KR100606898B1 - The method to manage radio resources for packet scheduling, and system using the same - Google Patents

Abstract

In the next generation communication system, a resource utilization method for packet scheduling, which is particularly suitable for efficiently managing packet scheduling, and a High Speed Downlink Packet Access (HSDPA) system using the method. The present invention relates to a resource utilization method for packet scheduling for more efficiently managing packet scheduling in an asynchronous next generation mobile communication system (3GPP), and a system using the same. It is an invention that has high utilization, and in particular, efficiently supports resource distribution among users.

High speed downlink packet access (HSDPA), packet scheduling

Description

The method to manage radio resources for packet scheduling, and system using the same}

1 is a diagram showing the configuration of a general UMTS interface and system.

2 is a diagram for explaining a function of a general HSDPA packet scheduler.

Figure 3 is a graph showing the output value of the conventional HSDPA packet scheduler.

Figure 4 is a graph showing the output value of the HSDPA packet scheduler according to the present invention.

5 is a diagram illustrating an output of an HSDPA packet scheduler according to an embodiment of the present invention.

The present invention relates to a next generation communication system, and more particularly, a resource utilization method for packet scheduling suitable for managing packet scheduling, and a High Speed Downlink Packet Access (HSDPA) using the method. Abbreviated) system.

Universal Mobile Terrestrial System (hereinafter, abbreviated as UMTS) is a third generation mobile communication system evolved from the European standard, Global System for Mobile Communications (GSM).

UMTS provides a wide range of services at up to 2Mbps by integrating Wideband Code Division Multiple Access (WCDMA) technology into a Radio Access Network (RAN) based on the Core Network of GSM. The goal is to.

1 is a diagram showing the configuration of a general UMTS interface and system.

Referring to FIG. 1, the UMTS includes a user equipment (UE), a wireless access network (UTRAN), and a core network (Core Network) as shown.

In particular, the radio access network (UTRAN) includes a plurality of radio network subsystems (RNS), each radio network subsystem (RNS) includes a base station (Node B) and a base station controller (RNC: Radio Network Controller) It is configured by.

Meanwhile, the radio access network (UTRAN) is connected to three core networks.

That is, the radio access network (UTRAN) is connected to a circuit switching domain (CS Domain) for circuit switching, to a packet switching domain (PS Domain) for packet switching, and to a broadcast service. It is connected to broadcasting domain (BC Domain: Broadcasting domain).

Meanwhile, UMTS provides the following four basic bearers through each of the core networks described above.

1. Conversational Class: Real-time service, circuit switched area

2. Streaming Class: Real time service, line / packet exchange area

3. Interactive Class: Non-real-time service, packet exchange area

4. Background Class: Non-real-time service, packet exchange area

Since the real-time service is a service sensitive to transmission delay, it has the highest priority. For this reason, it is mainly provided to users through circuit switching.

Non-real-time services are less sensitive to transmission delays than real-time services, and therefore have a lower priority than real-time services, and the services occur intermittently. For this reason, it is mainly provided to users through packet exchange.

In recent years, data transmission in downlink has become a high proportion. Accordingly, in the asynchronous communication system, HSDPA technology providing up to 10Mbps in a bearer providing 2Mbps is being developed.

The HSDPA is responsible for transmission through packet exchange among the four bearer services described above.

Meanwhile, in order to provide HSDPA, a medium access control (MAC) device is provided in a base station controller (RNC).

In particular, in order to reduce the maximum transmission rate, the transmission delay, and increase the throughput, the base station Node B further includes a medium access control (MAC) device for HSDPA.

The medium access control (MAC) device provided in the base station Node B receives information for packet scheduling from the base station controller RNC.

Meanwhile, an algorithm considered for packet scheduling at the base station is as follows.

1. Round Robin: Algorithms for scheduling in sequence

2. MAX C / I: Algorithms for scheduling to users who have the best wireless environment at the moment (best carrier to interference).

3. Proportional Fair: Scheduling algorithm using ratio of average transmission rate and current transmission rate in wireless environment

4. MAX Queue: Algorithm for scheduling to the users with the most packets to send to user queue.

The round robin algorithm transmits packets in the order of users without considering the wireless environment.

The MAX C / I algorithm allows users to transmit packets preferentially with the maximum throughput possible in a wireless environment.

Proportional Fair algorithm allows users with higher transmission rates than the average transmission rates in the wireless environment to transmit packets first.

