近年來由於IEEE 802.11a/b/g 無線區域網絡 (WLAN) 的成功發展，無線寬頻上網的普及化又向前一大步，但隨著時代的進步，新規格的積極發展，讓無線網路朝向可移動之行動通訊服務，並且朝著具有高速移動之行動台來做為研究和發展；例如常聽到的WiMAX為IEEE 802.16介面標準，就具有高頻寬、高傳輸速率和涵蓋範圍大等優點。雖然無線通訊有很多優點，但是伴隨而來的卻是各種的干擾和來自通道的衰減，因而會造成封包傳送的失敗，為了確保傳送時的準確性，所以有了不同的重傳機制的提出。
本篇論文以現行無線通訊蜂巢式系統為基礎，其系統效能受到來自同一細胞內，與其它細胞中用戶的同通道干擾(Co-Channel Interference；CCI)而被嚴重的限制；所以本論文模擬的系統，除了包含一般通道探討時必備的大範圍訊號衰減所造成的遮蔽衰落模型、路徑衰減模型，小範圍訊號衰減所造成的Rayleigh衰落之外；還建構出包含同通道干擾的通道模型，做為本論文系統模擬探討的依據。
重傳的機制，一般主要有二種，一種是自動回覆請求重傳(Automatic Repeat Request，ARQ)，但是ARQ的問題是他回傳的狀態報告(Status Report)，並不會在封包遺失的第一時間回傳，所以等到ARQ發現封包遺失需要重傳時已過了不小的延遲時間；所以我們探討的是另一種新的重傳機制，那就是混合式自動回覆請求(Hybrid ARQ，HARQ)。HARQ 是一種結合了前饋式錯誤修正(Forward Error Correction)與ARQ 方法的技術，可以由前一個失敗的嘗試中存下有用的資訊，供之後的解碼使用。在通訊進行時，基地台會透過每個傳輸時間間隔回傳的肯定或否定性的確認(ACK/NACK)與通道品質指標(ChannelQuality Indication，CQI)獲得目前通道的狀況資訊，進而用不同的編碼方式重新傳送，以提高重傳的成功機率。
在本篇論文建構的系統中，會探討無線通訊從低速到高速，在同通道干擾的影響之下，所必需要採行的混合式自動回覆請求的機制為何；本論文使用的自動回覆請求機制，首先是以原始的Type I型配合AMC和新型的Type I型(Chase Combining)的HARQ為主，前者在重傳的時候，會傳和原本Packet一樣大的資料，而舊的傳送資料，則予以刪除，重傳的資料配合較低的調變，可以達到減少錯誤發生的可能；至於Chase Combining，他重傳的Packet，也是和原本的一樣大，但是不同的地方在於舊的資料不會被刪去，會保留在Symbol Level的地方做Soft Combining，來增加解碼的效能；而最終重傳機制選擇的方式為何，是根據模擬時系統規格的要求，像是重傳次數限制、重傳暫存器大小限制，PER(Packet Error Rate)小於10%等限制為我們選擇的要件。

In recent years due to the successful development of wireless local area network such as IEEE 802.11-a,-b and -g, the applications and services of wireless broadband Internet have become widely populated. As time evolves and extensive development of new specifications the wireless network services have been expanded toward the mobile communication services. Its evolution is in the research and development of the services when the mobile is moving in the high mobility environment; for example, the development of WiMAX interfaces for the IEEE 802.16 standards that possess the advantages of high-bandwidth, high transmission speed and wide area coverage. Although there are many advantages of wireless communication, it is accompanied by a variety of interferences and attenuation influences when the data is transmitted through the communication channel that would cause the failure detection at the receiver end of the packet transmitted, and in order to ensure an acceptable system performance several packets retransmission techniques have been proposed.
In this study we consider a basic cellular communication system that the system performance is seriously affected by the Co-channel interference (CCI) from other cells operating at the same frequency and propose a complete system simulation model that it not only includes the common simulation model as discussed in the wireless communication system such as the shadowing fading due to large-scale attenuation, path-loss attenuation and small- scale Rayleigh fading etc. but also includes the model due to Co-channel interference effect.
