本實施形態係關於通訊終端、多點跳躍通訊系統、及程式。更詳細而言，本實施形態係關於進行前瞻型之多點跳躍通訊之通訊終端、多點跳躍通訊系統、及通訊終端所使用之程式。 以下，基於圖式對實施形態進行說明。 (實施形態) 如圖1所示，本實施形態之多點跳躍通訊系統10具備1台母機(Master)1、及複數個子機(Slave)2。圖1例示集合住宅之住戶作為用戶設施(Facility)3。然而，用戶設施亦可為獨幢住宅、事務所、店鋪、大樓之租戶等，其形態並無限定。再者，於個別地識別用戶設施3之情形時，記為用戶設施31、32、...、3N。又，子機2之台數亦可為1台以上，進而，子機2之台數較佳為2台以上。 母機1及子機2之各者為進行電力線傳輸通訊或無線通訊之通訊終端。再者，於個別地識別子機2之情形時，記為子機21、22、...、2N。 各子機2係設置於對應之1個用戶設施3。各子機2具有將與設置有該子機2之用戶設施3相關之特定資料向1台母機1發送之功能。母機1具有如下功能：自複數個子機2獲取與用戶設施3之各者相關之特定資料，並使用光纖線路或網際網路等廣域通訊網等將所獲取之特定資料向上位之管理裝置發送。例如，藉由母機1自子機2獲取用戶設施3之各者中之電力使用量、瓦斯使用量、自來水使用量等抄錶資料，而可構成遠距抄錶系統。又，藉由母機1於與子機2之間發送、接收預先設定之特定之資訊，而亦可構成監視用戶設施3之各個機器之狀態之遠距監視系統、控制用戶設施3之各個機器之狀態之遠距控制系統等。 於多點跳躍通訊系統10中，母機1及子機2藉由前瞻型之多點跳躍通訊而相互發送、接收信號。即，於多點跳躍通訊系統10中，於母機1與子機2之間直接或間接地進行通訊。而且，無法與母機1直接通訊之子機2可藉由使處於可通訊距離之其他子機2依序中繼通訊封包，而於與母機1之間進行通訊。再者，將中繼通訊終端(母機1、子機2)所發送之通訊封包之子機2稱為中繼終端。 母機1具備通訊部1a、記憶部1b、路由部1c、及通訊控制部1d。 通訊部1a作為於與其他通訊終端(子機2)之間授受信號之通訊介面而發揮功能。再者，通訊部1a所使用之通訊方式為電力線傳輸通訊或無線通訊等，通訊方式並不限定於特定方式。 記憶部1b較佳為例如包含EEPROM(Electrically Erasable and Programmable Read-Only Memory，電子可擦可編程唯讀記憶體)、快閃記憶體等可重寫之非揮發性記憶體。而且，記憶部1b記憶有表示於與子機2之間建立之通訊路線之通訊路線資訊。於通訊路線中，包含1個以上子機2。進而，記憶部1b亦儲存有用以使母機1進行動作之控制程式等各程式、或執行各程式所必需之資訊、及母機1之終端資訊等。再者，終端資訊係指例如通訊終端(本機)之位址資訊、及與通訊品質相關之資訊等。 路由部1c具備如下功能，即，藉由經由通訊部1a於與子機2之間通訊，而進行前瞻型之多點跳躍通訊之通訊協定所規定之路由處理。 通訊控制部1d控制使用路由部1c所建立之通訊路線之多點跳躍通訊。 子機2具備通訊部2a、記憶部2b、路由部2c、通訊控制部2d、及封包監視部2e。 通訊部2a作為於與其他通訊終端(母機1、其他子機2)之間授受信號之通訊介面而發揮功能。再者，通訊部2a所使用之通訊方式為電力線傳輸通訊或無線通訊等，通訊方式並不限定於特定方式。又，通訊部2a所使用之通訊方式與通訊部1a所使用之通訊方式相同。 記憶部2b較佳為例如包含EEPROM、快閃記憶體等可重寫之非揮發性記憶體。而且，記憶部2b儲存有表示於與母機1之間建立之通訊路線之通訊路線資訊。進而，記憶部2b亦儲存有用以使子機2進行動作之控制程式等各程式、或執行各程式所必需之資訊、子機2之終端資訊等。 路由部2c具備藉由經由通訊部2a於與母機1或其他子機2之間通訊而進行路由處理之功能。路由處理係由前瞻型之多點跳躍通訊之通訊協定規定。 通訊控制部2d控制使用路由部2c所建立之通訊路線之多點跳躍通訊。 封包監視部2e監視自連接終端發送之下述問候封包(Hello Packet)之接收狀況。於本實施形態中，子機2可直接通訊(能以1跳通訊)之母機1及其他子機2成為鄰接終端。建立通訊路線之1台子機2存在1個以上鄰接終端。進而，於本實施形態中，1個以上鄰接終端中、子機2建立通訊鏈路之鄰接終端成為連接終端。即，連接終端為於自子機2至母機1之通訊路線中第1跳之通訊終端。具體而言，如圖2所示，子機2之封包監視部2e監視自連接終端接收到問候封包100後至經過特定之待機時間T1之前，通訊部2a是否再次接收到來自該連接終端之問候封包100。又，問候封包100之發送週期T2係預先決定，待機時間T1例如設定為發送週期T2之時間長度之3倍。再者，待機時間T1只要長於發送週期T2即可，其具體時間長度並無限定。 而且，母機1之路由部1c定期地廣播問候封包100A作為問候封包100。問候封包100A為報告本機之存在之封包，具有作為用於建立、維持通訊終端間之通訊路線之路由封包的功能。於母機1所發送之問候封包100A中，附加有成為發送源之母機1之終端資訊(例如位址資訊、及與通訊品質相關之資訊等)。又，於母機1所發送之問候封包100中，亦可進而附加有成為發送源之母機1可直接通訊之子機2之終端資訊。 而且，子機2之路由部2c亦定期地廣播問候封包100B作為問候封包100。於子機2所發送之問候封包100B中，附加有成為發送源之子機2之終端資訊(例如位址資訊、及與通訊品質相關之資訊等)。進而，於子機2所發送之問候封包100B中，附加有本機可直接通訊之鄰接終端(子機2、母機1)之終端資訊(例如位址資訊、及與通訊品質相關之資訊等)。進而，於與母機1之間建立通訊路線之子機2所發送之問候封包100B中，進而附加有表示至母機1為止之通訊路線之通訊路線資訊、及表示該通訊路線之通訊品質之路線品質資訊。又，於子機2所發送之問候封包100B中，亦可僅附加有成為發送源之子機2之終端資訊、及成為發送源之子機2之連接終端(母機1或子機2)之終端資訊。 又，子機2係以基於自鄰接終端接收到之問候封包100而將鄰接終端之終端資訊儲存於記憶部2b之方式構成。 於圖3中，子機21之路由部2c藉由接收母機1所廣播之問候封包100A，而可於與母機1之間建立1跳之通訊路線。 子機22之路由部2c係於子機21建立通訊路線後，接收子機21所廣播之問候封包100B，而可建立經由子機21之與母機1之間之2跳之通訊路線。 子機23之路由部2c係於子機22建立通訊路線後，接收子機22所廣播之問候封包100B，而可建立經由子機22、21之與母機1之間之3跳之通訊路線。 且，子機21、22、23各者之路由部2c於與母機1之間建立通訊路線後，子機21、22、23各者之通訊控制部2d可於與母機1之間進行使用上述通訊路線之多點跳躍通訊(參照圖4)。再者，由於接收到問候封包100(100A或100B)後之子機2之通訊路線之建立處理為眾所周知，因此省略詳細說明。又，於圖4中，以「M」表示母機，以「S」表示子機。 進而，於圖4中，子機24於與母機1之間建立1跳之通訊路線。又，子機25建立經由子機24之與母機1之間之2跳之通訊路線。又，子機26建立經由子機25、24之與母機1之間之2跳之通訊路線。進而，子機27於與母機1之間建立1跳之通訊路線。又，子機28建立經由子機27之與母機1之間之2跳之通訊路線。 再者，於圖4中，以實線或虛線連接之2個通訊終端表示互為鄰接終端。進而，通訊終端間之實線表示構成當前之通訊路線之通訊鏈路。又，圖4之通訊終端間之通訊鏈路所附之( )內之數字表示通訊終端間之通訊鏈路之通訊品質。數字越小，則通訊品質越高(越良好)。 如上所述，子機2可基於附加於接收到之問候封包100之通訊路線資訊、路線品質資訊，而建立通訊品質最佳之通訊路線。而且，子機2之路由部2c於建立通訊路線後，亦定期地廣播問候封包100B。而且，已建立通訊路線之子機2之路由部2c藉由接收自連接終端發送之問候封包100，而可維持與連接終端之通訊鏈路。即，已建立通訊路線之子機2之路由部2c藉由接收自連接終端發送之問候封包100，而可維持現狀之通訊路線。 然而，有可能因通訊流量增大而產生壅塞，而因封包彼此之衝突等導致子機2無法接收自連接終端廣播之問候封包100之狀態發生。該問候封包100之無法接收狀態之主要原因在於通訊流量之增大，若通訊流量減少，則問候封包100之接收概率提昇。因此，子機2執行圖5之流程圖所示之處理。 首先，子機2之封包監視部2e於自連接終端接收到問候封包100後，成為等待接收下一問候封包100之狀態(S1)。 子機2之封包監視部2e具有計時功能，監視通訊部2a自接收到來自連接終端之問候封包100至經過待機時間T1為止，通訊部2a是否接收到來自連接終端之問候封包100(S2)。 若通訊部2a於待機時間T1內接收到問候封包100，則封包監視部2e重設計時值而再次成為等待接收狀態(S3)。此時，路由部2c維持與現狀之連接終端之通訊鏈路。 於通訊部2a未於待機時間T1內接收到問候封包100之情形時，通訊控制部2d使計測問候封包100之無法接收次數之計數器(S4)遞增。然後，通訊控制部2d對無法接收次數與預先決定之M次進行比較(S5)。 若無法接收次數未達預先決定之M次，則通訊控制部2d使通訊部2a發送封包之發送速率降低(S6)。發送速率降低後，封包監視部2e成為問候封包100之等待接收狀態(S1)。 又，若無法接收次數為M次以上，則通訊控制部2d重設無法接收次數(S7)。其次，通訊控制部2d使發送速率進一步降低(S8)。然後，通訊控制部2d切斷與現狀之連接終端之通訊鏈路，進行通訊路線之再建立(S9)。其後，封包監視部2e成為問候封包100之等待接收狀態(S1)。再者，於上述步驟S8中，通訊控制部2d亦可使發送速率增大至初始值(最大值)而使發送速率初始化。 以後，子機2反覆進行上述動作。 作為一例，參照圖4對子機22之動作進行說明。 於母機1以子機23作為目的地發送資料封包之情形時，子機21、22成為中繼終端而中繼發送資料封包。此時，母機1及子機21、22以發送速率10 Mbps發送資料封包。因此，存在子機22之周圍之通訊流量增大，子機22無法接收來自周圍之鄰接終端(子機21、23、25、26)之問候封包100的情況。 然後，設為子機22無法於待機時間T1內自作為連接終端之子機21接收問候封包100B(無法接收次數＝1次)。於該情形時，發送速率之降低量係設定為固定值、例如2 Mbps，子機22使發送速率自10 Mbps降低至8 Mbps。即，子機22於母機1向子機23發送資料封包時，亦以發送速率8 Mbps中繼發送資料封包，因此可使子機22之周圍之通訊流量降低。因此，藉由使通訊流量降低，子機22可自作為連接終端之子機21接收問候封包100B之概率提昇。 若即便於使發送速率降低至8 Mbps之情形時，子機22亦無法於待機時間T1內自作為連接終端之子機21接收到問候封包100B(無法接收次數＝2次)，則使發送速率自8 Mbps降低至6 Mbps。因此，藉由使通訊流量進一步降低，子機22可自作為連接終端之子機21接收問候封包100B之概率進一步提昇。 此處，若設為M＝3次，則若即便於降低至發送速率6 Mbps之情形時，子機22亦無法於待機時間T1內自作為連接終端之子機21接收問候封包100B(無法接收次數＝3次)，則將無法接收次數重設為0次。然後，子機22使發送速率自6 Mbps降低至4 Mbps，再建立通訊路線。以後，子機22藉由反覆進行上述動作，而可使發送速率階段性地降低。 因此，子機22可容易維持與現狀之連接終端即子機21之間之通訊鏈路，從而可抑制因通訊流量之增大而導致之通訊鏈路之切斷。又，子機22藉由使發送速率階段性地降低，抑制因使發送速率過度降低所致之通訊效率降低。 又，於步驟S2中，當通訊部2a於經過待機時間T1之前接收到來自連接終端之問候封包100之狀態連續之情形時，若該接收狀態持續固定期間，則通訊控制部2d使發送速率增大而恢復至初始值。或者，通訊控制部2d亦可隨著該接收狀態之持續時間變長，而使發送速率階段性地增大從而恢復至初始值。 其次，對本實施形態之變化例1進行說明。 子機2於記憶部2b中儲存有鄰接終端之終端資訊(例如位址資訊、與通訊品質相關之資訊等)。通訊控制部2d可參照記憶部2b而特定出鄰接終端之數量。又，通訊控制部2d可自通訊部2a所接收到之問候封包100特定出該問候封包100之發送源之通訊終端(母機1、子機2)。而且，通訊控制部2d於每一單位期間(例如每1分鐘)判定是否自鄰接終端之各者接收到問候封包100。即，通訊控制部2d可將作為於單位期間(自上次判定處理至本次判定處理為止之期間)中通訊部2a無法接收之問候封包100之發送源的鄰接終端辨識為該單位期間中之未接收終端。 然後，通訊控制部2d於每一單位期間求出未接收終端之數量相對於鄰接終端之總數之比率[未接收終端之數量/鄰接終端之總數]。進而，通訊控制部2d求出[未接收終端之數量/鄰接終端之總數]之移動平均值作為未接收終端比率。 表1以Y1、Y2、Y3、...表示每一單位期間Ta1、Ta2、Ta3、...之[未接收終端之數量/鄰接終端之總數](每一單位期間之未接收之比率)。再者，於表1中，將於單位期間中通訊部2a接收到問候封包100之情形設為「T」(True)，將於單位期間中通訊部2a無法接收問候封包100之情形設為「F」(False)。而且，通訊控制部2d求出最近之N個[未接收終端之數量/鄰接終端之總數]之平均值(移動平均值)作為未接收終端比率。例如，若設為N＝3，則單位期間Ta5中之未接收終端比率成為[(Y5＋Y4＋Y3)/3]。 [表1]
而且，通訊控制部2d較佳為僅於未接收終端比率為閾值以上之情形時使發送速率降低。即，如圖6之流程圖所示，通訊控制部2d於使發送速率降低之前(步驟S6之前段)，判定未接收終端比率是否為閾值以上(S11)。通訊控制部2d僅於未接收終端比率為閾值以上之情形時，前進至步驟S6而使發送速率降低。又，於未接收終端比率未達閾值之情形時，通訊控制部2d不使發送速率降低，而前進至步驟S7～S8進行通訊路線之再建立。再者，於變化例1(參照圖6)中，刪除步驟S9之發送速率降低處理(參照圖5)，於未接收終端比率未達閾值之情形時，亦可不使發送速率降低。 此處，認為若未接收終端比率較高，則通訊流量較高，因此子機2難以接收問候封包100。又，認為若未接收終端比率較低，則通訊流量較低，因此子機2容易接收問候封包100。 因此，認為於未接收終端比率為閾值以上之情形時，通訊流量較高，故而難以接收連接終端之問候封包100，因此子機2藉由使發送速率降低而使通訊流量降低。其結果為，子機2於待機時間T1內接收連接終端所發送之問候封包100之概率變高。 又，於未接收終端比率未達閾值之情形時，認為係因連接終端之撤除、連接終端之動作停止、或電氣機器之設置等所引起之背景雜訊之增大等而無法進行與連接終端之通訊。因此，子機2不執行發送速率之降低處理，藉此可於無法進行與連接終端之通訊之情形時，迅速地切斷通訊鏈路而不會多餘地延長無法通訊期間。 又，於上述變化例1中，通訊控制部2d較佳為不將作為於單位期間中通訊部2a所接收之問候封包100之發送源的鄰接終端中、所接收之問候封包100之通訊品質為特定位準以下之鄰接終端包含於鄰接終端之總數中。即，通訊控制部2d於求出未接收終端比率時所使用之式[未接收終端之數量/鄰接終端之總數]中，僅將所接收之問候封包100之通訊品質超過特定位準之鄰接終端作為鄰接終端之總數計數。通訊品質例如使用接收強度(RSSI：Received Signal Strength Indicator)、S/N比(Signal to Noise Ratio，信號雜訊比)等。 於該情形時，通訊控制部2d藉由僅計數通訊品質良好之鄰接終端，而可根據實時之通訊品質求出鄰接終端之總數。 其次，對本實施形態之變化例2進行說明。 如圖7所示，變化例2之子機2進而具備流量計算部2f。流量計算部2f具有基於通訊部2a所發送及接收之信號量而求出本機周圍之通訊流量之功能。具體而言，流量計算部2f定期地求出通訊部2a所接收之封包、及通訊部2a所發送之封包的、每單位時間之傳送路徑之佔有率作為通訊流量。單位時間例如係設定為1分鐘或1小時等任意之時間長度。 或者，流量計算部2f代替求出通訊部2a所接收之封包的每單位時間之傳送路徑之佔有率，而使用通訊部2a中之接收強度，求出每單位時間之傳送路徑之佔有率。於該情形時，流量計算部2f藉由使用接收強度而可求出亦考慮到其他通訊系統之封包、雜訊等之傳送路徑之佔有率。 進而，流量計算部2f亦可使用通訊部2a所接收之封包、通訊部2a中之接收強度、及通訊部2a所發送之封包之全部而求出每單位時間之傳送路徑之佔有率。 此處，通訊流量越高，則無法於待機時間T1內接收問候封包100之概率越高。另一方面，通訊流量越低，則於待機時間T1內無法接收問候封包100之原因為因連接終端之撤除、連接終端之動作停止、或電氣機器之設置等所致之背景雜訊之增大而無法進行與連接終端之通訊的可能性較高。 因此，較佳為通訊控制部2d基於流量計算部2f所求出之通訊流量(流量計算值)而決定發送速率之降低量。具體而言，通訊控制部2d基於容許流量與流量計算部2f所求出之通訊流量之差分(流量差分量)而決定發送速率之降低量。容許流量係指針對通訊流量預先決定之上限值，以傳送路徑之封包佔有率之上限值(例如40%)表示。 通訊控制部2d於流量計算值超過容許流量之情形時，於圖5及圖6之步驟S6中，以流量計算值與容許流量一致之方式決定發送速率之降低量。此時，通訊控制部2d可基於流量差分量而推定使流量計算值與容許流量一致之發送速率之降低量。 因此，子機2可於短時間內控制為可充分抑制通訊流量之發送速率。 又，通訊控制部2d於流量計算值低於容許流量之情形時，於圖5及圖6之步驟S6中，將發送速率之降低量設定為預先決定之固定值(例如2 Mbps)。再者，該固定之降低量只要根據母機1、子機2之規格設定為任意之值即可，不限定於具體數值。 再者，流量計算部2f亦可將通訊部2a接收到之封包數、通訊部2a發送出之封包數之合計即總封包數設為通訊流量。於該情形時，容許流量係以總封包數之上限值表示。 又，流量計算部2f較佳為於通訊流量之計算中使用不僅包含對本機發送之封包，亦包含並非對本機發送之封包在內之通訊部2a所接收之所有封包。於該情形時，流量計算部2f可精度良好地估算現狀之通訊流量。因此，通訊控制部2d可將發送速率之降低量設定為基於現狀之通訊流量之適當之值。 又，流量計算部2f較佳為根據中繼後之通訊路線之跳數而求出通訊部2a所接收之封包中向其他通訊終端(母機1、子機2)中繼之封包之通訊流量。具體而言，於封包之中繼後至到達母機1為止需要5跳之情形時，必須藉由另外5台中繼終端進行中繼處理。因此，流量計算部2f於封包之中繼後至到達母機1為止需要5跳之情形時，將該封包之傳送路徑之封包佔有率或封包數設為5倍而求出通訊流量。即，流量計算部2f係與通訊部2a所發送之封包到達母機1之通訊路線中所含之(通訊路線上之)中繼終端之數量成正比地，使該封包之通訊流量之計算值增大。其結果為，通訊控制部2d可考慮多點跳躍通訊系統10內更大範圍之通訊流量而決定發送速率之降低量。 因此，流量計算部2f可估算多點跳躍通訊系統10內之遍及更大範圍之通訊流量。因此，通訊控制部2d可將發送速率之降低量設定為基於遍及更大範圍之通訊流量之值。 又，流量計算部2f較佳為本機之鄰接終端之數量越多，則使通訊流量之計算值越為增大。