JP2009225372A - Scheduling method based on hybrid automatic request retransmission and the apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a scheduling method and apparatus based on a hybrid automatic request retransmission, which brings an idea of synthesis gain into a scheduling algorithm, fully considers impacts of the synthesis gain of the retransmitting user onto transmission rate, determines actual transmission rate of the user more accurately, and provides a wireless high-speed data communication with more effective and reliable transmission quality. <P>SOLUTION: A scheduling process determines a transmission rate which a user acquires, based on whether the user is the retransmitting user, and based on a signal-to-interference noise ratio fed back from the user, adds the synthesis gain of the retransmitting user to the signal-to-interference noise ratio fed back from the user to obtain an effective signal-to-interference noise ratio for the user, and performs the scheduling based on the effective signal-to-interference noise ratio. This is effectively combined with conventional methods such as channel-condition-based MaxC/I algorithm, PF algorithm or the like. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a radio packet scheduling technique in the communication field, and more particularly to a scheduling method and apparatus based on hybrid automatic request retransmission for ensuring the effectiveness and reliability of data transmission in high-speed wireless data communication.

  With the increasing application of multimedia services in wireless networks, wireless packet scheduling has become an important research topic. Fairness and system throughput are important indicators for determining radio packet scheduling strategies. As system throughput improves, each user is required to share radio resources as fairly as possible. However, in a wireless network, users are in different channel states, so there is a contradiction between improving system throughput and ensuring fairness. In order to guarantee fairness, it is necessary to allocate some channels to users with poor channel conditions, which reduces system throughput. In other words, there is a maximum fairness that can be guaranteed if the scheduling strategy assumes that a certain system throughput is reached (or if a certain fairness is guaranteed, the maximum system throughput that can be achieved is Exist).

  In a wireless network, different users have different channel capacities at different times, so the fairness of the scheduling algorithm is the time fairness determined by the time or probability that each user acquires the channel and the channel capacity acquired by each user. There are two types of capacity fairness to judge. In general, they are not equal. Further, in the scheduling strategy, in order to guarantee the fairness of the capacity, more system throughput is sacrificed than in the case of guaranteeing the fairness of time. In order to guarantee capacity fairness, users with good channel conditions get less channel time, and users with poor channel conditions get more channel time. This is because time is acquired. Therefore, capacity fair system throughput is lower than time fair.

  Scheduling is a method for realizing a high system capacity. There are three traditional scheduling methods. The first is MaxC / I (Maximum Signal to Interference and Noise Ratio Algorithm), which can obtain high system throughput and low fairness. The second is the Round Robin algorithm, which can obtain good fairness and low system throughput. The third is a proportional fair algorithm, which can obtain maximum system throughput and relatively good user fairness. Hybrid automatic request retransmission (HARQ) is an effective error recovery method at the link level. Currently, there are two effective hybrid automatic request retransmission schemes: chase combining and incremental redundancy. The former can acquire the time diversity gain, and the latter can acquire the coding synthesis gain.

  Currently, there are many scheduling algorithms based on channel conditions, but only simple scheduling based on the user's current channel conditions, and considering the probability that the user's data will be received correctly after being scheduled. Not. Although scheduling may be considered in combination with standard automatic request retransmission, scheduling and hybrid automatic request retransmission are not considered together. Even if any user is scheduled with any scheduling rule according to the traditional method, there is a possibility that the data of the user may not be received correctly on the receiving side. In consideration of the fact that any user retransmits data and there is a combined gain when scheduling retransmission users, the probability that data will be correctly received after the user is scheduled is higher than that of other users. Throughput is also improved.

を基地局へフィードバックするステップ１と、
基地局が、各ユーザのチャネル品質情報に基づいて、各自の最大許容伝送速度

を確定するステップ2と、

に基づいて、スケジューリングするユーザを確定するステップ3と、
ユーザが伝送しようとするデータが新しいデータであるかそれとも再送データであるかを判断するステップ4と、
新しいデータである場合、ステップ2で取得した最大速度で該データを送信し、再送データである場合、該ユーザが前回のデータ送信で採用した速度で該データを再送するステップ5と、
スケジューリング周期ごとに、ステップ1〜ステップ5を繰り返すステップ6とを含む。 Currently, there are two types of traditional scheduling algorithms that employ hybrid automatic request retransmission technology. One of them is the traditional maximum speed scheduling algorithm, the main scheduling procedure is
The communicating user is responsible for their channel quality information.

