JPH05145460A - Signal detector - Google Patents
Signal detectorInfo
- Publication number
- JPH05145460A JPH05145460A JP3307863A JP30786391A JPH05145460A JP H05145460 A JPH05145460 A JP H05145460A JP 3307863 A JP3307863 A JP 3307863A JP 30786391 A JP30786391 A JP 30786391A JP H05145460 A JPH05145460 A JP H05145460A
- Authority
- JP
- Japan
- Prior art keywords
- level
- threshold level
- signal wave
- channel
- probability
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Mobile Radio Communication Systems (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、互いに干渉妨害を受け
ない複数の無線局で同一チャネルを繰り返し使用する通
信方式において、チャネル割り当て時の空きチャネル検
出に用いる信号検出装置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal detecting apparatus used for detecting an empty channel at the time of channel allocation in a communication system in which a plurality of wireless stations which are not interfered with each other repeatedly use the same channel.
【０００２】[0002]
【従来の技術】自ら他の無線局が使用していないチャネ
ルを選択する無線局では、他の無線局からの信号波の有
無を検出して空きチャネルを判定する信号検出装置を備
えている。従来の信号検出装置は、レベル検出器で各チ
ャネルごとの信号波を包絡線検波し、得られた受信レベ
ルと予め設定された閾値レベルとを比較し、この受信レ
ベルが閾値レベル以下のチャネルを空きチャネルとして
検出する構成になっている。なお、この空きチャネル判
定の基準となる閾値レベルは、従来は固定値となってい
た。2. Description of the Related Art A radio station which selects a channel which is not being used by another radio station is equipped with a signal detection device which detects the presence or absence of a signal wave from another radio station and determines an empty channel. The conventional signal detection device, envelope detection of the signal wave for each channel in the level detector, and compares the obtained reception level with a preset threshold level, the reception level of the channel below the threshold level It is configured to detect as an empty channel. It should be noted that the threshold level that serves as a reference for determining an available channel has been a fixed value in the past.
【０００３】[0003]
【発明が解決しようとする課題】ところで、各チャネル
ごとの受信レベルを検出するレベル検出器には常に熱雑
音が存在する。すなわち、レベル検出器で得られる受信
レベルには熱雑音が含まれており、この熱雑音レベルが
閾値レベルを越えた場合には信号波が到来していなくて
もそのチャネルが使用中であると誤判断してしまうこと
になる。したがって、閾値レベルは熱雑音レベルの最大
値より高く設定する必要がある。By the way, thermal noise is always present in the level detector for detecting the reception level of each channel. That is, the received level obtained by the level detector contains thermal noise, and when this thermal noise level exceeds the threshold level, it means that the channel is in use even if no signal wave has arrived. You will make a wrong decision. Therefore, the threshold level needs to be set higher than the maximum value of the thermal noise level.
【０００４】また、他の無線局で使用中のチャネルの信
号波は干渉波として到来することになるために、それを
包絡線検波した受信レベルは瞬時的に大きな変動を伴
う。したがって、閾値レベルを高めに設定すると受信レ
ベルの変動に伴って閾値レベルを下回るごとに空きチャ
ネルと誤判断してしまうことになる。そこで、閾値レベ
ルは、干渉波として許容できるレベル（チャネル使用が
認められるものの、当方のチャネル使用には影響がない
と見なせるレベルであり、以下「許容干渉レベル」とい
う。）を越える信号波がレベル変動によって取りうるレ
ベルの最小値より低く設定する必要がある。Further, since the signal wave of the channel being used by another wireless station arrives as an interference wave, the envelope-detected reception level of the signal wave instantaneously fluctuates greatly. Therefore, if the threshold level is set to a high value, it will be erroneously determined as an empty channel each time the threshold level is dropped due to fluctuations in the reception level. Therefore, the threshold level is a level of a signal wave that exceeds a level allowable as an interference wave (a level at which the use of the channel is allowed but is considered to have no influence on the use of the channel of the other side, referred to as "allowable interference level" hereinafter). It must be set lower than the minimum level that can be taken due to fluctuations.
