KR20020039783A - Multimedia Traffic Control Method in CDMA Cellular System - Google Patents

Abstract

PURPOSE: A method for controlling multimedia traffic in a CDMA cellular system is provided to reduce a forced drop ratio of hand-off traffic according to the shortage of a channel by allocating traffic sensitive to time delay to a dedicated channel in case that the traffic performs a hand-off, and by storing and processing the traffic in a buffer capable of delaying determined time after that the dedicated channel is filled. CONSTITUTION: In case that a traffic processing request is received(S31), it is searched whether there's an available channel among common channels(S32). In case that there is the available channel, a channel among the channels is allocated. In addition, a traffic is processed(S33). In case that there is no available channel, it is checked whether a present traffic is a new or a hand-off traffic(S34). In case that the traffic is the new traffic, the processing of the traffic is stopped instead of allocating the channel(S35). In case that the traffic is the hand-off traffic, it is searched whether there is an available channel(S36). In case that there is the channel, the hand-off traffic is processed(S37). In case that there is no available channel, it is checked whether a present hand-off traffic is sensitive or not(S38). In case that the traffic is not sensitive, the processing is stopped(S39). In case that the traffic is sensitive, it is checked whether there is a space for waiting for the traffic in a buffer(S40). The traffic is stored in the buffer and stood ready(S41). The processing of the traffic is stopped(S42).

Description

Multimedia Traffic Control Method in CDMA Cellular System

The present invention relates to an efficient multimedia traffic control method according to traffic characteristics in a CDMA mobile communication system. More specifically, the present invention provides a dedicated channel for handoff traffic according to traffic characteristics and a buffer for handoff traffic sensitive to time delay. The present invention relates to a traffic control method for minimizing handoff truncation rate.

In the existing CDMA cellular system, various channel allocation techniques are used to efficiently control traffic. These channel allocation techniques include new and handoff traffic handling methods, a predetermined amount of dedicated channel (DC) allocation for handoff traffic, and handoff traffic instead of dedicated channels. The technique of using a buffer that waits for delay is mainly used. The above-mentioned schemes are highly efficient only when the traffic characteristics are the same. This means that the channel allocation for the multimedia traffic in the IMT-2000 system having various characteristics is handled because the traffic is classified into only the new traffic and the handoff traffic. There is a problem that is not suitable.

Looking at the above channel allocation techniques, when the channel usage of the system reaches a threshold, the method of processing new traffic and handoff traffic equally increases the forced truncation rate of the handoff traffic and thus the success rate of handoff decreases relatively. There is a problem. In addition, the technique using a dedicated channel (DC) does not distinguish between time-sensitive and time-sensitive traffic, and when the capacity of the system reaches a threshold value, when a handoff occurs, it is allocated to a dedicated channel (DC) unconditionally. Even when delay-sensitive traffic comes in, there is a problem of forced disconnection when there is no dedicated channel (DC) available. Also, in the method using the buffer, the traffic is not classified as in the method using the dedicated channel (DC). When the capacity of the system reaches the threshold value, when the handoff occurs, the channel is unconditionally waited in the buffer and the channel is allocated. When delay-sensitive traffic comes in, when there is a lot of traffic waiting in the buffer, it is forced to be truncated by the timeout even if it is waiting in the buffer. As a result, there is a problem that does not satisfy the quality of service QOS specified in the system, there is a problem that the efficiency in terms of performance and operation of the system is also significantly reduced.

Therefore, in order to process multimedia traffic having various characteristics to be serviced in IMT-2000 system in the future, a new channel allocation technique considering these characteristics is required.

Accordingly, an object of the present invention, which is devised to solve the above-mentioned problems of the prior art, is to first assign a traffic delay-sensitive traffic to a dedicated channel first when the currently serving traffic performs a handoff. After all the data is filled, it is stored in a buffer that delays a certain amount of time, and then processed to minimize the forced truncation rate of handoff traffic due to lack of channels when the channel usage of the system reaches a threshold. It is to provide a multimedia traffic control method in a CDMA cellular system that can maximize the success rate and satisfy the system's prescribed quality of service QOS.

1 is a configuration diagram of a CDMA cellular system to which the present invention is applied;

2 is a conceptual diagram of multimedia traffic processing in a CDMA cellular system to which the present invention is applied;

3 is a flowchart illustrating a method for controlling multimedia traffic in a CDMA cellular system according to an embodiment of the present invention.

