JP3306576B2 - Wireless channel allocation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio channel allocating method for dynamically allocating radio channels as needed in a mobile communication method in which a service area is constituted by a plurality of radio zones.

[0002]

2. Description of the Related Art In a mobile communication system in which a service area is covered by a plurality of radio cells (an area formed by a base station where mobile communication is possible), a conventional dynamic channel assignment method employs, as shown in FIG. A plurality of wireless channels that can be used in common are allocated, and each time a wireless communication channel allocation request (10) is made at a mobile station or a base station, whether or not the wireless communication channel to be allocated is used in another wireless cell (12), searching by measuring the interference wave level of the wireless communication channel, determining whether the required quality as a communication path of the wireless communication channel is satisfied, and determining that the required quality is satisfied. In this case, the wireless communication channel is assigned (18).
At this time, channels that can be allocated are searched for when a channel allocation request is issued. In some cases, the channel cannot be allocated for any of the reasons that the simultaneous communicable lines of the base station are all blocked or the channel cannot be allocated due to high interference wave level (20).

[0003]

In a conventional mobile communication system, as shown in FIG. 2, when many mobile stations are simultaneously communicating in a small area where they interfere with each other, a new communication is performed. When a channel allocation request occurs, the interference wave level is high and the wireless communication line does not satisfy the required quality as a communication channel, or all the communication channels that can be used simultaneously by the base station are in use and the channel cannot be allocated. At times, it was described as "call loss" in which communication could not be performed despite a request for communication.
As a result, not only the serviceability is reduced, but also the allocation is not performed even if the wireless communication channel is available after a moment, so that the frequency use efficiency is not high.

[0004] As a countermeasure, a method called a waiting system in which a channel is made available when there is no available communication channel can be considered. In mobile communication, however, the channel quality is greatly fluctuated, so that if the system waits for a long time, the channel becomes available. It is also conceivable that the mobile station goes out of the radio channel as the mobile station moves.

SUMMARY OF THE INVENTION It is an object of the present invention to improve the above problems and to provide a channel allocation method with high frequency utilization efficiency with reduced call loss.

[0006]

According to the present invention, as shown in FIG. 1, in a mobile communication system, when a channel cannot be allocated to a communication request such as an outgoing call or an incoming call, the channel cannot be temporarily allocated within a limited period of time. (14), a change in the quality of the wireless communication line or a change in the use state is expected, and a free channel is searched again to allocate a communication channel if it can be allocated.

However, in consideration of the mobile communication, the waiting time is limited to a short time. Also, the connection delay is notified to the mobile station by notifying the mobile station of the average waiting time or the probability of performing channel assignment within the maximum allowable waiting time using the statistical result.

[0008]

FIG. 3 shows an embodiment (1) of the present invention. If there is no vacant channel (32) when there is an outgoing or incoming call (30), a timer is started (34), and after waiting for a certain time (36), the channel is searched again (38). If a channel that can be allocated is found in this search, the allocation is repeated (42), and if not found, the process is repeated until the timer expires (40), waits for a certain time again (36) and performs a search again (38). The effect of the present invention increases as the period (36) of waiting for a certain time becomes shorter, but the number of processes for searching channels in the base station increases and a high-performance system is required. When the time is over (40), the call is lost (44).

FIG. 4 shows an embodiment (2) of the present invention. When there is no free channel, the same processing as in the above embodiment is performed, but the average waiting time is notified to the mobile station (48). As shown in FIG. 5, the average waiting time is obtained by statistically calculating the expected value of the waiting time for the traffic volume or the number of calls waiting at that time. This expected value is determined by the traffic conditions of the system, the number of channels that can be simultaneously used by the radio base station, the number of channels shared by the system, the radio wave propagation environment, and depends on the system. In addition to being obtained statistically, it can be obtained at the design stage by computer simulation or the like. By notifying the average waiting time, the mobile terminal displays the time and notifies the terminal user of the connection delay so that the user can determine whether or not the connection delay can be tolerated. It can also be expected to alleviate the mental distress caused by the connection delay of the user.

FIG. 6 shows an embodiment (3) of the present invention. When there is no vacant channel, the same processing as in the above embodiment is performed, but the mobile station is notified of the probability that a call connection can be performed within a predetermined time, that is, before the timer expires (50). As shown in FIG. 7, the probability is obtained by statistically calculating the expected value of the waiting time for the traffic volume or the number of calls waiting at that time. This expected value also depends on the system as in the above embodiment. By notifying the call connection success probability, the mobile terminal displays the probability, and by notifying the terminal user of the connection success probability, the user can determine whether to wait for a connection. It can also be expected to alleviate the mental distress caused by the connection delay of the user.

FIG. 8 shows a computer simulation result for confirming the effect of the present invention. The call blocking rate characteristic in the prior art corresponds to Tw = 0, and under the condition of the call blocking rate = 3%, the cell could only be transported up to about 6 Erlangs per cell. On the other hand, it can be seen from the graph of Tw = 10 that the maximum waiting time is allowed up to 10 seconds by applying the present invention, it is possible to carry up to about 11 erlangs per cell.

