JP3189845B2 - 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 communication channel allocating method in a TDMA mobile communication system.

[0002]

2. Description of the Related Art A conventional mobile communication system typified by an automobile telephone system employs a common control channel system, and a channel used for communication, a so-called communication channel, may be a base station or a control station. The mobile station is using the communication channel assigned by the base station. There are several ways to assign this traffic channel. One is to manage an empty communication channel in the base station, but to allocate any one of the available channels at the time of allocation. This is described, for example, in Japanese Patent Publication No. 55-51370. This is a simple method and is used in early car phone systems. The other is the same as in the previous example until the base station manages the vacant channel and assigns the vacant channel to the allocating channel. This is a method of selecting from channels without a channel. This is described in detail in Japanese Patent Publication No. 55-50427. This method is slightly indispensable in recent systems because the control becomes slightly more complicated because the process of measuring the amount of interference is added, but interference tends to occur as the wireless zone becomes smaller. In recent mobile phone systems, not only in the case of channel assignment during call setup, but also constantly measure the amount of interference during a call,
A technique of switching to another channel when the amount of interference exceeds a certain value is employed. All of the above examples are SCP
This is an example of an analog car phone using the C method.
Similarly, in the case of a digital system using the MA system, a technique is known in which the base station measures the amount of interference in an empty channel slot and uses the slot with the least amount of interference.
The same technology has been adopted not only in the car phone system but also in recent cordless phones.

[0003]

Since the mobile station and the base station are far apart, the interference conditions are usually quite different. However, in the above prior art, since the base station measures the amount of interference and selects the channel with the best characteristics, the channel is not necessarily a channel with good interference characteristics when judged from the mobile station. Disadvantageously, it is difficult to optimally allocate channels.

An object of the present invention is to provide a novel method for allocating a communication channel having good interference characteristics to both a mobile station and a base station.

[0005]

The first invention is a base station and
And a mobile station connected to this base station by a TDMA radio line
And a radio channel used in the TDMA radio line.
The channel has multiple communication channel slots and
Composed of multiple carrier frequencies with different wave numbers
Channel Assignment in Mobile Communication Systems
In the method, the base station has an idle communication channel slot
Detects the amount of carrier frequency interference at
The carrier frequency along with its communication channel slot,
Notify the mobile station to assign to the mobile station when making or receiving a call.
The mobile station communicates with the notified communication channel slot.
Interference detection for each of multiple sets of transmission frequencies
And select one of the sets that is less than
Is characterized in that Further, the second invention relates to a base station and this base station and a TDMA radio line.
The TDMA radio line, comprising:
The wireless channel used in the
And multiple carrier frequencies, each with a different frequency.
In a mobile communication system composed of a combination of
In the line channel assignment method, the base station comprises:
The amount of interference of the carrier frequency in the
The carrier frequency that is below a certain value
Notification to be assigned to the mobile station together with the
The mobile station communicates with the notified communication channel slot.
Interference detection for each of multiple sets of wave frequencies
The notified communication channel slot and the communication channel
One carrier frequency with low interference in flannel slot
Transmits a synchronization burst signal for every number of sets, is characterized in that it received the base station selects the best quality set.

[0006]

The base station notifies the mobile station of a plurality of vacant channels having a small amount of interference, and the mobile station also measures the amount of interference with respect to it and selects the channel with the least amount of interference. Both base stations can select a channel with a small amount of interference. In addition, the mobile station measures the amount of interference and measures the synchronization burst signals for all the channels that are equal to or less than a certain value, and the base station selects the best quality channel from among them, so the channel selection is completed. Since the quality check of the channel is completed at the stage, the time required for control can be reduced.

[0007]

Embodiment 1 FIG. 2 is a simple block diagram of a mobile communication system to which the present invention is applied. 11 is a base station, 12 is a mobile station, 1
Reference numeral 3 denotes a wireless zone formed by the base station 12. The mobile station 12 in the wireless zone 13 communicates with the base station 11 by radio. Note that the names of base stations and mobile stations are often used in car phones, and in cordless phones, they are called master and slave units. However, this is only a matter of how to call them, and the present invention is not limited to car phones. Of course, the present invention can be applied to other mobile communication systems such as a telephone.

