Design of a New Complex Sphere Decoder for Soft-Output MIMO Detection
Date Issued
2007
Date
2007
Author(s)
Wang, To-Ping
DOI
zh-TW
Abstract
The services, such as on-line videos, high definition TV (HDTV), interactive games, provided by the next generation wireless communication systems produce the demand for much higher throughput and better Quality of Service (QoS) under the situation of limited bandwidth. Nowadays, OFDM is widely adopted to improve bandwidth utilization in many communication systems and has become the main modulation technique of many standards. In the future, MIMO will be the next widely accepted technique because of its provision for diversity and spectrum efficiency.
MIMO system can easily satisfy the demand for high throughput by increasing the number of transmit and receive antennas. For the QoS concern, the detection complexity grows exponential with the antenna number in theory. Corresponding literatures propose sphere decoder to mitigate this problem and conserve the near ML performance. However, the arithmetic complexity is still much more than other detection schemes.
In order to overcome this trade-off problem, the thesis combines modified tabular enumeration and best-first tree search algorithm and therefore proposes the new sphere decoding algorithm: modified best-first (MBF) algorithm. After mathematic induction and software simulation by the iterative MIMO detection & decoding system, we demonstrate that MBF can not only reduce the enumeration complexity, especially for high-order QAM, but also conserve high performance from the characteristic of the best-first algorithm. Besides, in order to avoid the performance attenuation of high dimension MIMO system, we integrate successive interference cancellation algorithm, early termination algorithm and MBF into proposed MBF-SIC algorithm. Finally, we give the hardware design to show that the proposed soft-output MIMO complex-plane sphere decoder composed of MBF-SIC is reasonable for hardware implementation.
Subjects
多輸入多輸出系統信號偵測
軟性解調輸出
迭代解碼
球面解碼器
MIMO detection
soft-output
iterative decoding
sphere decoder
Type
thesis
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