The authors studied the opportunities of using WiFi offloading for Vehicle to Internet (V2I) communication, and how this has changed over the last decade.
To study the current landscape, we developed a system (X-Fi), which efficiently selects, associates to, authenticates with, and performs WiFi offloading for V2I communication with these networks, and a tool (X-Perf), which illustrates opportunities of WiFi offloading available today in these networks, with measurements and experiments across four metro areas across three continents over 22 months.
Our results indicate the feasibility of achieving 1 GB/hour application goodput, an order of magnitude higher than the number provided by open WiFi networks in the past, which can take a significant load away from alternative communication paths for V2I systems.
Besides, we decided to freely publish all the WiFi association attempts details in a dataset for further analysis.
If you use this dataset, please cite our paper.
Revisiting WiFi offloading in the wild for V2I applications
Furong Yang, Andrea Ferlini, Davide Aguiari, Davide Pesavento, Rita Tse., Suman Banerjee, Gaogang Xie, Giovanni Pau; Computer Networks, Volume 202, 15 January 2022, 108634
[PDF]
@article{YANG2022108634,
title = {Revisiting WiFi offloading in the wild for V2I applications},
journal = {Computer Networks},
volume = {202},
pages = {108634},
year = {2022},
issn = {1389-1286},
doi = {https://doi.org/10.1016/j.comnet.2021.108634},
url = {https://www.sciencedirect.com/science/article/pii/S1389128621005211},
author = {Furong Yang and Andrea Ferlini and Davide Aguiari and Davide Pesavento and Rita Tse and Suman Banerjee and Gaogang Xie and Giovanni Pau},
keywords = {V2I, WiFi offloading, Measurement},
}
The following packages are required to correctly read the data:
- mysql >= 14.14 Distrib 5.7.25
- libedit (EditLine wrapper)
The dataset can be download via Dropbox: https://www.dropbox.com/sh/5mp41c9uha1qus2/AABsXZ8kyuM3GVLDyDhlTcnNa?dl=0
- Merge all .sql files in a subfolder named by city into one .sql file.
cat macao/macao.sql* > macao/macao.sql
- Create a database in MySQL for a .sql file
Paris example
mysql -u root -p
# Input your passwd
# mysql cli
> create database carfi_paris;
> exit
- Import the corresponding .sql file into the database
mysql -u root -p carfi_paris < paris.sql
- APTCPInfoFails: this table contains all WiFi association attempts.
+----------------------+---------------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+----------------------+---------------------------+------+-----+---------+----------------+
| id | bigint(20) | NO | PRI | NULL | auto_increment |
| interface | varchar(32) | YES | | NULL | | # the network interface name
| avg_speed | decimal(64,10) | YES | | NULL | | # the average driving speed of the assoc.
| dist_km | decimal(64,10) | YES | | NULL | | # the driving of the assoc.
| l2_avg_signal | decimal(64,10) | YES | | NULL | | # the average AP signal level during the assoc.
| l2_stderr_signal | decimal(64,10) | YES | | NULL | | # the standard deviation of the AP signal level during the assoc.
| l2_essid | varchar(128) | YES | | NULL | | # the essid of the AP corresponding to the assoc.
| l2_bssid | varchar(128) | YES | | NULL | | # the bssid ...
| l2_freq | int(11) | YES | | NULL | | # the channel frequency of the AP ...
| l2_signal_lv | decimal(64,10) | YES | | NULL | | # the intial signal level of the assoc.
| l2_assoc_type | enum('NEW','REASSOC') | YES | | NULL | | # the type of association: new or reassociated
| l2_auth_t_s | decimal(64,10) | YES | | NULL | | # the time of authentication start
| l2_auth_t_e | decimal(64,10) | YES | | NULL | | # the time of authentication end
| l2_assoc_t_s | decimal(64,10) | YES | | NULL | | # the time of association start
| l2_assoc_t_e | decimal(64,10) | YES | | NULL | | # the time of association end
| l2_hs_t_s | decimal(64,10) | YES | | NULL | | # the time of 4WAY handshake start
| l2_hs_t_e | decimal(64,10) | YES | | NULL | | # the time of 4WAY handshake end
| l2_conn_t_s | decimal(64,10) | YES | | NULL | | # the time of L2 connectivity start
| l2_conn_t_e | decimal(64,10) | YES | | NULL | | # the time of L2 connectivity end
| l3_dhcp_t_s | decimal(64,10) | YES | | NULL | | # the time of DHCP start
| l3_dhcp_t_e | decimal(64,10) | YES | | NULL | | # the time of DHCP end
| l3_ip_t_s | decimal(64,10) | YES | | NULL | | # the time of IP connectivity start
| l3_ip_t_e | decimal(64,10) | YES | | NULL | | # the time of IP connectivity end
| l3_ip | varchar(32) | YES | | NULL | | # the IP address of the assoc.