Is fed back to the base station, and
The base station determines its maximum allowable transmission rate based on the channel quality information of each user.

Step 2 to confirm

Step 3 to determine which users to schedule based on:
Step 4 for determining whether the data to be transmitted by the user is new data or retransmission data; and
If it is new data, the data is transmitted at the maximum rate acquired in step 2, and if it is retransmission data, the user retransmits the data at the rate adopted in the previous data transmission; and
Step 6 that repeats Step 1 to Step 5 is included for each scheduling period.

を基地局へフィードバックするステップ1）と、
基地局が、各ユーザのチャネル品質情報に基づいて各自の最大許容伝送速度

を確定するステップ2）と、
ユーザが伝送しようとするデータが新しいデータであるかそれとも再送データであるかを判断するステップ3）と、
すべてのユーザが新しいデータを送信する場合、ステップ2）におけるすべてのユーザの最大許容伝送速度を並べて、最大速度のユーザを選出し、データを再送するユーザが存在する場合、該ユーザのチャネル品質に関係なく、該ユーザをスケジューリングし、再送ユーザが、前回のデータ送信で採用した速度でデータを再送するステップ4）と、
スケジューリング周期ごとに、ステップ1）〜ステップ4）を繰り返すステップ5）とを含む。 Another traditional method is a retransmission user data priority method. Detailed scheduling procedure is
Each user who communicates has their own instantaneous channel quality information

To feed back to the base station 1),
The base station determines its maximum allowable transmission rate based on the channel quality information of each user.

Step 2) to confirm
Step 3) for determining whether the data to be transmitted by the user is new data or retransmission data;
When all users transmit new data, the maximum permissible transmission rate of all users in step 2) is aligned, the user with the maximum rate is selected, and when there is a user who retransmits data, the channel quality of the user is determined. Regardless of the step 4) scheduling the user and retransmitting the data at the rate adopted by the previous data transmission by the retransmitting user,
Step 5) that repeats Step 1) to Step 4) for each scheduling period.

  The above two methods have the following main drawbacks. In the case of the method 1, the user having the maximum rate is selected and scheduled based on the instantaneous channel condition. However, in the actual transmission, the previous transmission rate is used for the retransmission user. This is not necessarily the user with the maximum transmission rate, but the system throughput is reduced. In the case of the method 2, scheduling is performed with priority on the retransmitting user, and the retransmitting user has high reliability, but may not be the user having the maximum transmission rate, resulting in a loss of system throughput.

  An object of the present invention is to provide a scheduling method and apparatus based on hybrid automatic request retransmission. In the prior art, the effect of the combined gain of the resending user on the transmission rate was not considered in detail, so the actual transmission rate of the user could not be accurately determined, and it was difficult to realize the maximum throughput of the system To solve.

  To achieve the above object, the present invention provides a scheduling method based on hybrid automatic request retransmission. In the scheduling process, the effective signal-to-interference noise ratio of the user is obtained by adding the combined gain of the retransmitting user to the signal-to-interference noise ratio fed back from the user, and based on the effective signal-to-interference noise ratio And schedule users according to a scheduling algorithm.

The above method
Step 1 for determining the user's maximum allowable transmission rate based on the user's channel quality information and retransmission information;
Step 2 to obtain the effective signal-to-interference noise ratio of the user by adding the combined gain when retransmitted to the instantaneous signal-to-interference noise ratio fed back from the user;
Scheduling users according to a scheduling algorithm based on the effective signal-to-interference and noise ratio.

  In the above method, the scheduling algorithm is an algorithm of maximum signal-to-interference noise ratio, and the step 1 includes a step in which a communicating user feeds back their channel quality information to a base station, and transmits new data. The base station directly determines the maximum allowable transmission rate of the user based on the channel quality information, and the maximum allowable transmission of the rate adopted by the retransmission user in the previous data transmission to the retransmission user. A step b that sets the maximum allowable transmission rate of each user, obtains the maximum rate among them, and establishes a user set having the maximum rate in step b. For only the users in the set, obtain the user's effective signal-to-interference and noise ratio, and step 3 Comprising the step of interference noise ratio schedules the maximum user.