In the CDMA cellular system according to the present invention for achieving the above object, a method for controlling multimedia traffic in the CDMA cellular system is divided into a common channel and a dedicated channel, a method for controlling multimedia traffic by operating a standby buffer In

A first step of, if an arbitrary traffic processing request is received, searching whether there is an available channel among the common channels, and if the available common channel exists, assigning and processing the traffic to one of the common channels;

A second step of checking whether the traffic is new traffic or handoff traffic if the available common channel does not exist as a result of the search of the first step, and stopping the traffic processing without assigning a channel if the traffic is new traffic;

As a result of the investigation of the second step, if handoff traffic is searched for whether there is an available channel among the dedicated channels, and if there is an available dedicated channel, allocating the handoff traffic to one of the dedicated channels for processing; 3 steps,

As a result of the search in the third step, if the available dedicated channel does not exist, it is examined whether the handoff traffic is time delay sensitive or traffic insensitive to time delay. The fourth step, and

As a result of the investigation in the fourth step, if the traffic is sensitive to the time delay, it is examined whether there is a space for storing the traffic in the standby buffer. If there is a space for storing the standby buffer, the traffic is temporarily stored in the standby buffer for waiting. And a fifth step of terminating the processing of the traffic if there is no space to store in the standby buffer.

Hereinafter, a method of controlling multimedia traffic in a CDMA cellular system according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

In the present invention, the CDMA mobile communication system serving multimedia traffic maximizes the use efficiency of limited radio channels and minimizes the forced truncation rate of traffic due to lack of channels when performing handoff. Dedicated channel (DC) is allocated and buffer is operated after all dedicated channels are filled.

In general, the traffic generated in any cell may be changed by the new traffic generated when the mobile subscriber attempts traffic in the corresponding cell service area, and the cell serviced by the subscriber's movement while receiving the service in the other cell service area. It can be classified as handoff traffic that occurs. Each traffic is divided into time delay sensitive and transmission error sensitive traffic such as voice and time delay sensitive and transmission error sensitive traffic such as data. Since one system must service a lot of traffic using a limited radio channel, efficient use of the channel has a significant impact on system capacity and performance and service traffic quality.

Since the mobile communication system receives traffic while the user moves, and the service must be maintained even when the user moves, the importance of service continuity for handoff traffic is emerging rather than service for new traffic. For this reason, when a channel of the CDMA mobile communication system reaches a threshold before saturation, the remaining channels are left blank to process handoff traffic. In the present invention, according to the characteristics of the traffic, Dedicated channel (DC) is allocated for handoff and buffer is used for handoff of traffic that is not sensitive to time delay.

Briefly explaining the contents of the present invention, when there are all N channels in one cell, a predetermined amount of r dedicated channels (DC) is preset in advance, and r of these dedicated channels (DC) are wireless channels. Is allocated for handoff traffic only when the usage of the " The remaining N-r channels, i.e., common channels, can be allocated and used regardless of the traffic characteristics based on time delay or new traffic, handoff traffic.

When the amount of use of the radio channel reaches a threshold again during handoff of the traffic, it waits and processes a buffer that functions to delay a time delay sensitive traffic for a predetermined time. This is generally based on the handoff characteristic of traffic in a mobile communication system, that is, the channel occupancy time has an exponential distribution, and when the serving traffic performs a soft handoff, the traffic is simultaneously established between the serving cell and the target cell. Considering the characteristics that are maintained for a certain period of time, the traffic that is sensitive to the time delay during this time is queued in the buffer to process the waiting traffic when the channel is released.

1 is a configuration diagram of a CDMA cellular system to which the present invention is applied, and main functions of each subsystem are as follows.

A mobile station (MS) is a mobile station, and a base station control processor (BCP) is a processor for managing a base station. CIN (Ccp Interface Network) and BIN (Bcp Interface Network) are responsible for transmitting packet-type control and traffic messages between designated processors. The Transcode Selector Bank (TSB) is connected to the CIN to match traffic voice data with the Base Transceiver Subsystem (BTS) and the Mobile Switching Center (MSC) and controls traffic according to control information of the Call Control Processor (CCP). The voice data matching of the TSB receives a PCM (Pulse Code Modulation) voice signal from the MSC, compresses it, sends the compressed signal to the base station, and restores the compressed signal from the base station to the MSC. The CCP functions to control traffic so that traffic processing can be performed smoothly, and to allocate and release selector / vocoder channels required for call service. In addition, it performs handoff control so that the traffic service is maintained while the subscriber is moving. In addition, it performs data services including service option 2 (SO2), subscriber registration and authentication functions. The BSM is a subsystem responsible for the operation management and maintenance of the entire control station and base station, including the BSC and BTS. To this end, information about initialization and system configuration at system startup is transferred from the BSM to each subsystem through the CCP, and state information from each subsystem is collected and retrieved to perform various diagnostic functions. In addition to basic call processing, the MSC is responsible for delivering authentication-related data between the Authentication Center (AC) and the control station. The AC verifies all data related to authentication.

