KR100313914B1 - Packet Data Transmission Rate Control Method in Mobile Communication System - Google Patents

Abstract

The present invention is provided in the base station controller or the mobile switching center, or provided in the base station controller and the mobile switching center, respectively, to store the load status information and various parameters of the forward or reverse channel of the base station, and adjacent to each base station The present invention relates to a method of controlling a packet data transmission rate of a mobile communication system using a base station load manager that periodically reports a load state of a base station or another base station. The mobile station can autonomously set from each base station load state reported periodically from a base station. Periodically determining the autonomous transmission threshold by the base station load management station to broadcast the base station load state including the determined threshold value to the respective terminals through the base station; Lot Determining the transmission rate to the base station by measuring the strength and using the strongest pilot strength, the pilot strength of the currently serving base station, and the currently received total power to transmit and receive data with the base station. It is done.

Description

Packet Data Transmission Rate Control Method in Mobile Communication System

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile communication system. In particular, a method of controlling a packet data transmission rate of a mobile communication system capable of variably controlling the transmission rate of packet data when transmitting packet data in a multimedia communication environment with minimal interference from neighboring base stations. It is about.

As wireless communication technology develops, various services for various subscribers are required. Next-generation wireless communication systems are also researching standards for various services that are suitable for this, and in terms of services, there are studies to provide various multimedia services such as data services as well as existing voice services.

In line with this trend, various standard proposals are also being studied in IMT 2000, the next generation mobile communication system. In the next generation mobile communication system, in particular, the data service is being actively researched due to various application additional services according to the existing voice service.

Unlike the voice service, the conventional packet data service requires a lot of power during transmission and thus can give a lot of interference to neighboring base stations. In the related art, transmission rate control in a reverse link channel environment is performed mainly by a base station. That is, the base station periodically broadcasts information of the base station using a forward common control channel to inform all terminals of the current load state of the base station. In addition, the base station sets the transmission rate by periodically exchanging the load state of the base station when the terminal wants packet transmission service, and provided the packet service using the transmission rate determined during this process.

That is, the base station can accurately determine the situation of the current neighboring base station by periodically transmitting and receiving load information between neighboring base stations. Therefore, if the terminal desires, the base station always determines the transmission rate and notifies the terminal based on the current load state of the neighboring base station. Therefore, the base station should always exchange information between a plurality of neighboring base stations periodically. The above-mentioned conventional technology is not a specially proposed standard, but is expected to be generally proposed in view of the level of current mobile communication technology.

However, in the conventional technology, when the terminal desires packet data service, the base station always determines the transmission rate based on the information of the neighboring base station. This method will have many variables depending on which period the base station selects. Therefore, if the communication period between the base stations is shortened, the base station can obtain an advantage of obtaining accurate information, but it requires an increase in the traffic load between the base stations. On the other hand, the longer the communication period, the less the call load between base stations, but it is difficult to obtain load information of neighboring base stations at the time of requesting data service.

In addition, the base station requires a lot of information from the terminal to determine all the situations required for packet service. That is, if necessary, the UE requests a pilot strength measurement message of a neighbor BS. As the terminal requests the packet service or the number of the terminals in progress increases, the base station providing the service takes a lot of communication load. In this case, not only the data service is provided to all subscribers under the multimedia communication environment, but also There was a problem that the quality of service is likely to fall.

An object of the present invention has been made in view of the above-mentioned problems of the prior art, and when a packet data service is desired in a forward / reverse direction, a terminal autonomously transmits packet data within a range that minimizes interference from a neighboring base station. The present invention provides a method of controlling a packet data transmission rate of a mobile communication system in which a terminal can variably adjust a transmission rate based on an accurate current position and interference of an adjacent base station by selecting a rate.

According to an aspect of the present invention for achieving the above object, the base station load management station periodically determines the autonomous transmission threshold that can be set autonomously by the terminal from each base station load state reported periodically from the base station Broadcasting a load state of a base station including a threshold to each terminal through a corresponding base station; and measuring the pilot strength of an adjacent base station by the terminal by referring to the determined threshold value; And determining the transmission rate to the base station by using the pilot strength and the total power currently received, and transmitting and receiving data with the base station.

