M.Sc Thesis

M.Sc StudentHomri Adi
SubjectOblivious Processing on a Gaussian Channel by a
Fronthaul Constrained Relay
DepartmentDepartment of Electrical and Computer Engineering
Supervisor PROF. Shlomo Shamai )Shitz(


Relaying exploits intermediate nodes to achieve communication between two distant nodes. We examine the ‘oblivious’ relay system that is, the specific codebooks used are unknown at the relay. In our setting, the transmitter conveys messages to the receiver through a capacity-limited fronthaul connected relay. The channel between the transmitter and the relay-station is modeled by a frequency selective additive Gaussian noise channel. We provide a comprehensive survey of relevant literature.
 We find the reliable information rate that can be achieved with Gaussian signaling,
and to that end, employ Gaussian bottleneck results combined with Shannon’s incremental frequency approach. We also prove that unlike classical water-pouring, the allocated spectrum (power and bit-rate) of the optimal solution could be discontinuous, and sometimes do not employ all available channel frequency  resources. We further study the oblivious relay operation under a limited entropy constraint of the quantized signal. This facilitates application of distortionless universal compressors, such as the Lempel-Ziv algorithm which are standard and
of limited complexity as compared to universal source coding procedures. It is shown that in this setting a per symbol deterministic quantizer is optimal. We present lower and upper bounds on the optimal performance (in terms of mutual information), and derive an analytical approximation.