针对半双工译码转发中继信道,提出了一种可逼近三节点中继信道容量限的空间耦合RA码的设计方法。针对二进制删除信道,源节点分别向中继节点和目的节点发送空间耦合RA码,中继节点先正确恢复出源节点发送的空间耦合RA,然后再次编码产生额...针对半双工译码转发中继信道,提出了一种可逼近三节点中继信道容量限的空间耦合RA码的设计方法。针对二进制删除信道,源节点分别向中继节点和目的节点发送空间耦合RA码,中继节点先正确恢复出源节点发送的空间耦合RA,然后再次编码产生额外的校验比特并转发给目的节点;目的节点结合中继节点发送的额外校验比特和源节点发送的空间耦合RA码进行译码,正确恢复出源节点的信息。为了评估所设计的空间耦合RA码在三节点中继信道下的渐近性能,推导了密度进化算法用于计算阈值。阈值分析结果表明,所提出的空间耦合RA码能够同时逼近源到中继链路和源到目的链路的容量限。同时,基于半双工二进制删除中继信道,仿真了所设计的空间耦合RA码的误码性能,结果表明,其误码性能与所推导的密度进化算法计算的阈值结果一致,呈现出逼近于容量限的优异性能,且优于采用空间耦合低密度奇偶校验(Low Density Parity Check,LDPC)码的性能。展开更多
In China today, learning English is very much in vogue, especially in big cities like Beijing, Shanghai and many others. Young people in their early twenties with a good command of English or just a little more than a...In China today, learning English is very much in vogue, especially in big cities like Beijing, Shanghai and many others. Young people in their early twenties with a good command of English or just a little more than a nodding acquaintance with the language find it easier to secure a desirable job than those without. As a result, short-term English training courses are springing up like mushrooms everywhere across the country. However, many people are heard to complain that however hard they work at English and however much time they spend on it, they are always unduly rewarded in progress. When asked about its cause, they all attribute it to what they call “inadequate vocabulary”. Is that so? Here, I have to disagree with my young friends.Words in a language play the same part as bricks do in civil engineering; they make up the elementary components of both. Yet words alone, however numerous, if devoid of the art of arranging them in a prescribed way, can never be organized into an intelligible speech in the same way as a man in mere possession of bricks yet without the knowledge of architecture can never put up a building.展开更多
文摘针对半双工译码转发中继信道,提出了一种可逼近三节点中继信道容量限的空间耦合RA码的设计方法。针对二进制删除信道,源节点分别向中继节点和目的节点发送空间耦合RA码,中继节点先正确恢复出源节点发送的空间耦合RA,然后再次编码产生额外的校验比特并转发给目的节点;目的节点结合中继节点发送的额外校验比特和源节点发送的空间耦合RA码进行译码,正确恢复出源节点的信息。为了评估所设计的空间耦合RA码在三节点中继信道下的渐近性能,推导了密度进化算法用于计算阈值。阈值分析结果表明,所提出的空间耦合RA码能够同时逼近源到中继链路和源到目的链路的容量限。同时,基于半双工二进制删除中继信道,仿真了所设计的空间耦合RA码的误码性能,结果表明,其误码性能与所推导的密度进化算法计算的阈值结果一致,呈现出逼近于容量限的优异性能,且优于采用空间耦合低密度奇偶校验(Low Density Parity Check,LDPC)码的性能。
文摘In China today, learning English is very much in vogue, especially in big cities like Beijing, Shanghai and many others. Young people in their early twenties with a good command of English or just a little more than a nodding acquaintance with the language find it easier to secure a desirable job than those without. As a result, short-term English training courses are springing up like mushrooms everywhere across the country. However, many people are heard to complain that however hard they work at English and however much time they spend on it, they are always unduly rewarded in progress. When asked about its cause, they all attribute it to what they call “inadequate vocabulary”. Is that so? Here, I have to disagree with my young friends.Words in a language play the same part as bricks do in civil engineering; they make up the elementary components of both. Yet words alone, however numerous, if devoid of the art of arranging them in a prescribed way, can never be organized into an intelligible speech in the same way as a man in mere possession of bricks yet without the knowledge of architecture can never put up a building.
