Halmsad Unversy For he Developmen of Organsaons Producs and Qualy of Lfe. Increasng he Probablly of Tmely and Correc Message Delvery n Road Sde Un Based Vehcular Communcaon Magnus Jonsson Krsna Kuner and Annee Böhm CERES Cenre for Research on Embedded Sysems For he Developmen of Organsaons Producs and Qualy of Lfe
The Presenaon s Based on he Followng Publshed Paper Jonsson M. K. Kuner and A. Böhm Increasng he probably of mely and correc message delvery n road sde un based vehcular communcaon Proc. 15h IEEE Inellgen Transporaon Sysems Conference (ITSC 2012) Anchorage AK USA Sep. 16-19 2012. For he Developmen of Organsaons Producs and Qualy of Lfe
Iner-vehcle communcaon Vehcle-o-vehcle (V2V) Vehcle-o-Infrasrucure (V2I) Road Sde Un (RSU) Sparsely spaced 3 For he Developmen of Organsaons Producs and Qualy of Lfe
Conrbuons/Feaures Addng deermnsc real-me communcaon Addng he possbly of (lmed) reransmssons Sll meeng deadlnes Real-me analyss o calculae on he performance for dfferen raffc scenaros The packe error rae can be consderably decreased dependng on he raffc scenaro For he Developmen of Organsaons Producs and Qualy of Lfe
Renroducng he collson-free phase o 802.11p CFP Collson-Free Phase CBP Conenon-Based Phase Safey-crcal realme daa Guaraneed delvery before deadlne Non-safey-crcal daa Bes-effor daa delvery 5 For he Developmen of Organsaons Producs and Qualy of Lfe
Renroducng he collson-free phase o 802.11p CFP Collson-Free Phase CBP Conenon-Based Phase Maser-slave scheme on op of IEEE 802.11p The RSU acs as maser Poll + daa packe or Daa packe + ACK Pure IEEE 802.11p Can be used for e.g.: connecon-seup Packes from nonconneced vehcles 6 For he Developmen of Organsaons Producs and Qualy of Lfe
Real-me layer above 802.11p MAC layer Number of vehcles and her communcaon requremens known by he RSU Packes are scheduled n he RSU (maser) accordng o EDF (Earles Deadlne Frs) Real-me (RT) feasbly analyss RT channels defned by sendng node recevng node perod maxmum packe lengh and relave deadlne: τ = {S R P L D } Deermne f all RT channels are able o mee her deadlnes CFP Collson-Free Phase CBP Conenon-Based Phase 7 For he Developmen of Organsaons Producs and Qualy of Lfe
Reransmsson scheme Dvde he delay bound no wo pars: one for ordnary ransmssons one for reransmsson(s): D = D ord + D rer Inroduce addonal RT-channels for reransmssons: τ rer = {S rer R rer P rer L rer D rer } 8 For he Developmen of Organsaons Producs and Qualy of Lfe
For he Developmen of Organsaons Producs and Qualy of Lfe 9 Real-Tme Feasbly Analyss Inroducon P perod D adaped deadlne E experenced ransm. me Q number of channels Two seps: Ulzaon check Workload check 1 1 U P E U Q h E P D h Q ) ( ' 1 ) ( 1
Adapaons o he RT analyss RSU schedules boh ordnary and reransmsson RT channels boh I2V and V2I (naed by a pollng packe from he RSU) T wa_poll : V2I ransmsson T wa_daa : I2V ransmsson T wa_rer_poll : V2I reransm. T wa_rer_daa : I2V reransm. T T T T T wa_poll procrsu AIFS poll T T T T T procv AIFS daa procrsu_crc T margn T T T T T prop prop wa_daa procrsu AIFS daa prop T T T T T procv_crc AIFS ACK procrsu T margn prop 10 For he Developmen of Organsaons Producs and Qualy of Lfe
RT analyss (con.) CFP Collson-Free Phase CBP Conenon-Based Phase r T T T. CFP* CFP blockng T e CFP* r. TSF T max max T max T. blockng wa_poll wa_daa For he Developmen of Organsaons Producs and Qualy of Lfe