具體而言，於鄰接終端之台數為4台(其中1台為連接終端)之情形時，將通訊部2a所發送之封包之傳送路徑之封包佔有率或封包數設為4倍而求出通訊流量。即，流量計算部2f係與鄰接終端之數量成正比地使該封包之通訊流量之計算值增大。其結果為，通訊控制部2d可考慮多點跳躍通訊系統10內之更大範圍之通訊流量而決定發送速率之降低量。 因此，流量計算部2f可估算多點跳躍通訊系統10內之遍及更大範圍之通訊流量。其結果為，通訊控制部2d可將發送速率之降低量設定為基於遍及更大範圍之通訊流量之值。 又，流量計算部2f較佳為本機之鄰接終端可直接通訊之母機1及子機2(即鄰接終端之鄰接終端，稱為1跳鄰接終端)之數量越多，則使通訊流量之計算值越為增大。自子機2觀察，1跳鄰接終端有成為隱藏終端之可能性。再者，將處於無法直接接收相互發送之信號之關係之通訊終端稱為隱藏終端。若處於該隱藏終端之關係之通訊終端之各者發送封包，容易產生封包之衝突，存在重複地重新發送或傳送延遲增加等不良影響。 因此，流量計算部2f與可能成為隱藏終端之1跳鄰接終端之數量成正比地使通訊流量之計算值增大。其結果為，通訊控制部2d可考慮多點跳躍通訊系統10內之更大範圍之通訊流量而決定發送速率之降低量。 又，通訊控制部2d較佳為自通訊部2a對其他子機2發送用以決定發送速率之降低量之資訊(降低量判斷資訊)。 具體而言，子機2之通訊控制部2d於發送問候封包100B時，將本機之流量計算部2f所求出之通訊流量之資料附加於問候封包100B。然後，子機2之通訊控制部2d藉由接收其他子機2之問候封包100B，而可辨識鄰接終端之通訊流量。然後，通訊控制部2d選擇本機之通訊流量、鄰接終端之通訊流量中最高之通訊流量。通訊控制部2d基於該選擇之最高通訊流量與容許流量之差分即流量差分量而決定發送速率之降低量。 因此，通訊控制部2d可考慮多點跳躍通訊系統10內更大範圍之通訊流量而決定發送速率之降低量。 或者，子機2之通訊控制部2d於發送問候封包100B時，將本機之發送速率之降低量之資料附加於問候封包100B。然後，子機2之通訊控制部2d藉由接收其他子機2之問候封包100B，而可辨識鄰接終端之發送速率之降低量。然後，通訊控制部2d選擇本機之現狀之發送速率之降低量、及鄰接終端之發送速率之降低量中較低之發送速率之降低量。通訊控制部2d以成為該選擇之發送速率之降低量之方式控制發送速率。 因此，通訊控制部2d可考慮多點跳躍通訊系統10內更大範圍之通訊流量而控制發送速率之降低量。 又，通訊控制部2d亦較佳為使自通訊部2a對其他子機2發送指示是否使發送速率降低之信號(指示信號)。 具體而言，設為子機2之通訊控制部2d於上述步驟S6中使發送速率降低後，流量計算部2f所求出之通訊流量超過容許流量。於該情形時，通訊控制部2d對其他子機2發送指示使發送速率之降低之降低指示信號(廣播或單播)。接收到降低指示信號之子機2中，通訊控制部2d使通訊部2a之發送速率降低固定值。或者，通訊控制部2d亦可使通訊部2a之發送速率降低至藉由所接收之降低指示信號所指示之值。 因此，子機2於流量計算部2f所求出之通訊流量較高之情形時，可抑制其他子機2(鄰接終端)之通訊流量。其結果為，子機2可抑制本機不參與發送、中繼之鄰接終端之通訊流量。 根據以上所述之實施形態明顯可知，本發明之第1態樣之通訊終端係用作多點跳躍通訊系統之子機2，該多點跳躍通訊系統係複數個子機2之各者於與母機1之間建立包含1個以上通訊鏈路之通訊路線，且母機1與複數個子機2之各者相互進行多點跳躍通訊。子機2具備通訊部2a、路由部2c、及通訊控制部2d。通訊部2a於與作為可直接通訊之母機1或其他子機2之1個以上鄰接終端之間授受信號。路由部2c藉由通訊部2a自鄰接終端接收用以決定通訊路線之路由封包(問候封包100)，而將1個以上鄰接終端中任一台鄰接終端設為連接終端，建立包含該連接終端之通訊路線。通訊控制部2d於通訊部2a於特定之待機時間T1期間未接收到來自連接終端之路由封包之情形時，使通訊部2a發送信號之發送速率降低。 因此，根據第1態樣，子機2可容易維持與現狀之連接終端之間之通訊鏈路，從而可抑制因通訊流量之增大而導致之通訊鏈路之切斷。 又，本發明之第2態樣之通訊終端係於第1態樣中，將鄰接終端中通訊部2a無法接收路由封包之鄰接終端設為未接收終端。而且，較佳為若未接收終端之數量相對於鄰接終端之總數之比率為閾值以上，則通訊控制部2d使發送速率降低。 於該情形時，認為於未接收終端比率為閾值以上之情形時，通訊流量較高，因此難以接收連接終端之問候封包100。因此，子機2藉由使發送速率降低而使通訊流量降低。其結果為，子機2於待機時間T1內接收連接終端所發送之問候封包100之概率變高。 於未接收終端比率未達閾值之情形時，認為係因連接終端之撤除、連接終端之動作停止、或電氣機器之設置等所引起之背景雜訊之增大等而無法進行與連接終端之通訊。因此，子機2藉由不執行發送速率之降低處理，而可於無法進行與連接終端之通訊之情形時，迅速地切斷通訊鏈路而又不會多餘地延長無法通訊期間。 又，本發明之第3態樣之通訊終端係於第2態樣中，較佳為通訊控制部2d僅將如下之鄰接終端作為鄰接終端之總數計數，該鄰接終端為通訊部2a接收時之通訊品質超過特定位準之路由封包之發送源。 於該情形時，通訊控制部2d藉由僅對通訊品質良好之鄰接終端進行計數，而可根據實時之通訊品質求出鄰接終端之總數。 又，本發明之第4態樣之通訊終端係於第2或第3態樣中，較佳為若未接收終端之數量相對於鄰接終端之總數之比率為閾值以上，則通訊控制部2d使發送速率降低固定量。 於該情形時，子機2藉由階段性地使發送速率降低，而可抑制因過度降低發送速率導致通訊效率降低。 又，本發明之第5態樣之通訊終端係於第2或第3態樣中，較佳為子機2進而具備基於通訊部2a所發送及接收之信號量而求出通訊流量之流量計算部2f。而且，若未接收終端之數量相對於鄰接終端之總數之比率為閾值以上，則通訊控制部2d基於流量計算部2f所求出之通訊流量與通訊流量之上限值之差而決定發送速率之降低量。 於該情形時，子機2可於短時間內控制至可充分抑制通訊流量之發送速率。 又，本發明之第6態樣之通訊終端係於第5態樣中，較佳為通訊部2a所接收之信號量包含以不包含本終端之通訊路線傳遞之信號量。 於該情形時，流量計算部2f可精度良好地估算現狀之通訊流量。因此，通訊控制部2d可將發送速率之降低量設定為基於現狀之通訊流量之適當之值。 又，本發明之第7態樣之通訊終端係於第5或第6態樣中，較佳為中繼終端之數量越多，則流量計算部2f使通訊流量之計算值越為增大。中繼終端係包含於通訊部2a所發送之信號到達母機1之通訊路線之子機2。 於該情形時，流量計算部2f可估算多點跳躍通訊系統10內之遍及更大範圍之通訊流量。因此，通訊控制部2d可將發送速率之降低量設定為基於遍及更大範圍之通訊流量之值。 又，本發明之第8態樣之通訊終端係於第5至第7態樣之任一者中，較佳為鄰接終端之數量越多，則流量計算部2f使通訊流量之計算值越為增大。 於該情形時，流量計算部2f可估算多點跳躍通訊系統10內遍及更大範圍之通訊流量。其結果為，通訊控制部2d可將發送速率之降低量設定為基於遍及更大範圍之通訊流量之值。 又，本發明之第9態樣之通訊終端係於第5至第8態樣之任一者中，較佳為鄰接終端可直接通訊之母機1及子機2之數量越多，則流量計算部2f使通訊流量之計算值越為增大。 於該情形時，通訊控制部2d可考慮多點跳躍通訊系統10內更大範圍之通訊流量而決定發送速率之降低量。 又，本發明之第10態樣之通訊終端係於第1至第9態樣之任一者中，較佳為通訊控制部2d使自通訊部2a對其他子機2發送用以決定發送速率之降低量之資訊。 於該情形時，通訊控制部2d可考慮多點跳躍通訊系統10內更大範圍之通訊流量而決定發送速率之降低量。 又，本發明之第11態樣之通訊終端係於第1至第9態樣之任一者中，較佳為通訊控制部2d使自通訊部2a對其他子機2發送指示是否使發送速率降低之信號。 於該情形時，子機2於流量計算部2f所求出之通訊流量較高之情形時，可抑制其他子機2(鄰接終端)之通訊流量。其結果為，子機2可抑制本機不參與發送、中繼之鄰接終端之通訊流量。 本發明之第12態樣之多點跳躍通訊系統10中，複數個子機2之各者於與母機1之間建立包含1個以上通訊鏈路之通訊路線，且母機1與複數個子機2之各者相互進行多點跳躍通訊。複數個子機2之各者具備通訊部2a、路由部2c、及通訊控制部2d。通訊部2a於與作為可直接通訊之母機1或其他子機2之1個以上鄰接終端之間授受信號。路由部2c藉由通訊部2a自鄰接終端接收用以決定通訊路線之路由封包(問候封包100)，而將1個以上鄰接終端中任一台鄰接終端設為連接終端，建立包含該連接終端之通訊路線。通訊控制部2d當通訊部2a於特定之待機時間T1期間未接收到來自連接終端之路由封包之情形時，使通訊部2a發送信號之發送速率降低。 因此，多點跳躍通訊系統10針對複數個子機2之各者，可容易地維持子機2與現狀之連接終端之間之通訊鏈路，從而可抑制因通訊流量之增大導致之通訊鏈路之切斷。 又，母機1具備電腦，藉由該電腦執行程式而實現上述母機1之各功能。電腦作為主要之構成要素而具備：器件，其包含執行程式之處理器；介面用器件，其用以於與其他裝置之間授受資料；及記憶用器件，其用以記憶資料。具備處理器之器件可為與半導體記憶體分開之CPU(Central Processing Unit，中央處理單元)或MPU(Micro Processing Unit，微處理單元)、及一體地具備半導體記憶體之微電腦之任一者。記憶用器件係併用如半導體記憶體般存取時間較短之記憶裝置、及如硬碟裝置般之大容量記憶裝置。 又，子機2具備電腦，該電腦載入並執行程式後，電腦實現子機2之上述各功能(尤其係路由部2c、通訊控制部2d、封包監視部2e、流量計算部2f之各功能)。即，電腦程式產品內建有於電腦載入並執行程式後，例如使處理器作為子機而發揮功能之程式。電腦作為主要之構成要素而具備：器件，其包含執行程式之處理器；介面用器件，其用以於與其他裝置之間授受資料；及記憶用器件，其用以記憶資料。具備處理器之器件可為與半導體記憶體分開之CPU或MPU、及一體地具備半導體記憶體之微電腦之任一者。記憶用器件係併用如半導體記憶體般存取時間較短之記憶裝置、及如硬碟裝置之大容量記憶裝置。 作為對於母機1及子機2之程式之提供形態，有預先儲存於電腦可讀取之ROM(Read Only Memory，唯讀記憶體)、光碟等記錄媒體之形態、及經由包含網際網路等之廣域通訊網而供給至記錄媒體之形態等。 本發明之第13態樣之電腦程式產品內建用以於電腦載入並執行程式後，使其作為如第1至第11態樣之任一通訊終端而發揮功能之程式。 因此，子機2可容易地維持與現狀之連接終端之間之通訊鏈路，從而可抑制因通訊流量之增大導致之通訊鏈路之切斷。 又，上述多點跳躍通訊方法具備以下各步驟。多點跳躍通訊系統10係複數個子機2之各者於與母機1之間建立包含1個以上通訊鏈路之通訊路線，且母機1與複數個子機2之各者相互進行多點跳躍通訊。 ・為了決定通訊路線而使通訊部2a接收自作為可直接通訊之母機或其他子機的1個以上鄰接終端發送之路由封包(問候封包100)，藉此將1個以上鄰接終端中任一台鄰接終端設為連接終端建立包含該連接終端之通訊路線之步驟。 ・當通訊部2a於特定之待機時間T1期間未接收到來自連接終端之路由封包之情形時，使通訊部2a發送信號之發送速率降低之步驟。 再者，上述實施形態為一例。因此，毋庸置疑，實施形態並不限定於上述構成，除該實施形態以外，只要於不脫離本發明之技術思想之範圍內，則可根據設計等而進行各種變更。This embodiment relates to a communication terminal, a multipoint hop communication system, and a program. More specifically, this embodiment relates to a program used for a communication terminal, a multipoint hop communication system, and a communication terminal for performing forward-looking multipoint hopping communication. Hereinafter, embodiments will be described based on the drawings. (Embodiment) As shown in Fig. 1, the multipoint hopping communication system 10 of the present embodiment includes one master (master) 1 and a plurality of slaves (slave) 2. FIG. 1 illustrates a resident of a collective residence as a user facility (Facility) 3. However, the user facilities may be single-family houses, offices, shops, tenants of buildings, etc., and the form is not limited. Furthermore, when the user facility 3 is individually identified, it is referred to as user facilities 31, 32, ..., 3N. Further, the number of the slaves 2 may be one or more, and the number of the slaves 2 is preferably two or more. Each of the parent machine 1 and the slave machine 2 is a communication terminal that performs power line transmission communication or wireless communication. Furthermore, when the child machine 2 is individually recognized, it is referred to as the slaves 21, 22, ..., 2N. Each slave 2 is installed in a corresponding one of the user facilities 3. Each of the slaves 2 has a function of transmitting specific data related to the user facility 3 in which the slave 2 is installed to one parent machine 1. The parent machine 1 has a function of acquiring specific data related to each of the user facilities 3 from a plurality of child machines 2, and transmitting the acquired specific data to the management device of the upper device using a wide area communication network such as an optical fiber line or an Internet. For example, the master meter 1 acquires the meter reading data such as the power usage amount, the gas usage amount, and the tap water usage amount in each of the user facilities 3 from the slave unit 2, thereby forming a remote meter reading system. Further, the parent machine 1 can transmit and receive predetermined information to and from the child machine 2, and can also constitute a remote monitoring system for monitoring the state of each device of the user facility 3, and each device controlling the user facility 3. State remote control system, etc. In the multipoint jump communication system 10, the parent machine 1 and the slave machine 2 transmit and receive signals to each other by a forward-looking multi-point jump communication. That is, in the multipoint hopping communication system 10, communication is directly or indirectly between the parent machine 1 and the child machine 2. Moreover, the slave 2 that cannot directly communicate with the parent machine 1 can communicate with the parent machine 1 by causing the other slaves 2 at the communicable distance to sequentially relay the communication packets. Furthermore, the slave 2 of the communication packet transmitted by the relay communication terminal (the parent machine 1 and the slave 2) is referred to as a relay terminal. The parent machine 1 includes a communication unit 1a, a storage unit 1b, a routing unit 1c, and a communication control unit 1d. The communication unit 1a functions as a communication interface for