FIG. 1 shows the operation of the base station 11 according to the present invention. (A) shows a case where four slots of TDMA are used as communication channels, and the second and third communication channel slots are in use. At this point, if there is a communication request and a communication channel is to be allocated, the base station transmits a carrier frequency (f in this example) to each of the first and second unused communication channel slots.
Sequentially measuring the reception level for each of the ₁ 5 wave of ~f _5). It should be noted that, as shown in the prior art, the base station
, Manages vacant channels and is a communication channel
Always know whether 4 slots of TDMA are used or not used
are doing. (B) is a measurement result at each frequency for the first slot. Frequencies whose reception level is higher than the determination level (f ₂ , f ₃ , f _{4 in} this example) are rejected because the interference amount is large, and it is determined that f ₁ and f ₅ can be used. Similarly for the fourth slot, f ₂ , f ₄ , f
₅ is determined to be usable. Thereafter, the base station notifies that the mobile station is available (first slot _-f 1, _{f 5)} (second slot _{-f 2, f 4, f 5} ). At this time, it is also possible to add information on the amount of interference for each frequency. Next, a notification method of this channel will be described. Broadly speaking, there are two methods, one is a method of notifying when a call signal or a call response signal from a mobile station is received, and the other is a method of constantly notifying. This procedure is shown in FIG. (A) is a procedure for notifying a call signal from a mobile station. 21 is a calling signal, and 22 is a channel candidate signal. Channels that can be used in the portion of the candidate channel among these, (in the above example, (first slot-f ₁ , f ₅ ) and (second slot-
f ₂ , f ₄ , f ₅ ) is sent. (B) is a procedure for constantly informing, where 23 is a notification signal and 24 is a call response signal. A channel usable in the candidate channel portion in the broadcast signal 23 is notified.

Next, the operation of the mobile station after receiving these notifications will be described. The mobile station measures the reception level, that is, the amount of interference for the designated channel. An example of the measurement is shown in FIG. (A) In the case of the first slot,
(B) shows the case of the fourth slot. In the first slot is only Nanoha f ₅ determination level or less, in the fourth slot is f ₄ and f _5. In this case, there are two channel selection methods, one is a method of randomly selecting one of the above three combinations, and the other is a logarithmic value of the interference level between the mobile station and the base station. Is added to select the minimum set. Through the above process, both the mobile station and the base station can select a channel having good interference characteristics.

[0010]

Embodiment 2 This embodiment is the same as Embodiment 1 up to the point where the base station extracts a candidate channel and notifies the mobile station of the candidate channel, and the operation after the mobile station receives the notification is different. In short, the mobile station, after measuring the amount of interference and selecting channels with low interference, transmits synchronization bursts for them to the base station, and the base station receives those bursts to obtain the channel with the best characteristics. Is to choose. That is, in this example, the base station determines the channel. The operation procedure in this case is shown in FIG. Reference numerals 21 and 22 are the same as those in FIG. 3. Reference numeral 23 denotes an uplink synchronization burst signal transmitted from the mobile station, and reference numeral 24 denotes a downlink synchronization burst signal transmitted from the base station. S1 is a step of narrowing down channel candidates in the mobile station, S2 is a step of switching the local oscillator synthesizer of the mobile station to a corresponding frequency, and S3 is a step of receiving a downlink synchronization burst signal from the base station and performing uplink synchronization on another channel. Stopping the transmission of the burst signal, step S4 waiting the candidate channel transmitted from the mobile station at the base station, and receiving the uplink synchronization burst signal from the mobile station at step S5, the channel having the best characteristics among the candidate channels. Is a step of selecting. As described above, in the mobile station, the base station transmits candidate channel information (in the example shown in FIG. 1, the first slots are f ₁ , f ₅ ,
When the slot receives f ₂ , f ₄ , and f ₅ ), it narrows down candidates as described later and transmits an uplink synchronization burst signal for the narrowed down specific channel. The base station selects a channel with the best characteristics from among these, and transmits a downlink synchronization burst signal on that channel. If the mobile station can receive the signal with good characteristics, the base station will formally select the channel by stopping the uplink synchronization burst signal of another channel. Next, the narrowing down of channel candidates in step S1 at the mobile station is usually performed by selecting one frequency having the best interference characteristic for each communication slot. For example, when the measurement result of the interference amount of the mobile station is that it is as shown in FIG. 4, f ₅ in the first slot, the second slot adopts f _4, process S2 is to switch to the frequency (see FIG. 5).

FIG. 6 shows an operation procedure of the base station in this embodiment. S10 is a step of transmitting a set of an idle communication channel slot and a carrier frequency, S11 is a step of waiting for an uplink synchronization burst signal from the mobile station on those candidate channels, and S12 is an uplink synchronization burst for the channel narrowed down by the mobile station. Receiving a signal, selecting a channel having the best characteristics among them, and transmitting a downlink synchronization burst signal, S13: detecting whether or not the uplink synchronization burst signal of this channel stops; S14: uplink synchronization burst signal The step of transmitting the downlink synchronization burst signal on the channel having the second best characteristic when the signal is stopped, and the step S15 is the step of completing communication channel allocation and starting communication. FIG.
Are taken from the base station side, and the details have already been described in the description of FIG.