【０００５】一方、通信品質の向上のために許容干渉レ
ベルを低く抑えた場合には、空きチャネルの検出基準と
なる閾値レベルも低くなるが、熱雑音レベルの最大値を
下回る状態となった場合には誤判断確率が増す。したが
って、その場合の閾値レベルは誤判断確率が最小となる
値が選択される。On the other hand, when the allowable interference level is suppressed to a low level in order to improve the communication quality, the threshold level, which is a reference for detecting a vacant channel, also decreases, but the thermal noise level falls below the maximum value. The probability of misjudgment increases. Therefore, the threshold level in that case is selected as a value that minimizes the probability of misjudgment.
【０００６】図２は、閾値レベルに対する誤判断確率を
概念的に示した図である。図において、横軸はレベル検
出器において検出される受信レベル（μＶ）であり、縦
軸は確率密度である。曲線は平均レベル０dBμの雑音
の確率密度分布であり、曲線はレイリー変動する平均
レベル10dBμの信号波に平均レベル０dBμの雑音を含め
たものの確率密度分布である。ここで例えば閾値レベル
を２μＶとすると、誤判断確率は、受信レベルが雑音で
あるにもかかわらず閾値レベルを越えているために干渉
波と見なされ、そのチャネルが使用中であると判断して
しまう領域と、干渉波であるにもかかわらず閾値レベ
ルを下回っているために雑音と見なし、そのチャネルが
空きチャネルであると判断してしまう領域の面積の和
として表される。したがって、両確率密度関数の交点が
誤判断確率を最小にする最適閾値レベルとなる。FIG. 2 is a diagram conceptually showing an erroneous decision probability with respect to a threshold level. In the figure, the horizontal axis is the reception level (μV) detected by the level detector, and the vertical axis is the probability density. The curve is a probability density distribution of noise with an average level of 0 dBμ, and the curve is a probability density distribution of a signal wave with an average level of 10 dBμ that changes Rayleigh and noise of an average level of 0 dBμ. Here, for example, when the threshold level is set to 2 μV, the misjudgment probability is regarded as an interference wave because the reception level exceeds the threshold level even though the reception level is noise, and it is determined that the channel is in use. It is expressed as the sum of the area of the area where the noise occurs and the area of the area where the channel is regarded as noise because it is below the threshold level even though it is an interference wave and the channel is determined to be an empty channel. Therefore, the intersection of both probability density functions is the optimum threshold level that minimizes the false decision probability.
【０００７】さて、最適閾値レベルが熱雑音レベルや許
容干渉レベルのみによって決められる場合には、それら
が予想可能であったり、予め所定値に決めておくことが
可能であるので、従来のように固定化しておいても特に
支障とはならなかった。しかし、誤判断確率は、トラヒ
ックに応じて変動する干渉波の到来確率によっても左右
されることが知られている。When the optimum threshold level is determined only by the thermal noise level and the allowable interference level, they can be predicted or can be set to a predetermined value in advance. Even if it was fixed, there was no particular problem. However, it is known that the misjudgment probability also depends on the arrival probability of an interference wave that fluctuates according to traffic.
【０００８】ここで、レベル検出器において検出される
受信レベルごとの閾値レベルに対する誤判断確率を図３
に示す。図において、横軸は閾値レベル（dBμ）であ
り、縦軸は誤判断確率（％）である。曲線〜は、各
々熱雑音（０dBμ）を含む受信レベル（０，10，20，30
dBμ）の各閾値レベルに対する誤判断確率であり、それ
ぞれの極小点に相当する閾値レベルが最適閾値レベルと
なる。図に示すように、受信レベルに応じて最適閾値レ
ベルが変化することがわかる。Here, the probability of misjudgment with respect to the threshold level for each reception level detected by the level detector is shown in FIG.
Shown in. In the figure, the horizontal axis is the threshold level (dBμ), and the vertical axis is the misjudgment probability (%). Curves ~ are the reception levels (0, 10, 20, 30) including thermal noise (0 dBμ).
dBμ) is the probability of misjudgment for each threshold level, and the threshold level corresponding to each minimum point is the optimum threshold level. As shown in the figure, it can be seen that the optimum threshold level changes according to the reception level.
