real-time streams, and these scheduling algorithms do not take into account the priority scheduling requirements of business streams. Prioritized scheduling is an important technology to ensure the effectiveness and practicability of wireless networks. However, the traditional prioritized scheduling algorithm is difficult to guarantee the delay and throughput due to the lack of scientific allocation of QoS parameters or other reasons. and other QoS indicators.

Contents of the invention

The purpose of the present invention is to propose a new priority-based scheduling method MP-MLWDF (Multi-priorites Modified Largest Wait Delay First) for the deficiency of the prior priority-based scheduling technology. The method considers not only the channel quality but also the quality of service requirements of multimedia services, and can prioritize and schedule according to the types of streams to provide QoS guarantee.

In order to achieve the above object, the technical solution proposed by the present invention is a priority-based scheduling method for heterogeneous flows in a 4G network, which specifically includes the following steps:

Step 1: According to the CQI fed back by the user, the delay and packet loss rate of the user are obtained and the weighting coefficient is calculated;

Step 2: According to the actual situation of 4G transmission, consider the four factors of packet header delay, queue length, rate, and throughput to establish a mathematical model;

Step 3: According to the flow priority, set the weight coefficient respectively, and calculate the scheduling priority factor.

Further, the algorithm of the weighting coefficients described in the above step 1 is:

Among them, the maximum packet loss rate specifies the packet loss threshold in the data transmission process, and the packet loss rate in the transmission process must be less than this value.

Further, the mathematical model described in the above step 2 is:

Among them, the packet header delay is the waiting delay of the user data packet in the buffer queue. When the user data packet exceeds the delay gate limit, the user's data packet will be discarded, and the maximum transmission rate refers to when the resource block is allocated to the user. The maximum transfer rate for this user.

The calculation steps of the scheduling priority factor described in the above step 3 are:

i. According to the flow priority, set the weight coefficient respectively, and the priority weight is expressed as:

Among them, _θi represents the priority of the business flow;

ii. According to the weighting coefficient, the calculation result of the mathematical model, and the priority weight, the scheduling priority factor is obtained:

Priority factor = weighting coefficient Scheduling model priority weight. (4)

Preferably, the values of θ _i are -1, 0, and 1, which respectively represent flows with three priorities: low, medium, and high.

Compared with prior art, the beneficial effect of the present invention:

1. Compared with the existing priority scheduling method, the method of the present invention can better distinguish the priority of service flows, and can effectively improve QoS performance indicators such as time delay, packet loss rate, and throughput.

2. The method of the present invention is a scheduling method based on service flow priority, which can be distinguished according to the type of flow, while effectively considering the channel quality, it also takes into account the quality of service requirements of multimedia services, thereby improving the performance of network transmission and user experience.

Description of drawings

Fig. 1 is a block flow diagram of the scheduling method according to the present invention.

Fig. 2 is a block diagram of the overall scheduling process of the present invention.

Fig. 3 is a comparison diagram of the simulation results of throughput between the present invention and the prior art.

Fig. 4 is a comparison diagram of the simulation results of the present invention and the prior art regarding the packet loss rate.

detailed description

The invention will be described in further detail below in conjunction with the accompanying drawings.

The main idea of the present invention is to use the CQI mechanism of the data link layer in the user terminal to obtain channel information, calculate the weighting coefficient according to the time delay and packet loss rate, and establish a mathematical model according to information such as packet header time delay, queue length, rate and throughput. Model. Set the priority weight and calculate the scheduling priority factor, and assign the corresponding resource block to the user with the highest priority according to the user's priority factor. The inventive method comprises the steps:

Step 1: According to the CQI fed back by the user, the delay and packet loss rate of the user are obtained and the weighting coefficient is calculated:

Among them, the maximum packet loss rate specifies the packet loss threshold in the data transmission process, and the packet loss rate in the transmission process must be less than this value.

Step 2: According to the actual situation of 4G transmission, consider the four factors of packet header delay, queue length, rate, and throughput to establish a mathematical model. The mathematical model establishment method is as follows:

Wherein, the packet header delay is the waiting delay of the user data packet HOL (Head-of-line) in the cache queue. When the delay of the user data packet exceeds the delay threshold, the user's data packet will be discarded. The maximum transmission rate refers to the maximum transmission rate of the user when resource blocks are allocated to the user.

Step 3: According to the flow priority, set the weight coefficient respectively, and calculate the scheduling priority factor, the specific steps are:

i. According to the flow priority, set the weight coefficient respectively, and the priority weight is expressed as:

Among them, _θi represents the priority of the business flow. According to the requirements of the flow, this paper divides it into three types representing low, medium and high priority flows respectively, and _θi corresponds to -1, 0, and 1 respectively.

ii. According to the weighting coefficient, the calculation result of the mathematical model, and the priority weight, the scheduling priority factor is obtained:

Priority Factor = Weighting Coefficient Scheduling Model Priority Weight (4)

As shown in Figure 1, it is a flowchart of a priority-based scheduling algorithm for heterogeneous flows in a 4G network, and its specific steps are as follows:

Step 1: Calculate the size of the weighting coefficient according to the information returned by the user and the two QoS indicators of the time delay and packet loss rate of the channel where the user is located at this time.

