This paper presents a scheduling scheme for packet transmission in OFDM wireless system with adaptive techniques.The concept of efficient transmission capacity is introduced to make scheduling decisions based on chann...This paper presents a scheduling scheme for packet transmission in OFDM wireless system with adaptive techniques.The concept of efficient transmission capacity is introduced to make scheduling decisions based on channel conditions.We present a mathematical technique for determining the optimum transmission rate, packet size, Forward Error Correction and constellation size in wireless system that have multi-carriers for OFDM modulation in downlink transmission. The throughput is defined as the number of bits per second correctly received. Trade-offs between the throughput and the operation range are observed, and equations are derived for the optimal choice of the design variables. These parameters are SNR dependent and can be adapted dynamically in response to the mobility of a wireless data terminal. We also look at the joint optimization problem involving all the design parameters together. In the low SNR region it is achieved by adapting the symbol rate so that the received SNR per symbol stays at some preferred value. Finally, we give a characterization of the optimal parameter values as functions of received SNR Simulation results are given to demonstrate efficiency of the scheme.展开更多
针对长期演进技术（LTE）下行多输入多输出正交频分多址链路（MIMO-OFDM）中的天线间干扰和多径干扰的问题,提出一种低复杂度的基于预编码矩阵的迭代均衡算法。该算法通过预编码矩阵将发射信号扩展到所有子载波上,降低由天线引起的部分...针对长期演进技术（LTE）下行多输入多输出正交频分多址链路（MIMO-OFDM）中的天线间干扰和多径干扰的问题,提出一种低复杂度的基于预编码矩阵的迭代均衡算法。该算法通过预编码矩阵将发射信号扩展到所有子载波上,降低由天线引起的部分子载波干扰。在接收端,利用最小均方误差排序QR分解（MMSE-SQRD）软输入软输出干扰消除均衡算法,从而避免传统基于MMSE并行软干扰消除均衡算法中矩阵求逆运算,进而降低了算法复杂度。在接收端,同时通过预编码对重建信号中误差进行扩展,进而缓解在迭代干扰消除过程中的误差传播。研究结果表明：在2发2收场景下,当误码率为10-3时,本文算法经过5次迭代后信噪比相比于传统MMSE-SQRD的迭代算法提高4.4~5.0 d B。展开更多
文摘This paper presents a scheduling scheme for packet transmission in OFDM wireless system with adaptive techniques.The concept of efficient transmission capacity is introduced to make scheduling decisions based on channel conditions.We present a mathematical technique for determining the optimum transmission rate, packet size, Forward Error Correction and constellation size in wireless system that have multi-carriers for OFDM modulation in downlink transmission. The throughput is defined as the number of bits per second correctly received. Trade-offs between the throughput and the operation range are observed, and equations are derived for the optimal choice of the design variables. These parameters are SNR dependent and can be adapted dynamically in response to the mobility of a wireless data terminal. We also look at the joint optimization problem involving all the design parameters together. In the low SNR region it is achieved by adapting the symbol rate so that the received SNR per symbol stays at some preferred value. Finally, we give a characterization of the optimal parameter values as functions of received SNR Simulation results are given to demonstrate efficiency of the scheme.
文摘针对长期演进技术（LTE）下行多输入多输出正交频分多址链路（MIMO-OFDM）中的天线间干扰和多径干扰的问题,提出一种低复杂度的基于预编码矩阵的迭代均衡算法。该算法通过预编码矩阵将发射信号扩展到所有子载波上,降低由天线引起的部分子载波干扰。在接收端,利用最小均方误差排序QR分解（MMSE-SQRD）软输入软输出干扰消除均衡算法,从而避免传统基于MMSE并行软干扰消除均衡算法中矩阵求逆运算,进而降低了算法复杂度。在接收端,同时通过预编码对重建信号中误差进行扩展,进而缓解在迭代干扰消除过程中的误差传播。研究结果表明：在2发2收场景下,当误码率为10-3时,本文算法经过5次迭代后信噪比相比于传统MMSE-SQRD的迭代算法提高4.4~5.0 d B。