transmitting and receiving signals with other communication terminals (slave 2). Furthermore, the communication method used by the communication unit 1a is power line transmission communication or wireless communication, and the communication method is not limited to a specific method. The memory unit 1b is preferably a rewritable non-volatile memory such as an EEPROM (Electrically Erasable and Programmable Read-Only Memory) or a flash memory. Further, the storage unit 1b stores communication route information indicating a communication route established between the slave unit 2. In the communication route, more than one slave 2 is included. Further, the storage unit 1b also stores programs such as a control program for causing the parent machine 1 to operate, information necessary for executing each program, and terminal information of the parent machine 1. Furthermore, the terminal information refers to, for example, the address information of the communication terminal (the local device) and the information related to the communication quality. The routing unit 1c has a function of performing routing processing defined by a forward-looking multipoint hopping communication protocol by communicating with the slave unit 2 via the communication unit 1a. The communication control unit 1d controls the multi-hop communication using the communication path established by the routing unit 1c. The slave 2 includes a communication unit 2a, a storage unit 2b, a routing unit 2c, a communication control unit 2d, and a packet monitoring unit 2e. The communication unit 2a functions as a communication interface for transmitting and receiving signals with other communication terminals (the parent machine 1 and the other child machines 2). Furthermore, the communication method used by the communication unit 2a is power line transmission communication or wireless communication, and the communication method is not limited to a specific mode. Further, the communication method used by the communication unit 2a is the same as that used by the communication unit 1a. The memory unit 2b is preferably a rewritable non-volatile memory including, for example, an EEPROM or a flash memory. Further, the storage unit 2b stores communication route information indicating a communication route established with the parent machine 1. Further, the storage unit 2b also stores programs such as a control program for causing the slave device 2 to operate, information necessary for executing each program, terminal information of the slave unit 2, and the like. The routing unit 2c has a function of performing routing processing by communicating with the parent machine 1 or other child machines 2 via the communication unit 2a. Routing processing is governed by a forward-looking multi-hop communication protocol. The communication control unit 2d controls the multi-hop communication using the communication route established by the routing unit 2c. The packet monitoring unit 2e monitors the reception status of the following hello packet transmitted from the connection terminal. In the present embodiment, the slave unit 2 and the other slave units 2, which can directly communicate (one-hop communication), become adjacent terminals. One slave 2 that establishes a communication route has one or more adjacent terminals. Further, in the present embodiment, among the one or more adjacent terminals, the adjacent terminal in which the slave 2 establishes the communication link becomes the connection terminal. That is, the connection terminal is the communication terminal of the first hop in the communication route from the slave 2 to the parent machine 1. Specifically, as shown in FIG. 2, the packet monitoring unit 2e of the slave unit 2 monitors whether the communication unit 2a receives the greeting from the connected terminal again after receiving the greeting packet 100 from the connection terminal until the predetermined standby time T1 elapses. Packet 100. Further, the transmission period T2 of the hello packet 100 is determined in advance, and the standby time T1 is set, for example, three times the length of the transmission period T2. Further, the standby time T1 may be longer than the transmission period T2, and the specific length of time is not limited. Further, the routing unit 1c of the parent machine 1 periodically broadcasts the greeting packet 100A as the greeting packet 100. The greeting packet 100A is a packet for reporting the existence of the local device, and has a function as a routing packet for establishing and maintaining a communication route between communication terminals. In the greeting packet 100A transmitted from the parent machine 1, terminal information (for example, address information, information related to communication quality, etc.) of the parent device 1 serving as the transmission source is added. Further, in the greeting packet 100 transmitted by the parent machine 1, terminal information of the slave device 2 to which the parent device 1 serving as the transmission source can directly communicate may be added. Further, the routing unit 2c of the child machine 2 also periodically broadcasts the greeting packet 100B as the greeting packet 100. In the greeting packet 100B transmitted from the slave device 2, terminal information (for example, address information, information related to communication quality, and the like) of the slave device 2 serving as the transmission source is added. Further, in the greeting packet 100B transmitted by the slave device 2, terminal information (for example, address information, information related to communication quality, etc.) of the adjacent terminal (the slave device 2, the parent device 1) to which the device can directly communicate is added. . Further, in the greeting packet 100B transmitted by the slave device 2 that establishes a communication route with the parent machine 1, communication route information indicating the communication route to the parent device 1 and route quality information indicating the communication quality of the communication route are added. . Further, in the greeting packet 100B transmitted by the slave device 2, only the terminal information of the slave device 2 serving as the transmission source and the terminal information of the connection terminal (the parent device 1 or the slave device 2) of the slave device 2 serving as the transmission source may be added. . Further, the slave 2 is configured to store the terminal information of the adjacent terminal in the storage unit 2b based on the greeting packet 100 received from the adjacent terminal. In FIG. 3, the routing unit 2c of the slave unit 21 can establish a one-hop communication route with the parent unit 1 by receiving the hello packet 100A broadcast by the parent machine 1. The routing unit 2c of the slave unit 22 receives the hello packet 100B broadcasted by the slave unit 21 after the slave unit 21 establishes the communication route, and can establish a communication route through the two-hop between the slave unit 21 and the parent unit 1. The routing unit 2c of the slave unit 23 receives the hello packet 100B broadcasted by the slave unit 22 after the slave unit 22 establishes the communication route, and can establish a communication route through the three-hop between the slave units 22 and 21 and the parent unit 1. Further, after the routing unit 2c of each of the slave devices 21, 22, and 23 establishes a communication route with the parent device 1, the communication control unit 2d of each of the slave devices 21, 22, and 23 can use the above-described parent machine 1. Multi-point jump communication of communication routes (refer to Figure 4). Furthermore, since the process of establishing the communication path of the child machine 2 after receiving the greeting packet 100 (100A or 100B) is well known, detailed description is omitted. Further, in Fig. 4, "M" indicates the parent machine, and "S" indicates the child machine. Further, in FIG. 4, the slave unit 24 establishes a one-hop communication route with the parent machine 1. Further, the slave unit 25 establishes a communication route via the two-hop between the slave unit 24 and