JPH04181828A - In-zone area identifying system in moving communication - Google Patents
In-zone area identifying system in moving communicationInfo
- Publication number
- JPH04181828A JPH04181828A JP2308679A JP30867990A JPH04181828A JP H04181828 A JPH04181828 A JP H04181828A JP 2308679 A JP2308679 A JP 2308679A JP 30867990 A JP30867990 A JP 30867990A JP H04181828 A JPH04181828 A JP H04181828A
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- 238000004891 communication Methods 0.000 title description 15
- 238000000034 method Methods 0.000 claims description 13
- 238000010295 mobile communication Methods 0.000 claims description 7
- 238000005562 fading Methods 0.000 abstract description 10
- 238000012935 Averaging Methods 0.000 abstract description 4
- 238000005259 measurement Methods 0.000 abstract description 2
- 230000005540 biological transmission Effects 0.000 description 6
- 238000010586 diagram Methods 0.000 description 6
- 230000007423 decrease Effects 0.000 description 4
- 230000010355 oscillation Effects 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 2
- 238000013459 approach Methods 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 230000001427 coherent effect Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000005314 correlation function Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000001902 propagating effect Effects 0.000 description 1
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Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は移動通信システムにおいて、移動機（特に携帯
機）が在圏する基地局の識別を高精度で行える在圏エリ
ア識別方式に関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an area identification method for identifying a base station in which a mobile device (particularly a portable device) is located in a mobile communication system with high accuracy.
自動車電話等の移動通信方式では、サービスエリアを複
数の基地局がカバーする複数のセルで構成しており、移
動機からの接続要求に応じて基地局が通信チャネルを割
り当てるとき、まず、その移動機がどの基地局のエリア
（セル）に在圏するかを識別して、次に、その在圏基地
局の空き通信チャネルを割り当てる。In mobile communication systems such as car phones, the service area consists of multiple cells covered by multiple base stations.When a base station allocates a communication channel in response to a connection request from a mobile device, it first The system identifies which base station area (cell) the device is located in, and then allocates a vacant communication channel of that base station.
また、このように通信チャネルを割り当てた後でも、移
動機が通信中に移動して今までの在圏基地局エリアを出
て隣の基地局のエリアに移行する事があり、この場合に
は、移動機の新しい在圏基地局のエリアを識別しなおし
て、基地局の空き通信チャネルを割当しなおす。このた
めに、必要な在圏基地局識別方法としては、従来、主と
して車載機を対象とした在圏基地局の識別方法があった
。Furthermore, even after allocating communication channels in this way, the mobile device may move during communication and leave the base station area it has been in and move into the area of the neighboring base station. , re-identify the area of the new base station in which the mobile device is located, and reallocate the vacant communication channel of the base station. For this reason, as a necessary method for identifying a base station in the area, there has conventionally been a method for identifying the base station in the area mainly for vehicle-mounted devices.
移動通信では基地局からの電波は建物などによる反射や
回折の結果、場所的に定在波を生じておリ、移動機がこ
の中を移動すると定在波に応した受信レベルの変動を生
ずる。これをフェージングという。In mobile communications, radio waves from base stations generate standing waves in certain places as a result of reflection and diffraction from buildings, etc., and when a mobile device moves through these waves, the reception level changes depending on the standing waves. . This is called fading.
移動機の在圏基地局の識別は各基地局からの電波の受信
レベルを相互に比較して、最大レベルで受信される基地
局を在圏基地局と識別するが、フェージングによる受信
レベルの変動はこの識別を不正確にする。To identify base stations within the mobile device's area, the received level of radio waves from each base station is compared with each other, and the base station that is received at the highest level is identified as the base station within the area, but fluctuations in the reception level due to fading occur. makes this identification inaccurate.
従来の車載機を対象にした識別方法では、例えば、８０
０ＭＨｚ帯自動車電話が時速数十ｋｍで走行した場合の
フェージング速度が数十Ｆｉｚになるため、１秒〜数秒
間受信レヘルを平均化すればフェージングの変動を十分
平均化する事が出来、平均受信レベルで在圏基地局を識
別する事が可能となり、誤差は比較的小さかった。In the conventional identification method for in-vehicle devices, for example, 80
When a 0MHz band car phone runs at several tens of kilometers per hour, the fading speed is several tens of Fiz, so if you average the reception level for one to several seconds, you can sufficiently average out the fluctuations in fading, and the average reception It became possible to identify the base station in the area based on the level, and the error was relatively small.