【０００９】なお、図３は雑音事象の生起確率を 0.5と
した。すなわち、熱雑音であるときと、他の無線局から
信号波が到来する確率が等しいとしたときの最適閾値レ
ベルを表すものである。この確率を変えたときの閾値レ
ベルに対する誤判断確率（各信号波存在確率ごとの閾値
レベルに対する誤判断確率）を図４に示す。図におい
て、横軸は閾値レベル（dBμ）であり、縦軸は誤判断確
率（％）である。曲線〜は、熱雑音を含む受信レベ
ルを20dBμとしたときに、信号波と熱雑音の存在確率比
が１：９、３：７、１：１、７：３、９：１であるとき
の誤判断確率であり、それぞれの極小点に相当する閾値
レベルが最適閾値レベルとなる。図に示すように、信号
波と熱雑音の存在確率比、すなわちトラヒックに応じて
変動する干渉波の到来確率に応じて最適閾値レベルが変
化することがわかる。In FIG. 3, the probability of occurrence of a noise event is 0.5. That is, it represents the optimum threshold level when it is thermal noise and when the probability that a signal wave from another wireless station arrives is equal. FIG. 4 shows an erroneous decision probability with respect to the threshold level when this probability is changed (erroneous decision probability with respect to the threshold level for each signal wave existence probability). In the figure, the horizontal axis is the threshold level (dBμ), and the vertical axis is the misjudgment probability (%). Curves (1) to (3) show that when the reception level including thermal noise is 20 dBμ, the existence probability ratio between the signal wave and thermal noise is 1: 9, 3: 7, 1: 1, 7: 3, 9: 1. This is the probability of misjudgment, and the threshold level corresponding to each minimum point becomes the optimum threshold level. As shown in the figure, it can be seen that the optimum threshold level changes according to the existence probability ratio of the signal wave and the thermal noise, that is, the arrival probability of the interference wave that changes according to the traffic.
【００１０】本発明は、以上示した閾値レベルと誤判断
確率との関係に基づいて誤判断確率を最小にする最適閾
値レベルを設定し、他の無線局から到来する信号波（干
渉波）の有無を判断して空きチャネルを効率良く検出す
ることができる信号検出装置を提供することを目的とす
る。The present invention sets the optimum threshold level that minimizes the false decision probability based on the above-described relationship between the threshold level and the false decision probability, and sets the signal wave (interference wave) coming from another radio station. An object of the present invention is to provide a signal detection device capable of efficiently determining an empty channel by determining the presence or absence of the signal.
【００１１】[0011]
【課題を解決するための手段】本発明は、各チャネルご
との信号波を包絡線検波し、その受信レベルを検出する
レベル検出器と、前記受信レベルと閾値レベルとを比較
し、受信レベルが閾値レベル以下のチャネルを空きチャ
ネルとして判定する判定器とを備えた信号検出装置にお
いて、前記チャネルごとの信号波到来確率を測定する信
号波到来確率測定手段と、外部から設定される熱雑音平
均レベルおよび許容干渉平均レベルと、前記信号波到来
確率測定手段で得られた信号波到来確率とに応じて、前
記判定器に設定する閾値レベルを決定する閾値レベル設
定手段とを備えたことを特徴とする。SUMMARY OF THE INVENTION The present invention compares the reception level and a threshold level with a level detector that detects the reception level of the signal wave for each channel by envelope detection and compares the reception level with the level detector. In a signal detection device provided with a determiner for determining a channel below a threshold level as an empty channel, a signal wave arrival probability measuring means for measuring a signal wave arrival probability for each channel, and a thermal noise average level set from outside And an allowable interference average level, and a threshold level setting means for determining a threshold level to be set in the judging device according to the signal wave arrival probability obtained by the signal wave arrival probability measuring means. To do.
