KR100841325B1 - Device for channel scheduler in wireless packet communication system and method for channel scheduling using the same - Google Patents

Abstract

The present invention relates to a method of scheduling a shared channel in a wireless packet communication system. In particular, the present invention relates to a shared channel in a wireless packet communication system capable of providing a flexible service for each user and improving system productivity in a wireless packet data service process. It relates to a scheduling method. The shared channel scheduling method in the wireless packet communication system of the present invention comprises the steps of scheduling priorities for the respective terminals according to signal power to noise power ratios and user and service priorities transmitted from a plurality of terminals; Transmitting packet data to each terminal according to a scheduling priority.

Scheduling

Description

Device for channel scheduler in wireless packet communication system and method for channel scheduling using the same

The present invention relates to a method of scheduling a shared channel in a wireless packet communication system. In particular, the present invention relates to a shared channel in a wireless packet communication system capable of providing a flexible service for each user and improving system productivity in a wireless packet data service process. It relates to a scheduling method.

Existing 1x CDMA2000 systems are designed to support voice services in circuit switched mode and medium to low speed data services.

In addition, as the desire for services such as wireless Internet has increased, a system for high-speed packet data communication has been proposed, excluding voice service, which is called HDR (High Data Rate) or 1x-EV DO (1x-Evolution Data Only). do. The integrated version of these two systems is called 1x-EV Data (Voice).

The 1x-EV DV system refers to a system capable of simultaneously performing a voice mode and data service of a circuit mode with a high speed packet data service.

Therefore, the 1x-EV DV system should be compatible with the lower layer of 1x of the existing CDMA2000. Accordingly, all currently considered 1x-EV DV standards are abbreviated as Radio Configuration (RC) of the existing CDMA2000. ), And additionally, a shared channel for packet data service is configured in an independent RC form.

In the 1x-EV DV system, there is a method of dynamically allocating extra base station power and Walsh code to the F-PDCH in the presence of existing line mode voice users and data users.

Then, this extra base station power and Walsh code are allocated to a particular user of good link quality, thereby increasing the data throughput of the base station.

At this time, for the operation of the F-PDCH, each user needs some feedback channel for transmitting the link quality between itself and the base station to the base station.

The base station selects a modulation scheme and channel coding rate suitable for the current link quality and transmits it to the planned target user based on the link quality reported by the users.

At this time, the method of measuring the quality of the link between the user and the base station is as follows.

First, the C / I value of the common pilot of the existing 1x system is measured at the terminal. And this method uses a method of quantizing the value and transmitting it to the base station through the reverse channel.

Through this process, the terminal selects a base station or sector that provides the best performance and reports the result to the base station. After octal Walsh covering is performed, the resulting 96-bit symbols are spread by the hexadecimal Walsh code and transmitted for a slot time of 1.25 ms. This process continues for every 1.25ms slot time.

Through this process, channel quality information between the base station (or sector) and the user is transmitted to the base station (or sector) through the R-CQICH channel, and only the selected base station (or sector) transmits data to the user based on the R-CQICH information. Done.

The biggest feature of 1xEV-DV system is that multiple users share one shared channel to perform packet data communication. In order to share one shared channel with multiple users, the algorithm for sharing resources is used. You should distribute the channel to multiple users. At this time, the scheduler is responsible for distributing one shared channel to multiple users.

The biggest function this scheduler should perform is to distribute resources appropriately to users while increasing system throughput.

In general, to maximize system throughput, allocate all resources to users with the highest signal-to-noise ratio (C / I). However, when using this scheduling algorithm, only a few users in a good environment (large signal / noise ratio (C / I)) can monopolize the resource, which causes the majority of other users. Will not communicate at all. In order to solve this problem, if the same transmission opportunity is given to all users, the resource share of the entire user will always be the same, but the overall system throughput will be very low.

In order to overcome such phenomena, a scheduling algorithm considering the system throughput and the user's resource occupancy is required. In the case of the HDR system, which is a wireless packet data communication system, the following scheduling algorithm is used by using system throughput and data rate request information received from the terminal.

P (k) = DRC (k) / Throughput for User k

Here, DRC (k) is the transmission data rate required from the k th user, throughput for User k is the amount of information sent by the k user during the unit time, P (k) is the priority function of the K th user In this case, the user whose maximum priority function is the maximum is allocated the slot and transmits the packet. This is commonly called a proportional fair scheduler.

