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arXiv 1903.07597cs.ITmath.IT
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关于计算广播的容量

On the Capacity of Computation Broadcast

Hua Sun, Syed A. Jafar

摘要:

两个用户计算广播问题被引入作为其中用户$1$想要消息$W_1$并且具有边信息$W_1'$、用户$2$想要消息$W_2$并且具有边信息$W_2'$、并且$(W_1, W_1', W_2, W_2')$可以具有任意依赖性的设置。计算广播方案的速率被定义为比率$H(W_1,W_2)/H(S)$,其中$S$是广播给两个用户以同时满足他们的需求的信息。可达速率的上确界称为计算广播容量$C_{CB}$。结果表明,$C_{CB}\leq H(W_1,W_2)/\left[H(W_1|W_1')+H(W_2|W_2')-\min\Big(I(W_1; W_2, W_2'|W_1'), I(W_2; W_1, W_1'|W_2')\Big)\right]$ .对于线性计算广播问题,其中$W_1, W_1', W_2, W_2'$是由一个独立的符号的基集的任意线性组合,边界被证明是紧的。对于非线性计算广播,它表明,这个界是不紧的一般。通过实例证明了具有相同熵结构的不同计算广播实例,对于$\{W_1,W_1',W_2,W_2'\}$的所有子集,相同的熵可以具有不同的容量。因此,即使对于两个用户的计算广播,额外的熵结构也很重要。通过一类非线性计算广播问题,其中容量的极值被证明对应于该类中的最小和最大结构问题,进一步探讨了额外的熵结构的意义。

英文摘要:

The two-user computation broadcast problem is introduced as the setting where User $1$ wants message $W_1$ and has side-information $W_1'$, User $2$ wants message $W_2$ and has side-information $W_2'$, and $(W_1, W_1', W_2, W_2')$ may have arbitrary dependencies. The rate of a computation broadcast scheme is defined as the ratio $H(W_1,W_2)/H(S)$, where $S$ is the information broadcast to both users to simultaneously satisfy their demands. The supremum of achievable rates is called the capacity of computation broadcast $C_{CB}$. It is shown that $C_{CB}\leq H(W_1,W_2)/\left[H(W_1|W_1')+H(W_2|W_2')-\min\Big(I(W_1; W_2, W_2'|W_1'), I(W_2; W_1, W_1'|W_2')\Big)\right]$. For the linear computation broadcast problem, where $W_1, W_1', W_2, W_2'$ are comprised of arbitrary linear combinations of a basis set of independent symbols, the bound is shown to be tight. For non-linear computation broadcast, it is shown that this bound is not tight in general. Examples are provided to prove that different instances of computation broadcast that have the same entropic structure, i.e., the same entropy for all subsets of $\{W_1,W_1',W_2,W_2'\}$, can have different capacities. Thus, extra-entropic structure matters even for two-user computation broadcast. The significance of extra-entropic structure is further explored through a class of non-linear computation broadcast problems where the extremal values of capacity are shown to correspond to minimally and maximally structured problems within that class.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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