KR20080062209A - Apparatus and method for call admission control in broadband wireless communication system - Google Patents

Abstract

An apparatus and a method for call admission control in a broadband wireless communication system are provided to perform the call admission control by referring wireless capacity change and input traffic variation in the broadband wireless communication system. An RF receiver(201) converts RF signals into base band analog signals. An ADC(Analog to Digital Converter)(203) converts the analog signals provided from the RF receiver into the digital signals. An OFDM(Orthogonal Frequency Division Multiplexing) demodulator(205) outputs frequency division signals by performing the FFT(Fast Fourier Transform) to the time division signals provided from the ADC. A de-mapping device(207) reconfigure the signals mapped in the frequency division into a configuration before mapped. The demodulator and a decoder(209) output the information bit rows by demodulating and decoding the signals provided from the de-mapping device. A terminal information management unit(213) maintains status information of each terminal. A call management unit(215) manages information about the call. A wireless capacity management unit(217) manages entire frame usage ratio information.

Description

APPARATUS AND METHOD FOR CALL ADMISSION CONTROL IN BROADBAND WIRELESS COMMUNICATION SYSTEM}

1 is a diagram illustrating a radio capacity utilization rate in a broadband wireless communication system according to the prior art;

2 is a block diagram of a base station in a broadband wireless communication system according to the present invention;

3 is a diagram illustrating a procedure of controlling a user-level acceptance request of a terminal by a base station in a broadband wireless communication system according to an embodiment of the present invention;

4 is a diagram illustrating a procedure of a base station controlling a call acceptance request of a terminal in a broadband wireless communication system according to an embodiment of the present invention; and

5 is a diagram illustrating a wireless capacity distribution measurement time point in a broadband wireless communication system according to an embodiment of the present invention.

The present invention relates to a broadband wireless communication system, and to an apparatus and method for call admission control in a broadband wireless communication system.

In general, the wired communication network has a characteristic that the input traffic fluctuates with time, but the output band is constant. However, the wireless communication network has a characteristic that not only the input traffic but also the wireless capacity varies with time. That is, path fading due to the distance between the terminal and the base station and slow fading due to shadowing due to terrain conditions such as buildings, high speed movement of the terminal, and multipath. Due to fast fading or the like, the wireless capacity is changed. In addition, due to interference from an adjacent cell, handover, network entry terminal, etc., the radio capacity is changed.

In a broadband wireless communication system, the radio capacity is determined by a signal to interference and noise ratio (hereinafter referred to as 'SINR') between a base station and a terminal. That is, the higher the SINR, the higher the modulation and coding (Modulation and Coding Scheme, hereinafter referred to as 'MCS') to communicate at a high data rate, the lower the SINR is lower using the lower level MCS Perform communication at the baud rate. Accordingly, the radio capacity between the base station and the terminal may vary depending on which terminal the base station communicates with, that is, how the scheduling is performed.

On the other hand, because the radio resources are limited, the base station should be able to limit the number of calls (Call) to ensure the quality of service to the terminal. That is, it is necessary to determine whether to allow a new incoming call in consideration of the current resource usage situation, and this decision process is called a call admission control (CAC).

According to the conventional CAC scheme, the base station sets the radio capacity threshold fixedly and accepts the call if the threshold is not exceeded in consideration of the capacity that the requested call will occupy. For example, as shown in FIG. 1, call acceptance occurs within a range in which the total traffic usage 103 does not exceed the threshold C _th 101. That is, by using a fixed threshold without considering the change in the radio capacity, there is a problem that whether to allow the call is determined without accurately reflecting the allowable radio capacity to the terminal. Furthermore, since the CAC is performed based on the maximum required capacity without considering the statistical characteristics of the incoming call, there is a problem in that waste of radio resources occurs.

Accordingly, an object of the present invention is to provide an apparatus and method for performing call admission control in consideration of a change in radio capacity in a broadband wireless communication system.

Another object of the present invention is to provide an apparatus and method for adjusting a threshold value and performing call admission control in a broadband wireless communication system.

According to a first aspect of the present invention for achieving the above object, in a broadband wireless communication system, a base station apparatus includes a management unit that manages the number of acceptable terminals and the current accommodating state information for each user level acceptance request type, and from the terminal. And a control unit for checking the request type of the terminal and determining whether to accept the request in consideration of the current acceptance status of the type.