There are two kinds of retransmission methods, one is the automatic repeat request (ARQ) technique, and in this retransmission method if a packet is lost this packet lost information will not be reached at the transmitting side instantaneously because of the propagation delay of the transmission of this information in the feedback channel. It needs to have some packets ‘re-arrangement and management’ processes at the transmitter/receiver side. The other retransmission mechanism, hybrid automatic repeat request (HARQ), is a technique that combines the forward error (FEC) correction technique and the ARQ process. In this retransmission technique when a packet is failed in the decoding process it is not deleted as in the ARQ retransmission but is saved to be used with the later received retransmitted new data Furthermore in HARQ retransmission, the adaptive modulation and coding technique (AMC) is exploited that different modulation method and/or different coding rate can be adopted in the packets initial transmission and retransmissions depending on the channel quality and system performance requirement to possibly improve the system throughput.
In this study we propose the system architecture for HARQ retransmission in a wireless communication system when a mobile moves in low and high mobility and suffers co-channel interference during the packet transmission. Two retransmission mechanisms are considered in the architecture, one is the combination of the conventional Type I retransmission with AMC and the other is the new Type I retransmission, Chase Combining. In the first HARQ retransmission mechanism the retransmitted packet will have the same size as the initially transmitted packet and when the packet is retransmitted it will be transmitted at lower modulation level to enhance the retransmitted packet quality; meanwhile the original failed decoded packet will be deleted at the receiver side. In the Chase Combing retransmission the retransmitted packet will also have the same size as the initially transmitted packet the failed transmitted packet will not be deleted but be kept at the symbol level for later used in the performing of Soft Combining to improve the decoding efficiency. It depends on the system requirements and system specifications such as the maximum retransmission number allowed, the buffer size in the store of the retransmitted packets and packet error rate (PER) etc. to determine which retransmission mechanism will be exploited.

