KR100525394B1 - Method for setting reverse activity bit in communication system - Google Patents

Abstract

According to the present invention, the reverse link load indication bit (RAB) state value corresponding to a state of a reverse overload measure (ROTm) and a value of ROTm are determined. Setting a RAB state transition degree value corresponding to a state transition degree for each predetermined section; determining whether a previous ROTm state and a received ROTm state are changed; and when the state of the received ROTm is changed, the set ROTm Calculating a RAB setting time using a RAB state value corresponding to a state of RAB and a RAB state transition degree value corresponding to a state of ROTm state transition; and if the calculated RAB setting time is greater than 0, by the RAB Setting the data rate downward; and comparing the reverse overload calculate (ROTc) with a threshold when the calculated RAB setup time is zero. And setting the data rate down by the RAB if the ROTc is greater than a threshold; and setting the data rate up by the RAB if the ROTc is less than a threshold. A method for setting a reverse link load indication bit of an apparatus, wherein the subscriber station in a base station (or sector) is controlled through a step-by-step control of a reverse link of a high-speed data communication system (eg, 1x EV-DO). It can receive stable service and increase the capacity of reverse link.

Description

Method for setting reverse link load indication bit in communication system {Method for setting reverse activity bit in communication system}

The present invention relates to reverse link control in a communication system. In particular, the reverse link load is indicated by the maximum capacity of the reverse link by efficiently controlling the load of the reverse link using Rise Over Thermal Noise (ROT). A reverse link setting method in a communication system capable of setting a bit (RAB).

The current reverse link load indication bit (Reverse Activity Bit) setting method will be described.

First, reverse data rate control of reverse link in 1x EV-DO is based on the terminal individually determining the rate.

The operation of the terminal is defined by the Reverse Traffic Channel MAC protocol of the air interface specification (Section 8.5 of IS-856). Briefly mentioned here:

Variables used first include a reverse activity load bit, a reverse rate limit, and a transition probabilities.

Here, RAB is a value indicating the congestion of the access network (1) is used as a value indicating that the reverse direction is a congestion state, 0 is a reverse direction is not a congestion state.

The reverse rate limit is a limit of the data rate at which an access terminal can transmit.

The transition probabilities are values that are referred to at the rate of transition.

The 1x EV-DO system may access the access terminal while the reverse frame quality indication bit (RAB) is set to 0 (when the reverse traffic channel load of the access network is not severe). Allow the access terminal to determine the reverse date rate by itself.

If the RAB is 1, all access terminals in the network must maintain or lower the data rate currently being transmitted.

While RAB is set to 0, it is not possible to increase the data rate unconditionally, but to generate a random value between 0 and 1 so that the data rate is smaller than the transition probability value. rate can be changed. This method can more effectively manage reverse link capacity by bursty traffic.

As such, reverse rate control in the 1x EV-DO system is mainly controlled using the RAB.

If RAB is 0, access terminals will gradually transmit at higher data rates. If RAB is set to 1, they will gradually transmit at lower data rates. will be. In other words, as the RAB becomes 1, the reverse load of the access network is gradually decreased.

At this time, Qualcomm proposed two methods for setting RAB, and recommends the first of these two methods.

The first method is based on measurement of Rise Over Thermal Noise (hereinafter referred to as ROT) versus Thermal Noise Power (hereinafter referred to as ROTm).

Here, rise over thermal (ROT) is a value obtained by dividing the total received power by thermal noise power to determine the load condition of the reverse link.

RAB is set to 1 when the measured ROT is higher than the threshold (recommended 5dB) in each slot and antenna at each receiver (1.67ms) at the receiving end of the access network. If it is low, set RAB to zero.

The second method is a method by ROT calculation (hereinafter abbreviated as ROTc).

In the second method, the reverse load can be obtained from the equation. First, the ratio of the received pilot power to the total received power for each received data rate may be obtained through variables such as DataOffsetNom and DataOffset9k6 (9,600). This value is multiplied by the sum of the f (DataRate) values of all access terminals in the sector, Ecp / Io (Power Spectral Density (PSD) of the total received signal versus the average energy per chip of the pilot channel in the antenna). In this case, a reverse link load of a corresponding sector can be obtained. However, this calculation has a disadvantage that the power by the ACK channel is not considered.

