CRAWDAD microsoft/vanlan

We measured from VanLAN, a modest-size testbed that we have deployed, to analyze the fundamental characteristics of WiFi-based connectivity between basestations and vehicles in urban settings.last modified :2007-12-05release date :2007-09-14date/time of measurement start :2007-01-22date/time of measurement end :2007-01-26collection environment :Our goal is to enable cheap and high-throughput wireless connectivity
to moving vehicles in urban areas. The available options for such
connectivity today fall short in significant ways. Cellular networks
are expensive and have low throughput. Same is likely to be true of
WiMax networks if they were to become a reality. While some exisiting
WiFi basestations can provide opportunistic connectivity to passing
vehicles, they are unable to support longer periods of connectivity.
However, WiFi deployment is becoming denser and in many cases,
entire cities are being covered.

We measured from VanLAN, a modest-size testbed that we have deployed,
to analyze the fundamental characteristics of WiFi-based connectivity
between basestations and vehicles in urban settings. Using this data,
we investigate whether the short range of WiFi and the presence of
many interferring sources can enable continuous, cheap, high-throughput
connectivity, by themselves or in conjunction with cellular and WiMax networks.network configuration :Our testbed, called VanLan, currently consists of eleven BSs and two
mobile clients. The basestations (BSs) are spread across five office
buildings on the Microsoft campus in Redmond, WA.

All nodes have two radios. One radio is configured to Channel 1
of 802.11g and the other to Channel 11. To reduce interference, the
two antennae are separated by at least one foot. By comparing
the cases where only one radio is active to where both are active,
we have confirmed that any residual interference is minimal.
Our radios operate in ad hoc (IBSS) mode using a locally modified
device driver.

VanLAN uses the following hardware. EnGenius' EMP-8602 modules,
which are based on the Atheros 5213 chipset, are used as radios.
Their output power is 400 mW at 1 Mbps and lower at higher
transmission rates. HyperLink's HG2403MGU antennae are used
for the vans and HGV-2404U antennae are used for the basestations.
Both types are omnidirectional in the horizontal plane but radiate
less energy directly above and below.

The clients also have an externally mounted GPS unit, so we
know their locations. We use GlobalSat's BU-353 GPS unit which
is based on the SiRF Star III chipset and outputs data once per
second. The uncertainty in the location estimate of this chipset is
under three meters 95% of the time.data collection methodology :We have deployed a testbed on the Microsoft campus. It currently consists
of 11 WiFi basestations and 2 moving vans that operate around the campus
during the day. The testbed is meant not only as a research vehicle
but will also provide connectivity to van riders. We use the testbed nodes
to generate and log probe traffic.sanitization :The data has no personally identifiable information. it was collected
over a tested (with fixed basestations and a moving van).Tracesetmicrosoft/vanlan/connectivityTraceset of WiFi-based connectivity between basestations and vehicles in urban settings.files: 2007-01-22, 2007-01-23, 2007-01-24, 2007-01-25, 2007-01-26description: We measured from VanLAN, a modest-size testbed that we have deployed, to analyze the fundamental characteristics of WiFi-based connectivity between basestations and vehicles in urban settings.measurement purpose: Network Performance Analysismethodology: A. VanLAN TESTBED Our testbed, called VanLan, currently consists of eleven BSs and two mobile clients. The basestations (BSs) are spread across five office buildings on the Microsoft campus in Redmond, WA. The network of BSs is connected, but not all pairs of BSs can hear each other. The mobile clients are vans that provide a shuttle service on and around the campus during the day. They visit the part of the campus where the BSs are present roughly ten times a day. The roads in this part are similar to urban neighborhood streets with a speed limit of around 40 Kmph. Both BSs and clients are small form factor desktops. BSs are placed on top floors of the buildings, but their antennae aremounted on the roofs. Low-loss coaxial cables connect the radios (inside the desktops) and antennae. Similarly, the clients are placed inside the vans and their antennae are mounted on the roof. The client desktops are powered by a dedicated battery that is different from the van's main battery. This battery charges when the van is on and powers the clients for about four hours after the van is switched off. This time is used for software updates through a wireless connection with another computer located near