【００１２】[0012]
【作用】本発明は、熱雑音平均レベル、許容干渉平均レ
ベルおよび信号波到来確率測定手段で求められる信号波
到来確率に応じて、空きチャネルの検出基準となる閾値
レベルを逐次変更することにより、常に誤判断確率を小
さくすることができる。According to the present invention, the threshold level serving as a reference for detecting an empty channel is sequentially changed according to the average level of thermal noise, the average level of allowable interference, and the signal wave arrival probability obtained by the signal wave arrival probability measuring means. The probability of misjudgment can always be reduced.
【００１３】[0013]
【実施例】図１は、本発明の一実施例構成を示すブロッ
ク図である。図において、アンテナ１１に到来した信号
波は増幅器１２で増幅された後に、帯域通過フィルタ１
３を介してレベル検出器１４に入力される。レベル検出
器１４は、各チャネルごとに包絡線検波することにより
受信レベル信号に変換して判定器１５に送出する。判定
器１５は、この受信レベルと閾値レベル設定回路１６か
ら設定される閾値レベルとの比較を行い、受信レベルが
閾値レベルを越えるか否かを判定する。なお、閾値レベ
ル以下のチャネルが空きチャネルとして検出される。1 is a block diagram showing the configuration of an embodiment of the present invention. In the figure, the signal wave arriving at the antenna 11 is amplified by the amplifier 12, and then the band pass filter 1
3 is input to the level detector 14. The level detector 14 performs envelope detection for each channel to convert it into a reception level signal and sends it to the determiner 15. The determiner 15 compares this reception level with the threshold level set by the threshold level setting circuit 16 to determine whether the reception level exceeds the threshold level. Channels below the threshold level are detected as free channels.
【００１４】ここで、本発明の特徴とするところは、本
実施例では判定器１５に設定される閾値レベルが閾値レ
ベル設定回路１６によって逐次制御される構成にある。
閾値レベル設定回路１６には、熱雑音平均レベルおよび
許容干渉平均レベルが設定され、さらに信号波到来確率
測定器１７で得られた信号波到来確率を入力して上式を
用いた演算処理を行い、最適閾値レベルを算出して判定
器１５に設定する。Here, the feature of the present invention is that the threshold level set in the decision unit 15 is successively controlled by the threshold level setting circuit 16 in the present embodiment.
The thermal noise average level and the allowable interference average level are set in the threshold level setting circuit 16, and the signal wave arrival probability obtained by the signal wave arrival probability measuring device 17 is input to perform arithmetic processing using the above equation. , The optimum threshold level is calculated and set in the determiner 15.
【００１５】ところで、図３，図４を参照して説明した
ように、熱雑音平均レベル、許容干渉平均レベルが与え
られ、さらに信号波到来確率が判れば、空きチャネルの
検出基準となる閾値レベルを最適化することができる。
この信号波到来確率を得るためには、当無線局に干渉を
及ぼすと予想されるすべての無線局のチャネル使用状況
を把握する必要があるが、近似的には当無線局の呼量を
測定しても信号波到来確率を得ることができる。なお、
この呼量測定法は公知の技術であり、例えば呼数測定
と時間測定により平均呼数密度と平均保留時間を求め、
その積から呼量を測定する方式、当無線局がある時間
区間の中で保留されている時間の延べ時間を測定して呼
量とする方式がある。この延べ時間の測定は、例えば回
線使用時の送受信機器等の入出力信号を一定電流が流れ
るように工夫した積算電流計を用いて観測時間との比か
ら容易に得ることができる。By the way, as described with reference to FIGS. 3 and 4, if the thermal noise average level and the allowable interference average level are given and the signal wave arrival probability is known, the threshold level serving as the detection reference of the empty channel is obtained. Can be optimized.
To obtain this signal wave arrival probability, it is necessary to understand the channel usage status of all wireless stations that are expected to interfere with this wireless station, but approximately measure the call volume of this wireless station. Even then, the probability of arrival of the signal wave can be obtained. In addition,
This call volume measuring method is a known technique. For example, the average call number density and the average holding time are obtained by measuring the number of calls and the time,
There are a method of measuring the call volume from the product and a method of measuring the total hold time of the wireless station in a certain time section and using it as the call volume. This total time can be easily obtained from the ratio to the observation time by using, for example, an integrating ammeter designed so that a constant current flows through an input / output signal of a transmitting / receiving device when a line is used.