RT analyss (con.) Ulzaon check ncludng boh ordnary and reransmsson RT channels U e e T wa_poll T wa_daa P P 1 1 T e e wa_rer_poll wa_rer_daa P P 1 re 1 re T 12 For he Developmen of Organsaons Producs and Qualy of Lfe
Adapaons o he RT analyss Wors case queung delay for ordnary ransmssons d D T T ordi2v ord CBP wa_daa max T T wa_daa wa_poll d D T T ordv2i ord CBP wa_poll max T T wa_daa wa_poll 13 For he Developmen of Organsaons Producs and Qualy of Lfe
Adapaons o he RT analyss Wors case queung delay for reransmssons Reransmsson deadlne s dvded no deadlne for he acual reransmsson RT channel dependng on number of allowed reransmsson aemps D re d D T T D reri2v re CBP wa_daa rer. N max T T wa_daa wa_poll aemp d D T T rerv2i re CBP wa_poll max T T wa_daa wa_poll For he Developmen of Organsaons Producs and Qualy of Lfe
For he Developmen of Organsaons Producs and Qualy of Lfe Adapaons o he RT analyss Workload funcon ncludng boh ordnary and reransmsson RT channels 1 1 1 1 1 1 ordv2i ordi2v rerv2i ordv2i e wa_poll d ordi2v e wa_daa d rerv2i w re d d h T P d T P d T P 1 1 reri2v e a_rer_poll reri2v e wa_rer_daa re d d T P
Smulaon resuls Merge Asssance Scenaro RSU as cenral node conrollng medum access for passng vehcles Smulaon deals Perod: 2Hz Max number of allowed reransmsson aemps: 3 Number of avalable reransmsson RT channels: 20 Packe error probably: 0.1 16 For he Developmen of Organsaons Producs and Qualy of Lfe
250 Pollng whou reransmssons Pollng wh reransmssons 200 Number of acceped channels 150 100 50 0 0 50 100 150 200 250 300 Number of requesed channels 17 For he Developmen of Organsaons Producs and Qualy of Lfe
8 7 Pollng whou reransmssons Pollng wh reransmssons 6 Average delay [ms] 5 4 3 2 1 0 40 60 80 100 120 140 160 Number of requesed channels For he Developmen of Organsaons Producs and Qualy of Lfe
Packe error rae for dfferen numbers of reransmsson aemps 10 0 10-1 10-2 10-3 10-4 Pollng whou reransmssons Pollng wh reransmssons afer one reransmsson aemp Pollng wh reransmssons afer wo reransmsson aemps Pollng wh reransmssons afer hree reransmsson aemps 10-5 40 60 80 100 120 140 160 Number of requesed channels For 40 requesed channels and hree aemps here are oo few erroneous packes o reach a correc value of 10-4 For he Developmen of Organsaons Producs and Qualy of Lfe
Merge Asssance Scenaro wh prory zones he send frequency of vehcles n he hree dfferen zones are se o 1 2 and 5 Hz Max number of allowed reransmsson aemps: 1 Number of avalable reransmsson RT channels: 20 250 Pollng whou reransmssons Pollng wh reransmssons 0.1 200 0.09 Number of acceped channels 150 100 Packe error rae 0.08 0.07 0.06 0.05 0.04 0.03 Pollng whou reransmssons Pollng wh reransmssons 50 0.02 0.01 0 0 50 100 150 200 250 300 Number of requesed channels 0 40 60 80 100 120 140 160 180 200 Number of requesed channels 20 For he Developmen of Organsaons Producs and Qualy of Lfe
Concluson Supporng relable real-me raffc for safey-crcal proacve ITS safey applcaons hrough: Inroducon of RT layer on op of IEEE 802.11p MAC Inroducng a reransmsson scheme Real-me guaranees for boh ordnary ransmssons and reransmssons are offered decreasng he PER by several orders of magnude. For he Developmen of Organsaons Producs and Qualy of Lfe