JP3423918B2

JP3423918B2 - Multicast communication method, wireless base station apparatus and wireless terminal station apparatus

Info

Publication number: JP3423918B2
Application number: JP2000125235A
Authority: JP
Inventors: 弘貴吉岡; 房夫布
Original assignee: Nippon Telegraph and Telephone Corp; NTT Inc USA
Current assignee: NTT Inc; NTT Inc USA
Priority date: 2000-04-26
Filing date: 2000-04-26
Publication date: 2003-07-07
Anticipated expiration: 2020-04-26
Also published as: JP2001308784A

Description

Detailed Description of the Invention

【０００１】[0001]

【発明の属する技術分野】本発明は、無線基地局より特
定の複数の無線端末局に対して同一データを伝送するマ
ルチキャスト通信方法に関し、特に、適切な無線回線品
質で、かつ使用帯域を大幅に増加させることなくスルー
プットの低下を招くことなくデータを伝送することの可
能なマルチキャスト通信方法ならびに無線基地局装置お
よび無線端末局装置に係る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multicast communication method for transmitting the same data from a wireless base station to a plurality of specific wireless terminal stations, and in particular, to an appropriate wireless channel quality and to significantly increase the used bandwidth. The present invention relates to a multicast communication method, a wireless base station apparatus, and a wireless terminal station apparatus that can transmit data without increasing the throughput without lowering the throughput.

【０００２】本明細書では、１基地局が複数端末局に対
して同一のデータを伝送し、受信データの誤り訂正のた
めのデータの再送を行わない通信形態を再送無しポイン
ト−マルチポイント通信と呼び、一方、１基地局が複数
端末局に対して同一データを伝送し、受信データの誤り
訂正のためのデータの再送を行う通信形態を再送有りポ
イント−マルチポイント通信と呼び、また、１基地局が
１端末局に対してデータを伝送し、受信データの誤り訂
正のためのデータの再送を行う通信形態を再送有りポイ
ント−ポイント通信と呼ぶ。In this specification, a communication mode in which one base station transmits the same data to a plurality of terminal stations and does not retransmit data for error correction of received data is referred to as non-retransmission point-multipoint communication. On the other hand, a communication form in which one base station transmits the same data to a plurality of terminal stations and retransmits data for error correction of received data is called point-multipoint communication with retransmission, and one base station A communication mode in which a station transmits data to one terminal station and retransmits data for error correction of received data is called point-to-point communication with retransmission.

【０００３】[0003]

【従来の技術】無線回線を用いて無線基地局より複数の
無線端末局に対しデータを伝送する従来のマルチキャス
ト通信装置として、以下に、として示すような通信
手段を有する装置が挙げられる。2. Description of the Related Art As a conventional multicast communication apparatus for transmitting data from a wireless base station to a plurality of wireless terminal stations using a wireless line, there is an apparatus having the following communication means.

【０００４】［誤りのあったデータの再送を行わない
マルチキャスト通信装置］この装置では、マルチキャスト通信において、無線回線
品質の劣化により無線端末局の受信したデータに誤りが
あった場合でもデータの再送を行わない（ＡＲＱ（Auto
matic Repeat Request）を行わない）。基地局では、無
線端末局での受信データの誤りの有無に関わらずマルチ
キャストデータを順番に送信する。[Multicast communication device that does not retransmit erroneous data] This device retransmits data even when there is an error in data received by a wireless terminal station due to deterioration of wireless channel quality in multicast communication. Not performed (ARQ (Auto
matic Repeat Request) is not done). The base station sequentially transmits the multicast data regardless of whether there is an error in the received data at the wireless terminal station.

【０００５】このような装置では、誤りデータを再送し
誤り訂正を行う装置に比べ、基地局側からデータを順次
送信するだけなので、使用帯域は少なくて済む。しか
し、再送により誤り訂正を行う装置に比べ、マルチキャ
スト通信における伝送品質が低下することは避けられな
い。In such a device, compared to a device that retransmits error data and corrects the error, only the data is sequentially transmitted from the base station side, so that the band used can be reduced. However, it is inevitable that the transmission quality in multicast communication will be lower than that of an apparatus that performs error correction by retransmission.

【０００６】［誤りのあったデータの再送を行うマル
チキャスト通信装置］この装置では、マルチキャスト通信において、無線回線
品質の劣化により無線端末局の受信したデータに誤りが
あった場合、、基地局に対してデータの再送を要求し、
再送を要求された基地局はデータの再送を行う。無線端
末局はこれによって受信データの誤り訂正を行う（ＡＲ
Ｑを行う）。[Multicast communication device for retransmitting erroneous data] In this device, when there is an error in the data received by the wireless terminal station due to deterioration of the wireless channel quality in the multicast communication, the base station is notified to the base station. Request to resend the data,
The base station, which is requested to retransmit, retransmits the data. The wireless terminal station performs error correction of the received data by this (AR
Do Q).

【０００７】[0007]

【発明が解決しようとする課題】マルチキャスト通信を
行う際、無線端末局の無線回線品質は，各無線端末局の
受信状態により大きく異なる。これに対して、上述した
ような、従来のマルチキャスト通信装置において、の
場合には、基地局側からデータを順次送信するだけで、
伝送中にデータの誤りを生じても、その訂正を行わない
ため、無線端末局によっては、要求されるサービス品質
を満たせない場合があると言う問題があった。When performing multicast communication, the wireless channel quality of the wireless terminal stations greatly differs depending on the reception state of each wireless terminal station. On the other hand, in the conventional multicast communication device as described above, in the case of, only by sequentially transmitting the data from the base station side,
Even if a data error occurs during transmission, the correction is not performed, and there is a problem that the required quality of service may not be satisfied depending on the wireless terminal station.

【０００８】一方、の場合には、伝送中にデータの誤
りを生じたとき、データを再び受け取り誤り訂正を行う
ので、受信データの品質向上が望めるが、無線回線品質
の悪い無線端末局の数が増加すると、データ再送用に用
いる帯域が大幅に増加し、通信システム全体のスループ
ットが大幅に低下してしまうという問題があった。On the other hand, in the case of (1), when an error occurs in the data during transmission, the data is received again and error correction is performed, so that the quality of the received data can be improved, but the number of wireless terminal stations with poor wireless line quality However, there is a problem that the bandwidth used for data retransmission increases significantly and the throughput of the entire communication system decreases significantly.

【０００９】本発明は、上述のような従来の課題を解決
するため、無線回線品質によって通信手段を選択、また
は組み合わせることができるマルチキャスト通信装置を
用いることにより、誤りのあったデータを再送すること
で受信データの品質を向上させつつ、再送により生じる
通信システム全体のスループットの低下、及び通信コネ
クション数の増加を抑えることの可能なマルチキャスト
通信手段を提供することを目的としている。In order to solve the above-mentioned conventional problems, the present invention retransmits erroneous data by using a multicast communication device capable of selecting or combining communication means depending on the radio channel quality. It is an object of the present invention to provide a multicast communication means capable of suppressing a decrease in throughput of the entire communication system and an increase in the number of communication connections caused by retransmission while improving the quality of received data.

【００１０】[0010]

【課題を解決するための手段】本発明によれば、上述の
課題は前記特許請求の範囲に記載した手段によって解決
される。すなわち、請求項１の発明は、無線基地局と、
マルチキャストグループに属する複数の無線端末局との
間でマルチキャスト通信を行うマルチキャスト通信シス
テムにおいて、無線基地局と、マルチキャストグループ
に属する無線端末局との間で再送無しポイント−マルチ
ポイント通信によりマルチキャスト通信を行っていると
き、According to the invention, the aforesaid problems are solved by the means defined in the claims. That is, the invention of claim 1 includes a radio base station,
In a multicast communication system that performs multicast communication with multiple wireless terminal stations belonging to a multicast group, wireless communication is performed between the wireless base station and wireless terminal stations belonging to the multicast group by point-to-multipoint communication without retransmission. When

【００１１】無線端末局の受信データに基づいて、該無
線端末局あるいは無線基地局において、無線回線品質の
良否を判定し、無線回線品質が劣化したと判定したと
き、当該無線端末局をマルチキャストグループから切り
離して該無線端末局と無線基地局との通信を再送有りポ
イント−ポイント通信に切り替え、再送有りポイント−
ポイント通信により通信を行っているとき、Based on the received data of the wireless terminal station, the wireless terminal station or the wireless base station determines whether the wireless channel quality is good or not, and when it is determined that the wireless channel quality has deteriorated, the wireless terminal station is set to the multicast group. From the wireless terminal station and the wireless base station, the communication between the wireless terminal station and the wireless base station is switched to point communication with retransmission-point with retransmission,
When communicating by point communication,

【００１２】無線端末局の受信データに基づいて、該無
線端末局あるいは無線基地局において、無線回線品質の
良否を判定し、無線回線品質が良好になったと判定した
場合に、当該無線端末局を、マルチキャストグループに
復帰させて、通信手段を、再送無しポイント−マルチポ
イント通信に切り替えるマルチキャスト通信方法であ
る。Based on the received data of the wireless terminal station, the wireless terminal station or the wireless base station determines whether the wireless channel quality is good or not, and when the wireless channel quality is determined to be good, the wireless terminal station , A multicast communication method for returning to a multicast group and switching communication means to point-without-retransmission-multipoint communication.

