Page 26 - Kaleidoscope Academic Conference Proceedings 2024

Proposed Technology IMT-2030 Goals achieved average ratio (PAPR) and power inefficiency. We introduce
OTFDM Ubiquitous connectivity, Orthogonal Time Frequency Division Multiplexing
Sustainability (OTFDM) [4] as a candidate for 6G mobile communication.
S-MIMO Ubiquitous connectivity, OTFDM is designed to address the shortcomings of
Innovation traditional OFDM and offer a waveform that enables
simultaneous transmission of reference signals (RS) and data
Table 3 – IMT-2030 goals achieved with proposed with low PAPR, high power efficiency, and reduced
technologies. overhead. The conventional downlink of cellular systems
often experiences high PAPR due to multiple users sharing
spectral resources. Consequently, power amplifiers (PA)
India played a crucial role in shaping the IMT-2030
framework, introducing the "Ubiquitous Communications" require significant back-off, resulting in poor power
scenario [1]-[3]. India's introduction of the "Ubiquitous efficiency and increased complexity. While 5G introduced
connectivity" scenario, along with enhanced coverage DFT-s-OFDM with lower PAPR for the uplink [4]-[5], the
capabilities, is one of the key enablers for 6G technology adoption of OFDM as the unified standard waveform for
development, offering affordable connectivity and both sub-6 GHz and mmWave services limited the power
broadband services to rural and sparsely populated areas. efficiency.
This strategic move will help bridge the digital divide and
create economic opportunities for India's vast rural To achieve the ambitious goals set by the International
population. Furthermore, India presented another critical Telecommunication Union (ITU) for 6G, including
capability named "Interface interoperability," aiming to extremely low latency, high data rates, and power efficiency,
promote open interfaces among system entities and facilitate a new waveform is needed. OTFDM presents an innovative
the deployment of interoperable radio access network solution by time-multiplexing RS and data within a single
systems. This approach will not only expedite the delivery of OFDM symbol, thereby allowing one-shot transmission with
next-gen 6G and beyond wireless infrastructure to operators flexible RS overhead and high-power efficiency. The
but also foster innovation and open market competition OTFDM symbol is generated by the following set of
among suppliers/product companies. The adoption of open operations: RS and Data/Control Information is Multiplexed
interfaces allows smaller vendors and operators to introduce into a single sequence and is fed to a DFT module followed
customized services, tailoring the network to suit their by excess bandwidth addition, spectrum shaping at
specific requirements. Additionally, India's emphasis on subcarrier level further followed by IFFT and CP addition
"Energy efficiency" brought a sustainability aspect to the operation which generates an OTFDM symbol. By
IMT-2030 document. This focus highlights the importance expanding the bandwidth and shaping the spectrum using a
o low-power consumpti technologies, reduce pulse shaping filter, the adverse effects of inter-symbol
greenhouse gas emissions, and resource utilization under the interference (ISI) are minimized, in addition to reducing the
circular economy model, contributing to climate change PAPR [6]-[12]. The design parameters of RS density, excess
mitigation and sustainable development goals. Following the bandwidth, and DFT size can be carefully selected to
publication of the IMT-2030 Framework in the 5D WP #44, eliminate the irreducible error floor caused by the channel's
the projected work plan for WP5 over the next 12 months impulse response.
includes the discussion on Test Performance Requirements
(TPR) and the mapping of Usage Scenarios with Capabilities Through extensive computer simulations based on 3GPP
in 5D WP #45 (Feb 2024). Subsequently, in 5D WP #47 (Oct channel models, we demonstrate the effectiveness of
2024), the discussions on Evaluation Methods and Test OTFDM in performing self-contained channel estimation in
Environment will commence, with the actual TPR values for typical delay spread channels for modulation sizes up to 256
different test environments being developed during the 2025 QAM. The provided PAPR results for different modulation
timeframe. To significantly contribute to 6G standards schemes indicate that OTFDM achieves low PAPR operation
development, India is encouraged to have technical concepts, and high PA efficiency, making it a promising candidate for
system architecture, initial prototypes, and early simulation 6G mobile communication. In the following sections of this
results available as soon as possible. The subsequent sections paper, we delve into the technical details of OTFDM, present
will introduce new technologies and their associated TPRs, simulation results, and discuss its applications and
which hold the potential to become integral components of implications for future wireless communication systems.
the 6G standards. Further, the achieved goals with these
technologies are summarized in Table 3. 2.1 OTFDM Symbol Generation
The OTFDM generation includes the following operations:
2. OTFDM WAVEFORM
Time multiplexing: The central idea is to time multiplex
Orthogonal Frequency Division Multiplexing (OFDM) has data/control information and the associated reference signal
been a fundamental technology in modern wireless (RS) in a block called OTFDM symbol. Symbol structure for
communication systems, such as WLAN, 4G, and 5G, due to the same is presented in Figure 1, where out of allocated M
its spectral efficiency, multi-user capability, and ease of samples for the OTFDM symbol, samples are allocated

channel estimation. However, the traditional OFDM for RS, and samples for data transmission. This operation

waveform has inherent limitations, including a high peak-to- enables self-contained channel estimation, data/control

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