the vans' overnight parking space. (Basestations have Ethernet connections for this purpose.) All nodes have two radios. One radio is configured to Channel 1 of 802.11g and the other to Channel 11. To reduce interference, the two antennae are separated by at least one foot. By comparing the cases where only one radio is active to where both are active, we have confirmed that any residual interference is minimal. Our radios operate in ad hoc (IBSS) mode using a locally modified device driver. One modification forces the use of a fixed BSSID instead of a randomly generated one. This prevents (temporary) network partitions when nodes end up with different BSSIDs. It also means that a BS and a client that come into range can start communicating immediately, without waiting for their BSSIDs to be reconciled. Yet another modification lets us log every received frame along with a hardware timestamp and PHY layer information such as RSSI while communicating normally (i.e., the radio is not put in 'monitor' mode). VanLAN uses the following hardware. EnGenius' EMP-8602 modules, which are based on the Atheros 5213 chipset, are used as radios. Their output power is 400 mW at 1 Mbps and lower at higher transmission rates. HyperLink's HG2403MGU antennae are used for the vans and HGV-2404U antennae are used for the basestations. Both types are omnidirectional in the horizontal plane but radiate less energy directly above and below. The clients also have an externally mounted GPS unit, so we know their locations. We use GlobalSat's BU-353 GPS unit which is based on the SiRF Star III chipset and outputs data once per second. The uncertainty in the location estimate of this chipset is under three meters 95% of the time. B. Positions of Basestations (supplementary information for the connectivity data) The positions of basestations are: our %BsCoords = (bs_1_1 => {lat => 47.6411476269696, lon => -122.125589847565}, bs_1_2 => {lat => 47.6406705247778, lon => -122.125589847565}, bs_3_1 => {lat => 47.6405584774192, lon => -122.125096321106}, bs_3_2 => {lat => 47.6400777553792, lon => -122.125096321106}, bs_4_1 => {lat => 47.6399729357003, lon => -122.125563025475}, bs_4_2 => {lat => 47.6394922082725, lon => -122.125563025475}, bs_5_1 => {lat => 47.6394054599949, lon => -122.125074863434}, bs_5_2 => {lat => 47.6389138837009, lon => -122.125096321106}, bs_5_3 => {lat => 47.6389138837009, lon => -122.125836610794}, bs_6_1 => {lat => 47.6388921964049, lon => -122.126222848892}, bs_6_2 => {lat => 47.6389066546033, lon => -122.126973867416}); The mapping from IP address to node-name:interface pair is: our %Ip2Name = ("10.198.17.2" => "bs_1_1:5211", "10.198.18.2" => "bs_1_1:6211", "10.198.17.3" => "bs_1_2:5211", "10.198.18.3" => "bs_1_2:6211", "10.198.17.4" => "bs_3_1:5211", "10.198.18.4" => "bs_3_1:6211", "10.198.17.5" => "bs_3_2:5211", "10.198.18.5" => "bs_3_2:6211", "10.198.17.6" => "bs_4_1:5211", "10.198.18.6" => "bs_4_1:6211", "10.198.17.7" => "bs_4_2:5211", "10.198.18.7" => "bs_4_2:6211", "10.198.17.8" => "bs_5_1:5211", "10.198.18.8" => "bs_5_1:6211", "10.198.17.9" => "bs_5_2:5211", "10.198.18.9" => "bs_5_2:6211", "10.198.17.10" => "bs_5_3:5211", "10.198.18.10" => "bs_5_3:6211", "10.198.17.11" => "bs_6_1:5211", "10.198.18.11" => "bs_6_1:6211", "10.198.17.12" => "bs_6_2:5211", "10.198.18.12" => "bs_6_2:6211", "10.198.17.102" => "r_1:5211", "10.198.18.102" => "r_1:6211", "10.198.17.103" => "r_2:5211", "10.198.18:103" => "r_2:6211", );last modified: 2007-12-05dataname: microsoft/vanlan/connectivityversion: 20070914change: the initial version.release date: 2007-09-14date/time of measurement start: 2007-01-22date/time of measurement end: 2007-01-26microsoft/vanlan/connectivity Traces2007-01-22: Trace of WiFi-based connectivity between basestations and vehicles in urban settings, collected on 2007-01-22.configuration: The directory contains data for a day on 2007-01-22. This is a subset of the data used in the following paper: Understanding WiFi-based Connectivity From Moving Vehicles Ratul Mahajan, John Zahorjan, and Brian Zill ACM/Usenix Internet Measurement Conference (IMC), October 2007format: The name of the directory is the date. There are three kinds of files in each directory. A. Application-level traces --------------------------- The workload for these traces consisted of an application broadcasting packets periodically on each of the two interfaces. The nodes logged all packets they sent or heard from other nodes. The filenames for such traces are in the following format: ...bcast-bcast.gz node-name: name of the machine where this trace was collected. r-1 was a van, and details on the basestations are below. start-time: when the tracing started in the machine's local time interface: the interface on which the trace was collected. ath5211 was on channel 1 and ath6211 was on channel 11. Traces