1 is a flowchart illustrating controlling a packet data transmission rate at an autonomous rate according to an embodiment of the present invention.

2 is a flow chart illustrating controlling packet data transmission rate at a non-autonomous rate according to an embodiment of the present invention.

FIG. 3 is a flow chart illustrating controlling a packet data transmission rate at an autonomous rate during transmission of packet data according to an embodiment of the present invention. FIG.

4 is a flowchart illustrating controlling a packet data transmission rate at a non-autonomous rate during transmission of packet data according to an embodiment of the present invention.

5 is a diagram for explaining inter-base station interference on a reverse link and a forward link channel, respectively.

Explanation of symbols for main parts of the drawings

MS: terminal BTS: base station

BSC: Base Station Controller BSLC: Base Station Load Manager

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

Unlike voice services, packet data services require a lot of transmit and receive power, which can cause a lot of interference to neighboring base stations. The environment of the forward link channel can determine the state of the forward link channel of the base station through the total transmission power of the base station, and the reverse link channel environment can also determine the load state of the reverse link channel of the base station by the total received power of the base station. The load information of such a base station is periodically reported to a base station load center (BSLC) provided in a base station controller (BSC) or a mobile switching center (MSC). The base station load manager (BSLC) periodically broadcasts the load status of neighboring base stations to each base station, and provides load information when any base station wants load information for a particular base station.

When a base station on a channel of a forward link transmits a packet to a terminal, the base station sequentially considers the highest transmission rate to the lowest transmission rate in consideration of the total transmission power in the base station, and selects the most appropriate transmission rate to transmit the packet. On the other hand, on the reverse link channel, the base station periodically broadcasts the load state of the base station to all terminals in the base station using the forward common control channel. The terminal transmits packet data by setting an appropriate transmission rate for the load between the base station and the terminal and between other base stations based on various load information provided by the base station.

Therefore, the autonomous rate control method, the pilot strength measurement message (PSMM) or the supplemental channel request message (Supplemental channel) through the mobile assist rate control that calculates the transmission path within the allowable range of the base station request message: Non-Autonomous rate control method using SCRM determines the transmission rate of packet data to be transmitted.

Unlike voice service, packet data service requires a lot of transmission and reception power, and it affects neighboring base station and other users. Therefore, various parameters should be considered when determining transmission rate.

Referring to FIG. 5, in general, when a is a speech activity factor and a user transmits a packet at a transmission rate of M times the full rate, an ideal power control is performed when a = 0.4. This will require a load of approximately 2.5 * M. If M = 4, the transmission and reception power corresponding to about 10 times that of voice service is required. This transmit and receive power has an effect as shown in FIG. 5 on the channel of the forward / reverse link.

Accordingly, when there is one data user in an integrated circuit (IC) voice and data system, the total interference between the base station and the neighboring base station is represented by Equation 1 below.

I_D` (Z_1`, Z_2`) = aN_v` (1 + eta) + M`eta`_d`` (Z_1`, Z_2`)

Where a is the voice activity, N _V is the number of voice users, M is a multiple of the full rate (basic rate), and eta`_d`` (Z_1`, Z_2`) is the current base station and adjacent base station path loss (Z). ₁ / Z ₂ ). Therefore, it is possible to determine the interference with respect to the adjacent base station through Equation 1. Through this, the base station can perform rate control to the terminal within a range that minimizes the influence on the neighbor base station load, and the terminal can be provided with the most appropriate packet data service autonomously through the base station load information broadcasted periodically by the base station.

Hereinafter, a transmission rate control method on a forward and a reverse link channel according to an embodiment of the present invention will be described.

First, the control of the packet data transmission rate on the channel of the forward link mainly uses a transmission power link budget technique. When a base station transmits packet data to the terminal, the total transmission power of the current base station is It can be calculated as the radio capacity due to packet service on the channel of the forward link. Therefore, when the base station transmits packet data to the terminal, the base station examines the load state of the current base station and the adjacent base station by using the load state information of the adjacent base station received from the base station load manager (BSLC) to determine the transmission rate satisfied by the base station and the adjacent base station. Set to send packet data.

