JPH04133532A - Incoming call controlling channel constructing method for mobile communication - Google Patents

Abstract

PURPOSE:To eliminate the need of synchronizing phases between base stations for transmission slots controlled at a center by making plural base stations to independently transmit incoming call signals for calling mobile stations at random periods. CONSTITUTION:Base station 111, 112, ..., 11n are respectively equipped with functions which independently generate transmission slots (with a slot length T) for transmitting incoming call signals, functions which count slot number of the transmission slots, and functions which generate uniform random numbers. The base stations transmit the incoming call signals by using the transmission slots at transmitting intervals equal to the slot numbers corresponding to the random numbers (r). Therefore, the need of synchronizing slot phases between base stations is eliminated and each base station can constitute an asynchronous incoming call controlling channel at independent timing.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention prevents collisions when a plurality of base stations to which a radio frequency of an incoming control channel is commonly assigned transmits an incoming signal to call a mobile station. The present invention relates to a method of configuring an incoming control channel in mobile communication to avoid such a problem.

[Conventional technology]

FIG. 6 is a diagram showing a station configuration in mobile communication.

In the figure, a plurality of base stations 61. ．． 61z,...61
, each form a wireless zone, and a wireless control station 63 centrally controls a calling area 65 consisting of a plurality of wireless zones.

In mobile communication with such a station configuration, when calling the mobile station 67, the radio control station 63 calls a plurality of base stations 61 . From 616 to 616, incoming signals are transmitted all at once using the incoming control channel.

Note that the incoming signal for calling the mobile station 67 is sent to a plurality of base stations 611 to 61 . Since this is done using an incoming control channel to which a common radio frequency is assigned, the radio control station 63 uses the incoming signals transmitted from each base station at the same time to avoid collision with each other. As shown in
Each base station 61-61. Multi-station sequential transmission control is performed, in which incoming signals are transmitted sequentially from one station to another. The situation will be specifically explained using FIG. 8.

The base stations 611 to 61° under the radio control station 63 are the eighth
As shown in Figure (a), it is assumed that m = 37 base stations exist in a plane (indicated by base station numbers 1 to 37 in the figure). Here, assuming that the wireless zones of adjacent base stations interfere with each other, the transmission slots of the base stations for adjacent wireless zones need to be different from each other. FIG. 8(b) shows
The slot number suitable for transmission by each base station that satisfies this condition is shown. That is, in the slot number P1 shown in FIG. 7, the base station number is 1.22.25.28.31.34.3.
7 base stations 61□ can transmit incoming signals all at once.

Incidentally, the slot, which is the transmission cycle of multi-station sequential transmission, corresponds to the number of base stations in an area (hereinafter referred to as a "cluster") where wireless zones interfere with each other. The example shown here corresponds to the case where k=7.

Therefore, incoming signals transmitted from 37 base stations are assigned to any of the 7 transmission slots, and at slot number Pk shown in FIG.
4.21.32 base station 61. can transmit incoming signals all at once.

[Problem to be solved by the invention]

In this manner, in the incoming control channel in conventional mobile communication, the radio control station 63 controls the base stations 61 . ~61
．． It is configured to centrally control the sequential transmission of incoming signals from multiple stations using transmission slots determined by the following.

Therefore, when adding base stations, the radio control station 6
3, it was necessary to conduct an on-site investigation of radio wave interference with existing base stations and secure a transmission slot that was not being used by the existing base stations in the cluster. In other words, when adding base stations, it is essential to conduct an on-site investigation of radio wave interference with existing base stations in the cluster.
It was not easy to deal with it.

In addition, multiple base stations that are assigned a common radio frequency for an incoming control channel that calls a mobile station avoid collisions by sequentially transmitting incoming signals in predetermined transmission slots. It has become essential to establish phase synchronization of transmission slots between base stations, making control technology complex.

An object of the present invention is to provide a method for configuring an incoming control channel in mobile communications that eliminates the need for inter-base station phase synchronization of transmission slots that are centrally controlled by a radio control station through simple control, and that facilitates the addition of base stations. purpose.