【００１３】請求項２の発明は、無線基地局と、マルチ
キャストグループに属する複数の無線端末局との間でマ
ルチキャスト通信を行うマルチキャスト通信システムに
おいて、無線基地局が、マルチキャストグループに属す
る無線端末局との間で再送無しポイント−マルチポイン
ト通信によりマルチキャスト通信を行っているとき、According to a second aspect of the present invention, in a multicast communication system for performing multicast communication between a wireless base station and a plurality of wireless terminal stations belonging to a multicast group, the wireless base station is a wireless terminal station belonging to the multicast group. When there is no retransmission between points-when performing multicast communication by multipoint communication,

【００１４】無線端末局の受信データに基づいて、該無
線端末局あるいは無線基地局において、無線回線品質の
良否を判定し、無線回線品質が劣化したと判定したと
き、無線基地局と当該無線端末局との間で、再送無しポ
イント−マルチポイント通信とは別に、再送有りポイン
ト−ポイント通信手段を確立し、前記無線端末局が受信
したデータ中に誤りを検出したとき、基地局に対して、
該データの再送を要求し、Based on the received data of the wireless terminal station, the wireless terminal station or the wireless base station determines whether the wireless channel quality is good or bad, and when it is determined that the wireless channel quality has deteriorated, the wireless base station and the wireless terminal concerned. With the station, in addition to the non-retransmission point-multipoint communication, establish a point-to-point communication means with retransmission, when the wireless terminal station detects an error in the received data, to the base station,
Request retransmission of the data,

【００１５】該無線基地局が、前記無線端末局に対して
当該データの再送を再送有りポイント−ポイント通信に
より行い、無線端末局において、該再送データが正しく
受信されたら、再送有りポイント−ポイント通信を終了
し、再送無しポイント−マルチポイント通信によってマ
ルチキャスト通信を行うマルチキャスト通信方法であ
る。The wireless base station retransmits the data to the wireless terminal station by retransmission point-to-point communication, and when the wireless terminal station correctly receives the retransmission data, the retransmission point-to-point communication. Is a multicast communication method of performing multicast communication by point-to-multipoint communication without retransmission.

【００１６】請求項３の発明は、無線基地局と、マルチ
キャストグループＧ１に属する複数の無線端末局との間
でマルチキャスト通信を行うマルチキャスト通信システ
ムにおいて、無線基地局が、マルチキャストグループＧ
１に属する無線端末局との間で、再送無しポイント−マ
ルチポイント通信によりマルチキャスト通信を行ってい
るとき、According to a third aspect of the present invention, in a multicast communication system for performing multicast communication between a wireless base station and a plurality of wireless terminal stations belonging to the multicast group G1, the wireless base station is a multicast group G.
When performing the multicast communication with the wireless terminal station belonging to No. 1 by the non-retransmission point-multipoint communication,

【００１７】無線端末局の受信データに基づいて、該無
線端末局あるいは無線基地局において、無線回線品質の
良否を判定し、無線回線品質が劣化したと判定したと
き、当該無線端末局を前記マルチキャストグループＧ１
とは別の、再送有りポイント−マルチポイント通信を行
うマルチキャストグループＧ２にも参加させ、Based on the data received by the wireless terminal station, the wireless terminal station or the wireless base station determines whether the wireless channel quality is good or not. When it is determined that the wireless channel quality has deteriorated, the wireless terminal station is set to the multicast. Group G1
Join the multicast group G2 that performs point-to-multipoint communication with retransmission, which is different from

【００１８】該マルチキャストグループＧ２に参加して
いる無線端末局と無線基地局との間で、通信を行ってい
て、当該無線端末局において受信データの誤りが発生し
たとき、マルチキャストグループＧ２で該データの再送
を受け、前記無線端末局で該再送データが正常に受信で
きたとき、該無線端末局をマルチキャストグループＧ２
から切り離すマルチキャスト通信方法である。When the wireless terminal station participating in the multicast group G2 and the wireless base station are communicating with each other and an error occurs in the received data at the wireless terminal station, the data is received in the multicast group G2. When the wireless terminal station normally receives the retransmitted data, the wireless terminal station is set to the multicast group G2.
This is a multicast communication method that is separated from.

【００１９】請求項４の発明は、無線基地局と、マルチ
キャストグループに属する複数の無線端末局との間でマ
ルチキャスト通信を行い、無線端末局が自局での受信状
態を監視していて、周期的に無線回線品質を示す値を無
線基地局に送信するマルチキャスト通信システムの無線
基地局装置であって、According to a fourth aspect of the present invention, the wireless base station and a plurality of wireless terminal stations belonging to the multicast group perform multicast communication, and the wireless terminal station monitors the reception state at the local station. A wireless base station device of a multicast communication system for transmitting a value indicating wireless channel quality to a wireless base station,

【００２０】マルチキャストグループに属する無線端末
局との間で、再送無しポイント−マルチポイント通信に
よりマルチキャスト通信を行う手段と、無線端末局から
の無線回線品質を示す値を、予め定めた閾値と比較して
無線回線品質の良否を判定する手段と、該手段により、
無線回線品質が否と判定されたとき、当該無線端末局を
マルチキャストグループから切り離し、該無線端末局と
の通信手段を、再送有りポイント−ポイント通信に切り
替える手段と、A means for performing multicast communication by wireless point-to-multipoint communication with a wireless terminal station belonging to a multicast group and a value indicating the wireless channel quality from the wireless terminal station are compared with a predetermined threshold value. And a means for determining the quality of the wireless line by
When it is determined that the wireless line quality is not good, the wireless terminal station is separated from the multicast group, and the communication means with the wireless terminal station is switched to point-to-point communication with retransmission.

【００２１】該無線端末局と、再送有りポイント−ポイ
ント通信により通信を行っているとき、該無線端末局か
ら受信した無線回線品質を示す値を、前記予め定めた閾
値と比較して無線回線品質の良否を判定する手段によっ
て、無線回線品質が良好になったと判定した場合に、該
無線端末局を、マルチキャストグループに復帰させ、通
信手段を再送無しポイント−マルチポイント通信に切り
替える手段を設けた無線基地局装置である。When communicating with the wireless terminal station by point-to-point communication with retransmission, the value indicating the wireless channel quality received from the wireless terminal station is compared with the predetermined threshold value to determine the wireless channel quality. When it is determined by the means for determining whether the wireless line quality is good, the wireless terminal station is returned to the multicast group, and the wireless means provided with a means for switching the communication means to the non-retransmission point-multipoint communication It is a base station device.

【００２２】請求項５の発明は、無線基地局と、マルチ
キャストグループに属する複数の無線端末局との間でマ
ルチキャスト通信を行い、無線端末局が自局での受信状
態を監視していて、周期的に無線回線品質を示す値を無
線基地局に送信するマルチキャスト通信システムの無線
基地局装置であって、According to the invention of claim 5, multicast communication is carried out between the radio base station and a plurality of radio terminal stations belonging to the multicast group, and the radio terminal station monitors the reception state at its own station, A wireless base station device of a multicast communication system for transmitting a value indicating wireless channel quality to a wireless base station,

【００２３】マルチキャストグループに属する無線端末
局との間で、再送無しポイント−マルチポイント通信に
よりマルチキャスト通信を行う手段と、無線端末局から
の無線回線品質を示す値を、予め定めた閾値と比較して
無線回線品質の良否を判定する手段と、該手段により、
無線回線品質が否と判定されたとき、当該無線端末局と
の間で行っている再送無しポイント−マルチポイント通
信とは別に、再送有りポイント−ポイント通信を行うこ
とが可能な状態を確立する手段と、A means for performing multicast communication by wireless point-to-multipoint communication with wireless terminal stations belonging to a multicast group and a value indicating wireless channel quality from the wireless terminal station are compared with a predetermined threshold value. And a means for determining the quality of the wireless line by
Means for establishing a state in which point-to-point communication with retransmission can be performed separately from point-to-multipoint communication without retransmission performed with the wireless terminal station when it is determined that the wireless line quality is not good. When,

【００２４】該無線端末局と、再送無しポイント−マル
チポイント通信により通信を行っているとき、前記無線
端末局からデータの再送の要求があったとき、該無線端
末局に対して再送有りポイント−ポイント通信によって
当該データの再送を行い、無線端末局において該再送デ
ータが正しく受信されたことが確認されたら再送有りポ
イント−ポイント通信を終了して、再送無しポイント−
マルチポイント通信のみによるマルチキャスト通信に切
り替える手段を設けた無線基地局装置である。Retransmission-free point with the wireless terminal station-When communication is performed by multipoint communication and a request for retransmission of data is made from the wireless terminal station, a point with retransmission is sent to the wireless terminal station- The point data is retransmitted by point communication, and when it is confirmed that the retransmitted data is correctly received at the wireless terminal station, the point with retransmission is completed.
The wireless base station device is provided with a means for switching to multicast communication using only multipoint communication.