In addition, the transmission rate control of the packet data on the channel of the reverse link has to consider many problems compared to the transmission rate control of the forward link. On the channel of the forward link, the base station can accurately determine the status of its base station, and can grasp the status of other base stations to some extent so that if there is data required for the terminal, the capacity is allowed to the terminal and the neighboring base stations are affected. Packet data can be transmitted by setting an appropriate transmission rate within the range.

However, on the reverse link channel, the terminal cannot determine what situation the base station is in and how the service transmission rate desired by the current terminal will affect the base station or the neighboring base station which is currently provided with the service. In addition, when the base station is in a poor environment for the service transmission rate desired by the terminal, a lot of negotiation process is performed with the base station and the neighboring base station, resulting in a lot of overhead on the wired / wireless link.

Accordingly, an embodiment of the present invention proposes a packet data rate control algorithm on a reverse link channel. In order to realize this, each terminal and the base station should provide the following functions.

First, the base station periodically broadcasts the load state on the channel of the reverse link of the base station to all terminals in the base station through the forward common control channel. At this time, the broadcast parameters broadcast to each terminal by the base station and the load information transmitted to the base station load manager are the maximum received total power (Current Received Total Power (CRTP), autonomous threshold value) (Autonomous Threshold Value).

Max Received Total Power

The base station broadcasts the maximum received power that can satisfy the required Eb / No in all terminals in the base station. Such a message is broadcast through a system parameter message or other message of a forward common control channel. Through this message, all the terminals can know how much reception power the base station can accommodate.

Current Received Total Power (CRTP)

The base station periodically broadcasts the received power received to all terminals in the current base station. Such a message is broadcast through an access parameter message or other message of the forward common control channel. Through this, all terminals in the base station can determine how much reception power is present in the base station.

Autonomous Threshold Value

It is the total power received in reverse direction so that all terminals in the base station can autonomously determine the transmission rate within this threshold range. Several parameters are required to calculate this autonomous threshold. First, the terminal first measures the pilot strength of the neighboring base station (Pilot strength) of the strongest pilot strength (strongest pilot strength (Z ₂ )), and currently serving base station pilot strength (Z ₁ ) and the current The autonomous threshold is calculated from the total power received, the service rate / base rate (M) at which to send the packet. Therefore, if the calculated value using the above parameter is less than the autonomous threshold value, the terminal transmits data by setting the transmission rate within the range that does not exceed the autonomous threshold value without the negotiation process with the base station. On the other hand, if the appropriate M cannot be selected or exceeds this value, the UE reports Z ₁ and Z ₂ values to the base station through a pilot strength measurement message and receives an appropriate transmission rate from the base station.

Here, each terminal must satisfy Equation 2 below to autonomously determine M.

Autonomous Threshold ≤Total Power Currently Received + M ^* (Z ₁ / Z ₂ )

On the other hand, the base station controller (BSC) or the mobile switching center (MSC) has a base station load center (BSLC) to report and store the load status and various parameters of the forward and reverse link channels of each base station. To have a database system function. The base station load manager is a database that stores base station loads and various parameters. The base station load manager can periodically report the current load state of neighboring base stations for each base station, or accurately transmit the load state of neighboring base stations or other base stations if desired. have.

In addition, each mobile station may set the M value through various parameters periodically received from each base station. The necessary parameters are autonomous thresholds, current total power received, and maximum total power received periodically. First, the terminal sets its own M value within a range that does not affect the neighboring base station by using a path loss radio distance between the base station currently serving and the nearest base station. The terminal sets M that meets the condition of Equation 3 below based on the autonomous threshold at which the base station periodically broadcasts.

Autonomous Threshold ≤Total Power Currently Received + M ^* (Z ₁ / Z ₂ )

The terminal sets M within a range that satisfies the condition of Equation 3 to immediately execute a packet data service without unnecessary rate negotiation with the base station.

On the other hand, if the above conditions are not satisfied or the above conditions cannot be satisfied due to a high user class request, the terminal may transmit a Z ₁ , Z ₂ , Z _n through a pilot strength measurement message (PSMM). Report to the base station.

Each base station sets a minimum M within a range that does not affect the neighboring base station most by using the PSMM received from the terminal and the latest load information of the neighboring base station received from the base station load manager or the newly requested load information. The base station sets a transmission rate corresponding to the set M and transmits packet data to the terminal. At this time, the setting method of M must satisfy the following expression (4).