[Means to solve the problem]

The invention according to claim 1 provides an incoming call control channel between a mobile station and a plurality of base stations forming a wireless zone, using an incoming call control channel to which a radio frequency is commonly assigned to the plurality of base stations. 2. A method for configuring a call control channel in mobile communication in which a base station transmits a call signal to call the mobile station, wherein each of the plurality of base stations sends a call signal to call the mobile station at mutually independent random cycles. In the invention described in claim 1, in the method for configuring an incoming control channel in mobile communication, each base station determines an interval for transmitting an incoming signal using a uniform random number, and each incoming signal includes at least the following: It is sent with information about the interval between it and the incoming signal.

[For production]

In the present invention, a plurality of base stations to which a radio frequency of an incoming control channel is commonly assigned transmits an incoming signal that calls a mobile station at mutually independent random cycles, thereby sequentially using a predetermined transmission slot. Even without transmitting, it is possible to ensure that incoming signals rarely collide.

[Example] Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 is a diagram showing the configuration of an embodiment of an incoming call control channel according to the present invention.

In the figure, each base station 11. ．． 11□,... 11B is the transmission slot (slot length T) for transmitting the incoming signal
, a function to count the number of transmission slots, and a function to generate −-like random numbers. Here, it is assumed that the inter-base station phases of transmission slots created by each base station may be different from each other as shown in the figure.

Each base station transmits incoming signals in transmission slots spaced apart by the number of slots corresponding to the generated random number r.

That is, the present invention eliminates the need for slot phase synchronization between base stations, and allows incoming control channels to be configured asynchronously at independent timings.

FIG. 2 is a diagram showing an incoming call control sequence according to the present invention.

In this embodiment, it is assumed that the random number r generated by the base station is incorporated into an incoming signal and notified to all mobile stations under its control. Therefore, even if there is no incoming signal for the mobile station under its control, the base station transmits a dummy incoming signal to notify the random number r.

If the slot length T of the base station is known, the mobile station can recognize the timing of the next received incoming signal from the notified random value r.
Intermittent reception processing that turns off the power of the transmitter/receiver and other parts becomes possible.

In the figure, each base station generates a −-like random number r and transmits an incoming signal in a predetermined transmission slot. Next, the base station monitors whether there is a response from the mobile station, and if there is no response, the base station counts the number of slots corresponding to the generated random value r until the number of transmissions R reaches a predetermined value, and then After that, the next incoming signal is transmitted.

In the mobile station, after turning on the transmitter/receiver unit, the random number r
If an incoming call signal including the above is received and it is determined that the own station is being called, an incoming call response is sent to the base station, and incoming call connection processing is performed with the base station. Furthermore, if the call is not for the own station, the power is turned off after setting the power to be turned on after the r slot.

Incidentally, the incoming signal may collide with transmissions from other base stations and may not notify the mobile station of the random value r.

At this time, the mobile station does not know the scheduled time of the next incoming signal, and the timing of subsequent standby operations will no longer be synchronized with the transmission from the base station.

A method for dealing with this problem is to stop intermittent reception when the mobile station does not receive an incoming signal at the scheduled time until the next incoming signal can be received. In order to reduce the possibility of stopping this intermittent reception, the base station generates a plurality of random numbers r+srt, etc. and transmits them in advance as information indicating each transmission interval of incoming signals that are transmitted sequentially. do.

That is, even if one incoming signal is not received, the timing for waiting for the next incoming signal is known in advance, so intermittent reception can be continued.

Furthermore, if the incoming signals transmitted independently from each base station collide, the call to the mobile station will fail. Therefore, it is assumed that the incoming signal is retransmitted until the probability of failure in the call (failure rate F) reaches a specified value.

The call failure rate F is equal to the probability of collision R times in a row, where the collision probability is C1 and the number of times the incoming signal is transmitted is R. Therefore, F=C''...(1
).

The collision probability C of the incoming signal is n!, since the number n of transmissions from each base station during a predetermined interval τ is Poisson distributed due to the randomness of Poisson arrival. given as. Here, λ is the average number of transmission occurrences of all base stations in the cluster during a unit time.