を算出し、

の値が最大のユーザをスケジューリングするステップを含み、そのうち、

が取得した平均速度である。 In the above method, the scheduling algorithm is a proportional fair algorithm, and the step 1 includes a step A in which a communicating user feeds back their channel quality information to a base station and a user who transmits new data. The base station directly determines the maximum allowable transmission rate of the user based on the channel quality information, and sets the maximum allowable transmission rate for the retransmission user to the rate adopted by the retransmission user in the previous data transmission. B, and in step 2, for each user, obtain the effective signal-to-interference and noise ratio of the user, the step 3 is equivalent transmission rate corresponding to each user

To calculate

Scheduling the user with the largest value of

Is the average speed obtained.

In the above method, the scheduling algorithm is a maximum signal-to-interference noise ratio algorithm;
The communicating user calculates his / her effective signal-to-interference / noise ratio based on his / her instantaneous channel quality information, retransmission information and composite gain, and feeds back the effective signal-to-interference / noise ratio to the base station Step a1 to
For the user transmitting new data, the base station directly determines the user's maximum allowable transmission rate based on the effective signal-to-interference and noise ratio, and for the retransmitting user, the retransmitting user Step b1 with the maximum allowable transmission speed as the speed adopted for transmission, and
Arranging the maximum allowable transmission rates of each user, obtaining the maximum rate among them, and determining a user set having the maximum rate, c1;
Scheduling d1 of users having the maximum effective signal-to-interference and noise ratio in the user set.

を算出するステップC1と、

の値が最大のユーザをスケジューリングするステップD1とを含み、
前記ステップD1において、

が取得した平均速度である。 In the above method, the scheduling algorithm is a proportional fair algorithm;
The communicating user calculates his / her effective signal-to-interference / noise ratio based on his / her instantaneous channel quality information, retransmission information and composite gain, and feeds back the effective signal-to-interference / noise ratio to the base station Step A1 to
For a user transmitting new data, the base station directly determines the maximum allowable transmission rate of the user based on the channel quality information, and for the retransmission user, the rate adopted by the retransmission user in the previous data transmission. Step B1 with the maximum allowable transmission rate,
Equivalent transmission rate for each user based on the effective signal-to-interference and noise ratio for each user

Step C1 for calculating

Scheduling a user with the largest value of D1 and
In step D1,

Is the average speed obtained.

  In the above method, when hybrid automatic request retransmission is realized by chase combining, the characteristic of maximum ratio combining, that is, the combining gain is the same as the sum of the signal-to-interference noise ratio that the retransmission user has received the signal several times so far. The composite gain is acquired based on the characteristic that

  In the above method, when hybrid automatic request retransmission is realized by the incremental redundancy method, an average combined gain is acquired based on a graph of a block error rate and a signal-to-interference noise ratio.

  In order to achieve the object of the present invention, the present invention further provides a scheduling apparatus based on hybrid automatic request retransmission. The apparatus includes a maximum allowable transmission rate determination module that determines a user's maximum allowable transmission rate based on the user's channel quality information and retransmission information, and a case where retransmission is performed to an instantaneous signal-to-interference noise ratio fed back from the user. An effective signal-to-interference / noise ratio acquisition module that acquires the effective signal-to-interference / noise ratio of the user by adding a composite gain, and a user according to a scheduling algorithm based on the effective signal-to-interference / noise ratio And a scheduling module for scheduling.

  In the above apparatus, when the hybrid automatic request retransmission employs chase combining, the effective signal-to-interference / noise ratio acquisition module obtains the sum of the signal-to-interference / noise ratio at which the retransmission user has received the signal several times. The composite gain is acquired.

  In the above apparatus, when the hybrid automatic request retransmission employs incremental redundancy, the effective signal-to-interference / noise ratio acquisition module acquires an average combined gain from a graph of a block error rate and a signal-to-interference / noise ratio. .

  The present invention has the following excellent points.

  1. The present invention introduces the idea of the composite gain into the scheduling algorithm, and can fully determine the actual transmission rate of the user by fully considering the effect of the retransmission user's composite gain on the transmission rate. Therefore, according to the scheduling method of the present invention in consideration of the combined gain, more reliable and more effective transmission quality can be provided for wireless high-speed data communication.