【００２５】請求項６の発明は、無線基地局と、マルチ
キャストグループに属する複数の無線端末局との間でマ
ルチキャスト通信を行い、無線端末局が自局での受信状
態を監視していて、周期的に無線回線品質を示す値を無
線基地局に送信するマルチキャスト通信システムの無線
基地局装置であって、According to a sixth aspect of the present invention, the wireless base station and a plurality of wireless terminal stations belonging to the multicast group perform multicast communication, and the wireless terminal station monitors the reception state of itself, and A wireless base station device of a multicast communication system for transmitting a value indicating wireless channel quality to a wireless base station,

【００２６】マルチキャストグループＧ１に属する無線
端末局との間で、再送無しポイント−マルチポイント通
信によりマルチキャスト通信を行う手段と、無線端末局
からの無線回線品質を示す値を、予め定めた閾値と比較
して無線回線品質の良否を判定する手段と、該手段によ
り、無線回線品質が否と判定されたとき、当該無線端末
局を前記マルチキャストグループＧ１とは別の、再送有
りポイント−マルチポイント通信を行うマルチキャスト
グループＧ２にも参加させる手段と、Means for performing multicast communication by wireless point stations without retransmission with wireless terminal stations belonging to the multicast group G1 and a value indicating wireless channel quality from the wireless terminal stations are compared with a predetermined threshold value. Means for determining the quality of the wireless channel, and when the wireless channel quality is determined by the means, the wireless terminal station performs a point-to-multipoint communication with retransmission different from the multicast group G1. Means to participate in the multicast group G2,

【００２７】該マルチキャストグループＧ２に参加して
いる無線端末局が、データに誤りが発生したことを通知
してきたとき、マルチキャストグループＧ２で該データ
の再送を行う手段と、前記無線端末局が該再送データが
正常に受信できたことを通知してきたとき、該無線端末
局をマルチキャストグループＧ２から切り離す手段とを
設けた無線基地局装置である。When the wireless terminal station participating in the multicast group G2 notifies that an error has occurred in the data, the wireless terminal station retransmits the data in the multicast group G2 and the wireless terminal station retransmits the data. The wireless base station device is provided with means for disconnecting the wireless terminal station from the multicast group G2 when notifying that the data has been normally received.

【００２８】請求項７の発明は、無線基地局と、マルチ
キャストグループに属する複数の無線端末局との間でマ
ルチキャスト通信を行うマルチキャスト通信システムの
無線端末局装置であって、自局での受信状態を監視して
いて、周期的に無線回線品質を示す値を算出する手段
と、算出した無線回線品質を示す値を、予め定めた閾値
と比較して無線回線品質の良否を判定する手段と、According to a seventh aspect of the present invention, there is provided a wireless terminal station device of a multicast communication system for performing multicast communication between a wireless base station and a plurality of wireless terminal stations belonging to a multicast group. And a means for periodically calculating a value indicating the wireless line quality, a means for comparing the calculated value indicating the wireless line quality with a predetermined threshold value, and determining the quality of the wireless line quality,

【００２９】マルチキャストグループに属し、無線基地
局との間で、再送無しポイント−マルチポイント通信に
よりマルチキャスト通信を行っているとき、無線回線品
質を否と判定した場合に、自局をマルチキャストグルー
プから切り離して該無線端末局との通信手段を再送有り
ポイント−ポイント通信に切り替えることを無線基地局
に要求する手段と、該無線基地局と再送有りポイント−
ポイント通信により通信を行っているとき、[0029] When the wireless channel quality is judged to be unacceptable when performing multicast communication with the wireless base station by the point-to-multipoint communication without retransmission, which belongs to the multicast group, the local station is disconnected from the multicast group. Means for requesting the wireless base station to switch the communication means with the wireless terminal station to point communication with retransmission-point communication with the wireless base station-
When communicating by point communication,

【００３０】受信データに基づいて算出した無線回線品
質を示す値を、予め定めた閾値と比較して無線回線品質
が良好になったと判定した場合に、無線基地局に対して
自局をマルチキャストグループに復帰させて、通信手段
を再送無しポイント−マルチポイント通信に切り換える
よう要求する手段とを備えた無線端末局装置である。When the value indicating the wireless channel quality calculated based on the received data is compared with a predetermined threshold value and it is determined that the wireless channel quality is good, the wireless base station is set to the multicast group of its own station. And a means for requesting that the communication means be switched to non-retransmission point-multipoint communication.

【００３１】請求項８の発明は、無線基地局と、マルチ
キャストグループに属する複数の無線端末局との間でマ
ルチキャスト通信を行うマルチキャスト通信システムの
無線端末局装置であって、自局での受信状態を監視して
いて、周期的に無線回線品質を示す値を算出する手段
と、算出した無線回線品質を示す値を、予め定めた閾値
と比較して無線回線品質の良否を判定する手段と、マル
チキャストグループに属し、無線基地局との間で、再送
無しポイント−マルチポイント通信によりマルチキャス
ト通信を行っているとき、無線回線品質を否と判定した
場合に、The present invention of claim 8 is a wireless terminal station device of a multicast communication system for performing multicast communication between a wireless base station and a plurality of wireless terminal stations belonging to a multicast group, the receiving state at the local station. And a means for periodically calculating a value indicating the wireless line quality, a means for comparing the calculated value indicating the wireless line quality with a predetermined threshold value, and determining the quality of the wireless line quality, When belonging to a multicast group and performing wireless communication with wireless base stations by point-multipoint communication without retransmission, when it is determined that the wireless line quality is not good,

【００３２】自局と無線基地局との間に再送有りポイン
ト−ポイント通信手段を確立することを無線基地局に要
求する手段と、無線基地局と通信中に受信データに誤り
が発生したとき、再送有りポイント−ポイント通信によ
って該データの再送を無線基地局に要求する手段と、無
線基地局から再送された該データが正しく受信されたと
き、再送有りポイント−ポイント通信を終了し、通信手
段を再送無しポイント−マルチポイント通信のみの通信
に戻すよう無線基地局に要求する手段とを備えた無線端
末局装置である。Means for requesting the wireless base station to establish point-to-point communication means with retransmission between itself and the wireless base station; and when an error occurs in received data during communication with the wireless base station, A means for requesting the wireless base station to retransmit the data by point-to-point communication with retransmission, and a point-to-point communication with retransmission is terminated when the data retransmitted from the wireless base station is correctly received, and a communication means is provided. A point of no retransmission-a means for requesting the radio base station to return to multipoint communication only communication.

【００３３】請求項９の発明は、無線基地局と、マルチ
キャストグループに属する複数の無線端末局との間でマ
ルチキャスト通信を行うマルチキャスト通信システムの
無線端末局装置であって、自局での受信状態を監視して
いて、周期的に無線回線品質を示す値を算出する手段
と、算出した無線回線品質を示す値を、予め定めた閾値
と比較して無線回線品質の良否を判定する手段と、According to a ninth aspect of the present invention, there is provided a wireless terminal station device of a multicast communication system for performing multicast communication between a wireless base station and a plurality of wireless terminal stations belonging to a multicast group, the receiving state at the local station. And a means for periodically calculating a value indicating the wireless line quality, a means for comparing the calculated value indicating the wireless line quality with a predetermined threshold value, and determining the quality of the wireless line quality,

【００３４】マルチキャストグループＧ１に属し、無線
基地局との間で、再送無しポイント−マルチポイント通
信によりマルチキャスト通信を行っているとき、無線回
線品質を否と判定した場合に、自局と無線基地局との間
に再送有りポイント−マルチポイント通信を行うマルチ
キャストグループＧ２への参加を無線基地局に要求する
手段と、When the wireless channel quality is judged to be unacceptable when performing multicast communication with the wireless base station belonging to the multicast group G1 by the non-retransmission point-multipoint communication, Retransmission between the point and means for requesting the wireless base station to participate in the multicast group G2 that performs multipoint communication,

【００３５】マルチキャストグループＧ２へ参加して無
線基地局と通信中に受信データに誤りが発生したとき、
該データの再送を無線基地局に要求する手段と、無線基
地局から再送された該データが正しく受信されたとき、
マルチキャストグループＧ２から離脱し、再送有りポイ
ント−マルチポイント通信を終了し、通信手段を再送無
しポイント−マルチポイント通信のみの通信に戻すよう
無線基地局に要求する手段とを備えた無線端末局装置で
ある。When an error occurs in the received data during the communication with the wireless base station by joining the multicast group G2,
Means for requesting the radio base station to retransmit the data, and when the data retransmitted from the radio base station is correctly received,
A wireless terminal station device provided with a means for leaving the multicast group G2, terminating point-to-multipoint communication with retransmission, and requesting the wireless base station to return the communication means to point-to-multipoint communication only communication without retransmission. is there.

【００３６】請求項１０の発明は、請求項１〜請求項９
のいずれか１項に記載のマルチキャスト通信方法または
無線基地局装置または無線端末局装置において、無線回
線品質を示す値として、無線端末局が受信したデータに
ついてのビット誤り率を算出し、一定期間における、そ
の平均値を用いるように構成したものである。The invention of claim 10 is defined by claim 1 to claim 9.
In the multicast communication method, the wireless base station device, or the wireless terminal station device according to any one of 1, the bit error rate for data received by the wireless terminal station is calculated as a value indicating the wireless channel quality, and , The average value is used.

【００３７】請求項１１の発明は、請求項１〜請求項９
のいずれか１項に記載のマルチキャスト通信方法または
無線基地局装置または無線端末局装置において、無線回
線品質を示す値として、無線端末局が受信した信号の受
信電力値についての一定期間の平均値を用いるように構
成したものである。The invention of claim 11 is from claim 1 to claim 9.
In the multicast communication method, the wireless base station device, or the wireless terminal station device according to any one of 1, the average value of the received power value of the signal received by the wireless terminal station for a certain period is used as the value indicating the wireless channel quality. It is configured to be used.