1 is a diagram illustrating a channel structure of a 1x EV-DO system which is a high speed data communication system.

Referring to FIG. 1, in a base station (or sector) 11, a forward channel includes a pilot channel 13, a medium access control (MAC) channel 15, a control channel, and a traffic channel 14. The MAC channel consists of a reverse activity channel, a DRCLock channel, and a reverse power control channel. The reverse channel is composed of an access channel 16 and a traffic channel 17. The traffic channel is a pilot channel, a reverse rate indicator (RRI) channel, and a data rate control channel. It consists of an Ack channel and a Data channel.

The pilot channel is used as a basic signal for system acquisition, and the traffic channel and control channel are used for data to be transmitted and control data.

In the forward link, the terminal 12 selects and transmits a transmission rate and a base station to be transmitted through a data rate control (DRC) channel, and the base station transmits data through a traffic channel at the required transmission rate.

In the reverse link, when a terminal transmits data through a traffic channel, the base station (or sector) informs the base station of a transmission rate to be transmitted through a reverse rate indication (RRI) channel to facilitate demodulation.

The reverse traffic channel has six data rates as shown in Table 1.

Bit rate (Kbps) Max payload (bits) 0 0 9.6 234 19.2 490 38.4 1002 76.8 2026 153.6 4076

The terminal transmits at one of the transmission rates shown in Table 1, where the terminal can increase or decrease the transmission rate of the reverse traffic channel, which is determined using information received from the base station (reverse link load indication bit (RAB)). do.

The base station transmits a reverse link activity indication bit (hereinafter abbreviated as RAB) indicating the maximum reverse rate, the probability of the rate transition, and the congestion of the reverse traffic channel to the terminal, and the terminal uses this value. To determine the data rate.

In this case, RAB has a value of 0 or 1 as described above, and in the case of 1, the reverse link has a congestion meaning, and the terminal selects and transmits a transmission rate lower than or equal to the current transmission rate. You can choose a higher bit rate than your bit rate.

Because the reverse link determines the reverse rate of each terminal scattered in the cell, it is not easy to identify the characteristics of the reverse link of the base station and the reverse link received from the antenna may be used even when using the RAB to prevent congestion. There is a need for a technique that accurately measures the degree of load.

However, in the current 1x EV-DO system, the accuracy of the load measured by the RF device is not yet reliable, so it is necessary to use the method with other values to determine the load. In deciding whether to congestion, it is necessary to consider referencing multiple factors and research is ongoing.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described aspects, wherein the received signal power measurement value (ROTm) compared to the thermal noise power measured by the wireless device of the base station, the reverse transmission rate and the total received signal to the average energy per chip of the pilot channel in the antenna The reverse link load is calculated by two ROTc values calculated using Power Spectral Density (PSD) (Ecp / Io), and is reversed in a high-speed data communication (e.g., 1x EV-DO) system. The present invention relates to a method for setting a reverse link load indication bit in a communication system for effectively controlling link load to improve and stabilize performance to obtain a maximum capacity of a reverse link.

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The reverse link load indication bit setting method in the communication system according to the present invention for achieving the above object is a reverse link corresponding to the state of the Rise Over Thermal measure (ROTm). Setting a reverse activity bit (RAB) state value and a RAB state transition degree value corresponding to a state transition degree of the ROTm for each predetermined interval; and changing a previous ROTm state and a received ROTm state. Determining a presence or absence, and when the state of the received ROTm is changed, the RAB setting time is calculated using a RAB state value corresponding to the set ROTm state and a RAB state transition degree value corresponding to the ROTm state transition degree. And setting the data rate down by the RAB when the calculated RAB setting time is greater than zero, and when the calculated RAB setting time is zero. Comparing a load overload calculated with a reverse over terminal calculate (ROTc) with a threshold; and setting the data rate down by the RAB when the ROTc is greater than a threshold; If the ROTc is less than a threshold value, the step of setting the data rate up by the RAB is included. In addition, the method for setting a reverse link load indication bit in a communication system according to the present invention measures a load degree of a reverse link. RAB state transition degree corresponding to the state of Reverse Activity Bit (RAB), corresponding to the state of Rise Over Thermal measure (ROTm) and the state transition degree of ROTm. Setting a value for each predetermined interval, determining whether a previous ROTm state and a received ROTm state are changed, and when the state of the received ROTm is changed, Calculating a RAB setting time by using a RAB state value corresponding to a preset ROTm state and a RAB state transition degree value corresponding to the ROTm state transition degree, and when the calculated RAB setting time is greater than zero, And setting the data rate down by the RAB, and setting the data rate up for the RAB when the calculated RAB set time is zero. It will be more apparent from the following detailed description taken in conjunction with the drawings. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the present invention, a method of determining whether a reverse link is congested will be described with reference to a plurality of data, preferably ROTm and ROTc.

