Energy Efficiency in the Low-SNR Regime under Queueing Constraints and Channel Uncertainty
Energy Efficiency in the Low-SNR Regime under Queueing Constraints and Channel Uncertainty
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DOI：
10.1109/tcomm.2011.051311.090315
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发表时间：
2009-06
影响因子：
8.3
通讯作者：
Deli Qiao;M. C. Gursoy;Senem Velipasalar
中科院分区：
文献类型：
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作者：
Deli Qiao;M. C. Gursoy;Senem Velipasalar
研究了在信道不确定性和传输约束条件下，固定速率传输的能量效率问题。假设发射机和接收机在传输之前都不具有信道侧信息。信道系数在接收机处借助于训练符号经由最小均方误差（MMSE）估计来估计。进一步假设系统在缓冲区违规概率限制形式的统计约束下运行。确定分配给训练的功率的最佳分数。采用有效容量公式，分析了低功率和宽带系统中频谱效率-比特能量的权衡。特别是，它示出的位能量增加，而没有约束，在低功率政权的平均功率为零。如果非交互子信道的数量随着带宽的增加而无限制地增长，则在宽带范围内得出类似的结论。另一方面，它被证明，如果可解析的独立路径的数量，因此非相互作用的子信道的数量保持有界的可用带宽增加，位能量减少到其最小值在宽带制度。对于这种情况下，表达式的最小比特能量和宽带斜率。总的来说，信道不确定性的能量成本和嵌入约束被识别，并且确定多径丰富度和稀疏度的影响。
Energy efficiency of fixed-rate transmissions is studied in the presence of queueing constraints and channel uncertainty. It is assumed that neither the transmitter nor the receiver has channel side information prior to transmission. The channel coefficients are estimated at the receiver via minimum mean-square-error (MMSE) estimation with the aid of training symbols. It is further assumed that the system operates under statistical queueing constraints in the form of limitations on buffer violation probabilities. The optimal fraction of power allocated to training is identified. Spectral efficiency-bit energy tradeoff is analyzed in the low-power and wideband regimes by employing the effective capacity formulation. In particular, it is shown that the bit energy increases without bound in the low-power regime as the average power vanishes. A similar conclusion is reached in the wideband regime if the number of noninteracting subchannels grow without bound with increasing bandwidth. On the other hand, it is proven that if the number of resolvable independent paths and hence the number of noninteracting subchannels remain bounded as the available bandwidth increases, the bit energy diminishes to its minimum value in the wideband regime. For this case, expressions for the minimum bit energy and wideband slope are derived. Overall, energy costs of channel uncertainty and queueing constraints are identified, and the impact of multipath richness and sparsity is determined.