【００３８】上述のように、本発明は、データの通信手
段として、通常は、受信データの誤り訂正のためのデー
タの再送を行わず、１基地局から複数端末局に対しデー
タを伝送する再送無しポイント−マルチポイント通信を
行っていて、無線回線品質が低下したとき、受信データ
の誤り訂正のためにデータの再送を行い得るように、、
１基地局対１端末局でデータを伝送する再送有りポイン
ト−ポイント通信手段、あるいは再送有りポイント−マ
ルチポイント通信手段を、適切に使い分けてマルチキャ
スト通信における端末局受信データの品質の向上を図
る。As described above, the present invention, as a data communication means, normally does not retransmit data for error correction of received data but retransmits data from one base station to a plurality of terminal stations. None-When multi-point communication is performed and the wireless line quality deteriorates, so that data can be retransmitted for error correction of received data,
The point-to-point communication means with retransmission and the point-to-multipoint communication means with retransmission, which transmit data between one base station and one terminal station, are properly used to improve the quality of terminal station reception data in multicast communication.

【００３９】一般に、受信データ品質を向上させるた
め、常に、受信時に誤りのあったデータを再送するよう
にすると、システムスループットの低下や、通信コネク
ション数の増加といった問題を生じるが、本発明では、
各通信手段を適切に組合わせることによりシステムスル
ープットの低下や通信コネクション数の増加を抑えつつ
受信データの品質を向上させることを可能としている。Generally, in order to improve the quality of received data, if the data having an error at the time of reception is always retransmitted, problems such as a decrease in system throughput and an increase in the number of communication connections occur.
By properly combining each communication means, it is possible to improve the quality of received data while suppressing the decrease in system throughput and the increase in the number of communication connections.

【００４０】本発明は、従来の技術とは、無線回線品質
をもとに、無線端末局ごとに適切な通信手段を使い分け
るか、またはそれらを組み合わせることにより、通信シ
ステム全体のスループットの低下や、通信コネクション
数の増加を抑えつつ、受信データの品質を向上させるこ
とができる点が異なる。The present invention is different from the conventional technique in that the appropriate communication means is properly used for each wireless terminal station based on the wireless line quality or they are combined to reduce the throughput of the entire communication system. The difference is that the quality of received data can be improved while suppressing an increase in the number of communication connections.

【発明の実施の形態】本発明を適用するマルチキャスト
通信システムの構成を図１に示す。同図において数字符
号１は無線基地局（ＡＰ）、２は無線端末局（ＭＴ）、
３はマルチキャストグループ４はマルチキャスト通信を
表している。この図に示すのは、有線網に接続された一
つの無線基地局（ＡＰ）と複数の無線端末局（ＭＴ）の
間で無線回線を用いてマルチキャスト通信を行う通信シ
ステムである。FIG. 1 shows the configuration of a multicast communication system to which the present invention is applied. In the figure, numeral 1 is a wireless base station (AP), 2 is a wireless terminal station (MT),
Reference numeral 3 indicates a multicast group, and reference numeral 4 indicates a multicast communication. Shown in this figure is a communication system in which one wireless base station (AP) and a plurality of wireless terminal stations (MT) connected to a wired network perform multicast communication using wireless lines.

【００４１】同一のデータを受信している各無線端末局
をひとつのグループとしてマルチキャストグループＧ１
と呼ぶとき、マルチキャストグループＧ１に属する各無
線端末局はマルチキャスト通信によりデータを受信する
が、受信したデータの品質は各端末局の無線回線品質に
よって大きく異なり、端末局によっては十分なデータ品
質を得られない場合がある。本発明はこのような場合に
無線回線品質の劣化した端末局Ａの無線回線品質を向上
させることができる。Multicast group G1 with each wireless terminal station receiving the same data as one group
, Each wireless terminal station that belongs to the multicast group G1 receives data by multicast communication. However, the quality of the received data greatly differs depending on the wireless channel quality of each terminal station, and some terminal stations obtain sufficient data quality. It may not be possible. The present invention can improve the wireless line quality of the terminal station A whose wireless line quality has deteriorated in such a case.

【００４２】図２は、本発明の無線基地局と無線端末局
の構成の例を示す図である。同図において数字符号１は
無線基地局、２は無線端末局、１１は再送無しポイント
−マルチポイント通信手段、１２は再送有りポイント−
ポイント通信手段、１３は再送有りポイント−マルチポ
イント通信手段、１４は通信方式制御手段、１５は端末
局管理手段、１６，２４は送信手段、１７，２１は受信
手段、２２は無線回線品質測定手段、２３は誤りデータ
再送要求手段を表している。FIG. 2 is a diagram showing an example of the configuration of the radio base station and the radio terminal station of the present invention. In the figure, numeral 1 is a wireless base station, 2 is a wireless terminal station, 11 is a point without retransmission-multipoint communication means, 12 is a point with retransmission-
Point communication means, 13 is point-multipoint communication means with retransmission, 14 is communication method control means, 15 is terminal station management means, 16 and 24 are transmission means, 17 and 21 are reception means, and 22 is wireless channel quality measurement means. , 23 represent error data resend request means.

【００４３】図２に示すように、無線端末局２は基地局
から送信されたデータを受信する受信手段２１を有し、
データの受信状況から無線回線品質を知る無線回線品質
測定手段２２を有する。この無線回線品質測定手段２２
は実際に無線回線品質を知る手段として２つの手段を持
つ。その１つは図１で示すマルチキャスト通信システム
において、無線端末局２が受信したデータの誤り率を算
出し、算出された誤り率から無線回線品質を知る手段で
ある。もう１つは無線端末局が受信した受信電力を算出
し、算出された受信電力から無線回線品質を知る手段で
ある。As shown in FIG. 2, the wireless terminal station 2 has a receiving means 21 for receiving the data transmitted from the base station,
It has a wireless line quality measuring means 22 for knowing the wireless line quality from the data reception status. This wireless line quality measuring means 22
Has two means for actually knowing the wireless line quality. One is a means for calculating the error rate of the data received by the wireless terminal station 2 in the multicast communication system shown in FIG. 1 and knowing the wireless channel quality from the calculated error rate. The other is a means for calculating the received power received by the wireless terminal station and knowing the wireless line quality from the calculated received power.

【００４４】無線端末局２はこの２つの手段のうちどち
らか一方、または両手段を用い無線回線品質の判定を行
う。また、無線端末局は受信時に誤りのあったデータに
対し、誤り訂正を行うため基地局に誤ったデータの再送
要求を行う誤りデータ再送要求手段２３を有する。無線
端末局の無線回線品質および誤りデータ再送要求は、無
線端末局２の有する送信手段２４を用い、無線基地局１
に送信される。The radio terminal station 2 judges the radio channel quality by using either one or both of these two means. Further, the wireless terminal station has error data retransmission request means 23 which requests the base station to retransmit erroneous data in order to perform error correction on the data having an error at the time of reception. For the wireless channel quality and error data resend request of the wireless terminal station, the wireless base station 1 uses the transmitting means 24 of the wireless terminal station 2.
Sent to.

【００４５】無線端末局２から送信された無線回線品質
および誤りデータ再送要求は基地局の有する受信手段１
７により受信され、各無線端末局の状況は端末局管理手
段１５に記憶され、各無線端末局ごとに管理される。端
末局管理手段１５で管理される内容としては各無線端末
局の無線回線品質、再送信要求の有無、通信手段などが
ある。また、無線基地局は通信手段として３つの通信手
段を有する。The wireless channel quality and the error data resend request transmitted from the wireless terminal station 2 are received by the receiving means 1 of the base station.
7, the status of each wireless terminal station is stored in the terminal station management means 15 and managed for each wireless terminal station. The contents managed by the terminal station management unit 15 include the wireless line quality of each wireless terminal station, the presence / absence of a retransmission request, the communication unit, and the like. The wireless base station has three communication means as communication means.

【００４６】すなわち、無線端末局の受信データのうち
誤りのあつたデータを誤り訂正用に再送することはせ
ず、データの伝送を１基地局対複数端末局で行う再送無
しポイント−マルチポイント通信手段と、無線端末局に
おいて受信時に誤りのあったデータを誤り訂正のために
再送し、データの伝送を１基地局対１端末局で行う再送
有りポイント−ポイント通信手段と、無線端末局におい
て受信時に誤りのあったデータを誤り訂正のために再送
し、データの伝送を１基地局対複数端末局で行う再送有
りポイント−マルチポイント通信手段である。That is, in the received data of the wireless terminal station, the error-free data is not retransmitted for error correction, and the data is transmitted between one base station and a plurality of terminal stations. Means for retransmitting data having an error at the time of reception in the wireless terminal station for error correction, and transmitting data by one base station to one terminal station with retransmission, point-to-point communication means, and receiving by the wireless terminal station It is a point-to-multipoint communication means with retransmission, in which data having an error at times is retransmitted for error correction and data is transmitted between one base station and a plurality of terminal stations.

【００４７】基地局は端末局の無線回線品質測定手段に
より算出した無線回線品質によりこの３つの通信手段を
切替える、または組み合わせる制御を行う通信方式制御
手段１４有し、この通信方式制御手段１４により通信手
段の制御を行う。図２に示すマルチキャスト通信装置に
よるマルチキャスト通信の具体的な例を実施の形態の例
として、以下に説明する。The base station has a communication system control unit 14 for controlling switching or combination of these three communication units according to the wireless line quality calculated by the wireless line quality measuring unit of the terminal station, and the communication system control unit 14 communicates. Control means. A specific example of the multicast communication by the multicast communication device shown in FIG. 2 will be described below as an example of the embodiment.