In the above embodiment, the embodiment has been described for mobile communication. However, in wireless communication, a wireless channel adopting a dynamic channel allocation for dynamically allocating a vacant channel when performing communication. It can be applied to many systems such as LAN.

[0013]

As described above, according to the present invention, the number of radio channels required for the system is increased by temporarily suspending channel assignment when the radio communication channel is congested in mobile communication. The call loss rate can be remarkably reduced without any problem. There is also an effect of increasing the frequency use efficiency.

Further, the present invention can be used in combination with a conventional dynamic channel allocation method such as a reuse partition, and in that case, the same effect is obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of the present invention.

FIG. 2 is a diagram illustrating a state in which the present invention exerts the most effect.

FIG. 3 is a diagram showing an embodiment (1) of the present invention.

FIG. 4 is a diagram showing an embodiment (2) of the present invention.

FIG. 5 is a diagram for explaining a method for obtaining an average waiting time in FIG. 4;

FIG. 6 is a diagram showing an embodiment (3) of the present invention.

FIG. 7 is a diagram illustrating a method for obtaining a call connection probability in FIG.

FIG. 8 is a graph showing the effect of the present invention and shows characteristics when the waiting time is set to 1 second.

FIG. 9 is a diagram illustrating a conventional wireless communication channel assignment method.

[Description of Signs] 10 Calling / Incoming Calls 12 Available Channels 14 Hold 16 Channel Assignment 18 Communication

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04Q ^7/ 00-7/38 H04B ⁷ /24-7/26

Claims (8)

(57) [Claims] 1. A two-way communication is performed between a wireless base station and a mobile station via a wireless line, and when a communication connection request is issued from the mobile station or the wireless base station, a communication path is required. In a wireless channel allocation method for dynamically allocating a wireless communication channel satisfying quality, when there is a communication connection request from the mobile station or the wireless base station, if the wireless base station has no channel that can be allocated, (1) Activate a timer that activates for a predetermined period of time, (2) temporarily suspend channel allocation, (3) set a maximum suspension time as the maximum value of the suspension time, After the start of (4), the channel is searched again until the allocated channel is detected. If the allocated channel is detected, (5) the channel is allocated and communication is performed. Is not detected, when the total of the activation time of the timer is smaller than the maximum hold time, (6) the timer is restarted and the channel is repeatedly searched again, and the total of the activation time of the timer is the maximum hold time. When the time is exceeded, (7) a radio channel assignment method characterized by a call loss. 2. A two-way communication is performed between a wireless base station and a mobile station via a wireless line. When a communication connection request is issued from the mobile station or the wireless base station, a communication path is required. In a wireless channel allocation method for dynamically allocating a wireless communication channel satisfying quality, when there is a communication connection request from the mobile station or the wireless base station, if the wireless base station has no channel that can be allocated, (1) Activate a timer that activates for a predetermined period of time, (2) temporarily suspend channel assignment, (3) Reactivate the timer periodically n times (n is a natural number) When the channel is re-searched while the timer is running and the allocated channel is detected, (4) a channel is allocated and communication is performed, and the allocated channel is not detected even after the n re-searches (5) a call loss and a radio channel assignment method which is characterized in that. 3. A two-way communication is performed between a wireless base station and a mobile station via a wireless line. When a communication connection request is issued from the mobile station or the wireless base station, a communication path is required. In a wireless channel allocation method for dynamically allocating a wireless communication channel satisfying quality, when there is a communication connection request from the mobile station or the wireless base station, if the wireless base station has no channel that can be allocated, (1) Activate a timer that activates for a predetermined period of time, (2) temporarily suspend channel allocation, (3) set a maximum suspension time as the maximum value of the suspension time, (4) ) The timer is periodically restarted n times (n is a natural number), and the channel is searched again while the timer is running. If the allocated channel is detected, (5) communication is performed by allocating a channel. , If the allocated channel is not detected even after the n re-searches, or if the total of the activation time of the timer exceeds the maximum hold time even if the re-search is less than n times, (6) call loss A wireless channel allocation method characterized by the above-mentioned. 4. The radio base station according to claim 1, wherein when suspending channel assignment, the radio base station notifies the mobile station of an average suspension time according to a surrounding communication environment. The wireless channel assignment method according to the paragraph. 5. The radio base station according to claim 1, wherein when suspending channel assignment, the radio base station notifies the mobile station of a call connection success probability according to a surrounding communication environment. 2. The wireless channel assignment method according to claim 1. 6. The radio base station according to claim 1, wherein when suspending channel assignment, the radio base station notifies the mobile station of an average suspension time and a call connection success probability according to a surrounding communication environment. 4. The wireless channel allocation method according to any one of 3. 7. The radio channel assignment method according to claim 1, wherein the radio base station is a master station of a LAN, and the mobile station is a slave station of the LAN. 8. The radio base station notifies the mobile station of the average holding time and / or the call connection success probability, and the mobile station determines that the notification result is a threshold for the average holding time. 8. The method according to claim 1, wherein when the call connection success probability is lower than a threshold value, the connection with the radio base station is automatically interrupted. 9. Radio channel allocation method.