In the case of the 1xEV-DO system, which is an evolution from the current commercially available CDMA system, the channel state information transmitted from the terminal is the signal power / noise ratio (C / I) of the channel unlike HDR. This is because in the case of the HDR system, the terminal determines the transmission data rate, but in the 1xEV-DO system, the base station sets the transmission data rate through the signal power to noise power ratio of the channel transmitted from the terminal. As described above, in a wireless packet data communication system in which the signal power / noise ratio (C / I) of a channel is transmitted, using the transmission data rate as a priority function for scheduling causes loss of information.

For example, even if a user with a signal power / noise ratio (C / I) of 4 dB and 7 dB is assigned the same transmission data rate, a user with 7 dB has a lower probability of error in the transmitted packet, so that the scheduler can increase the system throughput. Should allocate more slots. However, in the case of the PF scheduler, users transmitting the same data rate have the same priority, so that the overall system throughput is reduced.

In addition, the PF scheduler does not consider each user's priority or service priority at all.

That is, a user who requires a near real-time service, such as a video, should be transmitted with priority in the system. However, the PF scheduler does not consider the priority of such users, and it cannot guarantee the quality of each service by providing the same priority as the user who requires the non-real time service (WWW, FTP, etc.). In addition, there is a problem in that the priority of the user can be given in the system operation also has a disadvantage that can not be considered.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems of the prior art, and provides a shared channel scheduler device in a wireless packet communication system for providing a flexible service in a wireless packet data service process and increasing system throughput. It is to provide a shared channel scheduling method.

According to one aspect of the present invention, determining a user ID (user ID) for a plurality of terminals being connected, and at least one of the channel state, packet delay, user throughput of each terminal There is provided a channel scheduling method in a wireless packet communication system including determining one and scheduling packet data transmission to each terminal in consideration of the identified information.

In this case, the method may further include identifying a service ID of a packet data transmission service to be provided to each terminal, and adjusting the scheduling by weighting each of the identified information.

On the other hand, according to another aspect of the present invention, to determine the user ID (user ID) for the plurality of terminals being connected, at least one of the channel state, packet delay, user throughput of each terminal After identifying the information, a channel scheduling apparatus in a wireless packet communication system including a scheduler for scheduling packet data transmission to each terminal in consideration of the identified information and a transmitter for transmitting packet data to each terminal according to the schedule is provided. .

In this case, the scheduler may further include a function of identifying a service ID of a packet data transmission service to be provided to each terminal, and further includes a function of adjusting the scheduling by assigning a weight to each of the identified information. can do.

The service ID may be a main means for distinguishing each transport service existing on the network. In addition, the packet delay may be the amount of transmission data stored in the buffer, or may be a delay time after the data to be sent next time is stored in the buffer.

The present invention as described above has the following effects.

First, because it can provide priority to users and services, it can provide flexibility in system operation. In addition, the quality of the service can be provided in various forms according to the service or the user.

Second, unlike the conventional HDR system, the signal power / noise power ratio (C / I) value is used instead of the quantized transmission data rate, thereby reducing the error probability of the overall transmission packet and improving the system throughput.

Third, stable packet quality can be maintained by considering packet delay or user throughput.

Hereinafter, a configuration and an operation according to an exemplary embodiment of the present invention will be described with reference to the accompanying drawings.

1 is a view for explaining a shared channel scheduling method in a wireless packet communication system according to the present invention.

First of all, the present invention proposes a scheduling method in consideration of the signal power / noise power ratio (C / I) transmitted from a terminal and the user and service priority. Define the priority function for this scheduler as follows:

P (k) = α-f (user ID, service ID) + β-g (C / I) + γ-h (packet delay, user throughput)

Where f (user ID, service ID) is a function according to user and service type, g (C / I) is signal power / noise power ratio function, and h (packet delay, user throughput) is user's slot allocation (buffer delay, Function related to user throughput). Here, the throughput of the user and the slot allocation of the user related to the packet delay may also be regarded as a concept corresponding to the capacity of the data buffer waiting to be transmitted in the buffer of the user.

Α is a variable representing the importance of the user, the service required by the user, β is the channel environment (C / I), and γ is the packet delay and the user throughput.

First, as shown in FIG. 1, when a priority call is set (S11), a user identifier (user ID) is received from the upper layer (1). From the received user ID, it is determined whether the user is a user for transmitting / receiving packet data (S12), and the priority of the user is set (S13).

When the packet data is received from the upper layer 1 in the situation in which the call is set as described above (S14), the service priority is set accordingly by receiving which service the packet data is information for supporting (S15).