【００１６】熱雑音平均レベルσN 、許容干渉平均レベ
ルσS+N および信号波到来確率ｍから閾値レベルｈを算
出する解析式は、The analytical expression for calculating the threshold level h from the thermal noise average level σ N , the allowable interference average level σ S + N and the signal wave arrival probability m is
【００１７】[0017]
【数２】 [Equation 2]
【００１８】である。なお、ここでは、狭帯域フィルタ
通過後の熱雑音および信号波がレイリー分布則に従う包
絡線変動をしていると仮定している。この式を満たすｈ
が最適閾値レベルである。ただし、ｈ≠−∞，∞であ
る。It is Here, it is assumed that the thermal noise and the signal wave after passing through the narrow band filter have an envelope variation according to the Rayleigh distribution law. H that satisfies this formula
Is the optimum threshold level. However, h ≠ −∞ and ∞.
【００１９】このような解析式に応じて閾値レベルを演
算することにより、昼夜間のように時間的にトラヒック
が変動し、信号波（干渉波）が到来する確率が変化して
も、それに応じて閾値レベルを追従させることができ
る。したがって、柔軟な閾値レベルの設定が可能とな
り、常に誤判断確率を低く抑えることができる。By calculating the threshold level according to such an analytical expression, even if the traffic fluctuates temporally and the probability of arrival of a signal wave (interference wave) changes, such as day and night, it can be changed accordingly. The threshold level can be tracked. Therefore, the threshold level can be flexibly set, and the probability of misjudgment can always be kept low.
【００２０】[0020]
【発明の効果】以上説明したように本発明は、他の無線
局から到来する信号波（干渉波）の有無を判断する基準
となる閾値レベルを設定する際に、熱雑音平均レベル、
許容干渉平均レベルおよび信号波到来確率に応じて閾値
レベルの最適化を行うことができるので、誤判断確率を
最小にすることができる。すなわち、空きチャネルを効
率良くかつ精度良く検出することができる。As described above, according to the present invention, the thermal noise average level is set when the threshold level is set as a reference for determining the presence / absence of a signal wave (interference wave) coming from another wireless station.
Since it is possible to optimize the threshold level according to the allowable interference average level and the signal wave arrival probability, it is possible to minimize the misjudgment probability. That is, it is possible to detect an empty channel efficiently and accurately.
【図１】本発明の一実施例構成を示すブロック図であ
る。FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.
【図２】閾値レベルに対する誤判断確率を示す図であ
る。FIG. 2 is a diagram showing an erroneous decision probability with respect to a threshold level.
【図３】受信レベルごとの閾値レベルに対する誤判断確
率を示す図である。FIG. 3 is a diagram showing an erroneous decision probability with respect to a threshold level for each reception level.
【図４】各信号波存在確率ごとの閾値レベルに対する誤
判断確率を示す図である。FIG. 4 is a diagram showing an erroneous decision probability with respect to a threshold level for each signal wave existence probability.
１１ アンテナ １２ 増幅器 １３ 帯域通過フィルタ １４ レベル検出器 １５ 判定器 １６ 閾値レベル設定回路 １７ 信号波到来確率測定器 11 antenna 12 amplifier 13 band pass filter 14 level detector 15 decision device 16 threshold level setting circuit 17 signal wave arrival probability measuring device
Claims (2)
し、その受信レベルを検出するレベル検出器と、 前記受信レベルと閾値レベルとを比較し、受信レベルが
閾値レベル以下のチャネルを空きチャネルとして判定す
る判定器とを備えた信号検出装置において、 前記チャネルごとの信号波到来確率を測定する信号波到
来確率測定手段と、 外部から設定される熱雑音平均レベルおよび許容干渉平
均レベルと、前記信号波到来確率測定手段で得られた信
号波到来確率とに応じて、前記判定器に設定する閾値レ
ベルを決定する閾値レベル設定手段とを備えたことを特
徴とする信号検出装置。1. A level detector that envelope-detects a signal wave of each channel and detects a reception level of the signal wave, compares the reception level with a threshold level, and determines a channel whose reception level is equal to or lower than a threshold level as an empty channel. In the signal detection device with a determiner to determine as, a signal wave arrival probability measuring means for measuring the signal wave arrival probability for each channel, the thermal noise average level and the allowable interference average level set from the outside, the A signal detecting apparatus, comprising: a threshold level setting unit that determines a threshold level to be set in the determining unit according to the signal wave arrival probability obtained by the signal wave arrival probability measuring unit.
