Optimizing the Resource Allocation of Periodic Messages With Different Sizes in LTE-V2V

Abstract

Recently, 3GPP has added new features to long term evolution (LTE) that allow vehicles to communicate directly with each other and with surrounding objects. These short-range communications will play a key role in the so-called cellular vehicle-to-anything (C-V2X). As a particular service, which will be the basis of most applications for automated and connected cars, each vehicle will periodically broadcast information on its identity, status, and movements through short-range vehicle-to-vehicle (V2V) communications. Given the importance of this service, great attention has been given to the associated resource allocation procedures and the number of vehicles that can be simultaneously communicating in the network. However, little attention has been paid to handling messages of different sizes, which is actually foreseen in practice in order to transmit static information with a reduced periodicity. With this in mind, we evaluate the number of vehicles that can be allocated when parameters are optimized for messages of different sizes. This objective is pursued taking into account the numerous constraints imposed by the standard, through the formalization and solution of a combinatorial optimization problem. Example results, based on 3GPP indications, show that, with respect to the optimization of the allocation based on the larger packets, it is possible to obtain an increase that varies between 10% and 30%, depending on the conditions, with peaks above 150% in specific cases. INDEX TERMS C-V2X, connected vehicles, cooperative awareness, vehicular and wireless technologies, wireless networks.

Congestion Control Mechanisms in IEEE 802.11p and Sidelink C-V2X

“…2) IEEE 802.11p*: In order to avoid IEEE 802.11p vs. LTE-V2X performance comparisons and focus on the resource allocation and congestion control, here we assume a modified PHY layer for IEEE 802.11p, which performs similarly to LTE-V2X (same approach as in [21]). More specifically, the CSMA/CA mechanism, the inter-frame spaces, and the duration of the packet preamble are the same as in IEEE 802.11p; differently, the minimum signal to noise and interference ratio (SINR) and the raw data rate during transmission are those of LTE-V2X (refer to Table II).…”

“…3) MCS: The selected MCSs are listed in Table II; the values are taken from [1] and correspond to the minimum MCS in LTE-V2X to have one, two, three, or four packets of 300 bytes per TTI. The minimum SINR level is obtained as detailed in [21] and the same value is set both in LTE-V2X and IEEE 802.11p*. In IEEE 802.11p*, the duration of a transmission is calculated using the raw data-rate of LTE-V2X obtained as in [21].…”

“…The minimum SINR level is obtained as detailed in [21] and the same value is set both in LTE-V2X and IEEE 802.11p*. In IEEE 802.11p*, the duration of a transmission is calculated using the raw data-rate of LTE-V2X obtained as in [21]. 4) Outputs: The following metrics are considered:…”

Survey and Perspectives of Vehicular Wi-Fi versus Sidelink Cellular-V2X in the 5G Era

“…In IEEE 802.11p, the threshold only depends on the MCS, whereas the packet length has no impact. Regarding LTE-V2X, we adopt the procedure detailed in ( [36], Appendix A), which starts from the Shannon capacity and considers a parametric loss as suggested by 3GPP in [37]; this approach lets us set the threshold for any possible combination of MCS and packet size.…”

Geo-Based Scheduling for C-V2X Networks

“…C-V2X communications are managed by the cellular infrastructure when operating under mode 3, and several algorithms have been proposed in the literature for radio resource allocation (e.g. [4] and [5]). C-V2X mode 3 can benefit from the centralized control of the radio resource allocation, but it is only valid under cellular coverage.…”