According to a second aspect of the present invention for achieving the above object, a base station apparatus in a broadband wireless communication system, the call management unit for confirming the traffic rate probability distribution for the call, if the call acceptance is requested, modulation and coding in the frame A radio capacity management unit calculates the total frame utilization rate using the level distribution, and calculates the frame occupancy rate of the call using the traffic rate probability distribution information of the call, and whether the call is accepted using the total frame utilization rate and the frame occupancy rate of the call. It characterized in that it comprises a control unit for determining.

According to a third aspect of the present invention for achieving the above object, a method for accepting a terminal by a base station in a broadband wireless communication system includes: checking whether a user level acceptance request is generated from the terminal, and accepting the request type and the type of the request. And determining whether to accept the request in consideration of the current acknowledgment state of the corresponding type.

According to a fourth aspect of the present invention for achieving the above object, a call acceptance method of a base station in a broadband wireless communication system, the process of calculating the total frame utilization rate using the modulation and coding level distribution in the frame, the call acceptance request Determining a traffic rate probability distribution for the call, calculating a frame occupancy rate of the call using the traffic rate probability distribution information of the call, and using the total frame utilization rate and the frame occupancy rate of the call. And determining whether to accept the call.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In describing the present invention, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

Hereinafter, a description will be given of a technique for controlling a state change and a call acceptance request of a terminal in consideration of a change in radio capacity and a change in input traffic in a broadband wireless communication system. Hereinafter, the wireless communication system will be described using orthogonal frequency division multiplexing (hereinafter referred to as 'OFDM') based communication system as an example, and may be similarly applied to other wireless communication systems.

First, the communication system environment assumed by the present invention will be described.

The terminal may have multiple Calls, and in order for the terminal to have a call, acceptance at the user level must be made first. After being accepted at the user level, if the terminal requests to accept the call, the system determines whether to accept it. At this time, if the release occurs at the user level, the system releases all calls that the terminal has.

First, the user level acceptance will be described. The system classifies the user level acceptance request type of the terminal and applies another criterion. The terminal may have three states, namely, an awake mode, a sleep mode, and an idle mode, and the state change to the active mode is called a user level acceptance request. Also, in addition to the state change, when a handover is performed from a neighboring base station or when a terminal is powered on and enters a new network, it is referred to as a user level acceptance request. In this case, the user level acceptance request type is classified into two types according to the following Table 1 according to the state before the active mode.

 type  Classification criteria  First type  Terminal entering new network terminal changing in idle mode  Second type  Terminal that is handing over Terminal that changes in sleep mode

The user-level acceptance request type classification as shown in Table 1 is performed, and the maximum number of terminals that can be serviced in the active mode is divided and allocated to each type to independently determine acceptance. Here, it is preferable that the allocation ratio for each type is set to a ratio in which the second type is higher than the first type. This is because, in general, the denial of access in the second type case is greater in user dissatisfaction than in the first type case.

Next, the call level will be described. The call is divided into a preemptive call and a normal call according to whether there is an emergency. In addition, the general call is divided into a BE call (Best Effort Call) and a QoS call (Quality of Service Call) and an uplink and a downlink depending on the link direction according to a service. Each arc is defined by the features shown in Table 2 below.

 Arc classification  Characteristic  Emergency call  The call with the highest priority in scheduling due to system policy  General arc  BE issue  Call with lowest rank when scheduling  QoS call  Calls with delay requirements and real-time service characteristics Calls with minimum bandwidth requirements and non-real-time characteristics

After classifying the call as described above, it is determined whether to allow the call by applying each method according to the requested call.

Hereinafter, a configuration and an operation procedure of a base station for performing call admission control will be described in detail with reference to the accompanying drawings.

2 is a block diagram of a base station in a broadband wireless communication system according to the present invention.

As shown in FIG. 2, the base station includes a radio frequency (RF) receiver 201, an analog to digital converter (hereinafter referred to as an 'ADC') 203, an OFDM demodulator 205, and a resource decode. And a mapper 207, a demodulator and decoder 209, a message checking unit 211, a terminal information managing unit 213, a call managing unit 215, a wireless capacity managing unit 217, and a controlling unit 219. .

The RF receiver 201 converts an RF signal received through an antenna into a baseband analog signal. The ADC 203 converts an analog signal provided from the RF receiver 201 into a digital signal and outputs the digital signal. The OFDM demodulator 205 outputs a frequency domain signal by performing Fast Fourier Transform (FFT) on the time domain signal provided from the ADC 203.