Maximum autonomous threshold i ≤ total power currently received i + M _k ^* (Z ₁ / Z ₂ )

Maximum autonomous receive threshold i ≤ maximum received total power

Here, the maximum autonomous reception threshold i is the allowed received power that allows the base station to smoothly perform all packet services in the base station, and i denotes the number of base stations to which soft handoff will occur at the current base station, respectively.

In an embodiment of the present invention, a packet data transmission rate control method is divided into two operation modes of a terminal and a base station. The operation method will be described below with reference to FIGS. 1 to 4.

Autonomous rate control mode

As shown in FIG. 1, first, the base station (BTS) broadcasts the load state of the base station (BTS) to all terminals (MS) in the base station through the forward common channel (ST1). In this case, when the MS in the base station BTS wants a packet service, the MS first determines a transmission rate to be serviced by the current MS using an autonomous threshold, and then sends an auxiliary channel request message (SCRM). It is sent to the base station controller BSC (ST2). At this time, by setting the specific field value of the SCRM to 1 report that the transmission rate of the packet data is set within the range allowed by the current base station (BTS). After receiving the SCRM, the base station controller (BSC) determines that the configuration is within a range that has no effect in the base station (BTS), and then transmits a supplemental channel assign message (SCAM) to the terminal (MS) for transmission that is currently being used. Allow rate (ST3). After a certain time, each base station (BTS) periodically reports the current load state of the base station to the base station load manager (BSLC) (ST4).

The base station load manager (BSLC) reassembles the load information from all the base stations (BTS), calculates the autonomous threshold that is most suitable for each base station (BTS), and retransmits the reassigned autonomous threshold to each base station (BTS). (ST5). The base station BTS broadcasts the information received from the base station load manager BSLC to all the terminals MS in the base station BTS through the forward common control channel (ST6).

Non-rate rate control mode

As shown in FIG. 2, first, the base station BTS broadcasts a load state of the base station BTS to all terminals MS in the base station BTS through a forward common control channel (ST11). When the MS in the base station BTS wants the packet service, the MS first determines the transmission rate to be serviced by the current MS using an autonomous threshold. However, if the proper transmission rate cannot be set with the current autonomous threshold or if a higher rate than the rate determined by the various service classes of the MS is desired, the MS transmits an auxiliary channel request message (BTS) to the BS. SCRM) (ST12). At this time, by setting a specific field of the SCRM to 0, it is notified that the transmission rate cannot be determined within the range allowed by the current base station (BTS). The base station controller BSC checks the non-rate rate control mode of the terminal MS and requests the base station load manager BSLC to load information of the neighboring base station BTS (ST13). The base station load manager BSLC transmits adjacent base station load information of the base station BTS to the base station controller BSC (ST14).

The base station controller BSC sets a transmission rate based on load information of an adjacent base station and transmits an auxiliary channel assignment message SCAM to the terminal MS (ST15).

After a certain time, each base station (BTS) periodically reports the load status of the current base station (BTS) to the base station load manager (BALC) (ST16). The base station load manager (BSLC) reassembles the load information from all the base stations (BTS), calculates the autonomous threshold that is most suitable for each base station (BTS), and retransmits the reassigned autonomous threshold to each base station (BTS). (ST17). The base station (BTS) broadcasts the load state of the base station (BTS) through the information received from the base station load manager (BSLC) to all the terminals (MS) in the base station (BTS) through the forward common control channel (ST18).

In addition, according to another embodiment of the present invention, the transmission rate control during the movement of the terminal MS in the packet service occurs when the terminal (MS) moves to the movement or handoff region when the packet data transmission rate control method of Figure 3 This will be described with reference to FIG. 4.

