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　多元接続（ Multiple Access ）

　多元接続（ Multiple Access ）. Multiple Access. Point-to-Multipoint Connection. Point-to-Point Connection. ランダムアクセス方式 (pure ALOHA 方式 ). (Random Access Scheme). collision. success. success. Channel. Station １. birth. birth. ・・・. StationN. birth. birth.

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　多元接続（ Multiple Access ）

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  1. 　多元接続（MultipleAccess） Multiple Access Point-to-Multipoint Connection Point-to-Point Connection

  2. ランダムアクセス方式(pure ALOHA方式) (RandomAccessScheme) collision success success Channel Station１ birth birth ・・・ StationN birth birth LowLatency，　LowReliability

  3. Collisions Data Packet time

  4. Throughput-Traffic Characteristic Throughput (Channel Utilization) 18% (1/2e) Pure ALOHA Traffic

  5. collision ランダムアクセス方式(slotted ALOHA方式) (RandomAccessScheme) success success slot Channel Station１ birth birth ・・・ StationN birth birth LowLatency，　LowReliability

  6. Throughput-Traffic Characteristic Throughput (Channel Utilization) Slotted ALOHA 36% (1/e) 18% (1/2e) Pure ALOHA Traffic

  7. success 時分割アクセス方式(TDMA) (Time Division Multiple Access) Frame success S３ S８ S１ S２ S４ S５ S６ S７ S１ S２ S８ S３ Channel Station3(S3) wait birth ・・・ Station8(S8) birth wait High Latency, High Reliability

  8. Throughput-Traffic Characteristic Throughput (Channel Utilization) TDMA Slotted ALOHA 36% (1/e) 18% (1/2e) Pure ALOHA Traffic

  9. Throughput-Delay Performance TDMA Delay Good Slotted ALOHA Throughput (Channel Utilization)

  10. 多元接続方式に関する研究 Study on Multiple Access Schemes ー＞不安定、低い回線使用率(Low Throughput) 　　　　（低負荷向き） ー＞遅延が大きい(Huge Delay) 　　　　（高負荷向き） 両方式の利点を兼ね備えた 適用範囲の広い方式の構築 Next Generation CDMA/TDMA、OFDMA Make Good Use of the Both Schemes ランダムアクセス方式(Randdom Access Scheme : ALOHA) 　（即時性ー＞優れた遅延特性:Low Latency） 割り当て方式(Fixed Assignment Schemes : TDMA) 　（信頼性ー＞高い回線使用率:High Throughput）

  11. success wait birth birth FAWA方式(Window:2slots) (Fixed Assignment based Window Access) Frame success success S８ S１ S２ S３ S４ S５ S６ S７ S１ S２ S８ S３ Channel Window(S3) Window(S8) Window(S3) Random Access<-small Window Size large -> TDMA Station3(S3) ・・・ TDMA(inside of the window) Station8(S8) wait birth Low Latency, High Reliability Random Access(outside of the window) TDMA(inside of the window)

  12. Throughput-Delay Performance FAWA TDMA Delay Slotted ALOHA Throughput (Channel Utilization)

  13. Channel success success High Power Level failure success Low Power Level wait wait (Fixed Assignment based Window Access with Capture) FAWAC方式(Window:2slots) Frame S８ S１ S２ S３ S４ S５ S６ S７ S１ S２ S８ Window(S3) Window(S8) Window(S3) Station3(S3) birth birth ・・・ Station8(S8) birth

  14. Throughput-Delay Performance FAWA TDMA Delay FAWAC Slotted ALOHA Throughput (Channel Utilization)

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