# A Novel Procedure of Enhancing the Throughput of a Mode-2 Sidelink Based on Partial Sensing
###### Abstract  
Partial sensing is used to reduce the power consumption of pedestrian user equipment (P-UE) that operates in the signal environment of a mode-2 sidelink. However, because the data trans-mission is allowed only for the window duration of each corresponding P-UE, the throughput of the P-UE decreases by the ratio between the width of the window and the entire data period. This paper presents a novel method for enhancing the throughput of the P-UE that operates with partial sensing in the mode-2 sidelink. The proposed technique employs an additional UE, denoted the roadside unit (RSU), to collect the sensing results from each P-UE that operates with partial sensing. The proposed RSU sequentially aligns all of the partial sensing windows, such that the combination of each partial sensing window can eventually provide an almost complete sensing result. In this study, extensive computer simulations were performed. The results reveal that the proposed method enhances the throughput of each P-UE operating with partial sensing almost to that of full sensing without increasing the required power consumption. 5G NR mode-2 sidelink; V2X; partial sensing; roadside unit +
Footnote †: journal: 13 September 2021  
to [5], in the case of unicast communication, sensing accounts for 88.7% of the total power consumption, and, in the case of groupcast communication, 35.1% of the total power is used for sensing. In the case of vehicular user equipment (V-UE), power consumption is not a major problem because the power is provided by the vehicle; however, in the case of pedestrian user equipment (P-UE), the power consumption for sensing should be reduced because the battery life of each P-UE is extremely critical. To address these power consumption issues for sensing, a technology called partial sensing has been introduced for sidelink communication among P-UEs [6]. Partial sensing is a method of checking available resources by decoding PSCCH for only a part of the entire data period. When partial sensing is used, the power consumption is reduced as much as the decoding time is reduced. Although the power consumption can be considerably reduced using partial sensing, the throughput must be reduced because the validity of the usable resources is limited only during the period corresponding to the partial sensing window. Consequently, the throughput cannot be reduced as much as the amount of power saved, which is equivalent to the ratio of the partial sensing window duration to the entire data period. Although a number of pioneering works [7; 8; 9; 10] have addressed the scheduling techniques for resource allocation, most efforts in these studies have been focused on preserving the Basic Safety Message (BSM) [11] by reducing the collision rate among mode-2 sidelink devices. More specifically, [7] presented an approach to avoid the collision of safety messages using Lookahead Information within the sidelink control information, whereas [8] provided an accurate resource allocation state via a Foreseeing Semi-Persistent scheme. Furthermore, [9] considered a special condition in which each mobile device uses its own resource reservation interval to avoid the collision without introducing additional control information, whereas [10] noted the problem of collision between the Random Selection Device (RSD) and the sensing device using the information provided from the RSD. Sidelink, however, can be employed for the transmission of various kinds of multimedia data, in addition to the BSM only [12]. Furthermore, even when data transmissions among mobile devices cannot be properly handled through a given base station due to the congestion of the mobile devices in a particular area, the sidelink can be adopted to relay the data directly among the mobile devices [13]. Considering these kinds of sidelink scenarios, there is a clear need for a novel method of enhancing the throughput of all the mobile devices involved in a given sidelink scenario without sacrificing the merit of partial sensing, i.e., power saving in resource allocation.