[Legacy Report] IEEE seminar by Rohit Budhiraja on "Asymmetric Two-Way Relaying in Cellular Systems"

#IEEE #seminar

Relay-based communication is being actively investigated to meet the
demand of higher data rates and ubiquitous coverage in wireless systems.
The half-duplex constraint imposed on a relay, for ease of implementation,
prevents it from concurrently transmitting and receiving in the same time
slot. This reduces the spectral efficiency of conventional relaying, as two
time slots are required to transmit a single data unit.

Two-way relaying (TWR) exploits bi-directional data flow between two nodes
and eliminates this spectral loss by exchanging two data units in two time
slots. In TWR, it is assumed that a user simultaneously sends and receives
data from the base station via a relay. In cellular systems, data flow
between the base station and a user is usually not simultaneous e.g., a
user (say, TUE) may have uplink data to send in the first slot, but may not
have downlink data to receive in the second slot. Such uni-directional data
flow reduces TWR to spectrally-inefficient conventional relaying. We
propose an asymmetric two-way relaying (ATWR) protocol that restores the
bi-directional data flow via a relay and enables transmission of two data
units in two time slots. In ATWR, the second slot following the first-slot
transmission of a TUE is used to send downlink data to another user (say,
RUE). However, the RUE cannot cancel the back-propagating interference. We
design a structured precoder at the relay to cancel this interference. For
this precoder, we show that the optimization of various metrics e.g., sum
rate and relay transmit power, can be cast as convex geometric programs. We
demonstrate that the proposed solution outperforms the conventional ones.

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• Kanpur, Uttar Pradesh
• India

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