Sparse code multiple access(SCMA) is a novel non-orthogonal multiple access scheme proposed to meet the challenging demand of the future 5G communications, especially in support of the massive connections. The coded b...Sparse code multiple access(SCMA) is a novel non-orthogonal multiple access scheme proposed to meet the challenging demand of the future 5G communications, especially in support of the massive connections. The coded bits from each data stream will be directly mapped as multi-dimensional SCMA codeword in complex domain and then spread onto the physical resource elements in a sparse manner. The number of codewords that can be nonorthogonally multiplexed in one SCMA block can be made much larger than the number of orthogonal resource elements therein, resulting in an overloaded system. The sparsity in the spreading pattern and the design in the multidimensional modulator jointly ensure the SCMA codewords can be robustly decoded with low complexity. In this paper, we focus on the low complexity receiver design and verified the superior of an SCMA system via simulations and real-time prototyping. Lab tests and field tests all show that SCMA is a promising candidate for 5G non-orthogonal multiple access which can provide up to 300% overloading that triples the whole system throughput while still enjoying the link performance close to orthogonal transmissions.展开更多
针对车载网络、远程医疗、工业控制等领域需要低时延、高可靠性的网络传输应用场景,提出了一种经验回放的DQN(experience replay DQN,ERDQN)数据传输调度算法。该算法的主要目的和任务是降低网络时延和提高网络传输的稳定性。ERDQN算法...针对车载网络、远程医疗、工业控制等领域需要低时延、高可靠性的网络传输应用场景,提出了一种经验回放的DQN(experience replay DQN,ERDQN)数据传输调度算法。该算法的主要目的和任务是降低网络时延和提高网络传输的稳定性。ERDQN算法在最后期限感知的传输协议(deadline-aware transport protocol,DTP)的基础上优化了发送端的排队策略,充分考虑了数据块的优先级和截止日期(Deadline),将其作为计算进入等待队列顺序的重要因素,解决了数据块丢失Deadline的问题,降低了网络传输的排队延迟;同时在拥塞控制方面以当前时刻网络传输状态为特征向量,预测下一时刻网络传输状态参数,并赋予不同的奖励因子进行评估,通过ERDQN网络的迭代学习,自动调整到适合当前网络传输的最优参数,在后续的网络链路传输过程中,平均传输速率高且稳定,缓解了网络拥塞和传输不稳定的问题,降低了网络传输时延。实验结果表明ERDQN算法的平均排队时延和传输时延远远低于传统拥塞控制算法(Reno算法),在质量系数(quality of experience,QoE)方面远远高于传统的拥塞控制算法,能够最大程度减少网络传输速率波动、降低丢包率,提供稳定可靠的传输。展开更多
文摘Sparse code multiple access(SCMA) is a novel non-orthogonal multiple access scheme proposed to meet the challenging demand of the future 5G communications, especially in support of the massive connections. The coded bits from each data stream will be directly mapped as multi-dimensional SCMA codeword in complex domain and then spread onto the physical resource elements in a sparse manner. The number of codewords that can be nonorthogonally multiplexed in one SCMA block can be made much larger than the number of orthogonal resource elements therein, resulting in an overloaded system. The sparsity in the spreading pattern and the design in the multidimensional modulator jointly ensure the SCMA codewords can be robustly decoded with low complexity. In this paper, we focus on the low complexity receiver design and verified the superior of an SCMA system via simulations and real-time prototyping. Lab tests and field tests all show that SCMA is a promising candidate for 5G non-orthogonal multiple access which can provide up to 300% overloading that triples the whole system throughput while still enjoying the link performance close to orthogonal transmissions.
文摘针对车载网络、远程医疗、工业控制等领域需要低时延、高可靠性的网络传输应用场景,提出了一种经验回放的DQN(experience replay DQN,ERDQN)数据传输调度算法。该算法的主要目的和任务是降低网络时延和提高网络传输的稳定性。ERDQN算法在最后期限感知的传输协议(deadline-aware transport protocol,DTP)的基础上优化了发送端的排队策略,充分考虑了数据块的优先级和截止日期(Deadline),将其作为计算进入等待队列顺序的重要因素,解决了数据块丢失Deadline的问题,降低了网络传输的排队延迟;同时在拥塞控制方面以当前时刻网络传输状态为特征向量,预测下一时刻网络传输状态参数,并赋予不同的奖励因子进行评估,通过ERDQN网络的迭代学习,自动调整到适合当前网络传输的最优参数,在后续的网络链路传输过程中,平均传输速率高且稳定,缓解了网络拥塞和传输不稳定的问题,降低了网络传输时延。实验结果表明ERDQN算法的平均排队时延和传输时延远远低于传统拥塞控制算法(Reno算法),在质量系数(quality of experience,QoE)方面远远高于传统的拥塞控制算法,能够最大程度减少网络传输速率波动、降低丢包率,提供稳定可靠的传输。