the slave unit 1. Further, the slave unit 26 establishes a communication route via the two-hop between the slave units 25 and 24 and the master unit 1. Further, the slave unit 27 establishes a 1-hop communication route with the parent machine 1. Further, the slave unit 28 establishes a communication route via the two-hop between the slave unit 27 and the slave unit 1. Furthermore, in FIG. 4, two communication terminals connected by a solid line or a broken line indicate mutual adjacent terminals. Further, the solid line between the communication terminals indicates the communication link constituting the current communication route. Moreover, the number in ( ) attached to the communication link between the communication terminals of FIG. 4 indicates the communication quality of the communication link between the communication terminals. The smaller the number, the higher the communication quality (the better). As described above, the slave 2 can establish a communication route with the best communication quality based on the communication route information and the route quality information attached to the received greeting packet 100. Further, the routing unit 2c of the child machine 2 periodically broadcasts the greeting packet 100B after establishing the communication route. Further, the routing unit 2c of the child machine 2 having established the communication route can maintain the communication link with the connection terminal by receiving the greeting packet 100 transmitted from the connection terminal. That is, the routing unit 2c of the child machine 2 that has established the communication route can maintain the current communication route by receiving the greeting packet 100 transmitted from the connection terminal. However, there is a possibility that congestion may occur due to an increase in communication traffic, and the state in which the slave device 2 cannot receive the hello packet 100 broadcast from the connected terminal occurs due to collision of the packets with each other. The main reason for the unreceivable state of the hello packet 100 is that the communication traffic is increased. If the communication traffic is reduced, the reception probability of the hello packet 100 is increased. Therefore, the slave 2 executes the processing shown in the flowchart of FIG. First, after receiving the hello packet 100 from the connection terminal, the packet monitoring unit 2e of the slave 2 waits for receiving the next greeting packet 100 (S1). The packet monitoring unit 2e of the child machine 2 has a timer function, and the monitoring communication unit 2a receives the greeting packet 100 from the connection terminal (S2) from the reception of the greeting packet 100 from the connection terminal to the elapse of the waiting time T1. When the communication unit 2a receives the hello packet 100 during the standby time T1, the packet monitoring unit 2e redesigns the time value and again waits for the reception state (S3). At this time, the routing unit 2c maintains a communication link with the connection terminal of the current status. When the communication unit 2a does not receive the greeting packet 100 within the standby time T1, the communication control unit 2d increments the counter (S4) for measuring the number of times the greeting packet 100 cannot be received. Then, the communication control unit 2d compares the number of times the reception cannot be performed with the M times determined in advance (S5). If the number of unreceivable times is less than the predetermined number of times M, the communication control unit 2d lowers the transmission rate of the packet transmitted by the communication unit 2a (S6). When the transmission rate is lowered, the packet monitoring unit 2e becomes the waiting reception state of the greeting packet 100 (S1). When the number of times of unreceivable is M or more, the communication control unit 2d resets the number of times the reception cannot be performed (S7). Next, the communication control unit 2d further lowers the transmission rate (S8). Then, the communication control unit 2d cuts off the communication link with the connection terminal of the current status, and reestablishes the communication route (S9). Thereafter, the packet monitoring unit 2e becomes the waiting reception state of the greeting packet 100 (S1). Furthermore, in the above step S8, the communication control unit 2d may also increase the transmission rate to the initial value (maximum value) and initialize the transmission rate. Thereafter, the child machine 2 repeats the above operations. As an example, the operation of the slave unit 22 will be described with reference to Fig. 4 . When the parent machine 1 transmits the data packet as the destination of the child machine 23, the child machines 21 and 22 become relay terminals and relay the data packet. At this time, the parent machine 1 and the slave machines 21 and 22 transmit the data packet at a transmission rate of 10 Mbps. Therefore, there is a case where the communication traffic around the slave 22 is increased, and the slave 22 cannot receive the hello packet 100 from the neighboring terminals (the slaves 21, 23, 25, 26). Then, it is assumed that the slave unit 22 cannot receive the hello packet 100B from the slave unit 21 as the connection terminal within the standby time T1 (the number of times the reception cannot be received = 1). In this case, the decrease in the transmission rate is set to a fixed value, for example, 2 Mbps, and the slave 22 reduces the transmission rate from 10 Mbps to 8 Mbps. In other words, when the slave unit 1 transmits the data packet to the slave unit 23, the slave device 22 relays the data packet at the transmission rate of 8 Mbps, so that the communication traffic around the slave unit 22 can be reduced. Therefore, by lowering the communication traffic, the slave 22 can increase the probability of receiving the hello packet 100B from the slave 21 as the connection terminal. Even if the transmission rate is lowered to 8 Mbps, the slave unit 22 cannot receive the hello packet 100B from the slave unit 21 as the connection terminal within the standby time T1 (the number of times of reception cannot be 2 times), so that the transmission rate is self-generated. 8 Mbps is reduced to 6 Mbps. Therefore, by further reducing the communication traffic, the probability that the slave 22 can receive the hello packet 100B from the slave 21 as the connection terminal is further improved. Here, if M=3 times, even if the transmission rate is reduced to 6 Mbps, the slave unit 22 cannot receive the greeting packet 100B from the slave unit 21 as the connection terminal within the standby time T1 (the number of times of reception cannot be received) = 3 times), reset the number of unreceivable times to 0 times. Then, the slave 22 reduces the transmission rate from 6 Mbps to 4 Mbps, and then establishes a communication route. Thereafter, the slave unit 22 can perform the above operation in reverse, and the transmission rate can be gradually reduced. Therefore, the slave unit 22 can easily maintain the communication link with the connected terminal which is the current state, that is, the slave link 21, thereby suppressing the disconnection of the communication link due to the increase in the communication traffic. Further, the slave unit 22 suppresses a decrease in communication efficiency due to an excessive decrease in the transmission rate by gradually lowering the transmission rate. Further, in step S2, when the communication unit 2a receives the state in which the greeting packet 100 from the connection terminal is continuous before the standby time T1 elapses, the communication control unit 2d increases the transmission rate if the reception state continues for a fixed period. Large and restored to the initial value. Alternatively, the communication control unit 2d may gradually increase the transmission rate to the initial value as the duration of the reception state becomes longer. Next, a modification 1 of the embodiment will be described. The slave 2 stores terminal information (e.g., address information, information related to communication quality, etc.) of