しかし、携帯機ではその移動速度は一般に毎時０〜数ｋ
ｍであり、数ｋｍ／秒の場合でも平均化するのに数十秒
を要し、著しい時間がかかる上、時速Ｏｋｍすなわち停
止して使用している場合には平均化は本質的に不可能で
あり、フェージングの変動を残したまま在圏基地局を識
別せざるを得す、誤差が大きいという欠点があった。However, the moving speed of mobile devices is generally 0 to several kilometers per hour.
m, and it takes several tens of seconds to average even when the speed is several km/second, which is a significant amount of time, and averaging is essentially impossible when the speed is 0 km/h, that is, when the vehicle is stopped. However, this method had the disadvantage that the base station in the area had to be identified while keeping the fading fluctuations intact, resulting in a large error.
本発明はこのような従来の問題点を解決するため、停止
または極めて低速度で移動する携帯機においても在圏基
地局エリアの識別を高精度で行い得る方式を提供する事
を目的としている。 ゛〔課題を解決するための手
段〕
本発明によれば上述の目的は前記特許請求の範囲に記載
した手段により達成される。In order to solve these conventional problems, it is an object of the present invention to provide a system that can identify the area of a base station with high accuracy even in a mobile device that is stopped or moves at an extremely low speed. [Means for Solving the Problems] According to the present invention, the above objects are achieved by the means described in the claims.
すなわち、本発明は、複数の無線チャネルを有する複数
の基地局と移動機から構成される移動通信システムにお
いて、移動機が一基地局当たり複数の無線チャネルの信
号を受信して受信信号の平均的受信品質を判定し、基地
局ごとの受信品質の比較結果により、在圏する基地局を
識別する移動通信における在圏エリア識別方式である。That is, in a mobile communication system composed of a plurality of base stations having a plurality of radio channels and a mobile device, the present invention provides a mobile device that receives signals from a plurality of radio channels per base station and averages the received signals. This is an area identification method in mobile communications that determines the reception quality and identifies the base station within the area based on the comparison result of the reception quality for each base station.
本発明は１つの基地局から送信されている、瞬時レベル
変動の相関がＯまたは十分低い２つ以上の無線チャネル
を携帯機で受信し、これらのチャネルの受信品質の平均
値、または最大値等をその基地局の無線チャネルの受信
品質とし、この品質を基地局間で比較することにより携
帯機の在圏基地局を識別することを最大の特徴とする。The present invention allows a mobile device to receive two or more wireless channels transmitted from a single base station whose correlation of instantaneous level fluctuations is O or sufficiently low, and calculates the average value, maximum value, etc. of the reception quality of these channels. is the reception quality of the radio channel of that base station, and the main feature is that the base station in which the mobile device is located can be identified by comparing this quality between base stations.
瞬時レベル変動の相関がＯまたは極めて低い２つ以上の
無線チャネルを基地局から送信する方法としては、後述
するコヒーレント帯域幅以上離れた無線チャネルを少な
くとも１組各基地局に割り当てるか、または少なくとも
１組の無線チャネルを後述する距離以上離れた２つのア
ンテナがらそれぞれ送信することによって実現する事が
できる。As a method for transmitting from a base station two or more wireless channels in which the correlation of instantaneous level fluctuations is O or extremely low, at least one set of wireless channels separated by a coherent bandwidth or more, which will be described later, is allocated to each base station, or at least one This can be realized by transmitting a set of wireless channels from two antennas separated by a distance described later.
従来の技術では基地局からの１つの無線チャネルだけを
受信してこの受信品質により在圏基地局を識別していた
のに対して、本発明では前述のように１つの基地局当た
り２つ以上の無線チャネルを受信する点が異なるもので
ある。In the conventional technology, only one radio channel from a base station is received and the base station in the area is identified based on the reception quality, whereas in the present invention, as described above, two or more radio channels are received per base station. The difference is that it receives radio channels.
