5
5GAA
1.0 Introduction
During the last decade, a set of connected transportation services has been identified utilizing mobile network
communication. One question that has to be answered is whether these transportation services can be handled
by the current cellular networks or particular enhancements are needed in order to provide a commercially viable
solution.
This document tries to analyze the cellular V2X architectural solutions and to evaluate them against two particular
use cases of interest: the Intersection Movement Assist (IMA) and the Vulnerable User (VRU) Discovery. The
cellular V2X communication considered in this report are solutions based on PC5 interface and solutions relying
on Uu.
Regarding deployment aspect, the multi operator scenario, which is relevant for real-world environment, are
analyzed in this document as well.
2.0 V2V Architectural Proposals Analysis
2.1 V2V Architectural Proposals
Based on the understanding in 5GAA, V2V communication relates to communication where both endpoints
(application layer) are vehicles in close proximity. V2V is direct communication between vehicles. The
communicating vehicles for exchanging information use short range communication, for Release 14, LTE PC5. In
the current analysis V2V architectural proposals relate to the two modes of PC5 communications of V2V, namely
PC5 mode 3 (network scheduled operation mode) and mode 4 (UE autonomous selection mode).
PC5 Mode 3
In PC5 mode 3, scheduling and interference management of V2V traffic are assisted by eNBs via control signaling
over the Uu interface. The eNodeB will assign the resources being used for V2V signaling in a dynamic manner.
According to [3GPP TS36.331] for mode 3, when a UE in-coverage of an eNB receives SystemInformationBlock21,
it checks whether v2x-CommTxPoolNormalCommon is included in the sl-V2X-ConfigCommon carried in
SystemInformationBlock21[3GPP TS 36.331]. If v2x-CommTxPoolNormalCommon is not included, an RRC
connection establishment is initiated by the UE [3GPP TS 36.331].
An RRC_CONNECTED UE requests assignment of dedicated sidelink resources based on its Buffer Status Reports
(Sidelink BSR)
RRC controls BSR reporting for sidelink by configuring the relevant timers [3GPP TS 36.331]. Each sidelink logical
channel belongs to a ProSe Destination and is allocated to a Logical Channel Group (LCG) depending on its priority
and the mapping between LCG ID and priority provided by upper layers.
For transmitting in the sidelink a UE proceeds in V2X sidelink resource request. The respective resource allocation
may be based on Dynamic Scheduling, where the serving eNB allocates the respective resources to the UE or Semi-
Persistent Scheduling, where a set of resources is allocated and certain transmission opportunities.
PC5 Mode 4
In PC5 mode 4 scheduling and interference management of V2V traffic are based on distributed algorithms
implemented between the vehicles and they rely on sensing with semi-persistent transmission. Additionally,
geographical restrictions may be used for handling near far effect arising due to in-band emissions and hidden
terminal problem.