The priority according to the user ID and the service ID is set with reference to the value received from the upper layer 1. By using this value, the quality between users can be set differently from the service fee, the service provider's request, etc., and the multi-quality service according to the service provided by the service provider can be provided (S16).

In the next wireless packet data system, a user always goes through a process of reporting information about a channel state to a base station. That is, by using the state (C / I) of the channel received from the user (S17), the reception data control unit 2 of the base station has a process of preferentially selecting and transmitting to a user having a good channel environment so as to increase system throughput ( S18). This can increase the overall performance of the system.

Finally, the scheduler always calculates (S21) how much the delay time has passed since the data to be sent at the next moment is received in the buffer S19 in the course of transmitting data by a user. In addition, the user throughput of how much data each user has transmitted so far is determined from the number of data transmitted in the buffer S19 (S20). By calculating the priority from the packet delay and the user throughput calculated as described above (S22), it is possible to maintain fairness between users.

In this way, the service operator assigns weights through the scheduler to f (user ID, service ID), g (C / I), and h (packet delay, user throughput) calculated from the respective information, S23). Data is transmitted (S24). For this purpose, α, β, and γ are controlled, and by adjusting this value, the scheduler operates in various forms. That is, f (user ID, service ID) is the same for all users and services (i.e., f (user ID, service ID = 0 for all user and service), and g (C / I) is the signal power / noise power ratio. When h (packet delay, user throughput) = user throughput, and β = γ, the transmission data rate setting function is operated as the same scheduler as the conventional PF scheduler.

However, in the present invention, when β has a very large value, the system throughput can be maximized. When γ has a very large value, all users receive the same slot allocation regardless of the system throughput, thereby maintaining fairness among users. Done.

As such, each weight has its own role and may play the following roles.

First, α is a value for weighting the service priority to provide differentiated service quality and user priority according to the fee system and service provider's needs. It weights revenue.

And β is a value that adds a weight to the system throughput, which plays a role of weighting the profit that can be obtained by the operator.

Finally, γ is a value for weighting a role that prevents excessive degradation of service quality that may occur during service.

The service provider adjusts α, β, and γ so that priority is obtained from f (user ID, service ID), g (C / I), and h (packet delay, user throughput) to realize the desired service type. It will give a weight to the value.

That is, in the scheduling method of the present invention, the operation of the system can be made flexible by adjusting α, β, and γ, and the various services can be transmitted with desired quality by adjusting the priority for each user and service, and differentiated services for each user. There is an advantage to provide.
In this document, embodiments of the present invention have been described based on the relationship between a base station and a user. Here, it will be apparent to those skilled in the art that a user may be replaced with terms such as a user equipment (UE), a mobile station (MS), a mobile subscriber station (MSS), a mobile terminal, etc. as a user in a mobile communication system.

1 is a view for explaining a shared channel scheduling method in a wireless packet communication system according to the present invention.

* Description of the symbols for the main parts of the drawings *

1: upper layer 2: reception data control unit

3: transmission data buffer control unit

Claims (5)

In the shared channel scheduling method of a wireless communication system including at least one mobile terminal, Identifying a service ID supported by the received data by using information received from an upper layer and determining a priority corresponding to the service ID; And Scheduling the shared channel in consideration of the data buffer capacity and the priority of the mobile terminal waiting to be transmitted; Shared channel scheduling method of a wireless communication system comprising a. The method of claim 1, The scheduling of the shared channel may include considering channel state information for the mobile terminal. In the shared channel scheduling method of a wireless communication system including at least one mobile terminal, Identifying a service ID supported by the received data by using information received from an upper layer and determining a priority corresponding to the service ID; Scheduling the shared channel in consideration of a data buffer capacity waiting to be transmitted by the mobile terminal and channel state information of the mobile terminal; And Redoing the scheduling step if the scheduling needs to be changed; Shared channel scheduling method of a wireless communication system comprising a. A shared channel scheduling method in a wireless communication system for identifying an ID of a service supported by a received packet data using information received from an upper layer and determining a priority corresponding to the service ID, Scheduling the packet data transmission in consideration of at least one of a priority and a transmission data rate of a service supported by the packet data; And Adjusting the scheduling when a scheduling change is necessary to satisfy the Quality of Service (QoS) of the packet data Shared channel scheduling method in a wireless packet communication system comprising a. The method of claim 4, wherein The scheduling may include considering at least one of service priority and channel state information.

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