The MAX Queue algorithm gives priority to packet transmission to users who have a lot of data to transmit to the user queue provided in the base station.

In general, the MAX C / I algorithm is used to improve the transmission throughput of the base station, and the Proportional Fair algorithm is used when considering both the transmission delay and the transmission throughput of the base station.

Meanwhile, for the packet scheduling, the base station Node B includes a packet scheduler. This packet scheduler is essential for providing HSDPA service, and the performance of HSDPA service depends on the role of the packet scheduler. The packet scheduler of the base station Node B that influences HSDPA service performance is hereinafter referred to as HSDPA packet scheduler.

The HSDPA packet scheduler operates on values input to the scheduler, as shown in FIG.

Among the input values, the radio channel quality is measured in real time from the terminal device UE, and the base station Node B receives the measured value from the terminal device UE in real time.

Queue status, on the other hand, is the size of a packet waiting in a queue, and its input value is used to ensure that the queue does not overflow and also to guarantee transmission delay.

In addition, priorities are entered for the user or type of service, and various other inputs can be used to improve the performance of the HSDPA packet scheduler.

The HSDPA packet scheduler determines the priority for packet transmission from the input values. Based on the determination, it determines how the user's packet should go out in the current transmission time interval (hereinafter, abbreviated as TTI).

That is, the HSDPA packet scheduler determines a modulation coding scheme (MCS) for power currently available using input values. The two-dimensional representation of this decision is FIG. 3.

On the other hand, the conventional HSDPA described above, the state information and queue of the base station (Node B) queue that holds the information (radio channel quality) and data on the radio state for packet scheduling at the base station (Node B) Using the guaranteed rate of transmission, we decide how to send the user's packet. Then, the transmission power, available code resources, and modulation schemes for the code are allocated.

However, the above conventional packet scheduling is performed only in the current TTI. That is, the HSDPA packet scheduler operates only in the current TTI. As a result, even if there is a space for packet transmission in the next TTI, packet scheduling was inevitable based on the information of the current TTI.

In particular, retransmission packets should generally be sent with maximum priority. However, if such a retransmission packet also needs to be transmitted in the same TTI as other general transmission packets, a shortage of transmission power may occur or another general transmission packet (the packet first transmitted to the current TTI) may be affected by the retransmission packet.

In addition, if user data occurs periodically at the same time, there may be many sections in which packets are not transmitted as a whole, but data congestion may occur at the time when a packet corresponding to the generated user data is transmitted.

Disclosure of Invention An object of the present invention is to provide a resource utilization method for packet scheduling for more efficiently managing packet scheduling in an asynchronous next generation mobile communication system (3GPP), and a system using the same. It is.

It is still another object of the present invention to provide a resource utilization method for packet scheduling, and a system using the same, which is more useful for distributing radio resources in an HSDPA system, in particular, to efficiently support resource distribution among users.

A feature of the system according to the present invention for achieving the above object is a medium access control (MAC) of a base station having a packet scheduler operating with a plurality of time slots in the same scheduling period. It is configured to include a device.

More preferably, the packet scheduler uses a different packet scheduling algorithm in a plurality of timeslots belonging to the same scheduling period.

Also preferably, the packet scheduler may include a priority of a plurality of input user packets, a status of user queues provided in the MAC device, and a report from each UE. In consideration of the elements including the radio channel quality, packet scheduling is performed on the input plurality of user packets.

Also preferably, the packet scheduler allocates a time slot for transmitting each user packet to a plurality of user packets input during the scheduling period. Here, the packet scheduler allocates different timeslots to the plurality of input user packets. In addition, the different timeslots correspond to the same scheduling period, and the user packets have different priorities. In addition, when a plurality of user packets are allocated one time slot belonging to the scheduling period, another time slot is allocated to a predetermined user packet as the transmission power of the allocated time slot is insufficient. In addition, as a retransmission packet is input among the plurality of user packets, a time slot for the retransmission packet is allocated differently from the timeslot for the newly transmitted user packet.

Also preferably, the time slot is a transmission time interval (TTI) in which user packets are transmitted.

A feature of the method according to the present invention for achieving the above object is, in a high speed downlink packet access (HSDPA) system, a medium access control (MAC) device provided in the base station receives a plurality of user packets during one scheduling period And scheduling a plurality of user packets by a packet scheduler included in the medium access control device, and the packet scheduler provides a plurality of time slots to the input plurality of user packets during the one scheduling period. Distribution and allocating them.