【００４８】図３は本発明の実施の形態の第１の例を説
明する図である。数字符号１〜３は図１の場合と同様で
あり、５は再送無しポイント−マルチポイント通信、６
は再送有りポイント−ポイント通信を表している。図４
は本発明の実施の形態の第１の例の動作を示す図であっ
て、Ｓ１〜Ｓ８は動作のステップを表している。図５は
本発明の実施の形態の第１の例の通信の切替えのシーケ
ンスを示す図である。以下これらの図を参照して、実施
の形態の第１の例について説明する。FIG. 3 is a diagram for explaining the first example of the embodiment of the present invention. Numbers 1 to 3 are the same as in the case of FIG. 1, 5 is a point without retransmission-multipoint communication, 6
Indicates point-to-point communication with retransmission. Figure 4
[Fig. 6] is a diagram showing an operation of the first example of the exemplary embodiment of the present invention, and S1 to S8 represent steps of the operation. FIG. 5 is a diagram showing a communication switching sequence according to the first example of the embodiment of the present invention. The first example of the embodiment will be described below with reference to these drawings.

【００４９】図１に示すマルチキャスト通信システムに
おいて、マルチキャストグループＧ１に対し再送無しポ
イント−マルチポイント通信によりマルチキャスト通信
を行っている時、無線回線品質が劣化したと判断した無
線端末局Ａを図３に示すようにマルチキャストグループ
Ｇ１から切り離し、通信手段を再送無しポイント−マル
チポイント通信から再送有りポイント−ポイント通信に
切り換える場合（請求項１）のマルチキャスト通信装置
の動作を考える。In the multicast communication system shown in FIG. 1, the wireless terminal station A which is judged to have deteriorated the wireless line quality when performing the multicast communication by the point-to-multipoint communication without retransmission to the multicast group G1 is shown in FIG. Consider the operation of the multicast communication device in the case of disconnecting from the multicast group G1 and switching the communication means from the non-retransmission point-multipoint communication to the retransmission-existing point-point communication as shown (claim 1).

【００５０】この時の状態遷移は図４に示すようにな
る。同図において、通常は、再送無しポイント−マルチ
ポイント通信によりデータを受信している（Ｓ１）。無
線端末局Ａは先に示した無線回線品質測定手段により無
線回線品質の判定を行う（Ｓ２）。判定（Ｓ３）の結
果、無線回線品質がしきい値よりも良い場合にはそのま
ま再送無しポイント−マルチポイント通信によるマルチ
キャスト通信を続ける（Ｓ１）。The state transition at this time is as shown in FIG. In the figure, data is normally received by point-to-multipoint communication without retransmission (S1). The wireless terminal station A determines the wireless channel quality by the above-described wireless channel quality measuring means (S2). As a result of the determination (S3), if the wireless channel quality is better than the threshold value, the multicast communication by the non-retransmission point-multipoint communication is continued (S1).

【００５１】無線品質がしきい値よりも劣化した場合、
無線端末局Ａは基地局に対しマルチキャストグル−プか
らの切り離しを要求し、同時に再送有りポイント−ポイ
ント通信に切替えるための要求を行う。要求を受けた基
地局は端末局管理手段においてこの端末局Ａをマルチキ
ャストグループから削除し（Ｓ４）、通信方式制御手段
において再送有りポイント−ポイント通信手段に切替え
る（Ｓ５）。When the radio quality deteriorates below the threshold,
The wireless terminal station A requests the base station to disconnect from the multicast group, and at the same time requests to switch to point-to-point communication with retransmission. The base station receiving the request deletes the terminal station A from the multicast group by the terminal station management means (S4), and switches to the point-to-point communication means with retransmission by the communication method control means (S5).

【００５２】再送有りポイント−ポイント通信に切り換
えられた無線端末局Ａは受信時に誤ったデータについて
誤りデータ再送信要求手段により基地局に再送信要求を
行うことができる。この要求を受けた基地局はこの端末
局に対しデータの再送を行い、端末局は再送されたデー
タを受け取ることによりデータの品質を向上させること
ができる。The wireless terminal station A switched to the point-to-point communication with retransmission can make a retransmission request to the base station by the error data retransmission requesting means for the erroneous data at the time of reception. The base station receiving this request retransmits the data to this terminal station, and the terminal station can improve the data quality by receiving the retransmitted data.

【００５３】しかし，再送有りポイント−ポイント通信
によりデータの伝送を行う場合、再送無しポイント−マ
ルチポイント通信の帯域のほかに再送有りポイント−ポ
イント通信による帯域が必要となるため、再送有りポイ
ント−ポイント通信を行う無線端末局が多くなると通信
システム全体のスループットが低下してしまうことにな
る。However, when data is transmitted by point-to-point communication with retransmission, a band for point-to-point communication with retransmission is required in addition to the band for point-to-multipoint communication without retransmission, and therefore point-to-point with retransmission. If the number of wireless terminal stations that perform communication increases, the throughput of the entire communication system will decrease.

【００５４】そこで、再送有りポイント−ポイント通信
に切り換えらた無線端末局Ａについても無線回線品質の
判定を行い（Ｓ６）、判定の結果無線回線品質がしきい
値よりも劣化していない場合（Ｓ７）、つまり再送無し
ポイント−マルチポイント通信による無線回線品質と同
等と判断した場合には、再び再送無しポイント−マルチ
ポイント通信に戻す（Ｓ８）ことにより通信システム全
体のスループットが低下しないようにしている。Therefore, the wireless line quality of the wireless terminal station A switched to the point-to-point communication with retransmission is also judged (S6), and if the result of the judgment is that the wireless line quality is not lower than the threshold value ( S7), that is, if it is determined that the wireless line quality is the same as the wireless line quality by the non-retransmission point-multipoint communication, the non-retransmission point-multipoint communication is restored (S8) so that the throughput of the entire communication system does not decrease. There is.

【００５５】図６は本発明の実施の形態の第２の例を説
明する図である。数字符号１〜６は図の場合と同様であ
る。図７は本発明の実施の形態の第２の例の動作を示す
図であって、Ｓ１〜Ｓ７は動作のステップを表してい
る。図８は本発明の実施の形態の第２の例の通信の切替
えのシーケンスを示す図である。以下これらの図を参照
して、実施の形態の第２の例について説明する。FIG. 6 is a diagram for explaining a second example of the embodiment of the present invention. Numbers 1 to 6 are the same as those in the figure. FIG. 7 is a diagram showing an operation of the second example of the exemplary embodiment of the present invention, and S1 to S7 represent steps of the operation. FIG. 8 is a diagram showing a communication switching sequence according to the second example of the embodiment of the present invention. A second example of the embodiment will be described below with reference to these drawings.

【００５６】図１に示すマルチキャスト通信システムに
おいて、無線回線品質が劣化したと判断した無線端末局
Ａに対し、実施の形態の第１の例に示したように再送無
しポイント−マルチポイント通信から再送有りポイント
−ポイント通信に切り換えるのではなく、図６に示すよ
うに受信時に誤ったデータについてのみ再送有りポイン
ト−ポイント通信により再送を行う場合（請求項２）の
マルチキャスト通信装置の動作を考える。In the multicast communication system shown in FIG. 1, the wireless terminal station A, which has judged that the wireless channel quality has deteriorated, retransmits from the non-retransmission point-multipoint communication as shown in the first example of the embodiment. Consider the operation of the multicast communication device in the case of resending only the erroneous data at the time of reception as shown in FIG. 6 instead of switching to the existing point-to-point communication (claim 2).

【００５７】この場合の状態遷移は図７に示すようにな
る。再送無しポイント−マルチポイント通信によりデー
タを受信している（Ｓ１）無線端末局Ａは、無線回線品
質測定手段により無線回線品質の判定を行う（Ｓ２）。
判定の結果（Ｓ３）、無線回線品質がしきい値よりも良
い場合にはそのまま再送無しポイント−マルチポイント
通信を続ける（Ｓ１）。The state transition in this case is as shown in FIG. The wireless terminal station A which has received the data by the non-retransmission point-multipoint communication (S1) determines the wireless channel quality by the wireless channel quality measuring means (S2).
As a result of the determination (S3), if the wireless channel quality is better than the threshold value, the non-retransmission point-multipoint communication is continued (S1).

【００５８】無線品質がしきい値よりも劣化した場合、
無線端末局Ａは基地局に対し再送無しポイント−マルチ
ポイント通信とは別に、誤ったデータを再送してもらう
ための再送有りポイント−ポイント通信手段の確立要求
を行う。要求を受けた基地局は端末局管理手段において
この端末局が再送無しポイント−マルチポイント通信と
は別に再送有りポイント−ポイント通信も行うことを記
憶し、通信方式制御手段において再送有りポイント−ポ
イント通信手段の確立を行う（Ｓ４）。When the radio quality deteriorates below the threshold,
The wireless terminal station A requests the base station to establish point-to-point communication means with retransmission for retransmitting erroneous data, in addition to the point-to-multipoint communication without retransmission. The base station which has received the request stores in the terminal station management means that this terminal station also performs point-to-point communication with retransmission in addition to the point-to-multipoint communication without retransmission, and the communication system control means stores point-to-point communication with retransmission. The means is established (S4).