FIG. 2 is a diagram illustrating a channel allocation to which the present invention is applied according to a traffic processing request. First, when there are N channels, a predetermined amount of dedicated channels (DCs) r are preassigned among the N channels. (DC) r are allocated only for handoff traffic when the usage of the radio channel reaches a threshold. The remaining N-r channels, i.e., common channels, can be allocated and used regardless of traffic characteristics based on time delay or new traffic or handoff traffic. When the usage of the common channel reaches a threshold, the traffic delayed by the time delay waits in the buffer for a certain time delay and processes the waiting traffic when the previous channel is released. If the channel cannot be allocated until the time waiting in the buffer is timed out (T / O), the traffic is forcibly truncated.

3 is a flowchart illustrating a method of controlling multimedia traffic in a CDMA cellular system according to an embodiment of the present invention.

When the traffic processing request is received (S31), it is searched whether there is an available channel among the N-r common channels (S32). If there is a common channel available, one of the common channels is allocated and the traffic is processed regardless of the characteristics of the traffic (S33). However, in step S32, if all of the N-r common channels are in use and there are no available common channels, it is checked whether the current traffic is new traffic or handoff traffic (S34). If the new traffic does not allocate the channel, the traffic processing is stopped (S35). However, if it is the handoff traffic in step S34, it is searched whether there is an available channel among the r dedicated channels (S36). If there is a dedicated channel available, a common channel is allocated to handle handoff traffic (S37).

However, if there is no dedicated channel available in step S36, it is checked whether the current handoff traffic is time delay sensitive or traffic insensitive to time delay (S38). If the traffic is insensitive to the time delay, the traffic processing is stopped (S39). If the traffic is sensitive to the time delay, it is examined whether there is a space to wait for the traffic in the buffer (S40). If it can be stored in the buffer, the traffic is stored in the buffer to wait (S41). However, if there is no space to store in the buffer, traffic processing is stopped (S42). After storing the traffic in the buffer, if all channels are in use until timeout occurs, the processing of the traffic stored in the buffer is terminated.

This improves the channel usage efficiency when the system's channel usage reaches a certain threshold, rather than handling new or handoff traffic equally, and forcibly cuts off handoff traffic caused by lack of channels during handoff. Can be prevented in advance and handoff success rate can be improved.

While the invention has been described above based on the preferred embodiments thereof, these embodiments are intended to illustrate rather than limit the invention. It will be apparent to those skilled in the art that various changes, modifications, or adjustments to the above embodiments can be made without departing from the spirit of the invention. Therefore, the protection scope of the present invention will be limited only by the appended claims, and should be construed as including all such changes, modifications or adjustments.

As described above, according to the present invention, when the channel usage becomes a threshold, handoff traffic is preferentially allocated to the dedicated channel, and when the usage of the dedicated channel becomes the threshold, the delay-sensitive traffic is temporarily stored in a buffer for a predetermined time. By doing so after processing, it is possible to minimize the forced truncation rate of traffic due to the lack of channels and maximize the handoff success rate when the system's capacity reaches a threshold, thereby improving the efficiency of using the restricted channel to improve the prescribed service of the system. Satisfying quality QOS has the effect of maximizing system performance and efficiency.

Claims (1)

In a method of controlling a multimedia traffic by dividing all channels into a common channel and a dedicated channel in a CDMA cellular system, and using a standby buffer, A first step of, if an arbitrary traffic processing request is received, searching whether there is an available channel among the common channels, and if the available common channel exists, assigning and processing the traffic to one of the common channels; A second step of checking whether the traffic is new traffic or handoff traffic if the available common channel does not exist as a result of the search of the first step, and stopping the traffic processing without assigning a channel if the traffic is new traffic; As a result of the investigation of the second step, if handoff traffic is searched for whether there is an available channel among the dedicated channels, and if there is an available dedicated channel, allocating the handoff traffic to one of the dedicated channels for processing; 3 steps, As a result of the search in the third step, if the available dedicated channel does not exist, it is examined whether the handoff traffic is time delay sensitive or traffic insensitive to time delay. The fourth step, and As a result of the investigation in the fourth step, if the traffic is sensitive to the time delay, it is examined whether there is a space for storing the traffic in the standby buffer. If there is a space for storing the standby buffer, the traffic is temporarily stored in the standby buffer for waiting. And post-processing and terminating the processing of the traffic if there is no space to store in the standby buffer.