  2. For the MaxC / I scheduling algorithm and proportional fair scheduling algorithm of the present invention, an improved scheduling algorithm is introduced by introducing a combined gain, and the combined gain of the retransmitting user is added to the signal-to-interference noise ratio fed back from the user. In addition, the effective signal to interference noise ratio of the user is obtained. The effective signal-to-interference and noise ratio that incorporates the combined gain can truly reflect the actual transmission rate, so combining the effective signal-to-interference and noise ratio with the above two algorithms allows actual transmission as much as possible. Based on the speed, a user who matches the algorithm rule can be found, and the accuracy of the algorithm can be improved.

  3. In the present invention, when the user's maximum allowable transmission rate is determined for the first time, the retransmission user adopts the rate adopted in the previous data transmission as the maximum allowable transmission rate, so in the prior art, based on the channel quality information The maximum allowable transmission rate of the retransmission user is determined and used as a basis for scheduling, and transmission is performed at the previous transmission rate of the retransmission user, so that the problem that the scheduled user does not have the maximum rate can be avoided. Therefore, according to the present invention, it is possible to guarantee the coincidence between the rate on which the scheduling is based and the transmission rate, guarantee the accuracy and effectiveness of the scheduling, and improve the system throughput.

  4. The present invention provides two methods for determining the composite gain for different hybrid automatic request retransmission schemes, and can determine the composite gain of retransmission users easily and effectively. Furthermore, the present invention provides an implementation means that is effective and effective in determining the user's effective signal-to-interference and noise ratio and accurately determining the user's actual transmission rate.

  Whether or not the user's data is correctly received after scheduling is not known before scheduling the user, so the instantaneous transmission rate on which the user is scheduled in the prior art is not the actual transmission rate. Can not be reflected. The speed only indicates the speed after the user's data has been correctly received. When it is detected that the user data is incorrect, the actual transmission rate is 0, and the erroneous data is retransmitted or discarded. Such incorrect calculations are very disadvantageous in multi-user systems. Also, in many hybrid automatic request retransmission methods, retransmission data has a higher reception success rate than initial transmission data due to a composite gain by retransmission. Based on this, in the present invention, a gain by combining is introduced into the scheduling principle, and a multi-user scheduling method based on the combined gain of hybrid automatic request retransmission is designed for a wireless communication system, so that the actual transmission rate of the channel is determined. To be able to judge more accurately. As shown in FIG. 1, the scheduling method according to the present invention includes the following steps.

  In step 101, the user's maximum allowable transmission rate is determined based on the user's channel quality information and retransmission information.

  In step 102, the effective signal-to-interference and noise ratio of the user is obtained by adding the combined gain when retransmitted to the instantaneous signal-to-interference and noise ratio fed back from the user.

  In step 103, users are scheduled according to a scheduling algorithm based on the effective signal-to-interference and noise ratio.

  When the calculation of the effective signal-to-interference and noise ratio is completed at the base station, processing is performed according to the above procedure. When the calculation of the effective signal-to-interference and noise ratio is completed on the user side, the effective signal-to-interference and noise ratio is calculated by the user and fed back to the base station. Finally, step 103 is executed.

  When based on the maximum signal-to-interference and noise ratio scheduling algorithm, the first embodiment of the scheduling algorithm according to the present invention after introducing the combined gain is as follows.

を基地局へフィードバックする。 In step 1), each user who communicates has their own channel quality information.

Is fed back to the base station.

を確定し、新しいデータを送信するユーザに対して、フィードバックされた

を直接確定し、再送ユーザに対して、その

は前回のデータ送信で採用した速度と同じである。 In step 2), the base station determines its maximum allowable transmission rate based on the channel quality and retransmission information of each user.

Feedback to users sending new data

To the retransmit user

Is the same as the speed used in the previous data transmission.

を確定する。 In step 3), set the maximum allowable transmission rates obtained in the above steps,

Confirm.

を算出する。 In step 4), an effective signal-to-interference / noise ratio corresponding to each user in the user set.

Is calculated.

をスケジューリングする。 In step 5), the user with the highest effective signal-to-interference and noise ratio

To schedule.

  The above steps 1) to 5) are repeated for each scheduling period.

  Example 2 based on the maximum signal-to-interference and noise ratio algorithm is as follows.

を算出し、該実効的な信号対干渉雑音比を基地局へフィードバックする。 In step 1), the communicating users can determine their effective signal-to-interference and noise ratio based on their instantaneous channel quality information, retransmission information, and composite gain.

And the effective signal-to-interference / noise ratio is fed back to the base station.

