1 / 62

適用於 EPON 和 WIMAX 802.16 的整合性網路 並達到 QOS 的 Dynamic Bandwidth Allocation

適用於 EPON 和 WIMAX 802.16 的整合性網路 並達到 QOS 的 Dynamic Bandwidth Allocation. Adviser : 吳和庭教授 Speaker : 尹培華. Outline. Motivation Architecture Research Method Challenge Issues Future Work Q&A. Motivation. Motivation. EPON 可以提供 WIMAX 穩定的後置式傳輸 WIMAX 的特性也可以減少 EPON 的光纖佈建成本。

khuong
Download Presentation

適用於 EPON 和 WIMAX 802.16 的整合性網路 並達到 QOS 的 Dynamic Bandwidth Allocation

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. 適用於EPON和WIMAX 802.16的整合性網路並達到QOS的Dynamic Bandwidth Allocation Adviser :吳和庭教授 Speaker :尹培華

  2. Outline • Motivation • Architecture • Research Method • Challenge Issues • Future Work • Q&A

  3. Motivation

  4. Motivation • EPON可以提供WIMAX穩定的後置式傳輸 • WIMAX的特性也可以減少EPON的光纖佈建成本。 • 雙方其餘的互補性優點: 頻寬容量、傳輸可靠性、佈建網路之彈性。 • 希望能使EPON系統和WIMAX系統同時達到QOS 。

  5. Architecture

  6. WIMAX & EPON’s integrated architectures

  7. Comparison

  8. Combined ONU-BS’s functional modules

  9. Hybrid ONU-BS’s functional modules

  10. Logical operation

  11. Virtual ONU-BS

  12. Research Method

  13. EPON-Side

  14. Background Review • Architecture • Upstream data transmit mechanism: TDMA • Downstream data transmit mechanism: Broadcast

  15. Background Review • MPCP protocol MPCP協定讓OLT和多個ONU間在上傳方向採取 點對多點的連線方式 。主要功能有以下幾項 : (1)同步ONU (2) 控制Auto Discovery機制 (3)指定頻寬和time slot給ONU。 MPCP協定裡共有五種控制訊息

  16. Background Review • GATE message & REPORT message formant

  17. Background Review • LLID(Logic link identification) • EPON的QOS分級 (1)EF (2)AF (3)BE

  18. Background Review • DBA scheme • IPACT • IPACT example

  19. Background Review • Transmission window size to notify how many data that ONU can send to OLT in a cycle • Max Transmission window size : W[i]MAX 避免資源占用 • how the OLT should determine the granted window size if the requested window size W[i] <W[i]MAX • Some approach methods are as follow • FIXED • GATED • Limit

  20. Background Review • Max polling cycle time TMAX • If all ONU want to transmit data the Min assign BW is A[i]MIN • If only one ONU wants to transmit data the MAX assign BW is A[i]MAX (extremely case)

  21. Background Review • Fixed • Gated • Limited

  22. Problem description • 相較於WIMAX network，EPON對於QOS的 support顯的不足，對於不同層級的資料如果可 以按照different cycle time 來傳送將會使EPON 對QOS的support大大提升 • Solution 將原本EPON架構下LLID per ONU的方式換成 LLID per queue。

  23. LLID per queueapproach • LLID per queueapproachconcept LLID per queue藉由在不同的時間獨立送出REPORT訊 息。因此OLT的GATE 也可以針對per queue來grant。針 對per queue作scheduling，一個queue可以視為某種 QOS層級，針對不同的資料流需求達成QOS的目的。

  24. LLID per queueapproach example • Example description P0、P1、P2為三種不同QOS需求的traffic，P0可以 看成voice traffic，P1和P2則可以看成是FTP或是其 他具有highly busty特性的traffic。

  25. LLID per queueapproach example • 簡單來說就是所有的ONU裡在同一個時間內不是所有的queue都被scheduled到，以藉此來達成不同QOS需求的資料以different cycle time的方式來傳送。

  26. Predictive Credit Mechanism • Predictive Credit Mechanism (1)解決在waitingtime時有packet傳送所造成的starvation (2)REPORT message 可以回報負值 (3) Trade off : packet delay / wasted bandwidth (4)利用在waiting time時的packet arrival rate來作預測參考值 • Predictive Credit Mechanism’s parameters TT : transmission time WT : waiting time : this figure indicate the packet arrived time

  27. Problem description 在WTi進入的 data要在 TTi+2才可以傳送，對高優先權的data 可能產生starvation

  28. Predictive Credit Mechanism • Predictive Credit Mechanism’s Parameters summarized AR : packet arrival rate in the waiting time B : 沒有加上預測值時所給訂的頻寬 • AR表示式

  29. Predictive Credit Mechanism • Use three different base to predict credit (1) PAR(Previous Arrival Rate) (2) SAAR(Simple Average Arrival Rate ) (3) Ideal

