Fundamental Limits of Cooperation

By Angel E. Lozano, Robert W. Heath, Jeffrey G. Andrews. IEEE Transactions on Information Theory, 2012

342 citations recorded by the source corpus.

Cooperation is viewed as a key ingredient for interference management in wireless networks. This paper shows that cooperation has fundamental limitations. First, it is established that in systems that rely on pilot-assisted channel estimation, the spectral efficiency is upper-bounded by a quantity that does not depend on the transmit powers; in this framework, cooperation is possible only within clusters of limited size, which are subject to out-of-cluster interference whose power scales with that of the in-cluster signals. Second, an upper bound is also shown to exist if the cooperation extends to an entire (large) system operating as a single cluster; here, pilot-assisted transmission is necessarily transcended. Altogether, it is concluded that cooperation cannot in general change an interference-limited network to a noise-limited one. Consequently, the existing literature that routinely assumes that the high-power spectral efficiency scales with the log-scale transmit power provides only a partial characterization. The complete characterization proposed in this paper subdivides the high-power regime into a degree-of-freedom regime, where the scaling with the log-scale transmit power holds approximately, and a saturation regime, where the spectral efficiency hits a ceiling that is independent of the power. Using a cellular system as an example, it is demonstrated that the spectral efficiency saturates at power levels of operational relevance.

Subfields: Computer Networks and Communications, Electrical and Electronic Engineering

View Paper: https://www.semanticscholar.org/paper/33eec9b6e552b2c9d67eb6fcdd6180dcfae015db

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Citations in the corpus

Massive MIMO for Maximal Spectral Efficiency: How Many Users and Pilots Should Be Allocated? (2014, background): “The fundamental difference is that the DoF concept for P2P MIMO channels, where unbounded SE is achieved at high SNRs, does not apply to cellular networks [30].”
Topological Interference Management Through Index Coding (2013, background): “It is not surprising then that the DoF results for fully connected network models under realistic channel uncertainty tend to be overly pessimistic, often predicting a dramatic collapse of the DoF, when in fact practical networks work fine with even smaller amounts of CSIT [17], [18].”
User-Centric Cell-Free Massive MIMO Networks: A Survey of Opportunities, Challenges and Solutions (2021, background): “Thus, they do not focus on the topics explored herein.”
Five disruptive technology directions for 5G (2013, neutral): “tribution (e.g., via compressed sensing and/or multihop). ! Cooperative communications paradigms such as CoMP or relaying, which despite falling short of their initial hype are nonetheless beneficial [8], could require a redefinition of the functions of the different nodes. In the context of relayin”
Cell-Free Massive MIMO Versus Small Cells (2016, background): “A realistic analysis must account for imperfect CSI, which is an inevitable consequence of the finite channel coherence in a mobile system and which typically limits the performance of any wireless system severely [19].”
Seven ways that HetNets are a cellular paradigm shift (2013, result): “The Qualcomm HetNet system design team, for example, found that after accounting for necessary overheads, the “gains” from CoMP in a HetNet were less than 0% [16], while recent theoretical results show that if channel uncertainty and background interference are brought into the analysis, even the th”
A Joint Precoding Framework for Wideband Reconfigurable Intelligent Surface-Aided Cell-Free Network (2020, background): “The cooperation theory has determined that [6], the upper limit of the network capacity will be bounded by the inter-cell interference as long as the cell-centric network is used.”
What Will 5G Be? (2014, background): “This will require wholesale changes to the control plane and network management relative to 4G, whose overhead channels and state machines are not designed for such a diverse and large subscriber base.”
On the Total Energy Efficiency of Cell-Free Massive MIMO (2017, background): “However, it was shown in [3] that base station cooperation has fundamental limitations, i.”
Massive MIMO for next generation wireless systems (2013, background): “From a pure fundamental perspective, the ultimately limiting factor of the performance of any wireless network appears to be the availability of good enough channel state information (CSI), that facilitates phase-coherent processing at multiple antennas or multiple access points [20].”