We consider the information-theoretic optimality of treating inter-cell interference as noise (multi-cell TIN) in downlink cellular networks. We focus on scenarios modeled by the Gaussian interfering broadcast channel (IBC), comprising $K$ mutually interfering Gaussian broadcast channels (BCs), each formed by a base station communicating independent messages to an arbitrary number of users. We establish a new power allocation duality between the IBC and its dual interfering multiple access channel (IMAC), which entails that the corresponding generalized degrees-of-freedom regions achieved through multi-cell TIN and power control (TINA regions) for both networks are identical. As by-products of this duality, we obtain an explicit characterization of the IBC TINA region from a previously established characterization of the IMAC TINA region; and identify a multi-cell convex-TIN regime in which the IBC TINA region is a polyhedron (hence convex) without the need for time-sharing. We then identify a smaller multi-cell TIN regime in which the IBC TINA region is optimal and multi-cell TIN achieves the entire capacity region of the IBC, up to a constant gap. This is accomplished by deriving a new genie-aided outer bound for the IBC, that reveals a novel BC-type order that holds amongst users in each constituent BC (or cell) under inter-cell interference, which in turn is not implied by previously known BC-type orders (i.e. degraded, less noisy and more capable orders). The multi-cell TIN regime that we identify for the IBC coincides with a corresponding multi-cell TIN regime previously identified for the IMAC, hence establishing a comprehensive uplink-downlink duality of multi-cell TIN in the GDoF (and approximate capacity) sense.
翻译:我们认为将细胞间干扰视为下行网络中的噪音(多细胞TIN)的信息理论最佳性。我们侧重于由高盛干扰广播频道(IBC)模拟的情景,由高盛干扰广播频道(IBC)组成,每台由基地站组成,将独立信息传递给任意用户。我们在IBC及其双重干扰多个接入频道(IMAC)之间建立了新的权力分配双重性,这意味着两个网络通过多细胞TIN和电力控制(TINA区域)实现相应的普遍自由程度(TINA区域)完全相同。作为这种双重性的副产品,我们从以前确立的IMAC TIN区域特征中获得了对IBC TIN广播频道(BC TIN区域)的清晰描述;确定了多细胞间连接-TIN系统(IBC区域)的混合性(hence convexxx),然后我们确定了一个较小的多细胞TINA(IBC区域)的深度和多细胞间交易(IMINA区域)的深度和多细胞间规则。我们先前确定的IMINA系统显示,一个固定的直径直径直径直径的内,一个直径的内端的内端的BC的BC(IBC系统)的内,一个直径直径的内,一个直径的内,一个直径的内,一个直系的内,一个直系的直系的直径。