Future wireless access networks will support simultaneously a large number of devices with heterogeneous service requirements. These include data rates, error rates, and latencies. While there exist achievable rate and capacity results for Gaussian broadcast channels in the asymptotic regime, the characterization of second-order achievable rate regions for different blocklength constraints are not available. Therefore, we investigate a two-user Gaussian broadcast channel (GBC) with heterogeneous blocklength constraints under a maximal input power constraint and an average error probability constraint. Unlike the traditional GBC where two users have the same blocklength constraints, here the user with higher output SNR has a shorter blocklength constraint. We show that with sufficiently large output SNR, the stronger user can invoke the technique named early decoding (ED) to decode the interference. Then the successive interference cancellation (SIC) can proceed. This leads to an improved achievable rate region compared to the state of the art. To achieve it, we derive an explicit lower bound on the necessary number of received symbols for a successful ED, using an independent and identically distributed Gaussian input. A second-order rate of the weaker user who suffers from an SNR change due to the heterogeneous blocklength constraint, is also derived. We then formulate the rate region of the considered setting with individual and also sum power constraints and compare to that of the hybrid non-orthogonal multiple access (HNOMA) scheme. Numerical results show that ED has a larger rate region than HNOMA partly when the gain of the better channel is sufficiently larger than the weaker one. Under the considered setting, about 7-dB SNR gain can be achieved. This makes ED with SIC a promising technique for future wireless network.

中文翻译：

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异构块长度约束网络中的高斯广播信道

未来的无线接入网络将同时支持大量具有异构服务需求的设备。这些包括数据速率、错误率和延迟。虽然在渐近状态下存在高斯广播信道的可实现速率和容量结果，但对于不同块长度约束的二阶可实现速率区域的表征是不可用的。因此，我们研究了在最大输入功率约束和平均错误概率约束下具有异构块长度约束的双用户高斯广播信道 (GBC)。与两个用户具有相同块长度约束的传统 GBC 不同，这里具有较高输出 SNR 的用户具有较短的块长度约束。我们表明，具有足够大的输出 SNR，较强的用户可以调用称为早期解码 (ED) 的技术来解码干扰。然后可以继续进行连续干扰消除 (SIC)。与现有技术相比，这导致改进的可实现速率区域。为了实现它，我们使用独立且同分布的高斯输入推导出成功 ED 所需接收符号数量的显式下限。还导出了由于异构块长度约束而遭受 SNR 变化的较弱用户的二阶速率。然后，我们将所考虑设置的速率区域与单独的和功率约束相加，并与混合非正交多址 (HNOMA) 方案的速率区域进行比较。数值结果表明，当较好信道的增益比较弱信道的增益足够大时，ED 具有比 HNOMA 更大的速率区域。在所考虑的设置下，可以实现大约 7-dB SNR 增益。这使得带有 SIC 的 ED 成为未来无线网络的一项有前途的技术。