第１図は本発明の一実施例を示す図であって、（ａ）は
基地局、（ｂ）は移動機の構成を示しており、１は交換
局（図示せず）との間の通信線、２は制御装置、３−１
〜３−ｎは無線チャネル送受信装置、４はアンテナ共用
装置、５，７はアンテナ、６は送受分波器、８は受信機
、９は局部発信回路、１０は送信機、１１は制御回路、
１２は電話機を表わしている。FIG. 1 is a diagram showing an embodiment of the present invention, in which (a) shows the configuration of a base station, (b) shows the configuration of a mobile device, and 1 shows the configuration of a base station and a switching center (not shown). Communication line, 2 is a control device, 3-1
~3-n is a wireless channel transmitting/receiving device, 4 is an antenna sharing device, 5 and 7 are antennas, 6 is a transmitting/receiving duplexer, 8 is a receiver, 9 is a local oscillation circuit, 10 is a transmitter, 11 is a control circuit,
12 represents a telephone.
基地局にはその基地局内の移動機数に応じて必要な数だ
けの無線チャネル送受信袋Ｗ３−１〜３−ｎが設備され
ている。この内の例えば３−１は制御チャネル専用であ
り、移動機は通話していないいわゆる待ち受は中はこの
制御チャネルを受信している。基地局から移動機を呼び
出す場合は、この制御チャネルで呼出信号を送信するし
、逆に移動機から発呼する場合はこの制御チャネルで基
地局に対して発呼信号を送出する。The base station is equipped with as many wireless channel transmitting/receiving bags W3-1 to W3-n as necessary depending on the number of mobile devices within the base station. Of these, for example, 3-1 is dedicated to a control channel, and the mobile device receives this control channel during so-called standby mode when it is not talking. When a base station calls a mobile device, a paging signal is transmitted through this control channel, and conversely, when a mobile device calls a mobile device, a calling signal is sent to the base station through this control channel.
このような制御を実行するため、移動機は在圏基地局の
制御チャネルを正しく受信しておく必要がある。In order to perform such control, the mobile device needs to correctly receive the control channel of the base station in its area.
ところで、フェージングは前述のように、異なる経路を
通ってきた通路差の異なる多数の電波が合成される結果
場所的に定在波を生じることが原因である。したがって
、同一の場所から送信された電波であっても周波数が違
えば通路差に相当する距離を伝搬する間の位相回転量が
違うため合成される時の位相が異なることとなり、この
結果場所的な定在波の様子が違ったものになり、２つの
受信レベルの相関が低くなる。すなわち、異なる周波数
の電波では、ある場所で一方の電波のレベルが低くても
他方の電波は必ずしも低くくはないことになる。By the way, as mentioned above, fading is caused by the generation of standing waves locally as a result of combining a large number of radio waves with different path differences that have passed through different routes. Therefore, even if radio waves are transmitted from the same location, if the frequency is different, the amount of phase rotation will be different while propagating over a distance corresponding to the path difference, so the phase will be different when synthesized. The appearance of the standing waves becomes different, and the correlation between the two reception levels becomes low. In other words, with radio waves of different frequencies, even if the level of one radio wave is low at a certain location, the level of the other radio wave is not necessarily low.
２つの電波の周波数を離すほど受信レベルの相関は低く
なり、相関係数が例えば０．５になる時の周波数間隔を
相関帯域幅という。相関帯域幅の値は伝搬路の通路長差
によって異なるが一般には数１００ｋＨｚから数ＭＨｚ
程度である。したがって、第１図において制御チャネル
送受信装置３−１の周波数に対して数ＭＨｚ離れた周波
数を３−２〜３−ｎのいずれか１つまたは複数の送受信
装置の周波数として送信する。The correlation between the reception levels decreases as the frequencies of two radio waves are separated, and the frequency interval when the correlation coefficient becomes, for example, 0.5 is called the correlation bandwidth. The value of the correlation bandwidth varies depending on the difference in path length of the propagation path, but generally ranges from several 100 kHz to several MHz.
