Graduate School and Research Center in Digital Sciences

Wireless coded caching: A topological perspective

Zhang, Jingjing; Elia, Petros

ISIT 2017, IEEE International Symposium on Information Theory, June 25-30, 2017, Aachen, Germany

We explore the performance of coded caching in a SISO BC setting where some users have higher link capacities than others. Focusing on a binary and  fixed topological model where strong links have a fixed normalized capacity 1, and where weak links  have reduced normalized capacity τ < 1, we identify -- as a function of the cache size and τ -- the optimal throughput performance, within a factor of at most 8. The transmission scheme that achieves this performance, employs a simple form of  interference enhancement, and exploits the property that weak links attenuate interference, thus allowing for multicasting rates to remain high even when involving weak users. This approach ameliorates the negative effects of uneven topology in multicasting, now allowing all users to achieve the optimal performance associated to τ = 1, even if τ is approximately as low as τ ≥ 1 − (1 − w)g where g is the coded-caching gain, and where w is the fraction of users that are weak. This leads to the interesting conclusion that for coded multicasting, the weak users need not bring down the performance of all users, but on the contrary to a certain extent, the strong users can  lift the performance of the weak users without any penalties on their own performance. Furthermore for smaller ranges of τ , we also see that achieving the near-optimal performance comes with the advantage that the strong users do not suffer any additional delays compared to the case where τ = 1.    

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Title:Wireless coded caching: A topological perspective
Department:Communication systems
Eurecom ref:4953
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Bibtex: @inproceedings{EURECOM+4953, doi = {http://dx.doi.org10.1109/ISIT.2017.8006558}, year = {2017}, title = {{W}ireless coded caching: {A} topological perspective}, author = {{Z}hang, {J}ingjing and {E}lia, {P}etros}, booktitle = {{ISIT} 2017, {IEEE} {I}nternational {S}ymposium on {I}nformation {T}heory, {J}une 25-30, 2017, {A}achen, {G}ermany}, address = {{A}achen, {GERMANY}}, month = {06}, url = {} }
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