【００５９】再送有りポイント−ポイント通信手段が確
立された無線端末局Ａは受信時に誤ったデータについて
誤りデータ再送要求手段により基地局に再送要求を行う
（Ｓ５）。再送要求を受けた基地局はこの端末局に対し
再送有りポイント−ポイント通信により誤りのあったデ
ータの再送を行い、端末局は再送されたデータを受け取
る（Ｓ６）ことによりデータの品質を向上させることが
できる。With the point-to-point communication means with resending, the wireless terminal station A requests the base station for resending regarding erroneous data upon reception by the error data resending request means (S5). The base station that has received the retransmission request retransmits the erroneous data to this terminal station through the point-to-point communication with retransmission, and the terminal station receives the retransmitted data (S6) to improve the data quality. be able to.

【００６０】さらに無線端末局Ａはこのデータが誤りな
く受信できたかチェックを行う。チェックの結果、デー
タが誤っていた場合には再び基地局に対し誤りデータ再
送要求手段によりデータの再送要求を行う。誤ったデー
タの受け取りが完了した時点で無線端末局Ａは基地局に
対し再送有りポイント−ポイント通信の終了を要求し、
要求を受けた基地局は端末局管理手段においてこの端末
局が再送有りポイント−ポイント通信を終了することを
記憶し、通信方式制御手段において再送有りポイント−
ポイント通信を終了する（Ｓ７）。Further, the wireless terminal station A checks whether this data can be received without error. If the result of the check is that the data is incorrect, the error data retransmission request means again requests the base station to retransmit the data. When the reception of the incorrect data is completed, the wireless terminal station A requests the base station to end the point-to-point communication with retransmission,
The base station which has received the request stores in the terminal station management means that this terminal station has retransmitted point-point communication, and in the communication system control means the retransmitted point-
The point communication ends (S7).

【００６１】このマルチキャスト通信では再送無しボイ
ント−マルチポイント通信によりデータの伝送を行いつ
つ、受信時に誤りのあったデータについてのみ再送有り
ポイント−ポイント通信により再送信を行うので、通信
システム全体の帯域を効率良く使用することができ、実
施の形態の第１の例よりもシステム全体のスループット
の低下を抑えることができる。In this multicast communication, the point-to-point communication with retransmission is retransmitted only for the data having an error at the reception while transmitting the data by the point-to-multipoint communication without the retransmission, so that the bandwidth of the entire communication system is reduced. It can be used efficiently, and a decrease in the throughput of the entire system can be suppressed more than in the first example of the embodiment.

【００６２】図９は本発明の実施の形態の第３の例を説
明する図である。数字符号１〜６は図５の場合と同様で
あり、７はマルチキャストグループ（Ｇ２）、８は再送
有りポイント−マルチポイント通信を表している。図１
０は本発明の実施の形態の第３の例の動作を示す図であ
って、Ｓ１〜Ｓ７は動作のステップを表している。図１
１は本発明の実施の形態の第３の例の通信の切替えのシ
ーケンスを示す図である。FIG. 9 is a diagram for explaining a third example of the embodiment of the present invention. Numbers 1 to 6 are the same as those in FIG. 5, 7 indicates a multicast group (G2), and 8 indicates point-multipoint communication with retransmission. Figure 1
0 is a diagram showing an operation of the third example of the exemplary embodiment of the present invention, and S1 to S7 represent steps of the operation. Figure 1
FIG. 1 is a diagram showing a communication switching sequence according to a third example of the embodiment of the present invention.

【００６３】この例は、図１に示すマルチキャスト通信
システムにおいて、無線回線品質が劣化したと判断した
複数無線端末局に対し、図９に示すようにこれらの端末
局で数字符号７で示すように新たなマルチキャストグル
ープＧ２を形成し、再送有りポイント−マルチポイント
通信により誤りのあったデータの再送を行うもの（請求
項３）である。In this example, in the multicast communication system shown in FIG. 1, for a plurality of wireless terminal stations judged to have deteriorated wireless channel quality, as shown in FIG. A new multicast group G2 is formed, and the erroneous data is retransmitted by the retransmission-point-multipoint communication (claim 3).

【００６４】この場合の状態遷移を図１０に示す。同図
において、再送無しポイント−マルチポイント通信によ
りデータを受信（Ｓ１）している無線端末局Ａは、無線
回線品質測定手段により無線回線品質の判定を行う（Ｓ
２）。判定（Ｓ３）の結果、無線回線品質がしきい値よ
りも良い場合にはそのまま再送無しポイント−マルチポ
イント通信を続ける（Ｓ１）。FIG. 10 shows the state transition in this case. In the figure, the wireless terminal station A, which receives data (S1) by point-to-multipoint communication without retransmission, determines the wireless channel quality by the wireless channel quality measuring means (S1).
2). As a result of the determination (S3), if the wireless channel quality is better than the threshold value, the non-retransmission point-multipoint communication is continued (S1).

【００６５】無線回線品質がしきい値よりも劣化した場
合、無線端末局Ａは基地局に対し再送無しポイント−マ
ルチポイント通信が行われているマルチキャストグルー
プＧ１とは別に、誤りのあったデータの再送を行うため
に形成するマルチキャストグループＧ２に参加の要求を
行う。When the wireless channel quality deteriorates below the threshold value, the wireless terminal station A separates from the base station the data in error in addition to the multicast group G1 in which point-to-multipoint communication without retransmission is performed. A request for participation is made to the multicast group G2 formed for retransmission.

【００６６】無線端末局ＡはマルチキャストグループＧ
１とマルチキャストグループＧ２の２つのマルチキャス
トグループに属する状態になり（Ｓ４）、再送有りポイ
ント−マルチポイント通信により誤りのあつたデータの
再送を要求する（Ｓ５）とともに、再送無しポイント−
マルチポイント通信により通常のマルチキャスト通信に
よるデータの受信を行う。The wireless terminal station A is the multicast group G.
1 and the multicast group G2 are in a state of belonging to two multicast groups (S4), and there is a retransmission point-a request for retransmission of data that has been erroneous by multipoint communication (S5) and a retransmission point-
Data is received by normal multicast communication by multipoint communication.

【００６７】端末局ＡからマルチキャストグループＧ２
への参加要求を受けた基地局は、端末局管理手段におい
て端末局ＡがマルチキャストグループＧ２に参加するこ
とを記憶し、通信方式制御手段においてマルチキャスト
グループＧ２に対し再送有りポイント−マルチポイント
通信を行うための制御を行う。From terminal station A to multicast group G2
The base station that has received the request to participate in the memory stores that the terminal station A joins the multicast group G2 in the terminal station management means, and performs point-to-multipoint communication with retransmission to the multicast group G2 in the communication method control means. Control for.

【００６８】マルチキャストグループＧ２に参加した端
末局Ａは再送無しポイント−マルチポイント通信により
通常のマルチキャスト通信によるデータの受信を行いつ
つ、受信時に誤りのあったデータについては再送有りポ
イント−マルチポイント通信を用い、誤りデータ再送信
手段により基地局に対し再送信要求を行う（Ｓ５）。The terminal station A participating in the multicast group G2 receives the data by the normal multicast communication by the non-retransmission point-multipoint communication, and performs the retransmission-point-multipoint communication for the data having an error at the time of reception. Then, the error data retransmitting means makes a retransmit request to the base station (S5).

【００６９】再送要求を受けた基地局はマルチキャスト
グループＧ２に参加している各端末局から要求されたす
べてのデータを再送有りポイント−マルチポイント通信
によりマルチキャストグループＧ２に対して送信する。
マルチキャストグループＧ２に属する各端末局はこの再
送されたデータを受信し、受信できたか否かのチェック
を行う（Ｓ６）。The base station which has received the retransmission request transmits all the data requested by each terminal station participating in the multicast group G2 to the multicast group G2 by point-to-multipoint communication with retransmission.
Each terminal station belonging to the multicast group G2 receives the retransmitted data and checks whether or not the data was successfully received (S6).

【００７０】チェックの結果データが受信できなかった
場合には再び基地局に対し受信できなかったデータの再
送要求を行う。再送データの受け取りが完了した時点で
無線端末局Ａは基地局に対しマルチキャストグループＧ
２からの切り離しを要求し、要求を受けた基地局は端末
局管理手段においてこの端末局Ａをマルチキャストグル
ープＧ２から切り離す（Ｓ７）。When the check result indicates that the data cannot be received, the base station again requests the retransmission of the data that could not be received. When the reception of the retransmitted data is completed, the wireless terminal station A sends a multicast group G to the base station.
The request for disconnection from No. 2 is made, and the base station having received the request disconnects this terminal station A from the multicast group G2 by the terminal station management means (S7).

【００７１】このマルチキャスト通信では再送無しポイ
ント−マルチポイント通信によりデータの伝送を行いつ
つ、受信状況の悪い複数の無線端末局で新たなマルチキ
ャストグループを形成し、再送有りポイント−マルチポ
イント通信により誤りのあったデータのみ再送を行うこ
とで、システムのスループットの低下を抑えつつ受信デ
ータの品質を向上させている。In this multicast communication, while transmitting data by point-to-multipoint communication without retransmission, a new multicast group is formed by a plurality of wireless terminal stations having poor reception conditions, and error is caused by point-to-multipoint communication with retransmission. By retransmitting only the existing data, the quality of the received data is improved while suppressing the decrease in system throughput.