を確定し、新しいデータを送信するユーザに対して、フィードバックされた

を直接確定し、再送ユーザに対して、その

は前回のデータ送信で採用した速度と同じである。 In step 2), the base station determines its maximum allowable transmission rate based on the channel quality and retransmission information of each user.

Feedback to users sending new data

To the retransmit user

Is the same as the speed used in the previous data transmission.

を確定する。 In step 3), set the maximum allowable transmission rates obtained above and arrange the user set with the maximum rate.

Confirm.

をスケジューリングする。 Users with the highest effective signal-to-interference and noise ratio in step 4)

To schedule.

  The above steps 1) to 4) are repeated for each scheduling period.

  Embodiment 1 in which the idea of the composite gain of the present invention is applied to a traditional PF (proportional fair) scheduling algorithm is as follows.

を基地局へフィードバックする。 In step 1), each user who communicates has their own channel quality information.

Is fed back to the base station.

を確定し、新しいデータを送信するユーザに対して、フィードバックされた

を直接確定し、再送ユーザに対して、その

は前回のデータ送信で採用した速度と同じである。 In step 2), the base station determines its maximum allowable transmission rate based on the channel quality information of each user.

Feedback to users sending new data

To the retransmit user

Is the same as the speed used in the previous data transmission.

と、等価伝送速度

を算出する。 In step 3), an effective signal-to-interference / noise ratio corresponding to each user in the user set.

And equivalent transmission speed

Is calculated.

の原則に基づいて（伝統的なＰＦ方法は、

に基づく）、最大値を持つユーザをスケジューリングする。そのうち、

が取得した平均速度である。 In step 4)

(Traditional PF method is based on

To schedule the user with the maximum value. Of which

Is the average speed obtained.

を更新することができる。

According to the following formula:

Can be updated.

はプロポーショナル因子であり、tは時間を示しており、if scheduleは、該ユーザiがスケジューリングされる場合であることを示す。 Of which

Is a proportional factor, t indicates time, and if schedule indicates that the user i is scheduled.

  In step 5), the above steps 1) to 4) are repeated for each scheduling period.

  The second embodiment based on the PF scheduling algorithm is as follows.

を算出し、該実効的な信号対干渉雑音比を基地局へフィードバックする。 In step 1), the communicating users can determine their effective signal-to-interference and noise ratio based on their instantaneous channel quality information, retransmission information, and composite gain.

And the effective signal-to-interference / noise ratio is fed back to the base station.

を確定し、新しいデータを送信するユーザに対して、フィードバックされた

を直接確定し、再送ユーザに対して、その

は前回のデータ送信で採用した速度と同じである。 In step 2), the base station determines its maximum allowable transmission rate based on the channel quality information of each user.

Feedback to users sending new data

To the retransmit user

Is the same as the speed used in the previous data transmission.

を算出する。 In step 3), the equivalent transmission rate based on the effective signal-to-interference and noise ratio corresponding to each user

Is calculated.

の原則に基づいて（伝統的なＰＦ方法は、

に基づく）、最大値を持つユーザをスケジューリングする。そのうち、

が取得した平均速度である。 In step 4)

(Traditional PF method is based on

To schedule the user with the maximum value. Of which

Is the average speed obtained.

を更新することができる。

According to the following formula:

Can be updated.

はプロポーショナル因子であり、tは時間を示しており、if scheduleは、該ユーザiがスケジューリングされる場合であることを示す。 Of which

Is a proportional factor, t indicates time, and if schedule indicates that the user i is scheduled.

  In step 5), the above steps 1) to 4) are repeated for each scheduling period.

  The present invention further provides two types of methods for determining the composite gain.

Method 1: When the hybrid automatic request retransmission method employs chase combining, the signal-to-interference and noise ratio of the combined signal is equal to the signal-to-interference and noise ratio of the signal received several times based on the characteristics of maximum ratio combining. Since it becomes the same as the sum, the composite gain can be expressed by the following formula.

に伝送されるときの瞬時信号対干渉雑音比を示す。

新しいデータを送信するときの瞬時信号対干渉雑音比を示す。

同一データパケットを送信する回数を示す。 In the above formula,

The instantaneous signal-to-interference noise ratio when transmitted to is shown.

The instantaneous signal-to-interference noise ratio when transmitting new data is shown.

Indicates the number of times the same data packet is transmitted.