the adjacent terminal in the storage unit 2b. The communication control unit 2d can specify the number of adjacent terminals by referring to the storage unit 2b. Further, the communication control unit 2d can specify the communication terminal (the parent machine 1 and the slave device 2) of the source of the greeting packet 100 from the greeting packet 100 received by the communication unit 2a. Further, the communication control unit 2d determines whether or not the greeting packet 100 is received from each of the adjacent terminals every unit period (for example, every one minute). In other words, the communication control unit 2d can recognize the adjacent terminal as the transmission source of the greeting packet 100 that the communication unit 2a cannot receive in the unit period (the period from the previous determination processing to the current determination processing) as the unit period. The terminal was not received. Then, the communication control unit 2d obtains the ratio of the number of unreceived terminals to the total number of adjacent terminals in each unit period [the number of unreceived terminals/the total number of adjacent terminals]. Further, the communication control unit 2d obtains the moving average of [the number of unreceived terminals/the total number of adjacent terminals] as the unreceived terminal ratio. Table 1 shows, in Y1, Y2, Y3, ..., the number of unreceived terminals/the total number of adjacent terminals in each unit period Ta1, Ta2, Ta3, ... (the ratio of unreceived per unit period) . In addition, in Table 1, the case where the communication unit 2a receives the greeting packet 100 in the unit period is set to "T" (True), and the case where the communication unit 2a cannot receive the greeting packet 100 in the unit period is set to "F" (False). Further, the communication control unit 2d obtains the average value (moving average value) of the N most recent [number of unreceived terminals/total number of adjacent terminals] as the unreceived terminal ratio. For example, if N=3, the ratio of unreceived terminals in the unit period Ta5 becomes [(Y5+Y4+Y3)/3]. [Table 1] Further, it is preferable that the communication control unit 2d lowers the transmission rate only when the ratio of the unreceived terminal is equal to or greater than the threshold. That is, as shown in the flowchart of FIG. 6, the communication control unit 2d determines whether or not the unreceived terminal ratio is equal to or larger than the threshold before the transmission rate is lowered (step S6) (S11). When the unreceived terminal ratio is equal to or greater than the threshold value, the communication control unit 2d proceeds to step S6 to lower the transmission rate. When the unreceived terminal ratio does not reach the threshold value, the communication control unit 2d does not lower the transmission rate, and proceeds to steps S7 to S8 to reestablish the communication route. Further, in the first modification (see FIG. 6), the transmission rate reduction processing (see FIG. 5) of step S9 is deleted, and when the ratio of the unreceived terminal does not reach the threshold value, the transmission rate may not be lowered. Here, it is considered that if the ratio of the unreceived terminal is high, the communication traffic is high, and therefore it is difficult for the slave 2 to receive the hello packet 100. Further, it is considered that if the ratio of the unreceived terminal is low, the communication traffic is low, and therefore the slave 2 can easily receive the hello packet 100. Therefore, when the unreceived terminal ratio is equal to or higher than the threshold value, the communication flow rate is high, and it is difficult to receive the hello packet 100 of the connection terminal. Therefore, the slave device 2 reduces the communication flow rate by lowering the transmission rate. As a result, the probability that the slave device 2 receives the hello packet 100 transmitted by the connection terminal during the standby time T1 becomes high. Further, when the ratio of the unreceived terminal does not reach the threshold value, it is considered that the connection terminal cannot be connected due to the removal of the connection terminal, the stop of the operation of the connection terminal, or the increase of the background noise caused by the setting of the electric device. Communication. Therefore, the child machine 2 does not perform the transmission rate reduction processing, whereby the communication link can be quickly cut off without excessively extending the communication period when the communication with the connection terminal cannot be performed. Further, in the first modification, the communication control unit 2d preferably does not include the communication quality of the received greeting packet 100 in the adjacent terminal which is the transmission source of the greeting packet 100 received by the communication unit 2a in the unit period. Adjacent terminals below a certain level are included in the total number of adjacent terminals. In other words, the communication control unit 2d uses only the formula [the number of unreceived terminals/the total number of adjacent terminals] used to obtain the ratio of the unreceived terminals, and only the adjacent terminal whose communication quality of the received greeting packet 100 exceeds a certain level. Counted as the total number of adjacent terminals. The communication quality is, for example, a received signal strength (RSSI: Received Signal Strength Indicator), an S/N ratio (Signal to Noise Ratio), or the like. In this case, the communication control unit 2d can count the total number of adjacent terminals based on the communication quality in real time by counting only the adjacent terminals having good communication quality. Next, a modification 2 of the embodiment will be described. As shown in Fig. 7, the child machine 2 of the second modification further includes a flow rate calculation unit 2f. The flow rate calculation unit 2f has a function of obtaining a communication flow rate around the machine based on the amount of signals transmitted and received by the communication unit 2a. Specifically, the flow rate calculation unit 2f periodically obtains the occupancy rate of the transmission path per unit time of the packet received by the communication unit 2a and the packet transmitted by the communication unit 2a as the communication flow rate. The unit time is set to, for example, an arbitrary length of time such as 1 minute or 1 hour. Alternatively, the flow rate calculation unit 2f obtains the occupancy rate of the transmission path per unit time by using the reception intensity in the communication unit 2a instead of the occupancy rate of the transmission path per unit time of the packet received by the communication unit 2a. In this case, the flow rate calculation unit 2f can determine the occupancy rate of the transmission path in consideration of packets, noise, and the like of other communication systems by using the reception intensity. Further, the flow rate calculation unit 2f can obtain the occupancy rate of the transmission path per unit time using the packet received by the communication unit 2a, the reception intensity in the communication unit 2a, and the packet transmitted by the communication unit 2a. Here, the higher the communication traffic, the higher the probability that the greeting packet 100 cannot be received within the standby time T1. On the other hand, the lower the communication flow rate, the reason why the greeting packet 100 cannot be received during the standby time T1 is the increase of the background noise due to the removal of the connection terminal, the stop operation of the connection terminal, or the setting of the electric machine. The possibility of communication with the connected terminal is high. Therefore, it is preferable that the communication control unit 2d determines the amount of decrease in the transmission rate based on the communication flow rate (flow rate calculation value) obtained by the flow rate calculation unit 2f. Specifically, the communication control unit 2d determines the amount of decrease