That's about it. Therefore, in FIG. 1, a frequency that is several MHz apart from the frequency of the control channel transmitting/receiving device 3-1 is transmitted as the frequency of any one or more of the transmitting/receiving devices 3-2 to 3-n.
移動機は、受信機８で制御チャネルの周波数と上記３−
２〜３−ｎのいずれか１つまたは複数の周波数を交互に
受信し、その平均値をこの基地局からの電波の平均レベ
ルとする。他の基地局についても同様に２つまたはそれ
以上の無線チャネルを受信してその平均値をその基地局
からの平均受信レベルとし、この平均レベルの相互比較
により在圏基地局のエリアを決定する。受信機の受信周
波数は局部発振回路９から供給される局部発振周波数に
よって変えられる。The mobile device transmits the frequency of the control channel and the above 3-
Any one or more frequencies of 2 to 3-n are received alternately, and the average value thereof is taken as the average level of radio waves from this base station. Similarly, two or more radio channels are received from other base stations, and the average value is taken as the average reception level from that base station, and the area of the serving base station is determined by mutual comparison of these average levels. . The reception frequency of the receiver is changed by the local oscillation frequency supplied from the local oscillation circuit 9.
また受信周波数の指定や受信レベルの平均化などの制御
は制御回路１１によってなされる。Further, the control circuit 11 controls the designation of the reception frequency and the averaging of the reception level.
第２図は基地局構成の他の例を示す図であって、１３は
制御装置、１７．１８は送受分波器、１４−１〜１４−
ｎ、 １５−１〜１５−ｎは無線チャネル送受信装置、
１６．１９はアンテナを表わしている。同図において、
無線チャネル送受信装置の一部１４−１〜１４−ｎは送
受分波器１７によってアンテナ１６に接続され、他の無
線チャネル送受信装置１５−１＝１５−ｎは送受分波器
１８によって別のアンテナ１９に接続されている。FIG. 2 is a diagram showing another example of the base station configuration, in which 13 is a control device, 17.18 is a transmitting/receiving duplexer, and 14-1 to 14-
n, 15-1 to 15-n are wireless channel transmitting/receiving devices;
16.19 represents an antenna. In the same figure,
Some of the wireless channel transmitting/receiving devices 14-1 to 14-n are connected to the antenna 16 by the transmitting/receiving duplexer 17, and the other wireless channel transmitting/receiving devices 15-1=15-n are connected to another antenna by the transmitting/receiving duplexer 18. It is connected to 19.
異なる場所に設置されているアンテナ１６及び１９から
出た電波は異なる経路を経て移動機に達するが、経路が
異なるため合成される時の各電波の振幅や位相はアンテ
ナごとに異なっており、したがって第１の実施例と同様
に両アンテナからの無線チャネル電波の受信レベルの相
関は低くなる。Radio waves emitted from antennas 16 and 19 installed at different locations reach the mobile device via different routes, but because the routes are different, the amplitude and phase of each radio wave when combined differs for each antenna. Similar to the first embodiment, the correlation between the reception levels of radio channel radio waves from both antennas becomes low.
この時もアンテナの間隔を離すほど相関係数は小さくな
るが一般的には数ｍ離せば相関関数は十分小さくなる。At this time as well, the correlation coefficient decreases as the distance between the antennas increases, but in general, if the antennas are separated by several meters, the correlation function becomes sufficiently small.
以上の例では移動機の待ち受は中の在圏基地局エリア識
別について説明したが、以下に説明するように、通信中
に在圏基地局エリアを移行した場合の移行先基地局識別
にも本発明を適用することが可能である。In the above example, we explained how to identify the base station area in which the mobile device is in standby mode, but as explained below, it can also identify the destination base station when changing the base station area during communication. It is possible to apply the present invention.
