  The number of LTE users and their applications has increased significantly in
the last decade, which increased the demand on the mobile network. LTE-Advanced
comes with many features that can support this increasing demand. LTE-Advanced
supports Heterogeneous Networks deployment, in which it consists of a mix of
macro-cells, remote radio heads, and low power nodes such as Pico-cells, and
Femto-cells. Embedding this mix of base-stations in a macro-cellular network
allows for achieving significant gains in coverage, throughput and system
capacity compared to the use of macro-cells only. These base-stations can
operate on the same wireless channel as the macro-cellular network, which will
provide higher spatial reuse via cell splitting. Also, it allows network
operators to support higher data traffic by offloading it to smaller cells,
such as Femto-cells. Hence, it enables network operators to provide their
growing number of users with the required Quality of Service that meets with
their service demands. In-order for the network operators to make the best out
of the heterogeneous LTE-Advanced network, they need to use QoS-based packet
scheduling algorithms that can efficiently manage the spectrum resources in the
heterogeneous deployment. In this paper, we survey Quality of Service based
packet scheduling algorithms that were proposed in the literature for the use
of packet scheduling in Heterogeneous LTE-Advanced Networks. We start by
explaining the concepts of QoS in LTE, heterogeneous LTE-Advanced networks, and
how traffic is classified within a packet scheduling architecture for
heterogeneous LTE-Advanced networks. Then, by summarising the proposed
QoS-based packet scheduling algorithms in the literature for heterogeneous
LTE-Advanced Networks, and for Femtocells LTE-Advanced Networks. And finally,
we provide some concluding remarks in the last section.
