JPH0632502B2 - Terminal calling method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a mobile radio communication system, and more particularly to a method of calling a terminal in a system having a large number of radio communication zones and a terminal moving between the zones.

[Conventional technology]

Spatially reuse frequencies with multiple radio base stations,
The so-called small zone system is used in mobile phones as an effective system for expanding the communication range in mobile radio.
More recently, the tele-terminal system that provides services to data terminals is also adopting the small zone system. In these small zone systems, how to call a mobile terminal becomes a big problem. As a method of calling a terminal that moves between zones,
Conventionally, there are a registration method and a paging method.

The registration method is that the terminal sends a registration packet every certain period of time or every time the zone changes, and it is always a switching center
This is a method that enables the location of the terminal to be grasped. The paging system is a system in which a paging packet is generated only when there is a paging.

[Problems to be solved by the invention]

In the above-mentioned registration method, if the number of terminals is large, a considerable number of registration packets will be transmitted even if no call is made, and the wireless line will be squeezed. In addition, it is necessary to take measures against the failure of registration due to the effects of fading or the like in the exchange, which makes the control of the exchange complicated.

In the above-mentioned teleterminal system, since the terminal is assumed to be portable, it is important to minimize unnecessary transmission from the terminal in order to effectively use the battery. Therefore, the tele-terminal system is going to adopt the paging system. This method is described in detail in the report [Investigative Research Report on Teleterminal Systems] issued by August 1985 (Edited by the Ministry of Posts and Telecommunications Teleterminal System Study Group).

However, the simultaneous paging method has the drawback that the total number of paging packets increases steadily as the number of zones increases, although the control is simple.

An object of the present invention is to eliminate the above-mentioned drawbacks of the conventional terminal calling method, and to provide an efficient terminal calling method that transmits a calling packet only when a terminal is called and has a small number of calling packets.

[Means for solving problems]

The present invention relates to a terminal calling method in a mobile wireless communication system in which a terminal moves between a plurality of wireless communication zones, and when an exchange performs each communication, the change of the zone in which the terminal is located at the time of responding to the calling of each terminal It is characterized in that the movement information between the zones of each terminal is collected as the transition probability from the statistical information, and the zones are selectively defined based on the transition probability to sequentially call.

[Action]

Generally speaking, a mobile terminal does not move uniformly in all zones, and there is always a bias in the zone in which communication is performed. For example, a salesman will move around the area where he / she receives it, and a company employee will often communicate around his / her company. Furthermore, human beings have certain behavior patterns that are set to some extent, and they often act according to that pattern. Therefore, if the exchange can know the behavior pattern of the person, it should be able to predict the zone in which the person exists with considerable accuracy.

In the present invention, the behavior pattern in which the exchange moves between human zones is modeled as a stochastic process, and the transition probabilities of the stochastic process are collected during operation to accurately predict the position of the terminal and selectively switch zones. Calling reduces call traffic.

〔Example〕

 Next, the present invention will be described in detail with reference to the drawings.

FIG. 2 shows the behavior of a certain terminal modeled by the Markov process. For example, the salesman has three zones Z _k ,
Assuming that Z ₁ and Z ₂ are in charge, normally zone Z ₀
It is assumed that the work starts from 0, moves to the zone Z _1, goes to the zone Z ₂ , and finishes the work.

Although there are some customers in the zone Z _{0 and} there is a high probability of communication, the communication volume is relatively small because there are not so many customers in the zones Z ₁ and Z ₂ .

FIG. 3 shows the existence probabilities in each zone of this terminal. The total number of zones is 25, and the bar graphs in each zone show the existence probability in each zone. Communication from zones other than these is assumed to have a negligibly low probability. In such a case, if all zones are called at once, the average number of calling zones becomes 25. On the other hand, if the exchange knows that this terminal only communicates from almost 3 zones, the average number of paging zones can be reduced to about 3. Further, if the transition probability as shown in FIG. 2 is known, the average number of paging zones can be further reduced.

