Efficient use of paired spectrum bands through TDD small cell deployments

TL;DR

This paper explores using unpaired TDD spectrum for small cell deployments to improve spectrum efficiency amid asymmetric DL/UL traffic, by offloading users from traditional FDD systems.

Contribution

It proposes a novel approach of leveraging TDD spectrum for small cells to enhance spectrum utilization and traffic management in LTE networks.

Findings

TDD spectrum can alleviate DL saturation in FDD systems.

User offloading to TDD small cells improves spectrum efficiency.

The approach aligns with LTE standardization and regulatory considerations.

Abstract

Traditionally, wireless cellular systems have been designed to operate in Frequency Division Duplexing (FDD) paired bands that allocates the same amount of spectrum for both downlink (DL) and uplink (UL) communication. Such design is very convenient under symmetric DL/UL traffic conditions, as it used to be the case when the voice transmission was the predominant service. However, with the overwhelming advent of data services, bringing along large asymmetries between DL and UL, the conventional FDD solution becomes inefficient. In this regard, flexible duplexing concepts aim to derive procedures for improving the spectrum utilization, by adjusting resources to the actual traffic demand. In this work we review these concepts and propose the use of unpaired Time Division Duplexing (TDD) spectrum on the unused resources for small eNBs (SeNB), so that user equipment (UEs) associated to those SeNB could be served either in DL or UL. This proposal alleviates the saturated DL in FDD-based system through user offloading towards the TDD-based system. The flexible duplexing concept is analyzed from three points of view: a) regulation, b) Long Term Evolution (LTE)standardization, and c) technical solutions.