| l3_ip_prefix | int(11) | YES | | NULL | | # the IP prefix
| l3_ip_gw | varchar(32) | YES | | NULL | | # the IP adress of the gateway
| l3_dhcp_server | varchar(32) | YES | | NULL | | # the IP address of the DHCP server
| l3_dns_servers | blob | YES | | NULL | | # the IP address of the DNS server
| tcp_t_s | decimal(64,10) | YES | | NULL | | # the time of TCP connectivity start (from TCP application logs)
| tcp_t_e | decimal(64,10) | YES | | NULL | | # the time of TCP connectivity end (from TCP application logs)
| tcp_t_s_pcap | decimal(64,10) | YES | | NULL | | # the time of TCP connectivity start (from pcap file)
| tcp_t_e_pcap | decimal(64,10) | YES | | NULL | | # the time of TCP connectivity end (from pcap file)
| tcp_direction | enum('UPLOAD','DOWNLOAD') | YES | | NULL | | # the transmission direction
| tcp_cc | varchar(32) | YES | | NULL | | # the congestion control scheme
| tcp_flow_nb | int(11) | YES | | NULL | | # the concurrent flow number
| tcp_flows | blob | YES | | NULL | | # the list of 4-tuples of concurrent flows
| tcp_total_bytes_app | bigint(20) | YES | | NULL | | # the total bytes transferred (from application logs)
| tcp_total_bytes_pcap | bigint(20) | YES | | NULL | | # the total bytes transferred (from pcap file)
| tcp_goodput_app | decimal(64,10) | YES | | NULL | | # the average goodput (from application logs)
| tcp_goodput_pcap | decimal(64,10) | YES | | NULL | | # the average goodput (from pcap logs)
| tcp_test_local_id | int(11) | YES | | NULL | | #
| tcp_loss_rate | decimal(64,10) | YES | | NULL | | # the loss rate
| tcp_rxmt_pkts | decimal(64,10) | YES | | NULL | | # the number of retransmitted packets
| tcp_total_pkts | decimal(64,10) | YES | | NULL | | # the total number of all packets
+----------------------+---------------------------+------+-----+---------+----------------+
- APTCPInfo: this table has the same structure as APTCPInfoFails, but, it only contains all successful WiFi association attempts.
- Experiment: this table contains the information of all experiments.
+------------+----------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+------------+----------------+------+-----+---------+----------------+
| id | bigint(20) | NO | PRI | NULL | auto_increment |
| start_time | decimal(64,10) | YES | | NULL | |
| end_time | decimal(64,10) | YES | | NULL | |
+------------+----------------+------+-----+---------+----------------+
- GPS: this table contains all GPS coordinates recorded during our experiments. We use time to associate GPS coordiantes with associations and experiments.
+-----------+----------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-----------+----------------+------+-----+---------+----------------+
| id | bigint(20) | NO | PRI | NULL | auto_increment |
| latitude | decimal(64,10) | YES | | NULL | |
| longitude | decimal(64,10) | YES | | NULL | |
| elevation | decimal(64,10) | YES | | NULL | |
| time | decimal(64,10) | YES | | NULL | |
+-----------+----------------+------+-----+---------+----------------+
- Link, ScanAP, CarFiScanAP: these tables are not used.
The tarball includes the raw data collected from four cities (Paris, Bologna, Macao, Los Angeles).
In the directory of each city, there are many tarballs named as <city>-<start_time>-<end_time>.tar.gz. In each tarball, the data including association logs, DHCP logs, and TCP performance data are archived.
In each experiment tarball, there are some log files and a directory, e.g. gps.log linkmon.log roamingd.log tester.data wpa_supplicant.log:
gps.logstores the GPS coordinates during the experimentwpa_supplicant.logstores the WiFi association logsroamingd.logstores the DHCP logstester.datadirectory contains the data of all TCP performance tests. The data of each TCP performance test are stored in the sub-directory named as the number of that TCP test.
In each TCP test sub-directory, there are two key files:
tcp_tester.profileincludes the information as follows:
1579131540.566103 (TCP connections start time)
1579131622.562806 (TCP connections end time)
upload (transmission direction)
bbr (congestion control scheme)
41689088 (total bytes transferred)
1 (number of concurrent flows)
100.64.250.250 44918 149.248.15.30 5001 (the list of the 4-tuple of all TCP flows)
flows.pcapstores the packet traces of the TCP test.