On the other hand, as shown in Fig. 3, the collision of incoming signals occurs within an interval τ that is twice the length of the incoming signal transmitted by the base station of interest.
If a collision occurs when one or more other base stations transmit, the collision probability C is given as follows. Now, the number of base stations in the cluster k is 7, and the uniform random number r generated by each base station is 1.
~14 (average <r>- = 7), slot length T is 0.1
If the ratio t/T of the incoming signal length to the slot length T is 0.1, the number of transmissions λ of all base stations (k stations) in the cluster in a unit time is the average transmission interval of each base station. Since TX (r), it becomes. Therefore, λτ=2 λ t=2× (5).

Here, by applying the above model value to equation (5), λ
τ−0,2 times, and the collision probability C of the incoming signal is (3)
According to the formula, C=1-0.8187=0.1813. Here, if the number of times R of incoming call signals is transmitted is 3, then the call failure rate F is calculated by equation (1): F=0.18133=0.
00596.

FIG. 4 shows the relationship between the collision probability C of an incoming signal and the call failure rate F with respect to the ratio t/T of the incoming signal length t to the slot length T, based on the calculation example described above.

The call failure rate F is approximately 0. Assuming that the same quality of service as the conventional technology can be obtained in the case of OI, if the number of transmissions R of the incoming signal is 3, the ratio t/T of the incoming signal length to the slot length T is the same as that of the conventional technology. It should be about 0.125.

In this way, in the present invention, when the radio frequency of the incoming control channel is dedicated to incoming calls, the throughput must be reduced by the ratio t/T of the incoming signal length t to the slot length T, compared to the prior art. However, if the unused free time (1-t/T) is used for other purposes, the decline in radio frequency utilization efficiency can be minimized.

As shown in Fig. 5, an example of how free time is used is to time-divide a radio frequency with slot length T, and perform transmission and reception between base stations and mobile stations (TD D
, Time Division Duplex), and allocating transmission control channels and other channels, it is possible to make effective use of radio frequencies.

〔Effect of the invention〕

As described above, the present invention eliminates the need to centrally control each base station and set transmission slots for transmitting incoming signals even if the radio frequency of the incoming control channel is commonly assigned to multiple base stations. becomes. Therefore, it is no longer necessary to investigate the situation within the cluster to secure transmission slots, which is essential when adding base stations, and it is also possible to eliminate the need for phase synchronization of transmission slots between base stations.

In other words, it is possible to reduce the synchronization function for slot phase synchronization between base stations, and even when adding more base stations, there is no need to secure transmission slots in advance, making the expansion easier. .

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of an embodiment of an incoming call control channel according to the present invention. FIG. 2 is a diagram showing an incoming call control sequence according to the present invention. FIG. 3 is a diagram showing collision sections of incoming signals. Figure 4 shows the ratio t/of the incoming signal length to the slot length T.
3 is a diagram showing the relationship between the collision probability C of an incoming signal and the call failure rate F for T. FIG. FIG. 5 is a diagram showing an example of how radio frequency free time is used. FIG. 6 is a diagram showing a station configuration in mobile communication. FIG. 7 is a diagram showing the configuration of transmission slots for multi-station sequential transmission. FIG. 8 is a diagram explaining the relationship between base station numbers and transmission slot numbers. 61...Base station, 63...Radio control station, 65...
Calling area, 67...Mobile station. Figure 3 t/T Figure t/T = 0.125 Figure Figure Figure Figure (a) Base station number 0)) Transmission Slot number chart

Claims (2)

[Claims] (1) Between a mobile station and a plurality of base stations forming a wireless zone, the plurality of base stations communicate with the mobile station using an incoming control channel assigned a common radio frequency to the plurality of base stations. In a method for configuring an incoming call control channel in mobile communication in which each of the base stations transmits an incoming signal to call the mobile station, the plurality of base stations transmit incoming signals to call the mobile station at mutually independent random cycles. Control channel configuration method. (2) In the method for configuring an incoming control channel in mobile communication according to claim 1, each base station determines an interval for transmitting an incoming signal using a uniform random number, and each incoming signal includes at least the next incoming signal. 1. A method for configuring an incoming control channel in mobile communication, the method comprising: transmitting an incoming call with interval information added thereto.