The resource demapper 207 reconstructs the signal mapped to the frequency domain provided from the OFDM demodulator 205 in a form before it is mapped. The demodulator and decoder 209 demodulates and decodes a signal provided from the resource demapper 207 in a corresponding manner to output an information bit string. The message acknowledgment unit 211 receives a bit string of a message (eg, a user level accept request message, a call accept request message) received from the terminal from the demodulator and decoder 209 and checks the content of the message.

The terminal information manager 213 performs continuous signaling with all terminals located in the cell and maintains state information of each terminal. In other words, each terminal located in the cell monitors which of the active mode, sleep mode, idle mode. In particular, when a specific terminal requests user-level acceptance according to the present invention, it is checked whether the request of the specific terminal is any of the types shown in Table 1, and provides the checked information to the controller 219. In addition, the terminal information manager 213 manages the number of acceptable terminals and the current accommodating state information for each of the two types. That is, the total number of active mode terminals that can be accommodated by the base station is allocated to each type at a predetermined rate, and the current acknowledgment state information of the corresponding type is updated whenever a new terminal is connected. The type of accommodating terminal number and current accommodating state information for each type are provided to the controller 219 when the terminal requests a user level acceptance.

The call manager 215 manages information about a call with a terminal. In particular, when a call connection is requested from the terminal according to the present invention, it is checked whether the type of the call, i. If it is a general call, it checks whether it is a QoS call or a BE call, and at the same time, checks whether it is an uplink call or a downlink call. The call manager 215 also identifies the traffic class of the requested call. The traffic class is information required for calculating the frame occupancy of the call, and represents a traffic rate probability distribution of the call. Here, the type and traffic class of the call may be confirmed through scheduling instructions from the service providing server of the corresponding call. The identified call type information is provided to the controller 219, and the traffic class information is provided to the radio capacity manager 217.

The wireless capacity manager 217 manages the usage status of the wireless capacity, that is, the entire frame utilization rate information. The total frame usage rate is calculated as the sum of the frame occupancy rates of each call, and the frame occupancy rate for one call can be expressed by Equation 1 below.

In Equation 1, W _new represents a frame occupancy occupied by a new call, A _new represents a random variable representing a traffic rate of a new call, and C represents a random variable representing a radio capacity of a new call.

For example, the distribution of the traffic rate probability variable A _new may be expressed as shown in Table 3 below for each traffic class.

 Traffic class  Probability distribution  UGS Pr [A _new = m] = 1 (m: minimum guaranteed traffic rate)   ERT-VR RT-VR Pr [A _new = p] = ρ / p Pr [A _new == 0] = 1- (ρ / p) (ρ: maximum retention of traffic rate, p: frequency of maximum rate)  NRT-VR Pr [A _new = m] = 1 (m: minimum guaranteed traffic rate)

Here, traffic class information for the new call is provided from the call manager 215.

In addition, the distribution of the wireless capacity (C) is calculated as shown in Equation 2 below. Here, the wireless capacity distribution is measured based on a modulation and coding scheme (hereinafter, referred to as 'MCS') level.

In Equation 2, Pr [C = c _k ] is a probability that the radio capacity of any call becomes c _k , the K is the number of MCS levels, the c _k is the radio capacity of the MCS level k times, n _k Denotes the total number of slots occupied by the kth MCS level in a frame.

The average and variance of the frame occupancy of each call calculated using the wireless capacity distribution may be expressed by Equation 3 below.

The <Equation 3> the m _new is the corresponding arc frame share average, the a _j is the arc traffic rate, the c _k is the radio capacity of k times the MCS level, the q _j is a new call traffic rates a _j In one Pr [A _new = a _j ], where p _k is the probability that the MCS level of the new call is c _k (Pr [C = c _k ]), and σ ² _new denotes the variance of the frame occupancy of the call.

Here, the wireless capacity distribution calculated as in Equation 2 is periodically updated. In other words, the wireless capacity management unit 217 has a predetermined period 501 as shown in FIG. Update distribution information. Each time a new call is connected, Equation 3 calculates a frame occupancy average and variance of the corresponding call, and accumulates it to obtain total frame utilization average (M) and variance (V) information for all connected calls. That is, the wireless capacity management unit 217 maintains the overall frame utilization average (M) and variance (V) information, and when a request for connection of a new call occurs, the entire frame utilization information and the frame of the new call at the time of request generation Share information is provided to the controller 219. However, the overall frame utilization average (M) and variance (V) information are managed by dividing uplink and downlink.