【００７２】そして、実施の形態の第１の例および実施
の形態の第２の例に比べ、さらに受信状況の悪い無線端
末局数が増加した場合の通信コネクションの数も減少さ
せることができる。また従来の再送を行うマルチキャス
ト通信装置では、誤りのあった全てのデータに対し再送
要求を行ってしまうため、通信回線品質の悪い端末が増
加するとシステム全体のスループットが大幅に低下して
しまうという問題点があったが本装置では受信データの
品質によって再送要求を行うかを各端末局ごとに決める
ので、スループットの低下を抑えつつ受信データの品質
を向上させることができる。As compared with the first example of the embodiment and the second example of the embodiment, it is possible to reduce the number of communication connections when the number of wireless terminal stations having poor reception conditions increases. Further, in the conventional multicast communication device that performs retransmission, since a retransmission request is made for all erroneous data, if the number of terminals with poor communication line quality increases, the throughput of the entire system will drop significantly. Although there is a point, this device determines whether to make a retransmission request according to the quality of received data for each terminal station, so that it is possible to improve the quality of received data while suppressing a decrease in throughput.

【００７３】以上の説明では、説明が繁雑になって誤解
を生ずることを避けるため、一貫して、無線端末局が通
信回線品質の良否を判定し、その結果によって、無線基
地局に通信手段の切り替えを要求し、無線基地局がこれ
に応じて通信手段の確立や、切り替えを行うものとして
説明してきた。しかし、本発明はこれに限るものではな
く、無線端末局が通信回線品質を監視していて、これを
無線基地局に報告し、これに基づいて無線基地局が、通
信回線品質の良否を判定してこれを無線基地局に知ら
せ、通信手段の切り替えを行うようにしても目的を達成
できる。In the above description, the wireless terminal station consistently determines whether the communication line quality is good, and the wireless base station is notified of the communication means according to the result in order to avoid making the description complicated and misleading. It has been described that the wireless base station requests switching, and the wireless base station establishes or switches communication means accordingly. However, the present invention is not limited to this, and the wireless terminal station monitors the communication channel quality, reports this to the wireless base station, and based on this, the wireless base station determines the quality of the communication channel quality. Then, the object can be achieved by notifying the wireless base station of this and switching the communication means.

【００７４】このような構成を採る場合については、請
求項１〜６にも規定している。すなわち、請求項１〜３
では通信回線品質の良否の判定は、無線基地局あるいは
無線端末局のいずれで行っても可なるものとし、請求項
４〜６では、無線基地局で通信回線品質の良否の判定を
行う場合の無線基地局の構成を規定している。この場
合、先に説明した図２において、無線端末局２は無線回
線品質測定手段２２によって、無線回線品質の平均値を
算出し、これを送信手段２４によって無線基地局１に送
信し、無線基地局１では、これを受信手段１７で受信
し、端末局管理手段１５が無線回線品質を判定する。The case where such a structure is adopted is also defined in claims 1 to 6. That is, claims 1 to 3
Then, it is assumed that the quality of the communication channel quality can be determined by either the wireless base station or the wireless terminal station. In claims 4 to 6, when the wireless base station determines the quality of the communication channel quality. It defines the configuration of the radio base station. In this case, in FIG. 2 described above, the wireless terminal station 2 calculates the average value of the wireless channel quality by the wireless channel quality measuring means 22, and transmits the average value to the wireless base station 1 by the transmitting means 24. In the station 1, the receiving means 17 receives this, and the terminal station managing means 15 determines the wireless line quality.

【００７５】さらに、前記図５、図８、あるいは図１１
においては、無線端末局が通信回線品質の劣化を検出す
ると、通信手段の確立、切り替えや、マルチキャストグ
ループＧ２への参加を要求し、無線基地局がこれに応じ
て、処理を行うようにしているが、無線基地局が、通信
回線品質の良否を判定する構成とする場合には、この部
分を、無線端末局が通信回線品質を常に監視していて、
その測定値の平均を計算し、これを周期的に無線基地局
に報告し、無線基地局がこれに基づいて、通信回線品質
の良否を判定し、その結果に応じて無線端末局に通信手
段の切り替えを知らせるように置き換えれば良い。Further, FIG. 5, FIG. 8 or FIG.
In the above, when the wireless terminal station detects the deterioration of the communication line quality, the wireless base station requests the establishment and switching of the communication means and the participation in the multicast group G2, and the wireless base station performs the processing accordingly. However, when the wireless base station is configured to judge the quality of the communication line quality, the wireless terminal station constantly monitors the communication line quality for this part.
The average of the measured values is calculated, and this is periodically reported to the wireless base station, and the wireless base station determines the quality of the communication channel quality based on this, and the wireless terminal station communicates with the wireless terminal station according to the result. It should be replaced so as to notify the switch of.

【００７６】このように、無線端末局が通信回線品質を
常時監視していて、これを無線基地局に周期的に報告す
るように構成してあれば、これに基づいて無線基地局
が、通信回線品質の良否を判定することは容易である。
また、切り替え後に通信回線品質が良好になったときの
再切り替えなども容易に行うことができる。その他の動
作は前記図５、図８、あるいは図１１に示したものと同
様である。As described above, if the wireless terminal station constantly monitors the communication channel quality and is configured to periodically report the communication channel quality to the wireless base station, the wireless base station communicates based on this. It is easy to judge whether the line quality is good or bad.
Further, it is possible to easily perform switching again when the communication line quality becomes good after switching. Other operations are the same as those shown in FIG. 5, FIG. 8 or FIG.

【００７７】[0077]

【発明の効果】本発明によれば、無線回線の品質によっ
て通信手段を選択、または組み合わせることにより、誤
りのあったデータを再送することで受信データの品質を
向上させつつ、再送により生じるシステム全体のスルー
プットの低下、及び通信コネクション数の増加を抑える
ことができる利点がある。従来のマルチキャスト通信装
置とは無線回線品質により通信手段を動的に選択、また
は組み合わせることができる点が異なる。According to the present invention, by selecting or combining communication means depending on the quality of a wireless line, the quality of received data is improved by retransmitting erroneous data, and at the same time, the entire system caused by retransmission is generated. There is an advantage that it is possible to suppress a decrease in throughput and an increase in the number of communication connections. It differs from the conventional multicast communication device in that communication means can be dynamically selected or combined depending on the wireless line quality.

[Brief description of drawings]

【図１】本発明を適用するマルチキャスト通信システム
の構成を示す図である。FIG. 1 is a diagram showing a configuration of a multicast communication system to which the present invention is applied.

【図２】本発明の無線基地局と無線端末局の構成の例を
示す図である。FIG. 2 is a diagram showing an example of configurations of a wireless base station and a wireless terminal station of the present invention.

【図３】本発明の実施の形態の第１の例を説明する図で
ある。FIG. 3 is a diagram illustrating a first example of an embodiment of the present invention.

【図４】本発明の実施の形態の第１の例の動作を示す図
である。FIG. 4 is a diagram showing an operation of the first example of the exemplary embodiment of the present invention.

【図５】本発明の実施の形態の第１の例の通信の切替え
のシーケンスを示す図である。FIG. 5 is a diagram showing a communication switching sequence according to the first example of the embodiment of the present invention.

【図６】本発明の実施の形態の第２の例を説明する図で
ある。FIG. 6 is a diagram illustrating a second example of the embodiment of the present invention.

【図７】本発明の実施の形態の第２の例の動作を示す図
である。FIG. 7 is a diagram showing an operation of the second example of the exemplary embodiment of the present invention.

【図８】本発明の実施の形態の第２の例の通信の切替え
のシーケンスを示す図である。FIG. 8 is a diagram showing a communication switching sequence according to a second example of the embodiment of the present invention.

【図９】本発明の実施の形態の第３の例を説明する図で
ある。FIG. 9 is a diagram illustrating a third example of the embodiment of the present invention.

【図１０】本発明の実施の形態の第３の例の動作を示す
図である。FIG. 10 is a diagram showing an operation of the third example of the exemplary embodiment of the present invention.

【図１１】本発明の実施の形態の第３の例の通信の切替
えのシーケンスを示す図である。FIG. 11 is a diagram showing a communication switching sequence according to a third example of the embodiment of the present invention.

[Explanation of symbols]

１無線基地局２無線端末局３マルチキャストグループ（Ｃ１）４マルチキャスト通信５再送無しポイント−マルチポイント通信６再送有りポイント−ポイント通信７マルチキャストグループ（Ｃ２）８再送有りポイント−マルチポイント通信１１再送無しポイント−マルチポイント通信手段１２再送有りポイント−ポイント通信手段１３再送有りポイント−マルチポイント通信手段１４通信方式制御手段１５端末局管理手段１６，２４送信手段１７，２１受信手段２２無線回線品質測定手段２３誤りデータ再送要求手段 1 wireless base station 2 wireless terminal stations 3 Multicast group (C1) 4 Multicast communication 5 Retransmission-free point-multipoint communication 6 Point-to-point communication with resending 7 Multicast group (C2) 8 Retransmission point-multipoint communication 11 Retransmission-free point-multipoint communication means 12 Point-to-point communication means with resending 13 Point with retransmission-Multipoint communication means 14 Communication method control means 15 Terminal station management means 16,24 Transmission means 17,21 Receiving means 22 Radio link quality measuring means 23 Error Data Retransmission Request Means

───────────────────────────────────────────────────── フロントページの続き (56)参考文献特開平11−196088（ＪＰ，Ａ) 特開平２−90831（ＪＰ，Ａ) 特開平11−46161（ＪＰ，Ａ) 特開昭63−279633（ＪＰ，Ａ) (58)調査した分野(Int.Cl.⁷，ＤＢ名) H04B 7/24 - 7/26 102 H04Q 7/00 - 7/38 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-11-196088 (JP, A) JP-A-2-90831 (JP, A) JP-A-11-46161 (JP, A) JP-A-63- 279633 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H04B ^7/ 24-7/26 102 H04Q ^7/ 00-7/38

Claims

(57) [Claims]

1. In a multicast communication system for performing multicast communication between a wireless base station and a plurality of wireless terminal stations belonging to a multicast group, there is no retransmission between the wireless base station and wireless terminal stations belonging to the multicast group. When performing multicast communication by point-to-multipoint communication, the wireless terminal station or the wireless base station judges whether the wireless channel quality is good or not based on the received data of the wireless terminal station, and the wireless channel quality is degraded. When it is determined, the wireless terminal station is disconnected from the multicast group, the communication between the wireless terminal station and the wireless base station is switched to point-to-point communication with retransmission, and when communication is performed by point-point communication with retransmission, Based on the received data of the terminal station, the wireless terminal station or At the base station, if the wireless line quality is judged to be good, and if it is judged that the wireless line quality has become good, the wireless terminal station is returned to the multicast group and the communication means is changed to point-to-multipoint communication. A multicast communication method characterized by switching.