were rotated after a million packets. The filename suffix changed upon rotation. The format in these file is: (S|R): 2007-01-22T06:48:18.5156250-08:00 10.198.17.102 2007-01-22T06:47:43.9687500-08:00 309 1000 1 Column 1: S is for sent packets, and R is received packets Column 2: Timestamp when the packet was logged Column 3: Interface IP addresses of the packet source Column 4: Experiment Id of the packet sourcing application This Id was simply timestamp when the application was started Column 5: Source-specific sequence number of the packet Column 6: Transmission rate (in Kbps) at which the packet was sent B. Wifi traces from a van ------------------------- These contain all Wifi packets sent and captured by the van, including beacons from all APs in the environment and data packets from the application above. The filename format is: ...bcast-wifi.gz See above for the meaning of each component. The format in these files is: 2007-01-22T06:47:45.4062500-08:00 471 2566571334 2412 0 9 1000 89 MGMT_BEACON F 00:02:6F:3E:1D:77 FF:FF:FF:FF:FF:FF 02:03:04:05:06:07 DS:00 2270 Vanlan-g2412 Column 1: Timestamp (application-level) Column 2 and 3: Upper and lower 32 bits of the hardware timestamp Column 4: Frequency of the logged packet Column 5: status of this packet. 0 means the packet was correctly received 102 means the packet was successfully transmitted Ignore other status values Column 6: RSSI Column 7: Transmission rate of the packet (in Kbps) Column 8: Packet size Column 9: Retry? Column 10: Source MAC address Column 11: Destination MAC address Column 12: BSSID Column 13: DS field values; FromDS:ToDS Column 14: Sequence number of the packet Column 15: For beacons, the SSID For other packets, you can ignore everything beyond this column C. GPS logs from a van ----------------------- GPS data was logged by the van at most once per second. The filename format is: ..COM4.gps The format of these traces is: 2007-01-22T06:47:57.3593750-08:00 2007-01-22T14:47:15.0000000 47.644565 N 122.13342 W 0.13 157 2.9 1 2.7 Column 1: Machine time Column 2: UTC time Column 3: Latitude in degrees, followed by N (for north) Column 5: Longitude in degrees, following by W (for west) Column 7: Speed in knots (1 knot = 1.852 Kmph) Column 8: Direction of motion Columns 9, 10, 11: Percent, horizontal, and vertical dilution of precisiondescription: Trace of WiFi-based connectivity between basestations and vehicles in urban settings, collected on 2007-01-22.last modified: 2007-12-05dataname: microsoft/vanlan/connectivity/2007-01-22version: 20070914change: the initial versionrelease date: 2007-09-14date/time of measurement start: 2007-01-22date/time of measurement end: 2007-01-22url: /download/microsoft/vanlan/2007-01-22note: While unzipping some of the files, you will get "unexpected end of file" error from gzip. This is a side-effect of how I was sizpping the files on the fly and terminating the program. The data is still readable using 'gunzip -c' or 'zless'.2007-01-23: Trace of WiFi-based connectivity between basestations and vehicles in urban settings, collected on 2007-01-23.configuration: The directory contains data for a day on 2007-01-22. This is a subset of the data used in the following paper: Understanding WiFi-based Connectivity From Moving Vehicles Ratul Mahajan, John Zahorjan, and Brian Zill ACM/Usenix Internet Measurement Conference (IMC), October 2007format: The name of the directory is the date. There are three kinds of files in each directory. A. Application-level traces --------------------------- The workload for these traces consisted of an application broadcasting packets periodically on each of the two interfaces. The nodes logged all packets they sent or heard from other nodes. The filenames for such traces are in the following format: ...bcast-bcast.gz node-name: name of the machine where this trace was collected. r-1 was a van, and details on the basestations are below. start-time: when the tracing started in the machine's local time interface: the interface on which the trace was collected. ath5211 was on channel 1 and ath6211 was on channel 11. Traces were rotated after a million packets. The filename suffix changed upon rotation. The format in these file is: (S|R): 2007-01-22T06:48:18.5156250-08:00 10.198.17.102 2007-01-22T06:47:43.9687500-08:00 309 1000 1 Column 1: S is for sent packets, and R is received packets Column 2: Timestamp when the packet was logged Column 3: Interface IP addresses of the packet source Column 4: Experiment Id of the packet sourcing application This Id was simply timestamp when the application was started Column 5: Source-specific sequence number of the packet Column 6: Transmission rate (in Kbps) at which the packet was sent B. Wifi traces from a van ------------------------- These contain all Wifi packets sent and captured by the van, including beacons from all APs in the environment and data packets from the application above. The filename format is: ...bcast-wifi.gz See above for the meaning of each component. The format in these files is: 2007-01-22T06:47:45.4062500-08:00 471 2566571334 2412 0 9 1000 89 MGMT_BEACON F 00:02:6F:3E:1D:77 FF:FF:FF:FF:FF:FF 02:03:04:05:06:07 DS:00 2270 Vanlan-g2412 Column 1: Timestamp (application-level) Column 2 and 3: Upper and lower 32 bits of the hardware timestamp Column 4: Frequency of the logged packet Column 5: status of this packet. 