Grouping Based Uplink Resource Allocation for
Massive M2M Communications over LTE-A
Shaoyi Xu
1
, Junlong Li
2
, and Xintao Qin
1
,
Member, IEEE
1
School of Electronics and Information Engineering, Beijing Jiaotong University, Beijing, 10044, China
2
Huawei Technologies Co., Ltd., Beijing, China
E-mail: shyxu@bjtu.edu.cn, lijunlong@huawei.com, and 12120130@bjtu.edu.cn
Abstract—Deployment of massive machine type
communication devices (MTCDs) in the LTE-A network may
incur signaling and traffic congestion during the random access
(RA) and uplink scheduling. To overcome these problems, a
grouping based RA and uplink scheduling scheme is proposed in
this paper. The group leader will initiate RA and apply for the
uplink transmission resources on behalf of the group members.
Specifically, a second group paging scheme is designed to further
reduce the access delay and increase the access probability.
Implementation details are described in a practical LTE-A system
and simulations prove that our proposed approach outperforms
the traditional methods with respect to the access probability,
access time delay, collision probability and fairness.
Keywords—machine-to-machine (M2M); Machine Type
Communication Devices (MTCDs); Random Access (RA); Uplink
Scheduling; Signaling Congestion.
I.
I
NTRODUCTION
To support the so called “Internet of Things” and motivated
by the growing demands of machine-to-machine (M2M)
applications, it is expected that M2M devices will increase
greatly in the near future. An Ericsson report suggests that the
number of M2M devices by 2020 will be around 50 billion for
a projected population of around 8 billion at that time [1]. As a
result, many standardization bodies have been standardizing the
network architecture. In this sense, 3GPP has defined a new
device class category 0 for low-cost machine type
communication devices (MTCDs) and service provision aiming
to support the massive number of MTCDs connected to the
network [2]. It is also considered to be one of the main drivers
for the future 5G communication. Thus, 3GPP has raised the
need to revisit the design of LTE-A network to enable efficient
M2M communication.
It is known to all that there are two bottlenecks in M2M
communications. The first one is preamble collisions on
physical random access channel (PRACH) during random
access. When more than one MTCDs select the same preamble
on the same PRACH, the collision happens. The other is the
limited physical uplink shared channel (PUSCH) and physical
downlink control channel (PDCCH) resource that will be
insufficient when massive MTCDs apply for resources in the
uplink (UL) transmission. During the entire transmission
procedure, such massive deployments may generate an
enormous volume of signaling and traffic considering the fact
that a large number of MTCDs almost simultaneously try to
attach to the network and send data to the eNB.
To overcome these two problems, some solutions have been
proposed. For massive RA, there have been several studies to
tackle the preamble collisions. In the early study, based on the
access class barring (ACB), lots of schemes are developed to
enhance or improve it. The authors in [3] proposed a dynamic
ACB which enables the MTCDs to select an eNB for RA among
multiple eNBs for overload balance. In [4], a scheme is
proposed to provide more preambles by spatially partitioning
the cell coverage into multiple group regions and reducing the
cyclic shift size in RA preambles. To further study the RA delay
and improve RA performance, [5] evaluated the RA delay from
the mathematical perspective and proposed to reduce such delay
by configuring appropriate system parameters. Other
approaches include only allowing the MTCDs to perform RA
which have obtained enough power by harvesting energy [6] or
higher priorities [7]. For avoiding possible uplink signaling
storm and to minimize the energy consumption, the lifetime-
aware scheduling scheme is developed in [8]. For the scenario
that M2M devices coexist with human-to-human user
equipment (UE), [9] puts forward a downlink resource
allocation mechanism for packet downlink control channels
considering the impact of MTCDs on QoS provisioning.
The above work mainly focuses on to decrease the number
of MTCDs which are allowed to access the network
simultaneously. Different from the previous work, based on the
grouping massive MTCDs, a RA and following UL resource
scheduling mechanism is devised in this paper. During the
procedure, the group leader may initiate the RA procedure on
behalf of its group members and send related signaling.
Especially, a second group paging mechanism is developed to
further reduce the access delay and increase the access
probability. For the eNB, by using the group ID to mask the
corresponding signaling, it may send only one control signal
instead of massive information on the control channels such that
a possible signaling congestion is avoided effectively.
Simulation results confirm that the better effectiveness of the
proposed schemes can be obtained by comparing with the
traditional RA methods and scheduling mechanisms with
respect to access probability, access time delay, collision
probability and fairness.
The remainder of this paper is organized as follows. Section
II describes the system model. Section III elaborates the
proposed grouping based RA and UL scheduling mechanism.
Simulation results are presented in Section IV, followed by
conclusions in Section V.
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