FIG. 7 shows a similar operation procedure in the mobile station. S21 is a step of transmitting a call signal, S22 is a step of receiving a communication channel candidate selected by the base station, S23 is a step of narrowing down further candidates from the channel candidates selected by the base station, and S24 is a narrowed frequency. S25 is a step of transmitting an uplink synchronization burst signal at a narrowed frequency for each empty slot, S26 is a step of receiving a downlink synchronization burst signal from the base station, and S27 is a step of downlink synchronization. The step of determining the quality of the burst signal, the step S28 of stopping the transmission of the downlink synchronization burst signal other than the channel when the quality of the downlink synchronization burst signal is sufficient, and the step S29 when the quality of the downlink synchronization burst signal is not sufficient. In step S30, the transmission of the uplink synchronization burst signal of the channel is stopped. A step of to enter the communication. Here, steps S21 to S26 have already been described, and thus will be omitted, and the following steps will be described. The mobile station is S25
Transmit the uplink synchronization burst signal at the frequency having the best interference characteristic for each of the empty slots. Then, the base station selects one of the slots and frequencies having the best characteristics (step S12 in FIG. 6) and transmits the downlink synchronization burst signal only to that slot / frequency.
Wait at 6. If this is detected, it is checked in step S27 whether the quality of the signal is good. If it is good, the uplink synchronization of other slots is performed in step S28 to indicate to the base station that the channel is to be selected. Stop transmitting the burst signal. If not good,
Step S2 for indicating intention to select another slot
In step 9, only the uplink synchronization burst signal of the channel is stopped. Then, when the base station detects the stop (step S13 in FIG. 6), the base station transmits the downlink synchronization burst signal to the next highest quality channel (step S14 in FIG. 6). It will wait for a sync burst. If a channel of good quality can be selected in this way, transmission of the uplink synchronization burst signal other than that channel is stopped and the communication state S30 is entered. As described above, according to the present embodiment, the continuity of the channel can be checked by transmitting and receiving the synchronous burst, so that the radio continuity test after the transition to the communication state is not required, and the connection delay time is reduced as compared with the first embodiment. be able to.

[0013]

According to the present invention, since a communication channel having good interference characteristics can be assigned to both the base station and the mobile station, good communication can be realized. In addition, since the wireless continuity test is performed simultaneously in the channel assignment process, the connection delay time can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a method of detecting an interference state of each frequency at a base station for each of the available communication channel slots and extracting a candidate channel.

FIG. 2 is a diagram schematically illustrating a configuration of a mobile communication system to which the present invention is applied.

FIG. 3 is a diagram illustrating a method of transmitting a candidate channel extracted by a base station to a mobile station.

FIG. 4 is a diagram illustrating a method of further narrowing down a candidate channel extracted by a base station by a mobile station.

FIG. 5 is a diagram showing an operation procedure in a second embodiment of the present invention.

FIG. 6 is a diagram illustrating an operation procedure of a base station according to a second embodiment of the present invention.

FIG. 7 is a diagram illustrating an operation procedure of a mobile station according to the second embodiment of the present invention.

────────────────────────────────────────────────── (5) References JP-A-64-55924 (JP, A) JP-A-59-30333 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04B 7/24-7/26 H04Q 7/00-7/38

Claims (2)

(57) [Claims] 1. A radio channel including a base station and a mobile station connected to the base station by a TDMA radio channel , wherein the radio channel used in the TDMA radio channel includes a plurality of communication channels.
Slots and multiple carrier frequencies, each with a different frequency
A method for allocating radio channels in a mobile communication system comprising a combination of
Carrier circumference by detecting the amount of interference Namishu wavenumber equal to or less than a predetermined value
The wave number to the communication channel slot co, during a call or an incoming call, and notifies to assign to the mobile station, the mobile station, the amount of interference for each of a plurality of pairs of said notified communication channel slot and carrier frequency A wireless channel assignment method, comprising: detecting and selecting one of a set that is equal to or less than a certain value and assigning it to a communication channel. 2. A radio channel including a base station and a mobile station connected to the base station by a TDMA radio channel , wherein the radio channel used in the TDMA radio channel includes a plurality of communication channels.
Slots and multiple carrier frequencies, each with a different frequency
A method for allocating radio channels in a mobile communication system comprising a combination of
Carrier circumference by detecting the amount of interference Namishu wavenumber equal to or less than a predetermined value
Communication and notifies to assign the mobile station to the wave number in the communication channel slot co, the mobile station, which detects the amount of interference for each of a plurality of pairs of said notified communication channel slots and carrier frequencies were the notification Channel slot and the communication channel
Transmitting a synchronous burst signal for all of the one set of carrier frequencies having a small amount of interference in the channel slot ,
A radio channel assignment method, wherein a base station receiving the message selects a pair having the highest quality.