The controller 219 controls the overall operation of the base station. In particular, according to the present invention, it is determined whether the user level acceptance request and the call acceptance request of the terminal are allowed. When a user level acceptance request of an arbitrary terminal occurs, the control unit 219 receives the user level acceptance request type information of the terminal, the number of acceptable terminals of the type and the current acceptance state information from the terminal information management unit 213. Determines whether to accept the user level acceptance request. In addition, when a user-level release request occurs, that is, when a request for a state change to an idle mode or an idle mode occurs, such as a handover to an adjacent cell, a network departure due to power off, or a sleep mode, The state change of is released in consideration of the number of the sleep mode available terminals, and in the other case is released as requested. In this case, if the number of the sleep mode available terminals is saturated, the controller 219 controls the terminal to transition to the idle mode.

In addition, when a call acceptance request is generated from the terminal, the controller 219 first checks the number of CIDs (Connection IDs) allocated to the terminal and checks whether additional CID allocation is possible. If the CID allocation is possible, the controller 219 is provided with information on the call requested from the call manager 215 and the current full frame utilization information is received from the radio capacity manager 217 to allow the call. Judge. At this time, the criteria for determining whether or not to allow according to the type of the call varies. For example, if an emergency call or BE call is requested, the call is accepted unconditionally. Because the emergency call is a service having priority over all other services, and the BE call has the lowest scheduling priority and does not affect other calls, so the call is accepted without conditions in both cases. On the other hand, in the case of a QoS call, the estimated total frame utilization rate when the requested call is added using the frame occupancy information and the current total frame utilization rate of the new call provided from the radio capacity management unit 217 is exceeded, and then the reference utilization rate is exceeded. If not, accept the call. Here, the calculation methods of the reference utilization rate and the estimated total frame utilization rate are four cases, that is, four cases of an uplink second type access, an uplink first type access, a downlink second type access, and a downlink first type access. Depends on. The estimated total frame usage rate and the reference usage rate according to the above case are as shown in Table 4 below.

 Occation  Estimated Full Frame Utilization and Baseline Utilization  Uplink Second Type Connection

 UL first type connection

 Downlink Second Type Connection

 Downlink first type connection

In Table 4, the left terms of the inequality sign indicate the expected total frame utilization rate, and the right term represents the reference utilization rate. In addition, the M _UL is the uplink full frame utilization average, the m _new is the frame occupancy average of the requested call, the α ₁ and α ₂ is a variable that is determined by the target Overflow Probability, the V _UL is Uplink full frame utilization variance, sigma ² _new is the frame occupancy variance of the requested call, the M _DL is the downlink full frame utilization average, the V _DL is uplink full frame utilization variance, and β is a map in the downlink frame ( It shows the ratio of traffic area excluding map. Here, α ₁ and α ₂ are preset values, for example, as shown in Table 5 below.

 Target Overflow Probability α ₁ α ₂ 0.1 0.89 1.35 0.01 1.72 1.10 0.001 2.45 1.05

In other words, when the connection of the QoS call is requested, the control unit 219 accepts the call if the connection request call satisfies the criteria shown in Table 4. The controller 219 notifies the radio capacity manager 217 of whether the call is allowed or not and updates the entire frame utilization rate information. That is, the wireless capacity management unit 217 adds the frame occupancy average and variance of the new call to the overall frame utilization average and variance, respectively. In addition, when the QoS call is released, the controller 219 provides the radio capacity management unit 217 to update the entire frame utilization information by providing the released call information to the radio capacity manager 217. That is, the wireless capacity management unit 217 subtracts the frame occupancy average and variance of the new call from the overall frame utilization average and variance, respectively.

3 is a flowchart illustrating a procedure for controlling a user-level acceptance request of a terminal by a base station in a broadband wireless communication system according to an exemplary embodiment of the present invention.

Referring to FIG. 3, the base station determines whether a user level acceptance request of the terminal occurs in step 301. In other words, it is checked whether there is a terminal generating an event, such as an entry from a neighbor cell, a new network entry, or a state change from an idle mode or a sleep mode to an active mode.

When the user level acceptance request of the terminal occurs, the base station determines the user level acceptance request type of the terminal in step 303. In other words, it is checked whether the terminal is included in any of the two types classified as shown in Table 1 above.

