本資料は、掲載誌(URI)等のリンク先にある学位授与機関のWebサイトやCiNii Dissertationsから、本文を自由に閲覧できる場合があります。
博士論文
国立国会図書館館内限定公開
収録元データベースで確認する
国立国会図書館デジタルコレクション
デジタルデータあり
公開元のウェブサイトで確認する
DOI[10.14943/doctoral.k12485]のデータに遷移します
Wireless OFDM Channel Estimation using a Stochastic Approach
- 国立国会図書館永続的識別子
- info:ndljp/pid/10310774
国立国会図書館での利用に関する注記
資料に関する注記
一般注記:
- The rapidly increasing demand for wireless communication can be metusing orthogonal frequency division multiplexing (OFDM) transmission.OFDM transmiss...
書店で探す
障害者向け資料で読む
全国の図書館の所蔵
国立国会図書館以外の全国の図書館の所蔵状況を表示します。
所蔵のある図書館から取寄せることが可能かなど、資料の利用方法は、ご自身が利用されるお近くの図書館へご相談ください
書店で探す
障害者向け資料で読む
書誌情報
この資料の詳細や典拠(同じ主題の資料を指すキーワード、著者名)等を確認できます。
デジタル
- 資料種別
- 博士論文
- 著者・編者
- 萩原, 淳一郎
- 著者標目
- 出版年月日等
- 2016-12-26
- 出版年(W3CDTF)
- 2016-12-26
- 並列タイトル等
- 確率・統計的なアプローチを用いた無線OFDMチャネル推定
- 寄与者
- 大鐘, 武雄宮永, 喜一齊藤, 晋聖
- 授与機関名
- 北海道大学
- 授与年月日
- 2016-12-26
- 授与年月日(W3CDTF)
- 2016-12-26
- 報告番号
- 甲第12485号
- 学位
- 博士(工学)
- 博論授与番号
- 甲第12485号
- 本文の言語コード
- eng
- NDC
- 対象利用者
- 一般
- 一般注記
- The rapidly increasing demand for wireless communication can be metusing orthogonal frequency division multiplexing (OFDM) transmission.OFDM transmission is reliable, is suited to the wideband technology, andhas already been implemented in various fields. Unfortunately, multipathfading is an unavoidable phenomenon in mobile communication. Never-theless, it can be mitigated through the estimation of and compensationfor the fading channel. Thus, improving channel estimation accuracy isessential for improving radio capacity. This thesis aims to improve wire-less OFDM channel estimation using a powerful stochastic approach thatcan cope with the ambiguity. In particular, accurate channel estimationrequires channel statistics to assess the effects of averaging. This thesisproposes novel methods that appropriately consider time-variable chan-nel statistics in order to significantly improve the channel estimation ac-curacy. Furthermore, this thesis, for the first time, clarifies the practicaldifference between batch and sequential estimation processing, which aretheoretically equivalent, for stationary processes.This thesis is organized as follows. Chapter 1 provides an introduc-tion and presents the background, purpose, and structure of the thesis.Chapter 2 provides the preliminary background of the study, including theinvestigatory assumptions, formulation of OFDM transmission, and fun-damentals of stochastic filtering. Chapter 3 proposes a modeling schemethat appropriately reflects the channel statistics. This scheme comprisestwo methods: one for improving estimation accuracy and the other forreducing computational complexity. The first method is based on a state-space model and considers frequency correlation. The second method isbased on the first one and forces the observation matrix into a sparse bidi-agonal matrix to decrease the number of mathematical processes. Theeffectiveness of the proposed scheme is verified using numerical analysis.The coding gain achieved via the first method is up to 3 dB higher thanthat achievable via a conventional Kalman filter. The second method sup-presses increased complexity by up to 2% compared with a conventionalKalman filter.Chapter 4 proposes a joint channel and its statistics estimation methodto track time-varying channel statistics. The channel frequency responsesof the pilot subcarrier and its fixed hyperparameters (channel statistics)are estimated using a Liu and West filter (LWF), which is based on thestate-space model and the sequential Monte Carlo method. To the bestof our knowledge, for the first time, we demonstrate that a conventionalLWF biases the hyperparameters because of its poor estimation of the like-lihood caused by overfitting in noisy environments. Moreover, this prob-lem cannot be solved using conventional smoothing techniques. There-fore, we modify the conventional LWF and regularize the likelihood usinga Kalman smoother. The effectiveness of the proposed method is con-firmed via numerical analysis. When both the Doppler frequency and thedelay spread hyperparameters are unknown, the conventional LWF signif-icantly degrades the performance, sometimes below that obtained by theleast-squares estimation. By avoiding the failure of hyperparameter esti-mation, our method outperforms the conventional approach and achievesgood performance near the lower bound. The coding gain in our proposedmethod is up to 10 dB higher than that in the conventional LWF.Chapter 5 proposes a change-detection method to track abruptly chang-ing channel statistics. Any such change should be immediately followedby channel estimation in order to retain a high estimation accuracy. Thisimmediate follow-up can be achieved by resetting the channel estimationprocess according to adequate detection of the abrupt change. To this end,we investigate a method for detecting abrupt changes in the channel statis-tics using innovations obtained through a Kalman filter. We confirm theeffectiveness of the method via computer simulations using delay spreadas an example of channel statistics. The proposed method relies on thestate-space model and enables detection on the basis of statistical theory.Chapter 6 presents another novel investigation that clarifies character-istics based on estimation processing and practically compares the Wienerand Kalman filters for stationary processes. Under fair conditions, theperformance and complexity of each method are numerically investigated.Comparison results show that the performance of the Wiener smoother isslightly better that that of the Kalman one; the former avoids cumulativeerrors in its sequential processing, while the complexity of the latter is al-ways lower because there is no large matrix operation. Finally, a summaryof the discussions in the preceding chapters is given in Chapter 7.In wireless OFDM channel estimation, channel statistics have not beenconsidered sufficiently until now, having been assumed to be either knownor extractable. Our precise and pragmatic proposed methods should con-siderably improve the quality of mobile communication. Moreover, ourproposal is mathematically formulated and is applicable to not only wire-less technology but also related areas such as artificial intelligence andeconometrics.(主査) 教授 大鐘 武雄, 教授 宮永 喜一, 教授 齊藤 晋聖情報科学研究科(メディアネットワーク専攻)
- DOI
- 10.14943/doctoral.k12485
- 国立国会図書館永続的識別子
- info:ndljp/pid/10310774
- コレクション(共通)
- コレクション(障害者向け資料:レベル1)
- コレクション(個別)
- 国立国会図書館デジタルコレクション > デジタル化資料 > 博士論文
- 収集根拠
- 博士論文(自動収集)
- 受理日(W3CDTF)
- 2017-03-02T13:20:07+09:00
- 記録形式(IMT)
- PDF
- オンライン閲覧公開範囲
- 国立国会図書館内限定公開
- デジタル化資料送信
- 図書館・個人送信対象外
- 遠隔複写可否(NDL)
- 可
- 連携機関・データベース
- 国立国会図書館 : 国立国会図書館デジタルコレクション