Patent Application
20250047430
The aim of this invention is to devise a method for resource allocation in the delay-Doppler grid that assigns radio resources to the users in a flexible manner taking into consideration their specific requirements.
The method of invention provides a flexible structure for Orthogonal Time Frequency Space (OTFS) waveform in terms of resource allocation/scheduling. This flexibility is imperative for the ever-increasingly diverse user requirements of wireless communication systems in terms of reliability, latency, data rates, mobility, security etc.
Wireless communication has diverged and evolved continuously, growing from basic voice communication to enhanced broadband, massive connectivity, ultra-reliable and low-latency applications over time. This divergence in applications is expected to continue with the sixth-generation (6G) systems in the form of services such as further-enhanced mobile broadband (FeMBB), ultra-massive machine-type communication (umMTC), extremely reliable and low-latency communication (ERLLC), long-distance and high-mobility communication (LDHMC), and extremely low-power communication (ELPC) [1, 2].
While the first three services represent direct extension of the services proposed in the fifth generation (5G) of cellular systems, the latter two services represent a new paradigm. Current wireless systems predominantly use Orthogonal Frequency Division Multiplexing (OFDM) waveform, due to various benefits such as low peak-to-average-power ratio, higher reliability due so to diversity and better resilience to Doppler experienced in highly mobile environments however, OFDM and other multi-carrier techniques struggle significantly in the presence of mobility in the environment as the induced Doppler leads to intercarrier interference (ICI), resulting in significantly degraded quality-of-service (QoS). This issue is especially pertinent for high-mobility scenarios such as high-speed trains and non-geostationary satellite systems. This has led to the proposition of an alternative waveform, i.e., Orthogonal Time Frequency Space (OTFS), which has the capability to transform the time varying channel in time-frequency domain to invariant channel in the delay-Doppler domain.
In 5G, the 3GPP standardized the multi-numerology OFDM where flexible subcarrier spacing (and consequently symbol duration) options were provided to address the diverse user requirements such as latency, reliability, etc.
However, till this point only static delay-Doppler grids have been proposed in the available literature. The existing works only utilize homogenous delay-Doppler grids for different users in OTFS-based wireless networks.
The inventors believe that there is a need for flexible delay-Doppler grid design to fulfill the future user/application requirements.
The purpose of this invention is to provide a flexible delay-Doppler grid, and consequently a corresponding frame design, which allows flexible resolution in the delay-Doppler domain.
Therefore, the ultimate goal of the invention is to provide more flexibility in terms of wireless channel exploitation, channel richness and interference resilience compared with conventional wireless systems. The flexible resolution can be used for various purposes such as increased diversity gains, better reliability, mobility enhancements etc in a variety of user applications and services such as driving autonomous cars, remote surgery, smart city and agriculture as well as intelligent transportation.
Present invention relates to a method for flexible resource allocation in the delay-Doppler grid for an OTFS system with varying delay-Doppler grid for multi-user with doubly dispersive channel, wherein said method comprises the steps of;
The received signal of each user in processes considering the corresponding grid parameters and guard optimization is performed in either tine-frequency or delay-Doppler domain until the user constraints including desired signal-to-interference and noise ratio (SINR), data rate and round-trip time of communication are completed.
The presence of variable/flexible delay-Doppler grid for OTFS wireless systems according to the present invention, enables better exploitation of the wireless channel. This flexibility provides a better delay-Doppler resolution which can then be used to improve reliability of the system by allowing more diversity.
The method of invention enables devising a flexible delay-Doppler structure for different application and user requirements and exploiting the channel richness in delay-Doppler domain by picking the proper delay-Doppler grid structure.
To date, none of the work on OTFS has suggested the utilization of the radio resources in delay-Doppler domain in a flexible manner in order to support expoitation of a wide range used-cases in 5G and beyond wireless networks. As such, it is the most distinctive and unique element of the invention
As mentioned above, present invention relates to a method for flexible resource allocation in the delay-Doppler grid for an OTFS system with varying delay-Doppler grid for multi-user in doubly dispersive channel, wherein said method comprises the steps of;
For the application of the method of invention a single OTFS cell with multi-users active (Ne) that perform communication with one base station in downlink/uplink transmission is considered.
In the method of the invention, the scheduling of user equipments (UEs) is organized on a slot-by-slot basis where a queue of packets are stored at the base station (BS) for each of the UEs.
The method of the invention employs an algorithm that schedules multiple users with different applications in delay-Doppler domain, resulting in a varying radio source grids, as shown in
The algorithm that schedules multiple users with different applications in delay-Doppler domain, as per method step (i) can be given as;
{Nu,Mu}=max{SE,SINR}& min{RTT}
In the method of the invention a single OTFS cell with multi users active (Ne) that perform communication with one base station in downlink/uplink transmission is considered.
In the process of the invention, a flexible resource allocation is made because of the users' varying delay-Doppler grid, additionally this varying delay-Doppler grid needs to be controlled via a flexible radio resource scheduling algorithm.
The need for a varying delay-Doppler grid is due to the application that a particular user is serving or performing. For instance, if two users need to complete the communication within two different time durations, this causes a big problem called interference, which can distort the link for both users. Consequently, we propose the flexible radio resource utilization in order to prevent or mitigate this effect in accordance with the users' requirements (serving applications).
In the method of the invention, guard optimization makes our design different from the conventional OTFS schemes with fixed delay-Doppler, which needs to use fixed guard between the users. On the other hand, the guard for our system needs to be flexible in accordance with the flexible nature of delay-Doppler grids and users' needs.
In a preferred embodiment of the invention, for the method of the invention, a system of single antennas at both the transmitter (Tx) and the receiver (Rx) is considered
The reference system frame with fixed delay-Doppler grid consists of N number of symbols and M number of subcarriers with T symbol duration and Δf subcarrier spacing (SCS), respectively. Therefore, the OTFS frame occupies a total bandwidth of B=MΔf with a frame duration of Tf=TN. The data in delay-Doppler domain is given by x[k,] with k and l index representing Doppler and delay, respectively.
The invention is applicable to industrialization, and it represents an algorithm that can be applied to any signal performing transmission for adaptive grid design in delay-Doppler domain, time-frequency domain, or in a joint manner.
Around these basic concepts, it is possible to develop several embodiments regarding the subject matter of the invention; therefore, the invention cannot be limited to the examples disclosed herein, and the invention is essentially as defined in the claims. Separate embodiments of the invention can be combined where appropriate.
It is obvious that a person skilled in the art can convey the novelty of the invention using similar embodiments and/or that such embodiments can be applied to other fields similar to those used in the related art. Therefore, it is also obvious that these kinds of embodiments are void of the novelty criteria and the criteria of exceeding the known state of the art.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021/020126 | Dec 2021 | TR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/TR2022/051453 | 12/8/2022 | WO |