0 means the packet was correctly received 102 means the packet was successfully transmitted Ignore other status values Column 6: RSSI Column 7: Transmission rate of the packet (in Kbps) Column 8: Packet size Column 9: Retry? Column 10: Source MAC address Column 11: Destination MAC address Column 12: BSSID Column 13: DS field values; FromDS:ToDS Column 14: Sequence number of the packet Column 15: For beacons, the SSID For other packets, you can ignore everything beyond this column C. GPS logs from a van ----------------------- GPS data was logged by the van at most once per second. The filename format is: ..COM4.gps The format of these traces is: 2007-01-22T06:47:57.3593750-08:00 2007-01-22T14:47:15.0000000 47.644565 N 122.13342 W 0.13 157 2.9 1 2.7 Column 1: Machine time Column 2: UTC time Column 3: Latitude in degrees, followed by N (for north) Column 5: Longitude in degrees, following by W (for west) Column 7: Speed in knots (1 knot = 1.852 Kmph) Column 8: Direction of motion Columns 9, 10, 11: Percent, horizontal, and vertical dilution of precisiondescription: Trace of WiFi-based connectivity between basestations and vehicles in urban settings, collected on 2007-01-23.last modified: 2007-12-05dataname: microsoft/vanlan/connectivity/2007-01-23version: 20070914change: the initial versionrelease date: 2007-09-14date/time of measurement start: 2007-01-23date/time of measurement end: 2007-01-23url: /download/microsoft/vanlan/2007-01-23note: While unzipping some of the files, you will get "unexpected end of file" error from gzip. This is a side-effect of how I was sizpping the files on the fly and terminating the program. The data is still readable using 'gunzip -c' or 'zless'.2007-01-24: Trace of WiFi-based connectivity between basestations and vehicles in urban settings, collected on 2007-01-24.configuration: The directory contains data for a day on 2007-01-22. This is a subset of the data used in the following paper: Understanding WiFi-based Connectivity From Moving Vehicles Ratul Mahajan, John Zahorjan, and Brian Zill ACM/Usenix Internet Measurement Conference (IMC), October 2007format: The name of the directory is the date. There are three kinds of files in each directory. A. Application-level traces --------------------------- The workload for these traces consisted of an application broadcasting packets periodically on each of the two interfaces. The nodes logged all packets they sent or heard from other nodes. The filenames for such traces are in the following format: ...bcast-bcast.gz node-name: name of the machine where this trace was collected. r-1 was a van, and details on the basestations are below. start-time: when the tracing started in the machine's local time interface: the interface on which the trace was collected. ath5211 was on channel 1 and ath6211 was on channel 11. Traces were rotated after a million packets. The filename suffix changed upon rotation. The format in these file is: (S|R): 2007-01-22T06:48:18.5156250-08:00 10.198.17.102 2007-01-22T06:47:43.9687500-08:00 309 1000 1 Column 1: S is for sent packets, and R is received packets Column 2: Timestamp when the packet was logged Column 3: Interface IP addresses of the packet source Column 4: Experiment Id of the packet sourcing application This Id was simply timestamp when the application was started Column 5: Source-specific sequence number of the packet Column 6: Transmission rate (in Kbps) at which the packet was sent B. Wifi traces from a van ------------------------- These contain all Wifi packets sent and captured by the van, including beacons from all APs in the environment and data packets from the application above. The filename format is: ...bcast-wifi.gz See above for the meaning of each component. The format in these files is: 2007-01-22T06:47:45.4062500-08:00 471 2566571334 2412 0 9 1000 89 MGMT_BEACON F 00:02:6F:3E:1D:77 FF:FF:FF:FF:FF:FF 02:03:04:05:06:07 DS:00 2270 Vanlan-g2412 Column 1: Timestamp (application-level) Column 2 and 3: Upper and lower 32 bits of the hardware timestamp Column 4: Frequency of the logged packet Column 5: status of this packet. 