Autonomous Rate Control Mode in Packet Data Service

As shown in FIG. 3, the base station BTS first transmits a load state of the base station BTS to the terminal MS in the base station BTS through a forward common channel (ST21). Thereafter, when the terminal MS approaches or moves away from the base station BTS during the packet data transmission (ST22), or periodically, within the autonomous threshold range, the terminal MS wants to change the new transmission rate. The channel request message (SCRM) is sent to the base station (BTS) (ST23). At this time, the specific field of the SCRM is set to 1 to report that the transmission rate is set within the range allowed by the current base station (BTS). After receiving the SCRM, the base station (BTS) recognizes that the setting is within the unaffected range in the base station (BTS), and then transmits an auxiliary channel allocation message (SCAM) to the terminal MS to allow use of the set transmission rate (ST24). After a certain time, the base station BTS periodically reports the load state of the base station BTS to the base station load manager BSLC (ST25). Then, the base station load manager (BSLC) collects the load information from all the base stations (BTS) again, calculates an autonomous threshold that is most suitable for each base station (BTS), and returns it to the base station (BTS) through the base station controller (BSC). Transmit (ST26). The base station (BTS) loads the information received from the base station load manager (BSLC) to all the terminals (MS) of the base station (BTS) through the forward common control channel to all the terminals (MS) in the base station (BTS). Pass the status (ST27).

Non-rate rate control mode during packet data service

As shown in FIG. 4, first, the base station BTS transmits a load state of the base station BTS to the terminal MS in the base station BTS through a forward common control channel (ST31). At this time, if the terminal MS is transmitting packet data (ST32), as the terminal MS approaches or moves away from the base station, or periodically, the terminal MS may want to change a new transmission rate. If not, the terminal MS transmits an auxiliary channel request message (SCRM) through the base station controller (BSC) (ST33). At this time, by setting a specific field of the SCRM to 0, it is reported that the transmission rate within the range allowed by the current base station (BTS) cannot be set, and the pilot strength measurement message (PSMM) is transmitted through the base station controller (BTS). BSC) (ST34).

The base station controller BSC checks the non-rate rate control mode of the terminal MS and requests the base station load manager BSLC to load information of an adjacent base station (ST35). The base station load manager (BSLC) transmits adjacent base station load information of the base station (BTS) to the base station controller (BSC) (ST36). The base station controller BSC sets the transmission rate based on the load information of the neighbor base station and transmits the SCAM to the terminal MS (ST37). After a certain time, the base station BTS periodically reports the load state of the base station BTS to the base station load manager BSLC (ST38). Then, the base station load manager (BSLC) sums the load information from all the base stations (BTS), calculates the autonomous threshold that is most suitable for each base station (BTS), and assigns the reallocated autonomous threshold value through the base station controller (BSC). Retransmit to (BTS) (ST39). The base station BTS broadcasts the load information received from the base station load manager BSLC to all the terminals MS in the base station BTS through the forward common control channel (ST40).

As described above, in the IMT-2000 mobile communication system, when the packet data service is desired in the forward / reverse direction, the terminal autonomously selects the transmission rate of the packet data within the range of minimizing interference from the neighboring base station. By adjusting the rate variably based on the exact current position and interference of the neighboring base station, a higher quality packet data service can be provided. In addition, by applying the present invention to the field of mobile communication, it is possible to reduce the load of the entire channel during packet data service, thereby improving the communication quality.

Claims (11)