After checking the user level acceptance request type of the terminal, the base station determines the number of active mode terminals accommodated in the type in step 305. That is, since the number of active mode terminals that can be accommodated for each of the types classified as shown in Table 1 is managed, the base station checks whether the user type acceptance request of the identified type can be allowed.

If the number of active mode terminals of the corresponding type is saturated, the base station rejects the user level acceptance request of the terminal in step 307.

On the other hand, if the number of active mode terminals of the corresponding type is not saturated, the base station proceeds to step 309 and reduces the number of acceptable terminals of the type by one and allows the user level acceptance request of the terminal.

4 is a flowchart illustrating a procedure of controlling a call acceptance request of a terminal by a base station in a broadband wireless communication system according to an exemplary embodiment of the present invention.

Referring to FIG. 4, the base station determines whether a call accept request occurs in step 401.

When the call acceptance request occurs, the base station proceeds to step 403 to check the number of CIDs already allocated by the terminal requesting the call acceptance.

If the CID assigned by the terminal is already saturated, that is, when the terminal cannot receive the CID anymore, the base station rejects the call connection in step 405.

On the other hand, if the CID already allocated by the terminal is not saturated, that is, if the terminal can be further allocated to the CID, the base station proceeds to step 407 and checks the information on the requested call. That is, it is checked whether the call is an emergency call, a BE call, or a QoS call. At the same time, it is checked whether the call is uplink or downlink. In addition, in case of a QoS call, the traffic class information of the call is checked.

After confirming the information on the call, the base station proceeds to step 409 and determines whether the requested call is a QoS call.

If the call is not a QoS call, the base station proceeds to step 411 to check whether the call is an emergency call or a BE call.

If the call is an emergency call or a BE call, the base station proceeds to step 421 to allow connection of the call.

As a result of checking in step 409, if the call is a QoS call, the base station proceeds to step 413 to calculate the frame occupancy of the call. Here, the frame occupancy of the call is calculated as shown in Equation 3 above.

After calculating the frame occupancy rate of the call, the base station proceeds to step 415 to calculate the estimated total frame occupancy rate using the total frame utilization rate of the current base station and the frame occupancy rate of the call. In this case, since the total frame utilization rate of the base station is managed differently according to a link direction (uplink or downlink), the estimated total frame utilization rate is calculated by selecting all frame utilization information matching the link direction of the call.

After calculating the expected full frame usage rate, the base station proceeds to step 417 to compare the expected full frame usage rate with the reference usage rate. Here, the reference usage rate depends on the link direction of the call and the user level acceptance type of the terminal requesting the call. That is, as shown in Table 4, it depends on four cases of uplink second type access, uplink first type access, downlink second type access, and downlink first type access.

If the expected total frame utilization rate is greater, the base station rejects the call connection in step 405.

On the other hand, if the reference utilization is greater, the base station proceeds to step 419 to add the frame occupancy average and variance of the requested call to update the current full frame utilization information.

After updating the full frame utilization information, the base station proceeds to step 421 to allow the call connection.

The above-described embodiment with reference to FIGS. 3 and 4 has described a process of accepting a user level acceptance request and a call of the terminal. On the contrary, when the terminal requests the state change to the sleep mode during the release at the user level of the terminal, the base station checks the number of sleep mode terminals that can be accommodated, and when the terminal is not saturated, the base station detects the state change to the sleep mode. You must allow it. However, when the number of the sleep mode terminals is saturated, the base station transitions the terminal to the idle mode. In addition, when disconnecting the call, the overall frame utilization rate should be reduced by the frame occupancy rate due to the released call.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the scope of the following claims, but also by the equivalents of the claims.

As described above, call admission control is performed in consideration of a change in radio capacity and a change in input traffic in a broadband wireless communication system, thereby preventing waste of radio resources and satisfying the demand for each traffic.