2 is a flowchart for explaining a method for obtaining a reverse link load indication bit setting time in a communication system according to the present invention.

FIG. 2 illustrates a method for obtaining a reverse link load indication bit (RAB) setting time according to a value ROTm of a reverse link load degree measured through a base station wireless device.

First, ROTm, which is one of a plurality of data for determining whether the reverse link is congested, is received (S11), and it is determined whether the state of the previous state and the currently received ROTm has changed according to the state setting values for each section as shown in Table 2. (S12).

At this time, the state of ROTm is set in advance for each section as shown in Table 2 below, and the state is managed according to the received ROTm.

ROTmState ROTm (dB) STATE_0 A1-A2 STATE_1 A2-A3 STATE_2 A3-A4 STATE_3 A4

Here, for example, A1 to A2 are 0 to 3 dB, A2 to A3 are 3 to 6 dB, A3 to A4 are 6 to 8 dB, and A4 is 8 dB or more.

As a result of determination (S12), when the state of ROTm is changed, as shown in Tables 3 and 4, the RAB set time (RABSetTime) has a different setting time depending on the state of the ROTm and the degree of state transition, and the value of the received ROTm is in a state. If is changed, the RAB set time (RABSetTime) is calculated according to the following Equation 1 based on this value (S13). RAB_SetTime = RABSetTimeByState + RABSetTimeByStateTrans Here, RABSetTimeByState is, for example, a value of one of B1 to B4 in Table 3, and RABSetTimeByStateTrans is, for example, a value of one of C1 to C5 in Table 4.

In this case, as described above, ROTm is a value obtained by dividing the total received power by the thermal noise power to determine the load state of the reverse link. The ROTm is an antenna for each sector at the receiving end of the access network. For each slot (1.67ms), if the measured ROT value is higher than the threshold (recommended at 5dB), set RAB to 1; otherwise, set RAB to 0.

The ROTc calculates a reverse load through a calculation formula. The ROTc calculates a ratio of received pilot power to total received power for each received data rate to obtain all accesses in the sector. The sum of the f (DataRate) values of the access terminal is multiplied by Ecp / Io (Power Spectral Density (PSD) of the total received signal versus the average energy per chip of the pilot channel in the antenna) to reverse link load of the corresponding sector ( reverse link load). As described above, in the case of using ROTc, power by the ACK channel is not considered, but in the present invention, when the two methods recommended by Qualcomm are used in combination, the state of ROTm is distinguished. By setting the time for setting the RAB for each state differently, the time for setting the RAB according to the state transition step of the ROTm is different, and the state of the ROTm suddenly does not gradually increase sequentially up / down), the wireless environment is determined to be unstable and the RAB is set to 1 longer.

That is, in the present invention, for example, RAB is set using ROTm, and then RAB is set in consideration of ROTc, and ROTc is used as a method of correcting unstable measurement accuracy of ROTm.

In this way, the reverse link can be stably controlled in a progressive manner by managing section by section.

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At this time, whenever the value of ROTm increases, the setting time of RAB 1 is shortened, thereby preventing the continuous increase in advance.

In particular, in case of Table 4, if the load suddenly increases according to the degree of change in the previous state, the RAB is set to 1 for a longer time so that the terminal may require a long down time for the sudden increased load. do.

ROTmState RABSetTimeByState in RABLength (slot) STATE_0 B1 STATE_1 B2 STATE_2 B3 STATE_3 B4

ROTmState RABSetTimeByStateTrans (in units of RABLength (slot)) TransUp_1Step C1 TransUp_2Step C2 TransUp_3Step C3 TransDown_1Step C4 TransDown_2Step C5

In this case, in the case of B1 to B4 shown in Table 3, the slot length increases, and the slot length of C1 to C3 in Table 4 also increases. However, C4 to C5 have a reduced slot length. That is because the case of C4 is closer to the threshold value than C5. For reference, the slot length can be applied within 10 to 100 slots, and C1 to C5 10 to 1000 slots.