FIG. 1 shows an algorithm of an embodiment of the present invention. When a caller makes a call to the terminal K (step), the exchange first reads the previous communication zone of the terminal from the memory (step). Temporarily last time Zone X
Then, the exchange reads the zone transition probability P _k (X, I) of the terminal K and compares the threshold Q (J) with the transition probability P _k (X, I) for each zone I. Then, only the zones whose transition probability P _k (X, I) is larger than the threshold value Q (J) are called. There are multiple thresholds, Q
(J) are arranged in descending order.

First, J = 1 is set (step), and in the step, the zone I having a transition probability larger than the threshold value Q (1) is searched, the found zone is called, and at the same time, the exchange sets the timer to T ₀ (step). . If there is a response from any of the called zones (step), the switch connects to that zone (step).
If there is still no response even after T ₀ time has passed (step), if the calling of all zones has not ended (step), the exchange sets the threshold value to Q (2) (step), and then the transition probability. Call only zones that are greater than Q (2). In that case, already called zones are excluded.
Then, if there is a response from any zone, the zone is connected, and if there is no response, the threshold value is lowered again after a lapse of T ₀ to call some zones. If there is no response after calling all zones, the exchange judges that it cannot connect to the terminal K (step), and returns a connection failure message to the caller. In this way, calls are made in order from the zone with the highest probability, and useless call traffic can be omitted.

The transition probability between zones is the easiest if the user registers in advance. However, in reality, it is extremely difficult to register beforehand by knowing in advance how each terminal has a high probability of moving. Therefore, it is necessary that the exchange collects while operating the transition probability P _k (X, I). To do so, depending on which zone you are connected to, P
_It suffices to update _k (X, I). This update is the first
In the algorithm shown, this is done in steps.
Specifically, the total number of calls N _k in each zone of each terminal
(X) is memorized and the transition probability P _k (X,
Update I). To do so, P _k (X, J) = {P _k (X, J) × N _k (X) +1} / (N _k (X) +1) paging zone P _k (X, I) = P _k ( X, I) × N _k (X) / (N _k (X) +1) other zones N _k (X) = N _k (X) +1. Here, X is the zone at the time of the previous communication, and the exchange needs to remember this value for each terminal.

The number of thresholds is determined by the maximum time allowed for connection. If time is allowed, the method of calling the zones one by one in order from the zone having the highest existence probability can minimize the call traffic. However, in reality, the connection time is limited and it is not possible to call one zone at a time. If the connection can be made by calling at most two times and the threshold value Q (1) is set to 0.2, the average number of calling zones for the terminal having the transition probability as shown in FIG. 2 is about 4. If we knew that we could not go anywhere other than the three zones Z ₀ , Z ₁ and Z ₂ , the average number of paging zones would be 1.7, which would be a further significant reduction. The algorithm for defining the calling zone does not necessarily need to call only the zone in which the transition probability to that zone exceeds a certain value as in the present embodiment, and other algorithms, for example, transition probabilities in descending order of transition probability. May be added, and when the total exceeds a certain value, the zones up to that point may be called.

〔The invention's effect〕

Thus, according to the present invention, without registering from the terminal,
Moreover, it is possible to provide a terminal calling method in which the call traffic does not increase so much even if the number of zones increases.

[Brief description of drawings]

FIG. 1 is a diagram showing an algorithm of an embodiment of the present invention, FIG. 2 is a diagram showing an example of transition probability between each zone of a terminal used in the present invention, and FIG. 3 is a probability of existence in each zone of a terminal. It is a figure which shows the example of.

Claims (1)

[Claims] 1. In a terminal calling method in a mobile wireless communication system in which a terminal moves between a plurality of wireless communication zones, when a switching center carries out each communication, a change of the zone in which the terminal responds to the calling of each terminal. A method for calling a terminal, characterized in that movement information between zones of each terminal is collected as a transition probability from the statistical information, and zones are selectively defined based on the transition probability and the terminals are sequentially called.