Subject: [ipwave] latency comparison on new V2X links (802.11 vs 5G links)

From: Alexandre Petrescu <[email-masked]>
Date: Wed, 27 Feb 2019 13:40:48 +0100

Hi,

I am trying a comparison of latency that IP applications could afford on 
new V2X links from IEEE vs 3GPP cellular links.

Existing IP over 802.11-OCB (also known as 802.11p) with 10MHz channel 
width affords 1.2ms round-trip latency (DL plus UL) on average, as shown 
by the RTT field of the ping output, in a few trials.

Simulations and evaluations of New Radio (NR) of 3GPP claim a minimum 
0.23ms "DL latency using unicast transmission", as written in a publicly 
available document 3GPP TR 38.885 V1.0.0 (2018-11).

I wonder what would be a target latency that the newly formed group 
'802.11bd' would target?  Would it be still much lower than the 3GPP NR 
claimed latency? (currently, 802.11-OCB, aka p, offers much lower RTT 
latency than 4G+: it's 1.5ms vs 50ms).  Would 'bd' inherit the 
below-milisecond latencies experienced on 'ac'.

Latency has an importance in some use-cases like convoy maintenance, 
emergency messaging between cars, and similar.

Alex