0 means the packet was correctly received 102 means the packet was successfully transmitted Ignore other status values Column 6: RSSI Column 7: Transmission rate of the packet (in Kbps) Column 8: Packet size Column 9: Retry? Column 10: Source MAC address Column 11: Destination MAC address Column 12: BSSID Column 13: DS field values; FromDS:ToDS Column 14: Sequence number of the packet Column 15: For beacons, the SSID For other packets, you can ignore everything beyond this column C. GPS logs from a van ----------------------- GPS data was logged by the van at most once per second. The filename format is: ..COM4.gps The format of these traces is: 2007-01-22T06:47:57.3593750-08:00 2007-01-22T14:47:15.0000000 47.644565 N 122.13342 W 0.13 157 2.9 1 2.7 Column 1: Machine time Column 2: UTC time Column 3: Latitude in degrees, followed by N (for north) Column 5: Longitude in degrees, following by W (for west) Column 7: Speed in knots (1 knot = 1.852 Kmph) Column 8: Direction of motion Columns 9, 10, 11: Percent, horizontal, and vertical dilution of precisiondescription: Trace of WiFi-based connectivity between basestations and vehicles in urban settings, collected on 2007-01-24.last modified: 2007-12-05dataname: microsoft/vanlan/connectivity/2007-01-24version: 20070914change: the initial versionrelease date: 2007-09-14date/time of measurement start: 2007-01-24date/time of measurement end: 2007-01-24url: /download/microsoft/vanlan/2007-01-24note: While unzipping some of the files, you will get "unexpected end of file" error from gzip. This is a side-effect of how I was sizpping the files on the fly and terminating the program. The data is still readable using 'gunzip -c' or 'zless'.2007-01-25: Trace of WiFi-based connectivity between basestations and vehicles in urban settings, collected on 2007-01-25.configuration: The directory contains data for a day on 2007-01-22. This is a subset of the data used in the following paper: Understanding WiFi-based Connectivity From Moving Vehicles Ratul Mahajan, John Zahorjan, and Brian Zill ACM/Usenix Internet Measurement Conference (IMC), October 2007format: The name of the directory is the date. There are three kinds of files in each directory. A. Application-level traces --------------------------- The workload for these traces consisted of an application broadcasting packets periodically on each of the two interfaces. The nodes logged all packets they sent or heard from other nodes. The filenames for such traces are in the following format: ...bcast-bcast.gz node-name: name of the machine where this trace was collected. r-1 was a van, and details on the basestations are below. start-time: when the tracing started in the machine's local time interface: the interface on which the trace was collected. ath5211 was on channel 1 and ath6211 was on channel 11. Traces were rotated after a million packets. The filename suffix changed upon rotation. The format in these file is: (S|R): 2007-01-22T06:48:18.5156250-08:00 10.198.17.102 2007-01-22T06:47:43.9687500-08:00 309 1000 1 Column 1: S is for sent packets, and R is received packets Column 2: Timestamp when the packet was logged Column 3: Interface IP addresses of the packet source Column 4: Experiment Id of the packet sourcing application This Id was simply timestamp when the application was started Column 5: Source-specific sequence number of the packet Column 6: Transmission rate (in Kbps) at which the packet was sent B. Wifi traces from a van ------------------------- These contain all Wifi packets sent and captured by the van, including beacons from all APs in the environment and data packets from the application above. The filename format is: ...bcast-wifi.gz See above for the meaning of each component. The format in these files is: 2007-01-22T06:47:45.4062500-08:00 471 2566571334 2412 0 9 1000 89 MGMT_BEACON F 00:02:6F:3E:1D:77 FF:FF:FF:FF:FF:FF 02:03:04:05:06:07 DS:00 2270 Vanlan-g2412 Column 1: Timestamp (application-level) Column 2 and 3: Upper and lower 32 bits of the hardware timestamp Column 4: Frequency of the logged packet Column 5: status of this packet. 0 means the packet was correctly received 102 means the packet was successfully transmitted Ignore other status values Column 6: RSSI Column 7: Transmission rate of the packet (in Kbps) Column 8: Packet size Column 9: Retry? Column 10: Source MAC address Column 11: Destination MAC address Column 12: BSSID Column 13: DS field values; FromDS:ToDS Column 14: Sequence number of the packet Column 15: For beacons, the SSID For other packets, you can ignore everything beyond this column C. GPS logs from a van ----------------------- GPS data was logged by the van at most once per second. The filename format is: ..COM4.gps The format of these traces is: 2007-01-22T06:47:57.3593750-08:00 2007-01-22T14:47:15.0000000 47.644565 N 122.13342 W 0.13 157 2.9 1 2.7 Column 1: Machine time Column 2: UTC time Column 3: Latitude in degrees, followed by N (for north) Column 5: Longitude in degrees, following by W (for west) Column 7: Speed in knots (1 knot = 1.852 