Table 5 Categorization and comparison of energy/power saving-related proposals

Cooperative

Clustering and relay

[55]

Group devices into clusters;

High energy consumption

It is possible to combine

design

[56]

Cluster head relays the messages for

for cluster head;

cooperative relaying with

[12]

other cluster member in the same

Scheduling and resource issues in

other emerging technologies

[57]

group

order to manage the interference;

for the device-to-device

Delay increase cause of relay

link

Cooperation between MTC

[9]

Adjust MTC device setting

High complexity for MTC devices

server and MTC devices

according to context

M2M gateway

[23]

Similar to clustering and

Installation and deployment

Reduce implementation complexity

[58]

relay, except that M2M gateway

cost of M2M gateway

for MTC device.

[60]

is a special network node

for operators

Possible to use LoRa gateway

instead of a MTC device

as M2M gateway.

Design of

Modified DRX and

[62]

Make MTC devices stay in low

High delay

Simple method to

energy efficient

Idle state

[63]

power mode as long as possible

achieve energy saving

signaling and

operation

Extending paging cycle

[1]

Make MTC devices stay in low

High delay

[2]

power mode as long as possible

[64]

Reduction of RRC

[65]

Make MTC devices stay in low

Impact on H2H service

Inactivity timer

power mode as long as possible

Group-based and

[66]

Group paging for MTC devices

May reduce the paging capacity

M2M- dedicated

of H2H;

paging mechanism

Scalability and bacward-

compatibility issues.

Removal

[66]

Remove activities related to

Applicable uniquely for

Reduce the cost of MTC

of unnecessary activities

mobility management (MM)

M2M application with no

device and energy

for MTC Device

or low mobility

consumption

Disconnect MTC-device

[67]

Instead of staying in low power mode,

High delay

from network when inactive

turn devices radio off

Radio resource

Formulation of

[71]

Convert radio resource allocation

High complexity;

allocation

optimization problem

[72]

into an optimization problem with

Scalability issues;

and packet

constraints

Possible impact for human

Category

Subcategory

Reference

Principle for energy saving

Drawback

Notes

scheduling

users.

Optimized with periodicity

[73]

Leverage the periodicity of MTC

Applicable uniquely to periodic

[74]

M2M applications;

Not easy applied in the presence

of different period values.

Packet scheduling

[76]

Propose packet scheduling

Compatibility with H2H;

Ensure QoS requirements

[29]

adapted for cellular MTC context

May need modifications of the specification

Energy efficient

New random access protocol

[15]

ALOHA-based random

It may be difficult to find a specified

random access

access protocol is not

random access protocol suitable

and MAC

the best option for MTC

for all cellular users

Fixed time alignment

[78]

Leverage the low mobility of MTC

Only applicable for M2M

Reduce the access collision

with no mobility

Transmit message in

[23]

Transmit message directly

Scalability issues

Reduce the signaling overhead

MAC PDU or preamble

in access reservation stage