Method 2: When the hybrid automatic request retransmission method employs incremental redundancy, the composite gain is mainly the coding gain, and there is no clear formula for obtaining the composite gain. The average composite gain is obtained from the graph of signal to interference / noise ratio. FIG. 2 is a graph of block error rate (BLER) and signal-to-interference and noise ratio (SNR) for different retransmission times. For a given average signal-to-interference noise ratio, the present invention first determines a block error rate that can be obtained from the average signal-to-interference noise ratio when the number of retransmissions M is zero. In order to obtain the same block error rate, the average signal-to-interference / noise ratio required in the case of different number of retransmissions is also different. The greater the number of retransmissions, the smaller the required signal to interference noise ratio. The difference between the signal-to-interference noise ratio required in the case of different retransmission times and the signal-to-interference noise ratio required in the absence of retransmission is the combined gain corresponding to each retransmission number. For example, as shown in FIG. 2, assuming that the average signal-to-interference and noise ratio of the system is 12 dB, the block error rate that can be acquired when there is no retransmission data is approximately 10%. When the number of retransmissions is 1, 2, and 3, respectively, the average signal-to-interference noise ratios required to obtain a block error rate of 10% are 6 dB, 4 dB, and 1 dB, respectively. Therefore, the combined gain obtained when the number of retransmissions is 1, 2, and 3 is the signal-to-interference noise ratio required when the number of retransmissions is 1, 2, and 3, respectively, This is a difference value from the signal-to-interference noise ratio required when there is not, and is 6 dB, 8 dB, and 11 dB, respectively. Therefore, a composite gain comparison table as shown in FIG. 3 can be obtained with different average signal-to-interference and noise ratios. FIG. 3 is obtained when the modulation method is QPSK (quadrature phase shift keying) and the code rate is 1/2. Therefore, even if the system employs a different modulation and coding system, the present invention can obtain a comparison table as shown in FIG. 3, and the magnitude of the composite gain can be determined by examining the table. In the case of FIG. 3, the acquired composite gain can be expressed by the following formula.

  Next, the performance of the three types of scheduling algorithms will be compared with reference to the drawings.

  Algorithm 1 is the traditional maximum rate scheduling method. The method schedules the user with the highest rate in any scheduling period. When there are a plurality of users with the maximum speed, one user is selected at random, and it is not considered whether the scheduled user is a retransmission user.

  Algorithm 2 is a method for scheduling a retransmission user with priority. When there is no retransmission user, scheduling is performed according to algorithm 1.

  The algorithm of the present invention first determines a set of users with maximum speed on the principle of maximum speed, and then calculates their effective signal-to-interference and noise ratio for the users in the set, and finally Schedule users with maximum signal-to-interference and noise ratio.

  In order to evaluate the performance of the algorithm submitted in the present invention, the present invention compares the performance of the present invention with the traditional method from the three aspects of frequency utilization efficiency, retransmission wait delay, and user fairness.

  FIG. 4 shows a graph of frequency utilization efficiency performance when the average signal to interference noise ratio is 5 dB and the target block error rate is 1%. As shown in the figure, the frequency utilization efficiency increases as the number of users increases. Within all user ranges, the present invention obtains the best frequency utilization efficiency, with the lowest frequency utilization efficiency of algorithm 2 and the frequency utilization efficiency of algorithm 1 between them.

  FIG. 5 shows a graph of frequency utilization efficiency performance when the signal to interference noise ratio is 10 dB and the target block error rate is 1%. In this case, the frequency utilization efficiency is higher than the signal-to-interference noise ratio of 5 dB. This is because, in most cases, the user to be scheduled adopts the highest order modulation coding scheme. However, the performance improvement of the present invention was reduced. This is because when the signal-to-interference and noise ratio is 10 dB, both the probability that an erroneous packet appears and the probability that an event “a user with the maximum transmission rate retransmits data” will occur.

  FIG. 6 shows the time required from when each packet is transmitted for the first time until it is correctly received or discarded when the signal-to-interference noise ratio is 10 dB, the block error rate is 1%, and the number of users is 15. The probability distribution of As shown in FIG. 6, algorithm 1 schedules users based on the current instantaneous channel status at each scheduling time, so when an error occurs in data, the waiting time is very long until the next scheduling. . In Algorithm 2, scheduling is performed with priority on the user to be retransmitted each time, and therefore, retransmission is performed immediately without requiring a waiting time. In the case of the present invention, a retransmission user is scheduled at an appropriate time based on the retransmission status and its channel condition, so that the required delay is between Algorithm 1 and Algorithm 2. If algorithm 1 is used for a user who has a delay guarantee request, many users' data packets are discarded due to timeout. The present invention reduces the probability that a packet is discarded compared to Algorithm 1.