目錄
第一章	緒論	1
1.1研究動機和目的	1
1.2章節介紹	3
第二章 模擬環境的建立	4
2.1 SISO系統下單一子載波的SIR	5
2.2路徑損失模型(Pass Loss Model)	7
2.3遮蔽衰落模型 (Shadow Fading Model)	8
2.4同頻道間干擾模型(Co-channel interference Model)	12
2.5快速衰落模型 (Fast Fading Model)	16
2.6程式的參數設置和最後的結果	17
第三章 重傳的方式與錯誤曲線圖	26
3.1 HARQ簡介	28
3.1.1 HARQ的三型	29
3.1.2同步與非同步	29
3.1.3自適應與非自適應	30
3.1.4模擬所使用的二種方式	31
3.2 Type I with AMC	31
3.2.1編碼與調變	32
3.2.2 pilot的型式	33
3.2.3通道的介紹	34
3.2.4通道估測的方法	35
3.2.5程式使用的方式	36
3.2.6程式的參數和最後的結果	37
3.3 Chase Combining	41
3.3.1程式使用的方式	43
3.3.2程式的參數和最後的結果	43
第四章 HARQ重傳的判斷	48
4.1 HARQ重傳的單位	49
4.2 HARQ的組成	51
4.3單一訊號錯誤容錯數找尋程式	52
4.3單一SIR值錯誤訊號分配比例找尋程式	57
4.5程式的最後結果	60
第五章 HARQ的運作	63
5.1 HARQ的運作設定	63
5.2程式的運作流程	65
5.3簡易圖解Buffer運作流程	68
5.4程式的參數設定	73
5.5程式的最後結果	74
第六章 結論與未來展望	99
參考文獻	105

圖目錄
圖2. 1程式步驟一示意圖	4
圖2. 2 COST 231 HATA Model	7
圖2. 3 Cell被格子所均分示意圖	8
圖2. 4格子內Shadowing的值	9
圖2. 5 不同速度下遮蔽衰退之自相關函數	11
圖2. 6沒有使用FFR的同頻帶干擾示意圖	13
圖2. 7使用FFR的同頻帶干擾示意圖	14
圖2. 8本論文模擬時考慮的同頻帶干擾圖	15
圖2. 9本論文考慮的同頻帶干擾SIR變化圖	16
圖2. 10 IEEE 802.16m 速度3km/hr距離 300m SIR圖	19
圖2. 11 IEEE 802.16m 速度80km/hr距離 300m SIR圖	19
圖2. 12 IEEE 802.16m 速度350km/hr距離 300m SIR圖	20
圖2. 13 IEEE 802.16m 速度3km/hr距離 600m SIR圖	20
圖2. 14 IEEE 802.16m 速度80km/hr距離 600m SIR圖	21
圖2. 15 IEEE 802.16m 速度350km/hr距離 600m SIR圖	21
圖2. 16 LTE 速度3km/hr距離 300m SIR圖	22
圖2. 17 LTE 速度80km/hr距離 300m SIR圖	22
圖2. 18 LTE 速度350km/hr距離 300m SIR圖	23
圖2. 19 LTE 速度3km/hr距離 600m SIR圖	23
圖2. 20 LTE 速度80km/hr距離 600m SIR圖	24
圖2. 21 LTE 速度350km/hr距離 600m SIR圖	24
圖3. 1程式步驟二示意圖	27
圖3. 2 Type I with AMC系統模型圖	32
圖3. 3 IEEE 802.16m Resource Unit Pilot Structure	33
圖3. 4 LTE Resource Block Pilot Structure	34
圖3. 5 IEEE 802.16m 3km/hr SIR對SER曲線圖	38
圖3. 6 IEEE 802.16m 80km/hr SIR對SER曲線圖	38
圖3. 7 IEEE 802.16m 350km/hr SIR對SER曲線圖	39
圖3. 8 LTE 3km/hr SIR對SER曲線圖	39
圖3. 9 LTE 80km/hr SIR對SER曲線圖	40
圖3. 10 LTE 80km/hr SIR對SER曲線圖	40
圖3. 11 Chase Combining系統模型圖	42
圖3. 12 IEEE 802.16m 3km/hr QPSK1/2 SIR對SER圖	45
圖3. 13 IEEE 802.16m 3km/hr QPSK3/4 SIR對SER圖	45
圖3. 14 IEEE 802.16m 3km/hr 16QAM1/2 SIR對SER圖	46
圖3. 15 IEEE 802.16m 3km/hr 16QAM3/4 SIR對SER圖	46
圖3. 16 IEEE 802.16m 3km/hr 64QAM2/3 SIR對SER圖	47
圖3. 17 IEEE 802.16m 3km/hr 64QAM3/4 SIR對SER圖	47
圖4. 1 程式步驟3示意圖	48
圖4. 2 HARQ Structure	51
圖4. 3單一訊號錯誤容錯數找尋程式系統模型圖	53
圖4. 4 IEEE 802.16m QPSK1/2容錯數	53
圖4. 5 IEEE 802.16m QPSK3/4容錯數	53
圖4. 6 IEEE 802.16m 16QAM1/2容錯數	54
圖4. 7 IEEE 802.16m 16QAM3/4容錯數	54
圖4. 8 IEEE 802.16m 64QAM2/3容錯數	54
圖4. 9 IEEE 802.16m 64QAM3/4容錯數	55
