A Simulation Study of Hyper-Cellular Architecture
with Dynamic Temporal and Spatial Traffic
Zhengteng Zhu, Xiao Xu, Xi Zheng, Yuxuan Sun, Sheng Zhou, Jie Gong, Zhisheng Niu
Tsinghua National Laboratory for Information Science and Technology
Department of Electronic Engineering, Tsinghua University
Beijing, China
Email: zhuzt13@mails.tsinghua.edu.cn; sheng.zhou@tsinghua.edu.cn
Abstract—To provide the paradigm shift of green cellular
communications, Hyper Cellular Architecture (HCA), has been
proposed, in which the common control functionalities are de-
coupled from the data service functionalities at base station (BS)
level so that the traffic BSs can be more adaptive to the temporal
and spatial traffic fluctuations. In this paper, we develop a system
level simulator (SLS) for HCA to evaluate the HCA performance
under temporal and spatial traffic fluctuations. The SLS enjoys
low complexity, open interface and completed functions through
the carefully tuned modeling on long-term large-scale traffic
model, the separation architecture and the resource allocation
strategies. Simulation results show that even with some basic
BS sleeping algorithms, HCA can achieve up to 45% energy
efficiency (EE) gain over conventional cellular architecture with
macro BSs only or heterogeneous network during the low traffic
period, and about 36% EE gain on average for a typical daily
traffic pattern.
Keywords—system level simulation; hyper-cellular architecture;
dynamic traffic
I. INTRODUCTION
The next generation 5G cellular network is committed to
connect at least 100 billion devices, and achieve a 10 Gb/s
individual user experience capable of extremely low latency
and response times. [1]. Many innovatory technologies have
been introduced from the aspects of higher spectral efficiency,
denser cell deployment and so on [2].
However, as the capacity performance improves in 5G
networks, the system energy consumption increase rapidly [3].
Hence, the EE (Energy Efficiency) of cellular system should
be taken into account. In cellular networks, base stations (BSs)
consume a large portion of energy. Consequently, when traffic
load is low, it is necessary to reduce energy consumption by
BS sleeping, i.e. adapting energy consumption to the dynamic
traffic profile.
Hyper-cellular architecture (HCA), which separates control
signaling and data service, provides possibility to dynamically
schedule/coordinate the operation of BSs, according to the
spatial and temporal fluctuations of the traffic demand [3].
The notion of separation architecture, proposed in [4], [5] and
[6], focuses on the functional separation of control signaling
and data service in BSs. HCA consists of two kinds of BSs to
carry the control signaling and data traffic, namely the control
BS (CBS) and the traffic BS (TBS), respectively. In HCA the
common control functionalities are decoupled from the data
service functionalities at BS level so that the TBSs can be more
adaptive to the temporal and spatial traffic fluctuations. By
introducing BS sleeping, the TBSs or part of it can be switched
off [7]. Accordingly, HCA is expected to have the potential
to increase the network EE by the utilization of separation
architecture.
To quantitatively evaluate the EE gain brought by HCA,
extensive simplifications have been done in traditional theo-
retical analysis, which can not reflect the whole picture of
system performance. System simulation provides an effective
way to analyze the system. To verify the feasibility of candi-
date resource management algorithms in real communication
systems, many simulators have been developed to evaluate
link level (LL) or system level (SL) performance. Simulators
can be classified into two types: dynamic simulators (DS) and
static simulators (SS). An SS based on snapshot intervals omits
temporal correlation of 2-layers heterogeneous networks [8],
while a DS consider network events continuously over time
is able to model user mobility, traffic models, channel models
and other network details. DSs possess advantages in accuracy
with rational compromise in time complexity, when compared
with SS. As far as concerned, there is exploration on LTE/LTE-
A simulator, such as [9]-[12].
However, the simulators mentioned above can not analyze
the EE metrics of the HCA separation architecture, and do
not apply long-term large-scale traffic model to simulate
the different granularities of traffic. In order to fulfill the
comprehensive requirement for evaluating the performance of
HCA, we develop an SL Dynamic Simulator. We decreases the
complexity of theoretical analysis effectively through 2-layers
simulation architecture explained in section III.
The main contributions of our work are listed as follows:
• We use dynamic system level simulation to model the
function details of HCA. As a result, we can conduct
power allocation strategy and radio resource management
with conventional network metrics, such as throughput,
outage probability and spectral efficiency.
• We implement the separation architecture for TBSs and
CBSs in the simulator to support multi-CBS, multi-
TBS and multi-user scenarios, where various BS sleeping
algorithms can be applied to increase the energy effi-
ciency under spatial and temporal traffic fluctuations with
different granularities.