More preferably, the packet scheduler performs the scheduling with different scheduling algorithms for user packets to be transmitted in different timeslots.

Also preferably, includes a priority of the plurality of user packets, a state of user queues provided in the medium access control (MAC) device, and a radio channel quality reported from each user terminal device (UE). The scheduling is performed using elements.

Also preferably, assigning a first timeslot to at least one user packet having a first priority among the plurality of input user packets, and at least one having a second priority among the input plurality of user packets. Assign a second timeslot to the user packets of and assign a third timeslot to the remaining user packets.

Also preferably, the first time slot is assigned to at least one user packet having a different priority among the inputted plurality of user packets, and the second time is assigned to the at least one user packet having another different priority. Allocate a slot.

Also, preferably, different timeslots corresponding to the one scheduling period are allocated to user packets having different priorities among the inputted plurality of user packets.

Also preferably, when allocating a first time slot belonging to the one scheduling period to predetermined user packets of the input plurality of user packets, checking the transmission power of the allocated first timeslot; Assigning a second timeslot to a portion of the predetermined user packets when it is determined that transmission power of the allocated first timeslot is insufficient.

Also preferably, as retransmission packets are present in the input plurality of user packets, time slots for the retransmission packets are allocated differently than time slots for other user packets.

Other objects, features and advantages of the present invention will become apparent from the detailed description of the embodiments with reference to the accompanying drawings.

Hereinafter, with reference to the accompanying drawings illustrating the configuration and operation of the embodiment of the present invention, the configuration and operation of the present invention shown in the drawings and described by it will be described by at least one embodiment, By the technical spirit of the present invention described above and its core configuration and operation is not limited.

In the present invention, the output of the packet scheduler represented two-dimensionally as shown in FIG. 3 is to be output three-dimensionally as shown in FIG.

In the prior art, scheduling is applied in each time slot (or TTI) having a predetermined length, but in the present invention, scheduling is simultaneously performed in at least one or more intervals (time slots or TTIs).

If packet scheduling is performed every N _Schedule TTIs (or timeslots), every [N _Schedule × TTI], the packet scheduler determines how the packet should be transmitted.

The packet scheduler also assigns the transmission power of the packet, the modulation coding scheme (MCS: modulation scheme and coding scheme determination), and the timeslot (or TTI).

5 is a diagram illustrating an output of an HSDPA packet scheduler according to an embodiment of the present invention, and is an example in the case of N _Schedule = 2 (time slot or TTI).

Referring to FIG. 5, in the HSDPA system of the present invention, a packet scheduling period is defined as one or more timeslots (or TTIs), and various different packet scheduling algorithms are mixed in each of the plurality of timeslots (or TTIs).

Accordingly, as the MAC device included in the Node B receives a plurality of user packets during one scheduling period, the packet scheduler included in the MAC access device receives a plurality of inputted packets. Performs packet scheduling for user packets. In particular, since packet scheduling uses a plurality of timeslots (or TTIs) in one scheduling period, user packets input during the one scheduling period are not transmitted through one timeslot (or TTI).

That is, when the transmission power is sufficient in the packet scheduling of the present invention, all user packets are allocated to one time slot (or TTI) belonging to one scheduling period. However, when the transmission power of one time slot (or TTI) is insufficient, user packets are evenly distributed and allocated to a plurality of time slots (or TTIs) belonging to one scheduling period.

As described above, packet scheduling goes through the following process in order to allocate to user packets by further considering the transmission power of a time resource (time slot or TTI).

In the HSDPA packet scheduling of the present invention, it is basically desirable to allocate all user packets to one time slot (or TTI).

Therefore, it is preferable that a plurality of user packets to be transmitted are allocated to one timeslot belonging to one scheduling period. However, in the present invention, the transmission power of the timeslot is first checked prior to the allocation of the timeslot (or TTI). At this time, if the transmission power of the corresponding timeslot is sufficient, all user packets are allocated to that one timeslot. On the other hand, if the transmission power of the corresponding timeslot is insufficient, some user packets are allocated to other timeslots belonging to the same scheduling period so that the transmission power of all timeslots belonging to one scheduling period is not short.

In addition, when a plurality of different packet scheduling algorithms are mixed in each of a plurality of timeslots (or TTIs), different scheduling algorithms are applied to user packets to be transmitted in different timeslots (or TTIs).