in the transmission rate based on the difference between the allowable flow rate and the communication flow rate obtained by the flow rate calculation unit 2f (flow rate difference amount). The allowable traffic indicator predetermines the upper limit of the traffic flow, and is expressed by the upper limit of the packet occupancy of the transmission path (for example, 40%). When the flow rate calculation value exceeds the allowable flow rate, the communication control unit 2d determines the amount of decrease in the transmission rate so that the flow rate calculation value matches the allowable flow rate in step S6 of FIGS. 5 and 6. At this time, the communication control unit 2d can estimate the amount of decrease in the transmission rate that matches the flow rate calculation value with the allowable flow rate based on the flow rate difference amount. Therefore, the slave 2 can be controlled in a short time so as to sufficiently suppress the transmission rate of the communication traffic. Further, when the flow rate calculation value is lower than the allowable flow rate, the communication control unit 2d sets the amount of decrease in the transmission rate to a predetermined fixed value (for example, 2 Mbps) in step S6 of FIGS. 5 and 6. In addition, the amount of reduction of the fixing may be set to an arbitrary value according to the specifications of the parent machine 1 and the slave machine 2, and is not limited to a specific numerical value. Further, the flow rate calculation unit 2f may set the total number of packets received by the communication unit 2a and the total number of packets transmitted by the communication unit 2a, that is, the total number of packets, as the communication flow rate. In this case, the allowable flow rate is expressed as the upper limit of the total number of packets. Further, the flow rate calculation unit 2f preferably uses not only a packet transmitted to the own device but also all packets received by the communication unit 2a that are not packets transmitted to the device, in the calculation of the communication flow rate. In this case, the flow rate calculation unit 2f can accurately estimate the current communication flow rate. Therefore, the communication control unit 2d can set the amount of decrease in the transmission rate to an appropriate value based on the current communication flow rate. Further, it is preferable that the flow rate calculation unit 2f obtains the communication flow rate of the packet relayed to the other communication terminals (the parent machine 1 and the child machine 2) in the packet received by the communication unit 2a based on the number of hops of the communication route after the relay. Specifically, when it takes 5 hops after the relay of the packet to reach the parent machine 1, it is necessary to perform relay processing by the other five relay terminals. Therefore, when the flow rate calculation unit 2f needs 5 hops until the arrival of the parent machine 1 after the relay of the packet, the packet flow rate or the number of packets of the transmission path of the packet is set to 5 times to obtain the communication flow rate. That is, the flow rate calculation unit 2f is proportional to the number of relay terminals (on the communication route) included in the communication route of the packet transmitted by the communication unit 2a to the parent machine 1, so that the calculation value of the communication traffic of the packet is increased. Big. As a result, the communication control unit 2d can determine the amount of decrease in the transmission rate in consideration of a larger communication flow rate in the multipoint hop communication system 10. Therefore, the flow rate calculation unit 2f can estimate a communication flow over a wider range within the multipoint hop communication system 10. Therefore, the communication control unit 2d can set the amount of decrease in the transmission rate to a value based on the communication flow over a wider range. Further, the flow rate calculation unit 2f preferably increases the number of adjacent terminals of the own device, and increases the calculated value of the communication flow rate. Specifically, when the number of adjacent terminals is four (one of which is a connection terminal), the packet occupancy rate or the number of packets of the transmission path of the packet transmitted by the communication unit 2a is four times. Communication traffic. That is, the flow rate calculation unit 2f increases the calculated value of the communication flow rate of the packet in proportion to the number of adjacent terminals. As a result, the communication control unit 2d can determine the amount of decrease in the transmission rate in consideration of a larger range of communication traffic in the multipoint hop communication system 10. Therefore, the flow rate calculation unit 2f can estimate a communication flow over a wider range within the multipoint hop communication system 10. As a result, the communication control unit 2d can set the amount of decrease in the transmission rate to a value based on the communication flow over a wider range. Further, the flow rate calculation unit 2f preferably calculates the communication flow rate by the number of the parent machine 1 and the child machine 2 (that is, the adjacent terminal adjacent to the terminal, which is called the one-hop adjacent terminal) that can be directly communicated by the adjacent terminal of the own machine. The value increases. From the observation of the slave 2, the 1-hop adjacent terminal has the possibility of becoming a hidden terminal. Furthermore, a communication terminal that is in a relationship that cannot directly receive signals transmitted from each other is referred to as a hidden terminal. If each of the communication terminals in the relationship of the hidden terminal transmits a packet, it is easy to cause a collision of the packet, and there is an adverse effect such as repeated retransmission or an increase in transmission delay. Therefore, the flow rate calculation unit 2f increases the calculated value of the communication flow rate in proportion to the number of one-hop adjacent terminals that may become hidden terminals. As a result, the communication control unit 2d can determine the amount of decrease in the transmission rate in consideration of a larger range of communication traffic in the multipoint hop communication system 10. Further, it is preferable that the communication control unit 2d transmits information (decrease amount determination information) for determining the amount of decrease in the transmission rate from the communication unit 2a to the other child machines 2. Specifically, when the communication control unit 2d of the slave device 2 transmits the hello packet 100B, the data of the communication flow rate obtained by the flow rate calculation unit 2f of the own device is added to the greeting packet 100B. Then, the communication control unit 2d of the slave unit 2 can recognize the communication traffic of the adjacent terminal by receiving the hello packet 100B of the other slave unit 2. Then, the communication control unit 2d selects the communication traffic of the own device and the communication traffic of the highest among the communication flows of the adjacent terminals. The communication control unit 2d determines the amount of decrease in the transmission rate based on the difference between the selected maximum communication flow rate and the allowable flow rate, that is, the flow rate difference amount. Therefore, the communication control unit 2d can determine the amount of decrease in the transmission rate in consideration of a larger range of communication traffic in the multipoint hop communication system 10. Alternatively, when the communication control unit 2d of the slave unit 2 transmits the hello packet 100B, the data of the reduction rate of the transmission rate of the own device is added to the greeting packet 100B. Then, the communication control unit 2d of the slave unit 2 can recognize the decrease in the transmission rate of the adjacent terminal by receiving the hello packet 100B of the