The base station load management station periodically determines an autonomous transmission threshold that the terminal can autonomously set from each base station load state periodically reported from the base station, and transmits the base station load state including the determined threshold value to each terminal through the base station. Broadcasting, The terminal measures the pilot strength of the neighboring base station with reference to the determined threshold value to determine the transmission rate to the base station using the strongest pilot strength, the pilot strength of the currently serving base station and the currently received total power. Packet data transmission rate control method of a mobile communication system comprising the step of transmitting and receiving data with the base station. The method of claim 1, The autonomous transmission threshold that can be set autonomously by the terminal from the base station load state is, Each base station does not affect the neighboring base station by using the pilot strength measurement message (PSMM) received from the terminal and the latest load information of the neighboring base station received from the base station management station or the latest load information newly requested. The transmission rate M is determined within the range, wherein the terminal measures the pilot strength of the neighboring base station, the strongest pilot strength among them is Z ₂ , and the base station pilot strength currently serving is Z ₁ , and the transmission rate is When I say M And the transmission rate M is determined such that the value of the currently received total power + transmission rate M * (Z ₁ / Z ₂ ) satisfies a value equal to or greater than the autonomous threshold. Method of controlling the packet data transmission rate of the system. The method of claim 1, When a certain base station wants to transmit packet data to a certain terminal, the current base station and the neighboring base station satisfy the load state of the current base station and the neighboring base station by using the load state information of the neighboring base station received from the base station load management station. When setting a transmission rate, the transmission rate M of the packet data is If i is the number of base stations where soft handoff will occur, and M _k is the rate / full rate that can be transmitted to the UE, the following conditions are satisfied. Packet data transmission rate control method of mobile communication system. Maximum autonomous threshold i ≤ total power currently received i + M _k ^* (Z ₁ / Z ₂ ) Maximum Autonomous Receive Threshold i ≤ Maximum Received Total Power Here, the maximum autonomous reception threshold i is the allowed reception power that allows the base station to smoothly perform all packet services in the base station. The method of claim 1, The base station transmits a parameter including a maximum received total power indicating how much reception power the base station can accommodate to the maximum and a currently received total power indicating how much reception power in the current base station is. Packet data transmission rate control method of a mobile communication system characterized in that. The method of claim 1, When the transmission rate is set, the terminal measures the pilot strength of the neighboring base station and calculates the strongest pilot strength, the pilot strength of the currently serving base station, and the service rate to transmit packet data to the currently received total power. Obtaining an autonomous threshold value of one terminal, if the autonomous threshold value of the terminal does not exceed the autonomous threshold provided by the base station load manager, it is set autonomously within the autonomous threshold value of the mobile communication system Packet data transmission rate control method. The method of claim 5, If the autonomous threshold of the terminal exceeds the autonomous threshold provided by the base station load manager, or if the terminal is unable to determine the appropriate autonomous threshold, the terminal measures the pilot strength of the neighboring base station to the strongest pilot strength And reporting the pilot strength of the currently serving base station to the base station and receiving an appropriate transmission service rate from the base station. The method of claim 6, And the terminal satisfies the following conditions in order to determine the autonomous threshold value. Autonomous Threshold ≤Total Power Currently Received + M ^* (Z ₁ / Z ₂ ) The method of claim 1, The process of determining the transmission rate to the base station by the terminal with reference to the determined threshold value is determined by using the autonomous threshold value periodically provided by the base station load manager to determine the transmission rate to be serviced by the current terminal and the secondary channel request message (SCRM). ) Is transmitted to the base station controller, And a step of allowing the base station controller to allow a current transmission rate to the terminal. The method of claim 8, When the terminal determines the transmission rate to service, if the proper transmission rate cannot be set to the current autonomous threshold or if the terminal wants a higher rate than the rate determined by the various service classes of the terminal (MS), the terminal is a base station ( Transmitting a supplementary channel request message (SCRM) to the BTS; The base station controller requesting load information of an adjacent base station from the base station load manager; The base station load manager transmitting the adjacent base station load information to a base station controller; The base station controller transmitting a supplementary channel allocation message (SCAM) to a terminal by setting a transmission rate based on load information of an adjacent base station; The base station periodically reporting the load status of the current base station to the base station load manager; And retransmitting the autonomous thresholds reassigned to each base station after the base station load manager collects load information from a plurality of base stations again. The method of claim 1, If the terminal wants to change the new transmission rate as the terminal nears or moves away from the current base station during the transmission of packet data or periodically within the autonomous threshold range, The terminal transmitting a supplementary channel request message (SCRM) to a base station; The base station, after receiving the auxiliary channel request message, confirming that the base station is set within an unaffected range, and allowing the terminal to use the set transmission rate; The base station periodically reporting the load status of the base station to the base station load manager; And the base station load manager re-transmits load information from all base stations and retransmits an autonomous threshold reassigned to each base station. The method of claim 1, If the terminal MS does not want to change the new transmission rate as the terminal approaches or moves away from the base station or periodically within the autonomous threshold range, The terminal transmitting a secondary channel request message (SCRM) to a base station controller; The terminal transmitting a pilot strength measurement message (PSMM) to a base station controller; The base station controller requesting the base station load manager load information of an adjacent base station; The base station load manager transmits adjacent base station load information of the base station to the base station controller; Allowing the base station controller to set a transmission rate based on load information of an adjacent base station to allow the terminal to use the set transmission rate; The base station periodically reporting the load status of the base station to the base station load manager; And the base station load manager is configured to retransmit autonomous thresholds reassigned to each base station after summing load information from a plurality of base stations.