Kmph) Column 8: Direction of motion Columns 9, 10, 11: Percent, horizontal, and vertical dilution of precisiondescription: Trace of WiFi-based connectivity between basestations and vehicles in urban settings, collected on 2007-01-25.last modified: 2007-12-05dataname: microsoft/vanlan/connectivity/2007-01-25version: 20070914change: the initial versionrelease date: 2007-09-14date/time of measurement start: 2007-01-25date/time of measurement end: 2007-01-25url: /download/microsoft/vanlan/2007-01-25note: While unzipping some of the files, you will get "unexpected end of file" error from gzip. This is a side-effect of how I was sizpping the files on the fly and terminating the program. The data is still readable using 'gunzip -c' or 'zless'.2007-01-26: Trace of WiFi-based connectivity between basestations and vehicles in urban settings, collected on 2007-01-26.configuration: The directory contains data for a day on 2007-01-22. This is a subset of the data used in the following paper: Understanding WiFi-based Connectivity From Moving Vehicles Ratul Mahajan, John Zahorjan, and Brian Zill ACM/Usenix Internet Measurement Conference (IMC), October 2007format: The name of the directory is the date. There are three kinds of files in each directory. A. Application-level traces --------------------------- The workload for these traces consisted of an application broadcasting packets periodically on each of the two interfaces. The nodes logged all packets they sent or heard from other nodes. The filenames for such traces are in the following format: ...bcast-bcast.gz node-name: name of the machine where this trace was collected. r-1 was a van, and details on the basestations are below. start-time: when the tracing started in the machine's local time interface: the interface on which the trace was collected. ath5211 was on channel 1 and ath6211 was on channel 11. Traces were rotated after a million packets. The filename suffix changed upon rotation. The format in these file is: (S|R): 2007-01-22T06:48:18.5156250-08:00 10.198.17.102 2007-01-22T06:47:43.9687500-08:00 309 1000 1 Column 1: S is for sent packets, and R is received packets Column 2: Timestamp when the packet was logged Column 3: Interface IP addresses of the packet source Column 4: Experiment Id of the packet sourcing application This Id was simply timestamp when the application was started Column 5: Source-specific sequence number of the packet Column 6: Transmission rate (in Kbps) at which the packet was sent B. Wifi traces from a van ------------------------- These contain all Wifi packets sent and captured by the van, including beacons from all APs in the environment and data packets from the application above. The filename format is: ...bcast-wifi.gz See above for the meaning of each component. The format in these files is: 2007-01-22T06:47:45.4062500-08:00 471 2566571334 2412 0 9 1000 89 MGMT_BEACON F 00:02:6F:3E:1D:77 FF:FF:FF:FF:FF:FF 02:03:04:05:06:07 DS:00 2270 Vanlan-g2412 Column 1: Timestamp (application-level) Column 2 and 3: Upper and lower 32 bits of the hardware timestamp Column 4: Frequency of the logged packet Column 5: status of this packet. 0 means the packet was correctly received 102 means the packet was successfully transmitted Ignore other status values Column 6: RSSI Column 7: Transmission rate of the packet (in Kbps) Column 8: Packet size Column 9: Retry? Column 10: Source MAC address Column 11: Destination MAC address Column 12: BSSID Column 13: DS field values; FromDS:ToDS Column 14: Sequence number of the packet Column 15: For beacons, the SSID For other packets, you can ignore everything beyond this column C. GPS logs from a van ----------------------- GPS data was logged by the van at most once per second. The filename format is: ..COM4.gps The format of these traces is: 2007-01-22T06:47:57.3593750-08:00 2007-01-22T14:47:15.0000000 47.644565 N 122.13342 W 0.13 157 2.9 1 2.7 Column 1: Machine time Column 2: UTC time Column 3: Latitude in degrees, followed by N (for north) Column 5: Longitude in degrees, following by W (for west) Column 7: Speed in knots (1 knot = 1.852 Kmph) Column 8: Direction of motion Columns 9, 10, 11: Percent, horizontal, and vertical dilution of precisiondescription: Trace of WiFi-based connectivity between basestations and vehicles in urban settings, collected on 2007-01-26.last modified: 2007-12-05dataname: microsoft/vanlan/connectivity/2007-01-26version: 20070914change: the initial versionrelease date: 2007-09-14date/time of measurement start: 2007-01-26date/time of measurement end: 2007-01-26url: /download/microsoft/vanlan/2007-01-26note: While unzipping some of the files, you will get "unexpected end of file" error from gzip. This is a side-effect of how I was sizpping the files on the fly and terminating the program. The data is still readable using 'gunzip -c' or 'zless'.