other slave unit 2. Then, the communication control unit 2d selects the amount of decrease in the transmission rate of the current state of the device and the decrease in the transmission rate which is lower in the amount of decrease in the transmission rate of the adjacent terminal. The communication control unit 2d controls the transmission rate so as to be the amount of decrease in the selected transmission rate. Therefore, the communication control unit 2d can control the amount of decrease in the transmission rate in consideration of a larger range of communication traffic in the multipoint hop communication system 10. Further, it is preferable that the communication control unit 2d transmits a signal (instruction signal) indicating whether or not to lower the transmission rate from the other communication unit 2a to the other slave unit 2. Specifically, when the communication control unit 2d of the slave unit 2 lowers the transmission rate in the above-described step S6, the communication flow rate obtained by the flow rate calculation unit 2f exceeds the allowable flow rate. In this case, the communication control unit 2d transmits a lowering instruction signal (broadcast or unicast) indicating that the transmission rate is lowered to the other child machines 2. In the slave unit 2 that has received the lowering instruction signal, the communication control unit 2d lowers the transmission rate of the communication unit 2a by a fixed value. Alternatively, the communication control unit 2d may lower the transmission rate of the communication unit 2a to a value indicated by the received lowering instruction signal. Therefore, when the communication flow rate obtained by the flow rate calculation unit 2f is high, the slave device 2 can suppress the communication flow rate of the other slave devices 2 (adjacent terminals). As a result, the slave 2 can suppress the communication traffic of the adjacent terminal that the local device does not participate in transmission and relay. According to the embodiment described above, the communication terminal according to the first aspect of the present invention is used as the slave 2 of the multipoint hop communication system, and the multipoint hop communication system is the partner of the plurality of slaves 2 and the master 1 A communication route including one or more communication links is established, and each of the parent machine 1 and the plurality of child machines 2 performs multipoint jump communication with each other. The slave 2 includes a communication unit 2a, a routing unit 2c, and a communication control unit 2d. The communication unit 2a transmits and receives signals to and from one or more adjacent terminals of the parent machine 1 or other slave devices 2 that are directly communicable. The routing unit 2c receives the routing packet (the greeting packet 100) for determining the communication route from the adjacent terminal by the communication unit 2a, and sets one of the adjacent terminals of one or more adjacent terminals as the connection terminal, and establishes the connection terminal including the connection terminal. Communication route. When the communication unit 2a does not receive the routing packet from the connection terminal during the specific standby time T1, the communication control unit 2d lowers the transmission rate of the transmission signal of the communication unit 2a. Therefore, according to the first aspect, the slave unit 2 can easily maintain the communication link with the connection terminal of the present state, thereby suppressing the disconnection of the communication link due to the increase in the communication traffic. Further, the communication terminal according to the second aspect of the present invention is the first aspect, and the adjacent terminal in which the communication unit 2a in the adjacent terminal cannot receive the routing packet is set as the unreceived terminal. Furthermore, it is preferable that the communication control unit 2d lowers the transmission rate if the ratio of the number of unreceived terminals to the total number of adjacent terminals is equal to or greater than a threshold value. In this case, it is considered that when the unreceived terminal ratio is equal to or higher than the threshold, the communication traffic is high, and thus it is difficult to receive the hello packet 100 of the connected terminal. Therefore, the slave 2 reduces the communication traffic by lowering the transmission rate. As a result, the probability that the slave device 2 receives the hello packet 100 transmitted by the connection terminal during the standby time T1 becomes high. When the ratio of the unreceived terminal does not reach the threshold, it is considered that communication with the connected terminal cannot be performed due to the removal of the connected terminal, the stop of the operation of the connected terminal, or the increase of the background noise caused by the setting of the electrical device. . Therefore, the slave unit 2 can quickly cut off the communication link without excessively extending the communication period without performing the transmission rate reduction processing when the communication with the connection terminal cannot be performed. Further, in the second aspect of the present invention, the communication control unit 2d preferably counts only the adjacent terminals as the total number of adjacent terminals, and the adjacent terminal is received by the communication unit 2a. The source of the communication packet whose communication quality exceeds a certain level. In this case, the communication control unit 2d can count the number of adjacent terminals based on the communication quality in real time by counting only the adjacent terminals having good communication quality. Further, in the second or third aspect of the present invention, it is preferable that the communication control unit 2d makes the ratio of the number of unreceived terminals to the total number of adjacent terminals to be equal to or greater than a threshold value. The transmission rate is reduced by a fixed amount. In this case, the slave unit 2 can reduce the transmission rate due to the excessive reduction in the transmission rate by reducing the transmission rate step by step. Further, in the second or third aspect of the communication terminal according to the fifth aspect of the present invention, it is preferable that the slave unit 2 further includes a flow rate calculation for calculating the communication flow rate based on the amount of signals transmitted and received by the communication unit 2a. Department 2f. Further, if the ratio of the number of unreceived terminals to the total number of adjacent terminals is equal to or greater than the threshold value, the communication control unit 2d determines the transmission rate based on the difference between the communication flow rate obtained by the flow rate calculation unit 2f and the upper limit value of the communication flow rate. Reduce the amount. In this case, the slave 2 can be controlled in a short time to sufficiently suppress the transmission rate of the communication traffic. Further, in the fifth aspect of the present invention, in the fifth aspect, preferably, the semaphore received by the communication unit 2a includes a semaphore transmitted without a communication path of the terminal. In this case, the flow rate calculation unit 2f can accurately estimate the current communication flow rate. Therefore, the communication control unit 2d can set the amount of decrease in the transmission rate to an appropriate value based on the current communication flow rate. Further, in the fifth or sixth aspect of the communication terminal according to the seventh aspect of the present invention, it is preferable that the flow calculation unit 2f increases the calculated value of the communication flow rate as the number of the relay terminals increases. The relay terminal is a slave unit 2 that includes a signal transmitted from the communication unit 2a to the communication path of the parent machine 1. In this case, the flow rate calculation unit 2f can estimate a wider