  FIG. 7 is a graph of user fairness. Each graph reflects the scheduling opportunities that each user obtains when employing different scheduling algorithms. When the number of users is 15, and when performing completely fair scheduling, the probability that each user is scheduled is 1/15 = 0.0667. According to the graph, the fairness obtained by the three types of algorithms is not completely fair, but the probability that each user is scheduled is very close to 0.0667. Therefore, generally speaking, the fairness obtained by the three types of algorithms is basically the same.

  As can be seen from the above, the present invention has the following excellent points.

  1) The present invention introduces the idea of the combined gain into the scheduling algorithm, and can fully determine the actual transmission rate of the user by fully considering the influence of the combined gain of the retransmission user on the transmission rate. Therefore, according to the scheduling method of the present invention in consideration of the combined gain, more reliable and more effective transmission quality can be provided for wireless high-speed data communication.

  2) The scheduling algorithm of the MaxC / I and the proportional fair scheduling algorithm of the present invention is to introduce a scheduling algorithm improved by introducing the synthesis gain, and to set the combined gain of the retransmitting user to the signal-to-interference noise ratio fed back from the user. In addition, the effective signal to interference noise ratio of the user is obtained. The effective signal-to-interference and noise ratio that incorporates the combined gain can truly reflect the actual transmission rate, so combining the effective signal-to-interference and noise ratio with the above two algorithms allows actual transmission as much as possible. Based on the speed, a user who matches the algorithm rule can be found, and the accuracy of the algorithm can be improved.

  3) In the present invention, when the user's maximum allowable transmission rate is determined for the first time, the rate adopted by the retransmission user in the previous data transmission is set as the maximum allowable transmission rate. The maximum allowable transmission rate of the retransmission user is determined and used as a basis for scheduling, and transmission is performed at the previous transmission rate of the retransmission user, so that the problem that the scheduled user does not have the maximum rate can be avoided. Therefore, according to the present invention, it is possible to guarantee the coincidence between the rate on which the scheduling is based and the transmission rate, guarantee the accuracy and effectiveness of the scheduling, and improve the system throughput.

  4) The present invention provides two types of methods for determining the combined gain for different hybrid automatic request retransmission schemes, and can determine the combined gain of retransmission users easily and effectively. Furthermore, the present invention provides an implementation means that is effective and effective in determining the user's effective signal-to-interference and noise ratio and accurately determining the user's actual transmission rate.

  Although the present invention has been described in detail using the above-described embodiments, it is obvious for those skilled in the art that the present invention is not limited to the embodiments described in the present specification. The present invention can be implemented as modifications and changes without departing from the spirit and scope of the present invention defined by the description of the scope of claims. Therefore, the description of the present specification is for illustrative purposes and does not have any limiting meaning to the present invention.

FIG. 1 shows the flow of the method according to the invention. FIG. 2 is a graph of the block error rate and the signal-to-interference noise ratio with different numbers of retransmissions. FIG. 3 is a comparison diagram of combined gains acquired with different average signal-to-interference and noise ratios in the present invention. FIG. 4 is a comparison diagram of frequency utilization efficiency performance of different scheduling algorithms in a low signal-to-interference noise ratio environment. FIG. 5 is a comparison diagram of frequency utilization efficiency performance of different scheduling algorithms in a high signal-to-interference noise ratio environment. FIG. 6 is a data packet transmission delay distribution diagram based on different scheduling algorithms. FIG. 7 is a comparison diagram of user fairness by different scheduling algorithms.

Claims (11)