Here, RABSetTime is a value that is obtained again and updated whenever a state transition of ROTm occurs. At this time, the RABSetTime value is updated again whenever a state transition occurs, so even if the RAB SetTime (RABSetTime) is obtained with a large value due to the previous increase in width, if the state of ROTm falls back to a low state, The update prevents the RAB from being set to 1 unnecessarily.

At this time, if RAB is unnecessarily set to 1, the capacity of the overall reverse link may be reduced, but through such a method, it is possible to quickly control the change of the reverse link characteristics.

3 is a flowchart for explaining a method of setting a reverse link load indication bit in a communication system according to the present invention.

In FIG. 3, a method of using the RABSetTime value and the ROTc value obtained using the flowchart of FIG. 2 again will be described.

First, it is determined whether the value of the RAB set time RABSetTime is greater than zero (S21).

As a result of determination (S21), when the value of the RAB set time (RABSetTime) is greater than zero, RAB is set to 1 regardless of the ROTc value. The RAB set time RABSetTime decreases the RAB by 1 every time this process is performed, that is, every slot (S23).

However, when the determination result (S21), the value of the RAB set time (RABSetTime) is 0 (not greater than 0), the ROTc value is calculated (S22).

Next, it is determined whether the calculated ROTc value is larger than the ROT threshold ROTth (S24).

If the determination result (S24) is larger than the threshold value, the RAB is set to 1 (S26), and when it is low, it is set to 0 (S25).

ROTc is obtained by the sum of the ratios of the total received power and pilot received power of all terminals in the base station.

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.

As described above, the present invention provides a stable service for all subscribers in a base station (or sector) through a step-by-step control of a reverse link of a high-speed data communication system (for example, 1x EV-DO). It is also possible to increase the capacity of the reverse link.

1 is a diagram for explaining a channel structure in a high speed data communication system;

2 is a flowchart for explaining a method for obtaining a reverse link load indication bit setting time in a communication system according to the present invention.

3 is a flowchart for explaining a method for setting a reverse link load indication bit in a communication system according to the present invention.

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

11: terminal 12: base station

Claims (6)

The state of the reverse link load bit (RAB) corresponding to the state of a reverse overload measure (ROTm) and the state transition degree of the ROTm. Setting an RAB state transition degree value corresponding to each of predetermined intervals; Determining whether the previous ROTm state and the received ROTm state are changed; Calculating a RAB setting time using a RAB state value corresponding to the set ROTm state and a RAB state transition degree value corresponding to the ROTm state transition degree when the state of the received ROTm is changed; If the calculated RAB set time is greater than zero, setting the data rate down by the RAB; When the calculated RAB set time is 0, comparing a load degree of the reverse link (Rise Over Terminal calculate; 'ROTc') with a threshold; If the ROTc is greater than a threshold, setting the data rate down by the RAB; And And if the ROTc is less than a threshold, setting the data rate upward by the RAB. delete The method of claim 1, The RAB state value is a time corresponding to the ROTm value, and the RAB state transition degree value is a time according to the change of the ROTm state. The method of claim 3, wherein The RAB state transition degree value is a reverse link load indication, characterized by setting the data rate down by the RAB for a relatively longer time than the time corresponding to the RAB state value when the load of the reverse link increases. Bit setting method. The method of claim 1, And the RAB setting time is calculated and updated each time a state transition of ROTm occurs. The state of the reverse link load bit (RAB) corresponding to the state of a reverse overload measure (ROTm) and the state transition degree of the ROTm. Setting an RAB state transition degree value corresponding to each of predetermined intervals; Determining whether the previous ROTm state and the received ROTm state are changed; Calculating a RAB setting time using a RAB state value corresponding to the set ROTm state and a RAB state transition degree value corresponding to the ROTm state transition degree when the state of the received ROTm is changed; If the calculated RAB set time is greater than zero, setting the data rate down by the RAB; And And setting a data rate upward for the RAB when the calculated RAB setting time is zero.