Claims (46)

A base station apparatus in a broadband wireless communication system, A management unit which manages the number of acceptable terminals and current accommodating state information for each user level acceptance request type; And a controller for checking the request type of the terminal and determining whether to accept the request in consideration of the current acceptance status of the type when the user level acceptance request is received from the terminal. The method of claim 1, The user-level accept request is Apparatus characterized in that it is one of a request for the transition to the active mode (Awake) of the terminal, Handover, Network (Network). The method of claim 1, The management unit, Manage network transition or transition from idle mode to active mode as the first type, And managing the transition from the handover or sleep mode to the active mode as a second type. The method of claim 3, wherein The management unit, And setting the number of accommodating terminals of the second type to be larger than the number of accommodating terminals of the first type. The method of claim 1, The control unit, When the release request of the user level, if the release request is a request for a transition to the sleep mode, the device is characterized in that the transition to the idle mode, if it is saturated by checking the number of acceptable sleep mode terminal. A base station apparatus in a broadband wireless communication system, A call management unit confirming a traffic rate probability distribution for the call, when a call is accepted; A radio capacity management unit for calculating an overall frame utilization rate using a modulation and coding scheme (MCS) level distribution in a frame, and calculating a frame occupancy rate of the call using traffic rate probability distribution information of the call; And a controller for determining whether to accept the call using the total frame usage rate and the frame occupancy rate of the call. The method of claim 6, The call management unit, And checking the traffic rate probability distribution through a scheduling instruction from a service server for the call. The method of claim 6, The wireless capacity management unit, And calculating a radio capacity distribution by referring to the modulation and coding level distributions and accumulating the frame occupancy rates of previously accepted calls to calculate the total frame utilization rate. The method of claim 8, The wireless capacity management unit, And classifying and managing the entire frame usage rate into uplink and downlink. The method of claim 8, The wireless capacity distribution is calculated as shown in the following formula,

Where Pr [C = c _k ] is the probability that the radio capacity of any call will be c _k , where K is the number of MCS levels, c _k is the radio capacity at MCS level _k , and n _k is _k in a frame The total number of slots occupied by the first MCS level. The method of claim 8, The wireless capacity management unit, And update the wireless capacity distribution according to a predetermined period. The method of claim 8, The frame occupancy rate of the call is characterized in that calculated by the following formula,

Where m _new is the frame occupancy average of the requested call, a _j is the traffic rate of the requested call, c _k is the radio capacity of the MCS level k, q _j is the probability that the traffic rate of the requested call is a _j , Where p _k is the probability that the MCS level of the requested call is c _k and sigma ² _new represents the frame occupancy variance of the requested call. The method of claim 6, The control unit, And calculating the expected frame usage rate by adding the frame occupancy rate of the requested call to the overall frame usage rate, and determining whether to accept the call by comparing the estimated frame usage rate with a preset provisional usage rate. The method of claim 13, The expected frame utilization rate is calculated by the formula below,

Where M is the average of the current frame utilization, m _new is the frame occupancy average of the requested call, V is the variance of the current frame utilization, σ ² _new is the frame occupancy dispersion of the requested call, and α is a predetermined variance weight. Indicates. The method of claim 14, The average and variance of the frame utilization is The apparatus is classified and managed in an uplink or a downlink and used as a value for the same link direction as a previously requested call when calculating an expected frame usage rate. The method of claim 13, Further comprising a terminal information management unit for managing user-level acceptance request type information of the terminal, The controller selects and compares a corresponding reference usage rate among the reference usage rates set differently according to the user level acceptance request type and the link direction of the requested call. The method of claim 16, The terminal information management unit, Manage the transition from network entry or idle mode to awake mode as the first type, And managing the transition from the handover or sleep mode to the active mode as a second type. The method of claim 17, The reference usage rate when the user acceptance request type is the first type is less than the reference usage rate when the second type. The method of claim 16, The reference utilization rate corresponding to the case in which the link direction of the requested call is downlink is a value reflecting a ratio of a traffic area excluding a map in a downlink frame. The method of claim 6, The control unit, And checking the number of connection IDs (CIDs) being used by the terminal requesting the call, and determining whether to accept the call requested by the terminal when additional allocation is possible. The method of claim 6, The control unit, If the call is a preemptive call or a best effort (BE) call, accept the call without condition. The method of claim 6, The wireless capacity management unit, And when the call is accepted, updating the overall frame utilization to reflect an increase due to frame occupancy of the accepted call. The method of claim 6, The wireless capacity management unit, And when the call is released, updating the overall frame usage rate by reflecting the decrease due to the frame occupancy of the released call. In the broadband wireless communication system, the base station terminal acceptance method, Checking whether a user level acceptance request is generated from the terminal; Checking the type of the request and the number of acceptable terminals of the type; Determining whether to accept the request in consideration of the current acceptance status of the type. The method of claim 24, The user-level accept request is The method is characterized in that it is one of a request for a transition to the active mode of the terminal (Handover), network (Network). The method of claim 24, The request type is A first type, which is a request according to a network entry or transition from an idle mode to an active mode, And one of a second type, which is a request according to the transition from the handover or sleep mode to the active mode. The method of claim 26, And the number of accommodating terminals of the second type is set to be greater than the number of accommodating terminals of the first type. The method of claim 24, To check if user-level releases are requested, Checking whether the release request is a request for transition to a sleep mode; If the request is a transition to the sleep mode, determining whether the number of acceptable sleep mode terminals is saturated; If the saturation state, further comprising the step of transitioning the terminal to the idle mode. A method for accepting a call of a base station in a broadband wireless communication system, Calculating a total frame utilization rate using a modulation and coding scheme (MCS) level distribution in a frame; If a call acceptance is requested, checking a traffic rate probability distribution for the call;  Calculating a frame occupancy rate of the call using the traffic rate probability distribution information of the call; And determining whether to accept the call using the total frame usage rate and the frame occupancy rate of the call. The method of claim 29, The traffic rate probability distribution is And confirming through a scheduling instruction from the service server for the call. The method of claim 29, The process of calculating the total frame utilization rate, Calculating a wireless capacity distribution with reference to the modulation and coding level distributions; And accumulating the frame occupancy rate of the previously accepted call to calculate the total frame utilization rate. The method of claim 31, wherein The total frame usage rate is characterized in that the management is classified into uplink and downlink. The method of claim 31, wherein The wireless capacity distribution is calculated by the following formula,