我们通过自行部署的中等规模测试平台VanLAN开展测量，旨在分析城市环境中基站与车辆之间基于WiFi的连接的基本特征。
last modified：2007-12-05
release date：2007-09-14
date/time of measurement start：2007-01-22
date/time of measurement end：2007-01-26
collection environment：我们的目标是为城市区域内的移动车辆提供经济且高吞吐量的无线连接。当前此类连接的可用方案存在显著不足：蜂窝网络成本高昂且吞吐量较低；若WiMax网络得以普及，其表现可能亦如此。尽管部分现有WiFi基站可向过往车辆提供机会性连接（opportunistic connectivity），但无法支持长期连接。然而，WiFi部署正日益密集，许多城市已实现全面覆盖。
network configuration：我们的测试平台名为VanLAN，目前包含11个基站（BS，Basestation）和2个移动客户端。基站分布于华盛顿州雷德蒙德市微软园区内的5栋办公楼中。所有节点均配备两台无线电设备。一台配置为802.11g的1号信道，另一台配置为11号信道。为减少干扰，两根天线间距至少为1英尺。通过对比仅单台无线电活跃与两台均活跃的情况，我们证实残留干扰微乎其微。无线电设备采用本地修改的驱动程序，运行于自组织（IBSS，Independent Basic Service Set）模式。VanLAN采用以下硬件：无线电设备为基于Atheros 5213芯片组的EnGenius EMP-8602模块，其在1 Mbps速率下输出功率为400 mW，速率越高输出功率越低；车辆使用HyperLink HG2403MGU天线，基站使用HGV-2404U天线，两种天线在水平面均为全向辐射，但在垂直方向（正上方与正下方）辐射能量较低。客户端还配备外置GPS（Global Positioning System，全球定位系统）单元，以便获取其位置信息。我们使用基于SiRF Star III芯片组的GlobalSat BU-353 GPS单元，其每秒输出一次数据，95%情况下位置估计误差小于3米。
data collection methodology：我们在微软园区部署了测试平台，目前包含11个WiFi基站和2辆日间在园区周边运行的移动货车。该平台不仅用作研究工具，还为货车乘客提供连接服务。我们通过测试平台节点生成并记录探测流量。
sanitization：数据不含个人可识别信息，由固定基站与移动货车组成的测试平台收集。
Traceset
microsoft/vanlan/connectivity
城市环境中基站与车辆间基于WiFi的连接性轨迹集。
files：2007-01-22、2007-01-23、2007-01-24、2007-01-25、2007-01-26
description：我们通过自行部署的中等规模测试平台VanLAN开展测量，旨在分析城市环境中基站与车辆之间基于WiFi的连接的基本特征。
measurement purpose：网络性能分析
methodology：A. VanLAN测试平台
我们的测试平台名为VanLAN，目前包含11个基站（BS）和2个移动客户端。基站分布于华盛顿州雷德蒙德市微软园区内的5栋办公楼中。基站网络相互连接，但并非所有基站对均可通信。移动客户端为日间在园区及周边提供 shuttle服务的货车，每日约10次经过基站所在区域。该区域道路与城市居民区街道类似，限速约40公里/小时。基站与客户端均为小型桌面设备：基站放置于建筑顶层，天线安装于屋顶，通过低损耗同轴电缆连接无线电设备（位于桌面设备内部）；客户端放置于货车内部，天线安装于车顶，桌面设备由独立电池供电（与货车主电池分离），货车运行时充电，熄火后可供电约4小时，用于通过无线连接从货车夜间停放处附近的计算机获取软件更新（基站通过以太网连接实现此功能）。所有节点均配备两台无线电设备，一台配置为802.11g的1号信道，另一台为11号信道，天线间距至少1英尺以减少干扰，经测试残留干扰微乎其微。无线电设备采用本地修改的驱动程序运行于自组织（IBSS）模式：其一修改为使用固定BSSID（Basic Service Set Identifier，基本服务集标识符）而非随机生成，避免节点因BSSID不同导致临时网络分区，且基站与客户端进入范围后可立即通信，无需等待BSSID协调；其二修改为在正常通信时（无线电未处于监控模式）记录每个接收帧，包含硬件时间戳及RSSI（Received Signal Strength Indicator，接收信号强度指示）等物理层信息。硬件配置同前所述。
B. 基站位置（连接性数据补充信息）