range of communication traffic within the multipoint hop communication system 10. Therefore, the communication control unit 2d can set the amount of decrease in the transmission rate to a value based on the communication flow over a wider range. Further, in the communication terminal according to the eighth aspect of the present invention, in any one of the fifth to seventh aspects, preferably, the more the number of adjacent terminals, the more the flow rate calculation unit 2f calculates the communication flow rate. Increase. In this case, the flow rate calculation unit 2f can estimate the communication flow over a wider range in the multipoint hop communication system 10. As a result, the communication control unit 2d can set the amount of decrease in the transmission rate to a value based on the communication flow over a wider range. Further, the communication terminal according to the ninth aspect of the present invention is in any one of the fifth to eighth aspects, and preferably, the more the number of the parent machine 1 and the slave unit 2 that can directly communicate with the terminal, the flow rate is calculated. The portion 2f increases the calculated value of the communication flow rate. In this case, the communication control unit 2d can determine the amount of decrease in the transmission rate in consideration of a larger range of communication traffic in the multipoint hop communication system 10. Further, in the tenth aspect of the present invention, in the first to ninth aspects, preferably, the communication control unit 2d transmits the self-communication unit 2a to the other child machines 2 to determine the transmission rate. Information on the amount of reduction. In this case, the communication control unit 2d can determine the amount of decrease in the transmission rate in consideration of a larger range of communication traffic in the multipoint hop communication system 10. Further, in the communication terminal according to the eleventh aspect of the present invention, in any one of the first to ninth aspects, it is preferable that the communication control unit 2d causes the self-communication unit 2a to transmit an indication to the other slave unit 2 whether or not to increase the transmission rate. Reduce the signal. In this case, when the communication flow rate obtained by the flow rate calculation unit 2f is high, the communication flow rate of the other child machine 2 (adjacent terminal) can be suppressed. As a result, the slave 2 can suppress the communication traffic of the adjacent terminal that the local device does not participate in transmission and relay. In the multi-point hopping communication system 10 of the twelfth aspect of the present invention, each of the plurality of sub-machines 2 establishes a communication route including one or more communication links with the parent machine 1, and the parent machine 1 and the plurality of child machines 2 Each person performs multi-point jump communication with each other. Each of the plurality of slaves 2 includes a communication unit 2a, a routing unit 2c, and a communication control unit 2d. The communication unit 2a transmits and receives signals to and from one or more adjacent terminals of the parent machine 1 or other slave devices 2 that are directly communicable. The routing unit 2c receives the routing packet (the greeting packet 100) for determining the communication route from the adjacent terminal by the communication unit 2a, and sets one of the adjacent terminals of one or more adjacent terminals as the connection terminal, and establishes the connection terminal including the connection terminal. Communication route. When the communication unit 2a does not receive the routing packet from the connection terminal during the specific standby time T1, the communication control unit 2d lowers the transmission rate of the transmission signal of the communication unit 2a. Therefore, the multipoint hopping communication system 10 can easily maintain the communication link between the slave 2 and the connected terminal of the current status for each of the plurality of slaves 2, thereby suppressing the communication link due to the increase of the communication traffic. Cut off. Further, the parent machine 1 is provided with a computer, and the functions of the above-described parent machine 1 are realized by executing the program by the computer. The computer has as a main component: a device including a processor for executing a program; an interface device for transmitting and receiving data with other devices; and a memory device for memorizing data. The device having the processor may be any one of a CPU (Central Processing Unit) or an MPU (Micro Processing Unit) separated from the semiconductor memory, and a microcomputer integrally provided with the semiconductor memory. The memory device is a memory device that has a shorter access time than a semiconductor memory, and a large-capacity memory device such as a hard disk device. Further, the child machine 2 is provided with a computer. After the computer loads and executes the program, the computer realizes the above-described functions of the child machine 2 (particularly, the functions of the routing unit 2c, the communication control unit 2d, the packet monitoring unit 2e, and the flow rate calculation unit 2f). ). That is, the computer program product has a built-in program that causes the processor to function as a slave after the computer loads and executes the program. The computer has as a main component: a device including a processor for executing a program; an interface device for transmitting and receiving data with other devices; and a memory device for memorizing data. The device having the processor may be any one of a CPU or an MPU separate from the semiconductor memory and a microcomputer integrally provided with the semiconductor memory. The memory device is a memory device that has a shorter access time than a semiconductor memory, and a large-capacity memory device such as a hard disk device. The form of the program for the parent machine 1 and the child machine 2 is stored in advance in a form of a computer readable ROM (Read Only Memory), a recording medium such as a compact disk, and the like, and includes an Internet or the like. The form of the wide area communication network supplied to the recording medium. The computer program product of the thirteenth aspect of the present invention is built in a program for loading and executing a program as a function of any of the communication terminals of the first to eleventh aspects. Therefore, the child machine 2 can easily maintain the communication link with the connection terminal of the present state, thereby suppressing the disconnection of the communication link due to the increase of the communication traffic. Further, the multipoint jump communication method described above has the following steps. In the multipoint jump communication system 10, each of the plurality of slaves 2 establishes a communication route including one or more communication links with the parent machine 1, and each of the parent machine 1 and the plurality of slave machines 2 performs multipoint jump communication with each other.・In order to determine the communication route, the communication unit 2a receives a routing packet (greeting packet 100) transmitted from one or more adjacent terminals that are direct communication main machines or other slave devices, thereby setting one of one or more adjacent terminals. The adjacent terminal is configured to connect the terminal to establish a communication route including the connection terminal. When the communication unit 2a does not receive the routing packet from the connection terminal during the specific standby time T1, the communication unit 2a is configured to lower the transmission rate of the transmission signal. Furthermore, the above embodiment is an example. Therefore, the embodiment is not limited to the above-described configuration, and various modifications can be made in accordance with the design and the like without departing from the scope of the technical idea of the present invention.