  30. Predictive Credit Mechanism • PAR(Previous Arrival Rate) • SAAR(Simple Average Arrival Rate )

  31. Predictive Credit Mechanism • Ideal : In the ideal mechanism, the transmission and propagation delay are neglected 。 The result obtained from the ideal mechanism will be the optimal result of all predictive credit method 。

  32. Predictive Credit Mechanism • Note (1)predictive credit based DBA mechanism is suitable for the traffic which has smaller packet size and stable arrival rate but delay sensitive. (2) In the non-credit DBA mechanism Ri is always >=0and Bi=Ri

  33. WIMAX-Side

  34. Background Review • Architecture • BS->SS data transmit mechanism : Broadcast • SS->BS data transmit mechanism : TDD

  35. Background Review • TDD frame structure divide in two part (1)downlink subframe (2)uplink subframe

  36. Background Review • Downlink subframe &Uplink subframe structure

  37. Background Review • Downlink Subframe Preamble Broadcast Control TDM data TTG • Uplink Subframe Initial Ranging Opportunities Request Contention Opportunities Scheduled Data

  38. Background Review • CID(Connection Identification ) 在連線的過程中，BS與SS雙方會使用一個共同的CID 作為代表。使用CID最大的好處在於可以減少資料傳輸 時所需的設定參數交換；因此任何資料都必須在連線確 定建立之後才能進行傳輸，因為CID是在連線建立時才 被指派。 • WIMAX的QOS分級 (1) Unsolicited Grant Service(UGS) (2) Extended Real-time Polling Service(ertPS) (3) real-time Polling Service(rtPS) (4) Non-real-time Polling Service(nrtPS) (5)Best Effort(BE)

  39. Modified leaky bucket algorithm • Modified leaky bucket algorithm 1. under WIMAX network deal with packet fragmentation is too complicated so this mechanism is use to solve problem that when we decide not to do the packet fragmentation 2. let data transmit in different cycle time

  40. Background Review • DBA scheme Grant Per Connection Grant per SS • Schedule mechanism Earliest Deadline First(EDF) Weighted Fair Queue(WFQ)

  41. Background Review • Earliest Deadline First(EDF) • priority-driven preemptive Job with earliest (absolute) deadline has highest priority does not require knowledge of execution times • Execution profile of two periodic tasks • Process A • Arrives 0 20 40 … • Execution Time 10 10 10 … • End by 20 40 60 … • Process B • Arrives 0 50 100 … • Execution Time 25 25 25 … • End by 50 100 150 …

  42. Background Review • Weighted Fair Queue scheduling(WFQ) Packet by Packet GPS(General Processor Sharing) • GPS(General Processor Sharing) concept Each flow i has a weight fiand receives at leastr*fi/ ( fk) bits/s capacity of the outgoing link of capacity r [bits/s]

  43. Leaky bucket algorithm • Leaky bucket algorithm 1. often use in ATM network 2. a traffic control mechanism 3. packets are discarded when bucket overflows 4 . output rate is a constant rate. • Leaky bucket algorithm parameters L : packet leak rate B : Bucket Size(bytes) B/L : maximum latency at transmission

  44. Leaky bucket algorithm • Note Leaky bucket is used in ATM, where B and L be specified in units of cells and cells per second

  45. Token bucket algorithm • Tokenbucket algorithm 1. often use in ATM network 2. a traffic control mechanism 3. Each packet requires abstract “token”to be sent • Token bucket algorithm parameters b : bucket size r : token input rate p : peak rate

  46. Token bucket algorithm

  47. Token bucket algorithm example parameters: MaxTokens=5 r=3

  48. Modified leaky bucket algorithm • Modified leaky bucket algorithm 桶子的容量 : 一次可給予的最大頻寬上限。 漏出去的水 : 送出去的封包大小/消耗掉的頻寬。 注入的水量 : 每個frame所允許傳送的頻寬。 • Concept 此法是採用一次性分配多個frames來解決不做 packet fragmentation所產生的問題；當一次頻寬 無法傳送封包時，只要累積夠多frame的頻寬 量，就可以傳送封包同時達到使用different cycle time傳送data的功能。

  49. Modified leaky bucket algorithm • Divide in two step (1)第一階段頻寬分配 (2)第二階段頻寬分配A，B • 第一階段頻寬分配 (1)累積多餘的頻寬 (2)初步確定頻寬傳送量(最多一次可以給幾個frame的頻寬)

  50. Modified leaky bucket algorithm • 第一階段頻寬分配Parameters : GRANT : 連線做CAC時系統給予的頻寬。 THIS_FRAME_GRANT : 目前此frame可以給予的頻寬。 Buffer : 這條連線剩餘封包的頻寬要求總量。 Max_Packet_Size: 最大封包的大小。 accumulate : 目前為止這條連線所累積下的頻寬量。

More Related