1
Goal-Oriented Semantic Communications
for 6G Networks
Hui Zhou, Yansha Deng, Xiaonan Liu, Nikolaos Pappas, and Arumugam Nallanathan
Abstract—Upon the arrival of emerging devices, including
Extended Reality (XR) and Unmanned Aerial Vehicles (UAVs),
the traditional communication framework is approaching Shan-
non’s physical capacity limit and fails to guarantee the massive
amount of transmission within latency requirements. By jointly
exploiting the context of data and its importance to the task, an
emerging communication paradigm shift to semantic level and
effectiveness level is envisioned to be a key revolution in Sixth
Generation (6G) networks. However, an explicit and systematic
communication framework incorporating both semantic level and
effectiveness level has not been proposed yet. In this article,
we propose a generic goal-oriented semantic communication
framework for various tasks with diverse data types, which incor-
porates both semantic level information and effectiveness-aware
performance metrics. We first analyze the unique characteristics
of all data types, and summarise the semantic information,
along with corresponding extraction methods. We then propose
a detailed goal-oriented semantic communication framework
for different time-critical and non-critical tasks. In the goal-
oriented semantic communication framework, we present the
goal-oriented semantic information, extraction methods, recovery
methods, and effectiveness-aware performance metrics. Last but
not least, we present a goal-oriented semantic communication
framework tailored for Unmanned Aerial Vehicle (UAV) control
task to validate the effectiveness of the proposed goal-oriented
semantic communication framework.
Index Terms—6G, Task-oriented and semantics-aware commu-
nication, information extraction, effectiveness layer, performance
metric, data importance.
I. INTRODUCTION
Inspired by Shannon’s classic information theory, Weaver
and Shannon proposed a more general definition of a commu-
nication system involving three different levels of problems,
namely, (i) the bits conveying information should be reliably
transmitted to the recipient (the technical problem); (ii) the
context conveyed by the transmitted bits should accurately
reflect the intentions of the sender (the semantic problem);
and (iii) the conduct or action of the system in response
to communications should be effective in accomplishing a
desired task (the effectiveness problem) [1]. The first level
of communication, which is the transmission of bits, has
been well studied and realized in conventional communication
systems based on Shannon’s technical framework. However,
Hui Zhou, and Yansha Deng are with the Department of Engineering, King’s
College London, London, U.K. (e-mail: {hui.zhou, yansha.deng}@kcl.ac.uk)
(Corresponding author: Yansha Deng).
Xiaonan Liu, and Arumugam Nallanathan are with the School of Electronic
Engineering and Computer Science, Queen Mary University of London,
London, U.K. (e-mail: {x.l.liu, a.nallanathan}@qmul.ac.uk).
Nikolaos Pappas is with the Department of Computer and Information
Science, Link¨
oping University, Sweden (email:nikolaos.pappas@liu.se).
with the massive deployment of emerging devices, includ-
ing Extended Reality (XR) and Unmanned Aerial Vehicles
(UAVs), diverse tasks with stringent requirements pose critical
challenges to traditional communications, which are already
approaching the Shannon physical capacity limit. This imposes
the Sixth Generation (6G) network towards a communication
paradigm shift to semantic level and effectiveness level by
exploiting the context of data and its importance to the task.
It is noted that the significance and importance of information
evaluates the importance of extracted semantic information in
accomplishing a specific task and is closely coupled with the
considered task.
Initial works on “semantic communications” have mainly
focused on identifying the content of the traditional text and
speech [2], and the information freshness, i.e., age of informa-
tion (AoI) [3] as a semantic metric that captures the timeliness
of the information. However, these cannot capture the data
importance sufficiently of achieving a specific task. In [4], a
joint design of information generation, transmission, and re-
construction was proposed. Although the authors explored the
benefits of including the effectiveness level in [5], an explicit
and systematic communication framework incorporating both
semantic level and effectiveness level has not been proposed
yet. There is an urgent need for a unified communication
framework aiming at task-oriented performances for diverse
data types.
Motivated by this, in this paper, we propose a generic goal-
oriented semantic communication framework, which jointly
considers the semantic level information about the data con-
text and effectiveness-aware performance metrics about data
importance for different tasks with various data types. The
main contributions of this paper are:
1) We first present the existing semantics for traditional
text, speech, image, and video data types. More impor-
tantly, we analyze the unique characteristics of emerging
data types, including 360◦video, sensor, haptic, and
machine learning models, and propose corresponding se-
mantics definition and extraction methods in Section II.
2) We then propose a generic goal-oriented semantic com-
munication framework for typical time-critical and non-
critical tasks, where semantic level and effectiveness
level are jointly considered. Specifically, by exploiting
the unique characteristics of different tasks, we present
goal-oriented semantic information, their extraction and
recovery methods, and effectiveness-aware performance
metrics to guarantee the task requirements in Section III.
3) To demonstrate the effectiveness of our proposed
goal-oriented semantic communication framework, we
arXiv:2210.09372v3 [eess.SY] 6 Apr 2024