For example, if HSDPA considers the maximum transmission throughput in a wireless environment while simultaneously considering both the transmission delay and the transmission throughput of the base station, the MAX C / I algorithm in one time slot (or TTI) TTI) uses Proportional Fair algorithm.

On the other hand, as another example of the present invention, using one scheduling algorithm during a scheduling period that is a plurality of timeslots (or TTIs), time resources (timeslots or TTIs) are distributed according to a priority given to a user. For example, if the time slot (or TTI) belonging to one scheduling period is 3, the first time slot is allocated to the user packet having the highest priority among the input user packets. And assigns a second timeslot to the next user packet having a second priority. Finally, assign a third timeslot to at least one user packet having a priority after the next third. As another example, when the time slot (or TTI) belonging to one scheduling period is 2, the first time slot is allocated to the user packet having the highest priority among the input user packets. And assigning a second timeslot to at least one user packet having the remaining priority. As another example, in the present invention, when a plurality of time slots (or TTIs) belonging to one scheduling period and a plurality of user packets are divided, the user packets having the same priority are divided into user packets having the same priority. Assign the same timeslot. User packets with different priorities are then assigned different timeslots.

In the present invention, even when different scheduling algorithms are mixed in a plurality of timeslots (or TTIs), retransmission packets and new transmission packets are not transmitted at the same time. That is, if there is a retransmission packet among a plurality of inputted user packets, the retransmission packet allocates a different time slot than other user packets to be newly transmitted. In particular, since the retransmission packet has the highest priority, it is assigned to the first timeslot belonging to one scheduling period.

Hereinafter, the configuration and operation of the present invention will also be described.

The HSDPA system of the present invention comprises a medium access control (MAC) device of a base station having a packet scheduler.

In the above, the packet scheduler of the present invention operates in a scheduling period corresponding to several timeslots (or TTIs). That is, one scheduling period is a time corresponding to several timeslots (or TTIs).

As described above, each timeslot belonging to the scheduling period uses a different packet scheduling algorithm.

Meanwhile, the packet scheduler of the present invention performs packet scheduling for a plurality of input user packets in consideration of the following input elements. The elements are the priority of user packets, the status of user queues provided in the MAC device, the radio channel quality reported from each UE terminal, and the like.

The radio channel quality is measured in real time from the user terminal device UE, and the base station Node B receives a measurement value from the user terminal device UE in real time.

Queue status is the size of packets queued in the queue. This is used to ensure that the queue does not overflow and also guarantees transmission delay.

The priority of the packet transmission is determined by adding the priority of the user packet according to the user or service type to the radio channel quality and the queue state, and in particular, each user packet is transmitted through a certain time slot of each scheduling period. Decide if

In more detail, the packet scheduler of the present invention determines how to exit each user packet, and assigns a time slot (or TTI) to user packets input during each scheduling period, and at which time slot. Determine.

In the present invention, even if there are a plurality of timeslots belonging to one scheduling period, the same timeslot is allocated to a plurality of input user packets in some cases.

However, if a plurality of user packets are assigned the same timeslot and the transmission power of the timeslot is determined to be insufficient, the packet scheduler allocates another timeslot to a certain user packet.

Meanwhile, in the present invention, time slots are allocated so that a plurality of user packets inputted to time slots belonging to one scheduling period are evenly distributed. If the incoming user packets have different priorities, the packet scheduler assigns different timeslots among the various time slots belonging to one scheduling period to the user packets. This is most appropriate when retransmission packets are scheduled. That is, if a retransmission packet is input, the packet scheduler assigns another new timeslot to the retransmission packet so that the retransmission packet and the new transmission packet are not transmitted in the same time slot. However, the timeslot allocated to the retransmission packet corresponds to the same scheduling period as the timeslot allocated to the new transmission packet.

In the above-described present invention, packet scheduling is performed by further considering a time slot (or TTI) resource in packet scheduling.

The packet scheduler of the present invention receives user's channel information and Ack / Nack information for packet transmission every time slot (or TTI). A scheduling decision including a time slot allocation for the user packet to be transmitted is performed every [N _Schedule × TTI].

On the other hand, when the packet scheduler performs scheduling decisions (timeslot allocation, how packets should be transmitted), consider the following:

1. The retransmission packet allocates a different time slot than the new transmission packet.

2. The retransmission packet is determined as the highest priority among the timeslots belonging to the scheduling period.

3. Even if there is room in the time slots belonging to the scheduling period, if the resource (transmission power) of one time slot does not run out, the user packet to be transmitted is allocated to the one time slot.

