Payload Damage Estimation for Hybrid ARQ
Date Issued
2007
Date
2007
Author(s)
Wang, Wei-Chen
DOI
en-US
Abstract
Hybrid automatic retransmission request (HARQ) is an important technique for communications without CSI. When the retransmission arrives, as opposed to simple ARQ, in HARQ all the received transmissions for a payload are used together to determine the common underlying payload. This could allow the transmitter to be more aggressive in its selection of the transmission rate. Intuitively, the amount of resources that a transmitter needs to invest in a retransmission to repair a previously failed transmission depends on how severely the prior transmission is damaged. If the payload damage information (PDI) can be made available at the transmitter, it could signi‾cantly improve the effciency of retransmission. Compared to a typical HARQ scheme, a PDI-available HARQ transmission scheme requires the estimation and description of damage at the receiver and a corresponding resource allocation determination scheme at the transmitter. In this thesis, we investigate the problem of how and how well a receiver can estimate the damage suffered by a failed payload. First, we will show that in order to achieve the ultimate performance in damage estimation, one must estimate damage from the received signal itself. Auxiliary signals and the received payload can be used in the process of channel state estimation. As will be shown in this paper, fundamentally this type of approach cannot reach the optimal level of damage estimation. Next, we look at how the payload damage is to be estimated directly from the received signal. Our main approach is to carefully examine the geometrical space around the received signal to assess potential damage. The constellations near the received signal can be estimated using a multiple-output decoder such as a list decoder. To illustrate how the idea can be applied in practice, we introduce a simple yet effective damage estimator for an convolutionally-coded OFDM link over a frequency selective medium. We can compute the effective minimum distance of the received signal and apply this result to assist in designing retransmission mechanism. We also discuss the output patterns of list decoder in the rest of this thesis.
Subjects
混合自動重發請求
資料傳輸損害估計
多輸出解碼器
頻率選擇性衰減通道
hybrid ARQ
payload damage estimation
channel state information
frequency selective fading channel
multi-output decoder
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-96-R94942054-1.pdf
Size
23.31 KB
Format
Adobe PDF
Checksum
(MD5):b740ebbc9cf654a1312ce41a630f6f55