圖4. 10 LTE QPSK1/2容錯數	55
圖4. 11 LTE QPSK3/4容錯數	55
圖4. 12 LTE 16QAM1/2容錯數	55
圖4. 13 LTE 16QAM3/4容錯數	56
圖4. 14 LTE 64QAM2/3容錯數	56
圖4. 15 LTE 64QAM3/4容錯數	56
圖4. 16單一SIR值錯誤訊號分配比例找尋程式系統模型圖	58
圖4. 17 LTE 64QAM2/3 80km/hr at SIR 20 Symbol Error Ratio	59
圖4. 18 LTE 64QAM2/3 80km/hr at SIR 25 Symbol Error Ratio	59
圖4. 19 LTE 64QAM2/3 80km/hr at SIR 30 Symbol Error Ratio	59
圖4. 20 IEEE 802.16m 3km/hr不同SIR不同MCS的錯誤訊號容忍數	60
圖4. 21 IEEE 802.16m 80km/hr不同SIR不同MCS的錯誤訊號容忍數	61
圖4. 22 IEEE 802.16m 350km/hr不同SIR不同MCS的錯誤訊號容忍數	61
圖4. 23 LTE 3km/hr不同SIR不同MCS的錯誤訊號容忍數	61
圖4. 24 LTE 80km/hr不同SIR不同MCS的錯誤訊號容忍數	62
圖4. 25 LTE 350km/hr不同SIR不同MCS的錯誤訊號容忍數	62
圖5. 1 IEEE 802.16m Frame Structure FDD	64
圖5. 2 LTE Frame Structure FDD	64
圖5. 3 IEEE 802.16m HARQ運作時序圖	65
圖5. 4 LTE HARQ運作時序圖	65
圖5. 6 程式運作流程圖	67
圖5. 7 第一個Subframe時間下Buffer內的情況	69
圖5. 8第二個Subframe時間下Buffer內的情況	70
圖5. 9 第七個Subframe時間下Buffer內的情況	71
圖5. 10第八個Subframe時間下Buffer內的情況	72
圖5. 11  IEEE 802.16m 速度80km/hr距離 300m SIR圖	75
圖5. 12 資料傳輸比例0.6 Buffer的情況	76
圖5. 13 資料傳輸比例0.6時相關模擬數據結果	76
圖5. 14 資料傳輸比例0.55 Buffer的情況	77
圖5. 15  資料傳輸比例0.55時相關模擬數據結果	77
圖5. 16 資料傳輸比例0.5 Buffer的情況	78
圖5. 17  資料傳輸比例0.5時相關模擬數據結果	78
圖5. 18  資料傳輸比例0.45 Buffer的情況	79
圖5. 19  資料傳輸比例0.45時相關模擬數據結果	79
圖5. 20  資料傳輸比例0.4 Buffer的情況	80
圖5. 21  資料傳輸比例0.4時相關模擬數據結果	80
圖5. 22  資料傳輸比例0.25 Buffer的情況	81
圖5. 23  資料傳輸比例0.25時相關模擬數據結果	81
圖6. 1 HARQ硬體傳送端與接收端圖	102
圖6. 2 Packet Allocation A內部運作圖	103
圖6. 3 Packet Allocation B內部運作圖	103
圖6. 4 並行混合自動重傳請求(HARQ)的QoS排程器	104

 
表目錄
表2. 2 IEEE 802.16m 遮蔽衰退標準差	9
表2. 3不同速度時的格子大小	12
表2. 4程式步驟一模擬參數表	18
表3. 2 重傳可使用的降級MCS選項表	36
表3. 3程式步驟二Type I with AMC模擬參數表	37
表3. 4程式步驟二Chase Combining模擬參數表	44
表4. 1 IEEE 802.16m HARQ Packet Size for a Subchannel	49
表4. 2 LTE HARQ Packet Size for a Subchannel	50
表4. 3 使用Type I with AMC重傳時需要付出的RU數目	51
表5. 1 HARQ模擬參數設定	73
表5. 2  IEEE 802.16m距離300m速度3km/hr	82
表5. 3  IEEE 802.16m距離300m速度80km/hr	83
表5. 4  IEEE 802.16m距離300m速度350km/hr	84
表5. 5  IEEE 802.16m距離600m速度3km/hr	85
表5. 6  IEEE 802.16m距離600m速度80km/hr	86
表5. 7  IEEE 802.16m距離600m速度350km/hr	87
表5. 8  LTE距離300m速度3km/hr	88
表5. 9  LTE距離300m速度80km/hr	89
表5. 10  LTE距離300m速度350km/hr	90
表5. 11  LTE距離600m速度3km/hr	91
表5. 12  LTE距離600m速度80km/hr	92
表5. 13  LTE距離600m速度350km/hr	93
表5. 14  最高Date Rate考量下的傳輸MCS與重傳方式選擇組合	95
表5. 15 IEEE 802.16m觀察在300m不同速度時HARQ技術的選擇	96
表5. 16 IEEE 802.16m觀察在600m不同速度時HARQ技術的選擇	97
表5. 17 LTE觀察在300m不同速度時HARQ技術的選擇	97
表5. 18 LTE觀察在600m不同速度時HARQ技術的選擇	98

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