4. When assigning multiple user packets to multiple time slots in one scheduling period, ensure that they are evenly distributed over each time slot.

Meanwhile, for the present invention, a bearer to be set for a user terminal is identified when a radio resource control (RRC) connection is established, and then to a base station Node B at the time of channel setup for HSDPA. Tells the type of bearer.

In addition, in the present invention, when the base station controller (RNC) transmits the user packet to the base station (Node B) after the channel setting for the HSDPA, it informs the bearer type through each user packet.

 In addition, in the present invention, the base station controller (RNC) distributes a priority queue in the base station Node B according to the bearer type.

 As described above, in the present invention, since time resources (that is, timeslots or TTIs) can be distributed in scheduling of user packets, there is almost no chance of collision of transport packets at the same time. In the present invention, since the scheduling algorithm is used in combination with the distribution of time resources, there is no data congestion of the transport packet. This reduces the burden on processor processing power.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the embodiments, but should be defined by the claims.

Claims (17)

High speed downlink packet access (HSDPA), comprising a medium access control (MAC) device of a base station having a packet scheduler operating with a plurality of time slots in the same scheduling period : High Speed Downlink Packet Access System. The method of claim 1, wherein the packet scheduler, A high speed downlink packet access (HSDPA) system, characterized by using different packet scheduling algorithms in a plurality of timeslots belonging to the same scheduling period. The method of claim 1, wherein the packet scheduler, And a time slot for transmitting each user packet to a plurality of user packets input during the one scheduling period. The method of claim 3, wherein the packet scheduler, Elements including a priority of a plurality of input user packets, a state of user queues provided in the MAC device, and a radio channel quality reported from each UE. High Speed Downlink Packet Access (HSDPA) system, characterized in that to perform packet scheduling for the plurality of incoming user packets. The method of claim 4, wherein the packet scheduler, When allocating to different timeslots corresponding to the same scheduling period, the user packet transmission priority is determined by adding the radio channel quality and the queue state to the priority of the user packets. Access (HSDPA) system. The method of claim 5, wherein the packet scheduler, And assigning different time slots corresponding to the one scheduling period in user packets having different priorities according to the determined user packet transmission priority. The method of claim 3, wherein the packet scheduler, High Speed Downlink Packet Access (HSDPA) system, characterized in that as the retransmission packet is input among the plurality of user packets, the retransmission packet is different from the time slot for the newly transmitted user packet. The method of claim 3, wherein the packet scheduler, A high speed downlink packet access (HSDPA) system, if the transmission power of the one time slot is sufficient, all user packets are allocated to one time slot belonging to one scheduling period. The method of claim 3, wherein the packet scheduler, In case that the transmission power of the one time slot is insufficient, a high speed downlink packet access system (HSDPA) system, characterized in that some user packets are distributed evenly among a plurality of time slots belonging to one scheduling period. The method of claim 1, wherein the time slot (time slot), A high speed downlink packet access (HSDPA) system, characterized in that a transmission time interval (TTI) in which user packets are transmitted. In High Speed Downlink Packet Access (HSDPA) system, A medium access control (MAC) device provided at a base station receiving a plurality of user packets during one scheduling period; A packet scheduler included in the medium access control apparatus for scheduling the user packet; And The packet scheduler distributing and allocating a plurality of timeslots to the input plurality of user packets during the one scheduling period Resource utilization method for packet scheduling, characterized in that comprises a. The method of claim 11, wherein the packet scheduler, And scheduling the user packets to be transmitted in different timeslots using different scheduling algorithms. The method of claim 11, wherein the packet scheduler, Use elements including the priority of the user packets, the state of user queues provided in the MAC device and the radio channel quality reported from each UE And determining a user packet transmission priority. The method of claim 13, And assigning different timeslots corresponding to the one scheduling period to user packets having different packet transmission priorities among the plurality of input user packets. The method of claim 11, And a time slot for the retransmission packet is different from a time slot for other user packets as a retransmission packet exists among the inputted plurality of user packets. The method of claim 11, Checking the transmission power of the allocated timeslot when allocating the input plurality of user packets to one timeslot belonging to the one scheduling period; And If it is determined that transmission power of the allocated time slot is insufficient, allocating the predetermined some user packets to another time slot belonging to the one scheduling period. Resource utilization method for packet scheduling, characterized in that it further comprises. delete

Images