基站位置：our %BsCoords = (...);
IP地址到节点名:接口对的映射：our %Ip2Name = (...);
last modified：2007-12-05
dataname：microsoft/vanlan/connectivity
version：20070914
change：初始版本
release date：2007-09-14
date/time of measurement start：2007-01-22
date/time of measurement end：2007-01-26
microsoft/vanlan/connectivity 轨迹
2007-01-22：2007年1月22日收集的城市环境中基站与车辆间基于WiFi的连接性轨迹。
configuration：该目录包含2007年1月22日的单日数据，是论文《Understanding WiFi-based Connectivity From Moving Vehicles》（Ratul Mahajan等，ACM/Usenix互联网测量会议（IMC）2007年10月）所用数据的子集。
format：目录名为日期，包含三类文件：
A. 应用层轨迹
此类轨迹的工作负载为应用程序在两个接口上周期性广播数据包，节点记录所有发送或接收的数据包。文件名格式为...bcast-bcast.gz：node-name为收集轨迹的机器名（r-1为货车，基站详情见下）；start-time为机器本地时间的轨迹开始时间；interface为收集轨迹的接口（ath5211对应1号信道，ath6211对应11号信道）。轨迹每百万数据包轮转一次，文件名后缀变更。文件格式：
(S|R): 2007-01-22T06:48:18.5156250-08:00 10.198.17.102 ...
列1：S表示发送的数据包，R表示接收的数据包；列2：数据包记录的时间戳；列3：数据包源的接口IP地址；列4：数据包源应用程序的实验ID（即应用程序启动时间戳）；列5：源特定的数据包序列号；列6：数据包发送的传输速率（单位：Kbps）。
B. 货车的WiFi轨迹
包含货车发送和捕获的所有WiFi数据包，包括环境中所有AP的beacon帧及上述应用程序的数据包。文件名格式为...bcast-wifi.gz。文件格式：
2007-01-22T06:47:45.4062500-08:00 ... Vanlan-g2412
列1：应用层时间戳；列2-3：硬件时间戳的高32位与低32位；列4：数据包频率；列5：数据包状态（0表示正确接收，102表示成功发送，忽略其他值）；列6：RSSI；列7：传输速率（Kbps）；列8：数据包大小；列9：是否重试；列10：源MAC地址（Media Access Control Address）；列11：目的MAC地址；列12：BSSID；列13：DS字段（Distribution System Field）值（FromDS:ToDS）；列14：数据包序列号；列15：beacon帧为SSID（Service Set Identifier，服务集标识符），其他数据包可忽略后续内容。
C. 货车的GPS日志
货车每秒最多记录一次GPS数据，文件名格式为..COM4.gps。日志格式：
2007-01-22T06:47:57.3593750-08:00 ...
列1：机器时间；列2：UTC时间；列3：纬度（度）+N（北）；列5：经度（度）+W（西）；列7：速度（节，1节=1.852公里/小时）；列8：运动方向；列9-11：精度因子（dilution of precision）的百分比、水平及垂直分量。
description：2007年1月22日收集的城市环境中基站与车辆间基于WiFi的连接性轨迹。
last modified：2007-12-05
dataname：microsoft/vanlan/connectivity/2007-01-22
version：20070914
change：初始版本
release date：2007-09-14
date/time of measurement start：2007-01-22
date/time of measurement end：2007-01-22
url：/download/microsoft/vanlan/2007-01-22
note：解压部分文件时，gzip可能报“unexpected end of file”（意外文件结束）错误，这是实时压缩并终止程序的副作用，数据仍可通过‘gunzip -c’或‘zless’读取。
2007-01-23至2007-01-26的内容与2007-01-22类似，仅日期及对应dataname调整。