て、 閾値レベル設定手段は、熱雑音平均レベルをσN 、許容
干渉平均レベルをσS+N 、信号波到来確率をｍとしたと
きに、閾値レベルｈは、 【数１】 の式を満たす値に決定することを特徴とする信号検出装
置。2. The signal detection device according to claim 1, wherein the threshold level setting means is such that when the thermal noise average level is σ N , the allowable interference average level is σ S + N , and the signal wave arrival probability is m. , The threshold level h is A signal detecting device characterized in that the value is determined to satisfy the expression of.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3307863A JPH05145460A (en) | 1991-11-22 | 1991-11-22 | Signal detector |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3307863A JPH05145460A (en) | 1991-11-22 | 1991-11-22 | Signal detector |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH05145460A true JPH05145460A (en) | 1993-06-11 |
Family
ID=17974075
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3307863A Pending JPH05145460A (en) | 1991-11-22 | 1991-11-22 | Signal detector |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH05145460A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1999039536A1 (en) * | 1998-01-28 | 1999-08-05 | Ntt Mobile Communications Network Inc. | Communication channel selecting method and base station device |
| KR100876812B1 (en) * | 2002-11-05 | 2009-01-07 | 삼성전자주식회사 | Method for adjusting and signalling of desired noise rise over thermal value in using node b controlled scheduling of enhanced uplink dedicated transport channel in wcdma communication system |
| US7653020B2 (en) | 2004-01-28 | 2010-01-26 | Harris Corporation | Wireless ultra wideband network having interference mitigation and related methods |
| WO2011004875A1 (en) | 2009-07-09 | 2011-01-13 | 日本電信電話株式会社 | Wireless communication method, wireless communication system, radio base station and radio terminal station |
-
1991
- 1991-11-22 JP JP3307863A patent/JPH05145460A/en active Pending
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1999039536A1 (en) * | 1998-01-28 | 1999-08-05 | Ntt Mobile Communications Network Inc. | Communication channel selecting method and base station device |
| US6453166B1 (en) | 1998-01-28 | 2002-09-17 | Ntt Mobile Communications Network Inc. | Communication channel selecting method and base station device |
| KR100876812B1 (en) * | 2002-11-05 | 2009-01-07 | 삼성전자주식회사 | Method for adjusting and signalling of desired noise rise over thermal value in using node b controlled scheduling of enhanced uplink dedicated transport channel in wcdma communication system |
| US7653020B2 (en) | 2004-01-28 | 2010-01-26 | Harris Corporation | Wireless ultra wideband network having interference mitigation and related methods |
| WO2011004875A1 (en) | 2009-07-09 | 2011-01-13 | 日本電信電話株式会社 | Wireless communication method, wireless communication system, radio base station and radio terminal station |
| US8830965B2 (en) | 2009-07-09 | 2014-09-09 | Nippon Telegraph And Telephone Corporation | Radio communication method, radio communication system, radio base station, and radio terminal station |
| EP2890022A1 (en) | 2009-07-09 | 2015-07-01 | Nippon Telegraph And Telephone Corporation | Radio communication method, radio communication system, radio base station, and radio terminal station |
| US9094973B2 (en) | 2009-07-09 | 2015-07-28 | Nippon Telegraph And Telephone Corporation | Radio communication method, radio communication system, radio base station, and radio terminal station |
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