2. In a multicast communication system for performing multicast communication between a wireless base station and a plurality of wireless terminal stations belonging to a multicast group, the wireless base station does not retransmit with wireless terminal stations belonging to the multicast group. When performing multicast communication by point-to-multipoint communication, the wireless terminal station or the wireless base station judges whether the wireless channel quality is good or not based on the received data of the wireless terminal station, and the wireless channel quality is degraded. When judged, between the wireless base station and the wireless terminal station, a point without retransmission-a point with retransmission-in addition to multipoint communication-
Point communication means is established, and when the wireless terminal station detects an error in the received data, it requests the base station to retransmit the data, and the wireless base station Retransmission of the data is performed by point-to-point communication with retransmission, and when the retransmitted data is correctly received at the wireless terminal station, point-to-point communication with retransmission is ended, and multicast communication is performed by point-to-multipoint communication without retransmission. A multicast communication method characterized by the above.

3. A multicast communication system for performing multicast communication between a wireless base station and a plurality of wireless terminal stations belonging to a multicast group G1, wherein the wireless base station is between a wireless terminal station belonging to the multicast group G1. , Non-retransmission point-When performing multicast communication by multipoint communication, the wireless terminal station or wireless base station judges whether the wireless channel quality is good or not based on the received data of the wireless terminal station, When it is determined that the wireless terminal station has deteriorated, the wireless terminal station also participates in a multicast group G2 that performs point-to-multipoint communication with retransmission, which is different from the multicast group G1, and the wireless terminal station that participates in the multicast group G2. Between the wireless base station and When an error occurs in the received data in the wireless terminal station, the data is retransmitted in the multicast group G2, and when the retransmitted data can be normally received in the wireless terminal station, the wireless terminal station is sent from the multicast group G2. A multicast communication method characterized by separation.

4. A wireless base station performs a multicast communication between a plurality of wireless terminal stations belonging to a multicast group, and the wireless terminal station monitors the reception status of itself, and the wireless channel quality is periodically measured. A wireless base station device of a multicast communication system for transmitting a value indicating to a wireless base station, between wireless terminal stations belonging to a multicast group,
Non-retransmission point-means for performing multicast communication by multipoint communication, means for comparing the value indicating the wireless channel quality from the wireless terminal station with a predetermined threshold value, and determining whether the wireless channel quality is good or not, , When the wireless line quality is determined to be no, disconnect the wireless terminal station from the multicast group,
Means for switching the communication means with the wireless terminal station to point-to-point communication with retransmission, and a wireless line received from the wireless terminal station when communicating with the wireless terminal station by point-to-point communication with retransmission When it is determined that the wireless line quality has become good by the means for determining the quality of the wireless line quality by comparing the value indicating the quality with the predetermined threshold value, the wireless terminal station is returned to the multicast group. ,
A radio base station apparatus comprising means for switching the communication means to point-to-multipoint communication without retransmission.

5. A wireless base station and a plurality of wireless terminal stations belonging to a multicast group perform multicast communication, and the wireless terminal station monitors the reception status of itself, and the wireless channel quality is periodically measured. A wireless base station device of a multicast communication system for transmitting a value indicating to a wireless base station, between wireless terminal stations belonging to a multicast group,
Non-retransmission point-means for performing multicast communication by multipoint communication, means for comparing the value indicating the wireless channel quality from the wireless terminal station with a predetermined threshold value, and determining whether the wireless channel quality is good or not, , When it is determined that the wireless line quality is not good, it establishes a state in which it is possible to perform point-to-point communication with retransmission separately from point-to-multipoint communication without retransmission performed with the wireless terminal station. Means for communicating with the wireless terminal station by point-to-multipoint communication without retransmission, when there is a request for retransmission of data from the wireless terminal station,
The data is retransmitted to the wireless terminal station by point-to-point communication with retransmission, and if it is confirmed that the retransmitted data is correctly received at the wireless terminal station, the point-to-point communication with retransmission is terminated and re-transmitted. None point-A radio base station device, characterized in that means is provided for switching to multicast communication of only multipoint communication.

6. A wireless base station and a plurality of wireless terminal stations belonging to a multicast group perform multicast communication, and the wireless terminal station monitors the reception status of itself, and the wireless channel quality is periodically measured. Which is a wireless base station device of a multicast communication system which transmits a value indicating to a wireless base station, and means for performing multicast communication by means of non-retransmission point-multipoint communication with wireless terminal stations belonging to a multicast group G1; Means for comparing the value indicating the wireless line quality from the wireless terminal station with a predetermined threshold value to determine whether the wireless line quality is good or bad; and when the unit determines that the wireless line quality is not good, the wireless terminal concerned The station is also allowed to participate in a multicast group G2 that performs point-to-multipoint communication with retransmission, which is different from the multicast group G1. And a means for retransmitting the data in the multicast group G2 when the wireless terminal stations participating in the multicast group G2 are performing the multicast communication and notifying that an error has occurred in the data. A radio base station device, comprising means for disconnecting the radio terminal station from the multicast group G2 when the radio terminal station notifies that the retransmitted data has been normally received.

7. A wireless terminal station device of a multicast communication system for performing multicast communication between a wireless base station and a plurality of wireless terminal stations belonging to a multicast group, wherein a receiving state at the local station is monitored. A means for periodically calculating a value indicating the wireless channel quality, a means for comparing the calculated value indicating the wireless channel quality with a predetermined threshold value to determine whether the wireless channel quality is good or not, belonging to the multicast group, With the wireless base station,
Point-to-point communication with retransmission without transmission-If point-to-multipoint communication is performed and if the wireless channel quality is judged to be bad, the station is disconnected from the multicast group and the communication means with the wireless terminal station is retransmitted. Means for requesting the wireless base station to switch to, and a value indicating the wireless line quality calculated based on the received data when communicating with the wireless base station by point-to-point communication with retransmission is set in advance. Means for requesting the wireless base station to restore itself to the multicast group and switch the communication means to the non-retransmission point-multipoint communication when it is judged that the wireless line quality has become better than the threshold value And a wireless terminal station device.

8. A wireless terminal station device of a multicast communication system for performing multicast communication between a wireless base station and a plurality of wireless terminal stations belonging to a multicast group, the receiving state being monitored by the local station. A means for periodically calculating a value indicating the wireless channel quality, a means for comparing the calculated value indicating the wireless channel quality with a predetermined threshold value to determine whether the wireless channel quality is good or not, belonging to the multicast group, With the wireless base station,
When multicast is performed by point-to-multipoint communication without retransmission, if it is judged that the wireless channel quality is not good, it is necessary to establish a point-to-point communication means with retransmission between itself and the wireless base station. A means for requesting the base station, and a means for requesting the wireless base station to retransmit the data by point-to-point communication when an error occurs in the received data during communication with the wireless base station, and a means for retransmitting from the wireless base station. When the received data is correctly received, the wireless base station is requested to terminate the point-to-point communication with retransmission and request the wireless base station to return the communication means to the point-to-multipoint communication without retransmission. A characteristic wireless terminal device.

9. A wireless terminal station device of a multicast communication system for performing multicast communication between a wireless base station and a plurality of wireless terminal stations belonging to a multicast group, wherein a receiving state of the wireless terminal station is monitored by itself. A means for periodically calculating a value indicating the wireless line quality, a means for comparing the calculated value indicating the wireless line quality with a predetermined threshold value to judge whether the wireless line quality is good or not, belonging to the multicast group G1 , A point without retransmission between the wireless base station and a point with retransmission between the own station and the wireless base station when it is determined that the wireless link quality is not good during multicast communication by multipoint communication. Means for requesting the wireless base station to participate in the multicast group G2 for performing multipoint communication, and wirelessly participating in the multicast group G2 When an error occurs in the received data during communication with the ground station, means for requesting the wireless base station to retransmit the data, and when the data retransmitted from the wireless base station is correctly received, A wireless terminal station, characterized by: leaving and point for ending retransmission-multipoint communication, and requesting the wireless base station to return the communication means to communication without retransmission-point-multipoint communication only apparatus.

10. A bit error rate for data received by a wireless terminal station is calculated as a value indicating wireless channel quality, and an average value thereof in a certain period is used.
The multicast communication method, the wireless base station device, or the wireless terminal station device according to claim 9.

11. The multicast communication according to claim 1, wherein an average value of a received power value of a signal received by a wireless terminal station for a certain period is used as a value indicating the wireless line quality. Method or wireless base station device or wireless terminal station device.