第３図はこれを説明するための移動機の通信チャネルに
おける送信及び受信のタイミングを示す図である。基地
局と移動機の間の無線チャネルはＴＤＭＡ ／ＦＤＭで
あり、第３図は４チャヱルＴＤＭＡでの場合を示してい
る。ある特定の移動機で考えると、２０．２８は基地局
との間で通信している送信のタイミング、２１．２９は
同じく受信のタイミングであり、その他のタイミング２
２〜２７はこの無線チャネルを使用する他の３台の移動
機が使用する送信及び受信のタイミングである。FIG. 3 is a diagram showing the timing of transmission and reception in a communication channel of a mobile device to explain this. The radio channel between the base station and the mobile device is TDMA/FDM, and FIG. 3 shows the case of 4-channel TDMA. Considering a particular mobile device, 20.28 is the transmission timing when communicating with the base station, 21.29 is the same reception timing, and other timings 2
2 to 27 are the transmission and reception timings used by the other three mobile devices that use this wireless channel.
この移動機にとっては、２２〜２７のタイミングは、基
地局との間の通信で送信または受信する必要のないタイ
ミングであり、この時間の間に在圏基地局の周辺基地局
が送信している電波を順次受信して、在圏基地局電波の
受信レベルと比較する事により在圏基地局を移行したか
否かを識別することができる。この時に、現在の在圏基
地局の電波受信レベル及び周辺基地局の電波の受信レベ
ル測定に当たって前記実施例で説明したように２つ以上
の無線チャネルを受信して同様に平均化処理をする。For this mobile device, timings 22 to 27 are timings when there is no need to transmit or receive in communication with the base station, and base stations surrounding the serving base station are transmitting during this time. By sequentially receiving the radio waves and comparing them with the reception level of the radio waves from the serving base station, it is possible to identify whether or not the serving base station has been migrated. At this time, in measuring the radio wave reception level of the current base station in the area and the radio wave reception level of neighboring base stations, two or more radio channels are received and averaged in the same manner as described in the previous embodiment.
以上の説明では２つ以上の無線チャネルの受信レベルを
平均化する方法について述べているが、フェージングの
性質上、受信レベルは通常は平均値に近いレベルである
が、希に非常に低いレベルにまで減衰する事を考えると
、受信レベルの最大値をとればほぼ平均値に近い値が得
られると考えられる。この方法によれば若干の誤差はあ
るが平均値をとる必要がなく最大値をとるだけの簡単な
処理で本発明の方式を実現することが可能である。The above explanation describes a method for averaging the reception levels of two or more wireless channels, but due to the nature of fading, the reception level is usually close to the average value, but in rare cases it may be at a very low level. Considering that the received level is attenuated to a maximum value, it is considered that a value close to the average value can be obtained by taking the maximum value of the received level. According to this method, although there is a slight error, it is possible to realize the system of the present invention with a simple process of only taking the maximum value without the need to take the average value.
また、以上の説明では受信レベルの大小を識別の根拠と
する方法について述べているが、受信レベルに限らず、
デジタル符号の誤り率、デジタル符号の再生クロツクの
ジッタの大きさ、ＦＭ通信方弐におけるベースバンド帯
域外の復調雑音など、通信品質に対応する測定可能な受
信品質であれば、いずれでもよい。In addition, although the above explanation describes a method that uses the size of the reception level as the basis for identification, it is not limited to the reception level.
Any measurable reception quality that corresponds to the communication quality may be used, such as the error rate of the digital code, the magnitude of jitter of the recovered clock of the digital code, or the demodulation noise outside the baseband in FM communication method.
〔発明の効果］
以上説明したように、本発明では携帯機を低速移動中ま
たは停止中に使用した場合の在圏エリア識別を１つの周
波数でなく２つ以上の周波数の受信品質をもとに行うた
め、１つの周波数だけで識別する従来の方法では避は得
なかった、フェージングによる受信品質測定の誤差を軽
減する事ができる利点がある。[Effects of the Invention] As explained above, in the present invention, when a portable device is used while moving at low speed or stopped, the area in which it is located is identified based on the reception quality of two or more frequencies instead of one frequency. This has the advantage of reducing reception quality measurement errors due to fading, which were unavoidable with conventional methods that identify only one frequency.
