Theses Doctoral

Coding Techniques for Advanced Wireless Communication Systems

Gong, Chen

Motivated by the ever increasing demand of wireless communication for larger capacity and higher quality, wireless communication system grows from a single-pair point-to-point communication system to a multiple-transceiver pair communication network. Various new communication techniques, for example, cooperative communication, interference management, multi-carrier communication, are employed to enhance the system capacity and improve the communication quality. Even for some single-pair communication scenarios, due to the different quality demands for different types of information messages, more advanced coding schemes should be designed to provide more protection for more important information messages, for example, the system emergency message.
This thesis proposes several coding schemes to address the above questions. More specifically, the proposed coding schemes are summarized as follows.
Message-wise error protection is a new unequal error protection scheme where in a codebook some special messages are more protected than other ordinary messages. We propose the first practical coding scheme for message-wise error protection based on LDPC codes, where codeword flipping is employed to separate the special message codewords from the ordinary message codewords.
We consider a half-duplex 4-node joint relay system with two sources, one relay, and one destination, where the relay combines the information from both sources and transmits it to the destination together with both sources. We propose joint network and channel coding schemes based on the superposition coding (SC) and the Raptor coding (RC), and design practical Raptor codes for the proposed coding schemes.
We propose novel coding and decoding methods for a fully connected K-user Gaussian interference channel. Each transmitter encodes its information into multiple layers and transmits the superposition of those layers. Each receiver performs a twofold task by first identifying which interferers it should decode and then determining which layers of them should be decoded. We propose practical coding schemes that employ the quadrature amplitude modulations (QAM) and Raptor codes.
We propose group decoding and the associated rate allocation schemes for the multi-relay assisted interference channels, where both the relays and the destinations employ constrained group decoding. We consider two types of relay systems, the hopping relay system with no direct source-destination links, and the inband relay system with direct source-destination links. For each relay type, our objective is to design the relay assignment and group decoding strategies at the relays and destinations, to maximize the minimum information rate among all source-destination pairs.
We consider a distributed storage system employing some existing regenerate codes where the storage nodes are scattered in a wireless network. The existing full-downloading approach, where the data collector downloads all symbols from a subset of the storage nodes for data reconstruction, becomes less efficient in wireless networks. This is because that, due to fading, the wireless channels may not offer sufficient bandwidths for full downloading.
We propose a partial downloading scheme that allows downloading a portion of the symbols from any storage node, and formulate a cross-layer wireless resource allocation problem for data reconstruction employing such partial downloading. We derive necessary and sufficient conditions for the data reconstructability for partial downloading, in terms of the numbers of downloaded symbols from the storage nodes. We also propose channel and power allocation schemes for partial downloading in wireless distributed storage systems.


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More About This Work

Academic Units
Electrical Engineering
Thesis Advisors
Wang, Xiaodong
Ph.D., Columbia University
Published Here
March 20, 2014