Enhanced C-V2X Mode-4 Subchannel Selection

Abstract

In Release 14, the 3rd Generation Partnership Project (3GPP) introduced Cellular Vehicle-to-Everything (C-V2X) mode-4 as a novel disruptive technology to support sidelink vehicular communications in out-of-coverage scenarios. C-V2X mode-4 has been engineered to operate in a distributed manner, wherein vehicles autonomously monitor the received power across sidelink subchannels before selecting one for utilization. By means of such an strategy, vehicles attempt to (i) discover and (ii) reserve subchannels with low interference that may have the potential to maximize the reception likelihood of their own broadcasted safety messages. However, due to dynamicity of the vehicular environment, the subchannels optimality may fluctuate rapidly over time. As a consequence, vehicles are required to make a new selection every few hundreds of milliseconds. In consonance with 3GPP, the subchannel selection phase relies on the linear average of the perceived power intensities on each of the subchannels during a monitoring window. However, in this paper we propose a nonlinear power averaging phase, where the most up-to-date measurements are assigned higher priority via exponential weighting. We show through simulations that the overall system performance can be leveraged in both urban and freeway scenarios. Furthermore, the linear averaging can be considered as a special case of the exponentially-weighted moving average, ensuring backward compatibility with the standardized method. Finally, the 3GPP mode-4 scheduling approach is described in detail.

On the Design of Sidelink for Cellular V2X: A Literature Review and Outlook for Future

“…The power sensing procedure is instead revised in [106], [107]. In [106], the authors propose to use an exponential weight to the measured received power levels during the sensing interval, thus giving more emphasis on the recent values, deemed more relevant due to the dynamicity of the environment.…”

“…The power sensing procedure is instead revised in [106], [107]. In [106], the authors propose to use an exponential weight to the measured received power levels during the sensing interval, thus giving more emphasis on the recent values, deemed more relevant due to the dynamicity of the environment. An exponential weight is used also in [107], with the addition of multiplicative factors that account for re-This article has been accepted for publication in a future issue of this journal, but has not been fully edited.…”

Performance Evaluation of NOMA for Sidelink Cellular-V2X Mode 4 in Driver Assistance System With Crash Warning

“…The transmission power was set to 23 dBm [7]. We assumed that the power was divided into occupied RBPs [32]. The transmitted signals attenuated along to the WINNER+ B1 model [33], which METIS has recommended for mode 4 [34].…”

Age of Information Optimized MAC in V2X Sidelink via Piggyback-Based Collaboration

“…Different from calculating the average value of the energy of the corresponding sub-channels in sensing window in standard, Ref. [29] highlights the proportion of the latest channel occupancy state though exponentially weighting the energy of the corresponding sub-channels in the time domain and achieves a better performance. From the perspective of transmitting power, it is found in [30] that higher transmitting power responds to a larger communication range while more easily leads to channel interference, especially under the high channel busy ratio.…”