On the tightness of inner and outer bounds for broadcast channels with three and more receivers.

• Other Authors: Wang, Zizhou
• Format: Others
• Language: English; Chinese
• Published: 2010
• Subjects: Broadcast data systems > Mathematical models; Multichannel communication > Mathematical models; Wireless communication systems > Mathematical models
• Online Access: http://library.cuhk.edu.hk/record=b6074892; http://repository.lib.cuhk.edu.hk/en/item/cuhk-344525

The last part considered a k-receiver broadcast channel with two unmatched degraded components, and degraded message sets where receiver Ys, s ∈ {1, ··· , k} requires messages (Ms, ··· , Mk). We established the capacity region for this class of broadcast channels by showing that superposition coding is optimal. In the process of proving the achievability, we showed a general superposition coding region for any broadcast channels with degraded message requirement. === The main contributions in this thesis consist of the following three parts: The first part studied the existing inner and outer bounds to the capacity region for 3-receiver broadcast channels with 2-degraded message sets, in an attempt to find the deficiencies with the current techniques of establishing the bounds. We produced a simple example where we were able to explicitly evaluate these bounds to show that they are indeed different. For a class of channels where the bounds differ, we used a new argument to show that the inner bound is tight and outer bound is weak. === The second part considered a broadcast channel consisting of k receivers that lie in a less noisy sequence. The capacity region for this scenario had been unknown since the mid 1970s, when k ≥ 3. We solved this open problem for the case k = 3. Indeed we proved that superposition coding is optimal for a class of broadcast channels with a sequence of less noisy receivers. This class contains the k = 3 case, thus resolving its capacity region. === This thesis focused on a fundamental problem of network information theory called broadcast channel, which models the communication from a single sender to multiple receivers (say, from a cellular tower to cell phone users in its coverage area). The goal is to determine the set of achievable communication data rates where each receiver can decode the messages it requires with high fidelity. From a purely theoretical standpoint, however, this problem of characterizing the feasible rate region (capacity region) had stumped researchers for over three decades. === Wang, Zizhou. === Advisers: Shua-Yen Robert Li; Nair Chandra M. === Source: Dissertation Abstracts International, Volume: 72-04, Section: B, page: . === Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. === Includes bibliographical references (leaves 67-70). === Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. === Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. === Abstract also in Chinese.