Step 2: Obtain information such as header delay, queue length, rate, and throughput from the QoS parameter list, and obtain calculation results through a mathematical model.

Step 3: According to the high or low priority of the stream, the weight coefficients are set respectively, which are divided into three priority weights: low, medium and high. Multiply the weighting coefficient obtained in step 1, the mathematical model calculation result obtained in step 2, and the priority weight obtained in step 3 to obtain the scheduling priority factor. The scheduler allocates the resource block to the user with the highest priority factor according to the size of the scheduling priority factor.

For the specific process of the above scheduling, see Figure 2:

(1) At the beginning of each time slot, execute the scheduling algorithm in this paper to allocate resources

(2) Calculate the value of the user's scheduling priority

(3) Determine whether the scheduling priority value of the new user is greater than that of the previous user, if it is greater than the previous user, continue to perform the fourth step, otherwise, sort according to the scheduling priority value, and then perform the fourth step

(4) Determine whether the allocation of idle resources in the current time slot is completed, if the allocation is completed, perform the fifth step, if there are remaining resources, return to the first step

(5) When a transmission time interval ends, update the waiting delay and physical layer measurement information of data packets of each user service in the queue.

For the convenience of those skilled in the art to further understand the present invention, the simulation results of the present invention are provided below:

The simulation experiment of the present invention is simulated on the LTE-Sim platform, and the simulation topology adopts three sub-districts. Compared with the existing SQPS (Single-Queue Priority Scheduler Alogrithm) algorithm, the simulation diagrams of Fig. 3-Fig. 4 are obtained, the horizontal axis represents the number of users, and the vertical axis represents the number of users. The axis represents the corresponding QoS metric.

Figure 3 shows the simulation results of the throughput. When the number of users is 5, it indicates that the resource blocks are sufficient, so the throughput of the two algorithms is about 400kbps. As the number of users grows, the throughput increases gradually. However, when the number of users increases to 15, the performance of SQPS drops significantly, while the MP-MLWDF algorithm still maintains a high throughput. Because the MP-MLWDF algorithm considers the throughput and is optimized during scheduling, it can slow down the throughput drop caused by insufficient resource blocks.

Figure 4 shows the packet loss rate simulation results. When the number of users is small, the packet loss rates of the two algorithms are close to 0. However, as the number of users increases, the packet loss rate of the SQPS algorithm increases rapidly, while the MP -The growth rate of the packet loss rate of the MLWDF algorithm is much lower than the growth rate of the SQPS. In addition to packet loss rate and throughput, MP-MLWDF can also guarantee good proportional fairness and low latency.

Claims (5)

1. a priority distinguishing scheduling method for heterogeneous flows in a 4G network, characterized in that the method comprises the following steps: Step 1: According to the CQI fed back by the user, the delay and packet loss rate of the user are obtained and the weighting coefficient is calculated; Step 2: According to the actual situation of 4G transmission, consider the four factors of packet header delay, queue length, rate, and throughput to establish a mathematical model; Step 3: According to the flow priority, set the weight coefficient respectively, and calculate the scheduling priority factor. 2. according to the priority distinguishing scheduling method of heterogeneous flow in the 4G network of claim 1, it is characterized in that the algorithm of weighting coefficient described in step 1 is: Among them, the maximum packet loss rate specifies the packet loss threshold in the data transmission process, and the packet loss rate in the transmission process must be less than this value. 3. according to claim 1 or 2 described in the 4G network priority distinguishing scheduling method of heterogeneous flow, it is characterized in that described in step 2 mathematical model is: Among them, the packet header delay is the waiting delay of the user data packet in the buffer queue. When the user data packet exceeds the delay gate limit, the user's data packet will be discarded, and the maximum transmission rate refers to when the resource block is allocated to the user. The maximum transfer rate for this user. 4. according to the priority distinguishing scheduling method of heterogeneous flow in the 4G network of claim 3, it is characterized in that the calculation step of scheduling priority factor described in step 3 is: i. According to the flow priority, set the weight coefficient respectively, and the priority weight is expressed as: Among them, _θi represents the priority of the business flow; ii. According to the weighting coefficient, the calculation result of the mathematical model, and the priority weight, the scheduling priority factor is obtained: Priority Factor = Weighting Coefficient Scheduling Model Priority Weight (4). 5. The priority-based scheduling method for heterogeneous flows in a 4G network according to claim 4, wherein the values of _θi are -1, 0, 1, representing three priorities of low, medium and high respectively flow.