すなわち、受信品質がたまたまフェージングの落ち込み
により極めて劣化している場合でも受信レベル相関が無
相関に近い他の無線チャネルの受信品質も利用するため
、これら複数の無線チャネルの受信品質が同時に落ち込
まない限り本発明による識別に利用する受信品質が平均
受信品質と太き（異なることはなく、平均品質に近い値
を得ることができる。なお受信品質が同時に落ち込む確
率は、受信レベルの相関係数が０に近くなるよう周波数
間隔またはアンテナ間隔を離すことにより十分小さくす
る事が可能である。In other words, even if the reception quality happens to be extremely degraded due to a decline in fading, the reception quality of other radio channels whose reception level correlation is close to uncorrelated is also used, so as long as the reception quality of these multiple radio channels does not deteriorate at the same time. The reception quality used for identification according to the present invention is thicker than the average reception quality (there is no difference, and a value close to the average quality can be obtained.The probability that the reception quality decreases at the same time is that the correlation coefficient of the reception level is 0) This can be made sufficiently small by increasing the frequency spacing or antenna spacing so that it approaches .
第１図は本発明の一実施例を示す図、第２図は基地局の
他の構成の例を示す図、第３図は移動機の通信チャネル
における送信及び受信のタイミングの例を示す図である
。
■・・・交換局との間の通信線、２・・・制御装置、３
−１〜３−ｎ、 １４−１〜１４−ｎ、 １５−１〜１
５〜ｎ・・・無線チャネル送受信装置、４・・・アンテ
ナ共用装置、５．７・・・アンテナ、６・・・送受分波
器、８・・・受信機、９・・・局部発振回路、１０・・
・送信機、１１・・・制御回路、１２・・・電話機、１
７．１８・・・送受分波器、１６゜１９・・・アンテナ
、２０，２２．２４，２６．２８・・・基地局との間で
通信している送信のタイミング、２１．２３，２５，２
７．２９・・・受信のタイミングFIG. 1 is a diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing an example of another configuration of a base station, and FIG. 3 is a diagram showing an example of transmission and reception timing in a communication channel of a mobile device. It is. ■...Communication line with switching center, 2...Control device, 3
-1 to 3-n, 14-1 to 14-n, 15-1 to 1
5 to n... Radio channel transmitting/receiving device, 4... Antenna sharing device, 5.7... Antenna, 6... Transmitting/receiving duplexer, 8... Receiver, 9... Local oscillation circuit , 10...
- Transmitter, 11... Control circuit, 12... Telephone, 1
7.18... Transmission/reception duplexer, 16° 19... Antenna, 20, 22.24, 26.28... Timing of transmission during communication with the base station, 21.23, 25 ,2
7.29...Reception timing
Claims (1)
構成される移動通信システムにおいて、移動機が一基地
局当たり複数の無線チャネルの信号を受信して受信信号
の平均的受信品質を判定し、基地局ごとに受信品質の比
較結果により、在圏する基地局を識別することを特徴と
する移動通信における在圏エリア識別方式。In a mobile communication system consisting of a plurality of base stations having a plurality of radio channels and a mobile device, the mobile device receives signals of a plurality of radio channels per one base station and determines the average reception quality of the received signal, A service area identification method for mobile communications, which is characterized by identifying base stations within the service area based on the results of comparison of reception quality for each base station.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2308679A JPH07121145B2 (en) | 1990-11-16 | 1990-11-16 | Location area identification method in mobile communication |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2308679A JPH07121145B2 (en) | 1990-11-16 | 1990-11-16 | Location area identification method in mobile communication |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH04181828A true JPH04181828A (en) | 1992-06-29 |
| JPH07121145B2 JPH07121145B2 (en) | 1995-12-20 |
Family
ID=17983985
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2308679A Expired - Lifetime JPH07121145B2 (en) | 1990-11-16 | 1990-11-16 | Location area identification method in mobile communication |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH07121145B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6223036B1 (en) | 1997-01-16 | 2001-04-24 | Nec Corporation | Adjacent cell monitoring method and mobile station |
-
1990
- 1990-11-16 JP JP2308679A patent/JPH07121145B2/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6223036B1 (en) | 1997-01-16 | 2001-04-24 | Nec Corporation | Adjacent cell monitoring method and mobile station |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH07121145B2 (en) | 1995-12-20 |
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