A scheduling method based on hybrid automatic request retransmission,
In the scheduling process, the effective signal-to-interference noise ratio of the user is obtained by adding the combined gain of the retransmitting user to the signal-to-interference noise ratio fed back from the user, and based on the effective signal-to-interference noise ratio Scheduling users according to a scheduling algorithm. Step 1 for determining the user's maximum allowable transmission rate based on the user's channel quality information and retransmission information;
Step 2 to obtain the effective signal-to-interference noise ratio of the user by adding the combined gain when retransmitted to the instantaneous signal-to-interference noise ratio fed back from the user;
2. The method of claim 1, comprising: scheduling 3 users according to a scheduling algorithm based on the effective signal-to-interference and noise ratio. The scheduling algorithm is a maximum signal to interference noise ratio algorithm;
Step 1 includes
A step in which a communicating user feeds back their channel quality information to a base station;
For a user transmitting new data, the base station directly determines the maximum allowable transmission rate of the user based on the channel quality information, and for the retransmission user, the rate adopted by the retransmission user in the previous data transmission. Step b with the maximum allowable transmission rate,
Arranging the maximum permissible transmission rates of each user, obtaining the maximum rate among them, and determining a user set having said maximum rate, c.
In step 2, for only the users in the user set, obtain the effective signal-to-interference and noise ratio of the user,
3. The method of claim 2, wherein step 3 includes scheduling a user with a maximum effective signal to interference noise ratio. The scheduling algorithm is a proportional fair algorithm,
Step 1 includes
Step A in which the communicating users feed back their channel quality information to the base station,
For a user transmitting new data, the base station directly determines the maximum allowable transmission rate of the user based on the channel quality information, and for the retransmission user, the rate adopted by the retransmission user in the previous data transmission. Including step B with the maximum allowable transmission rate,
In step 2, for each user, obtain the user's effective signal-to-interference and noise ratio,
Step 3 is equivalent transmission rate corresponding to each user.

To calculate

Scheduling the user with the largest value of

3. The method according to claim 2, wherein is an average speed obtained. The scheduling algorithm is a maximum signal to interference noise ratio algorithm;
The communicating user calculates his / her effective signal-to-interference / noise ratio based on his / her instantaneous channel quality information, retransmission information and composite gain, and feeds back the effective signal-to-interference / noise ratio to the base station Step a1 to
For the user transmitting new data, the base station directly determines the user's maximum allowable transmission rate based on the effective signal-to-interference and noise ratio, and for the retransmitting user, the retransmitting user Step b1 with the maximum allowable transmission speed as the speed adopted for transmission, and
Arranging the maximum allowable transmission rates of each user, obtaining the maximum rate among them, and determining a user set having the maximum rate, c1;
2. The method according to claim 1, comprising scheduling d1 of users having a maximum effective signal-to-interference and noise ratio in the user set. The scheduling algorithm is a proportional fair algorithm,
The communicating user calculates his / her effective signal-to-interference / noise ratio based on his / her instantaneous channel quality information, retransmission information and composite gain, and feeds back the effective signal-to-interference / noise ratio to the base station Step A1 to
For a user transmitting new data, the base station directly determines the maximum allowable transmission rate of the user based on the channel quality information, and for the retransmission user, the rate adopted by the retransmission user in the previous data transmission. Step B1 with the maximum allowable transmission rate,
Equivalent transmission rate for each user based on the effective signal-to-interference and noise ratio for each user

Step C1 for calculating

Scheduling a user with the largest value of D1 and
In step D1,

2. The method according to claim 1, wherein is an average speed obtained.   When hybrid automatic request retransmission is realized by chase combining, based on the feature of maximum ratio combining, the combining gain is the same as the sum of the signal-to-interference noise ratio that the retransmission user has received signals several times so far 7. The method according to claim 1, wherein the composite gain is acquired.   7. When implementing hybrid automatic request retransmission by the incremental redundancy method, an average composite gain is obtained based on a graph of a block error rate and a signal-to-interference noise ratio. The method according to one item. In a scheduling device based on hybrid automatic request retransmission,
A maximum allowable transmission rate determination module for determining a user's maximum allowable transmission rate based on the user's channel quality information and retransmission information;
An effective signal-to-interference noise ratio acquisition module that acquires the effective signal-to-interference noise ratio of the user by adding a composite gain when retransmitted to the instantaneous signal-to-interference noise ratio fed back from the user;
And a scheduling module that schedules users according to a scheduling algorithm based on the effective signal-to-interference and noise ratio.   When hybrid automatic request retransmission employs chase combining, the effective signal-to-interference and noise ratio acquisition module determines the combined gain by determining the sum of signal-to-interference and noise ratios when the retransmission user has received the signal several times. 10. The device according to claim 9, wherein the device is obtained.   When the hybrid automatic request retransmission employs incremental redundancy, the effective signal-to-interference and noise ratio acquisition module acquires an average combined gain from a graph of a block error rate and a signal-to-interference and noise ratio. The apparatus according to claim 9.

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