Where Pr [C = c _k ] is the probability that the radio capacity of any call will be c _k , where K is the number of MCS levels, c _k is the radio capacity at MCS level _k , and n _k is _k in a frame The total number of slots occupied by the first MCS level. The method of claim 31, wherein The wireless capacity distribution is updated according to a predetermined period. The method of claim 31, wherein The frame occupancy rate of the arc is calculated by the following formula,

Where m _new is the frame occupancy average of the requested call, a _j is the traffic rate of the requested call, c _k is the radio capacity of the MCS level k, q _j is the probability that the traffic rate of the requested call is a _j , Where p _k is the probability that the MCS level of the requested call is c _k and sigma ² _new represents the frame occupancy variance of the requested call. The method of claim 29, The process of determining whether to accept the call, Calculating an expected frame usage rate by adding the frame occupancy rate of the requested call to the overall frame usage rate; And determining whether to accept a call by comparing the estimated frame usage rate with a preset provisional usage rate. The method of claim 36, The expected frame utilization rate is calculated by the following formula,

Where M is the average of the current frame utilization, m _new is the frame occupancy average of the requested call, V is the variance of the current frame utilization, σ ² _new is the frame occupancy dispersion of the requested call, and α is a predetermined variance weight. Indicates. The method of claim 37, wherein The average and variance of the frame utilization is The method is characterized by being managed separately in the uplink or the downlink, and when calculating the expected frame utilization rate, it is used as a value for the same link direction as the previously requested call. The method of claim 36, The process of determining whether to accept the call, Checking the user level acceptance request type information of the terminal; Selecting a corresponding reference usage rate among the reference usage rates differently set according to the user level acceptance request type and the link direction of the requested call; And comparing the selected reference usage rate with an expected frame usage rate to determine whether to accept the call. The method of claim 39, A first type, which is a request according to a network entry or transition from an idle mode to an awake mode, And one of a second type, which is a request according to the transition from the handover or sleep mode to the active mode. The method of claim 40, The reference usage rate when the user acceptance request type is the first type is less than the reference usage rate when the second type. The method of claim 39, The reference utilization rate corresponding to the case in which the link direction of the requested call is downlink is a value reflecting a ratio of a traffic area excluding a map in the downlink frame. The method of claim 29, Checking the number of CIDs (Connection IDs) being used by the terminal requesting the call; If the additional allocation of the CID is possible, further comprising the step of determining whether to accept the call requested by the terminal. The method of claim 29, If the call is a Preemptive Call or Best Effort call, further comprising accepting the call without condition. The method of claim 29, And if the call is accepted, updating the overall frame utilization to reflect an increase due to frame occupancy of the accepted call. The method of claim 29, And when the call is released, updating the overall frame usage rate by reflecting the decrease due to the frame occupancy of the released call.

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