CRAWDAD sunysb/mobisteer

Dataset collected from a moving car equipped with a steerable directional antenna.

This data set includes data traces that were collected from a moving car equipped with an electronically steerable directinal antenna. We drove the car in two different environments in Stony Brook University campus - Apartment Complex and Parking lot.

last modified: 2007-07-18

release date: 2007-06-30

date/time of measurement start: 2006-09-28

date/time of measurement end: 2006-11-29

collection environment: We investigate the use of directional antennas and beam steering techniques to improve performance of 802.11 links in the context of communication between a moving vehicle and roadside APs. To this end, we develop a framework called MobiSteer that provides practical approaches to perform beam steering. MobiSteer can operate in two modes - cached mode - where it uses prior radio survey data collected during "idle" drives, and online mode, where it uses probing. The goal is to select the best AP and beam combination at each point along the drive given the available information, so that the throughput can be maximized. We conducted extensive experiments and collected data traces using a commercially available eight element phased-array antenna.

network configuration: Our directional antenna set up uses electronically steerable Phocus Array antennas from Fidelity Comtech for the 2.4 GHz band used in IEEE 802.11b/g. The Phocus Array antenna system consists of eight element phased arrays driven by eight individual T/R (transmit-receive) boards that receive radio signals from the wireless card via an eight way RF splitter. The phased arrays combine radio waves by introducing different phase differences and gains in the eight arrays. A T/R board is essentially a vector modulator with bi-directional amplifier controlled by software. Various beam patterns are possible by setting the phases and gains in different boards. The antenna is set to behave identically for transmit and receive, i.e., the antenna gains for transmit and receive are the same. A software program running on an embedded computer (a Soekris net4511 board) controls the antenna over a serial-line interface to produce different beam patterns. The embedded computer is equipped with a 802.11 b/g miniPCI card based on Atheros chipset with the external antenna interface. The mbedded computer runs pebble Linux with the Linux 2.4.26 kernel and the widely used madwifi device driver for the 802.11 interface. For convenience, we will refer to the entire vehicular setup, including the embedded computer with 802.11 and GPS interfaces and the directional antenna as the MobiSteer node. The APs are Soekris net4826 router boards with similar Atheros based 802.11 a/b/g miniPCI cards connected to regular rubber duck omnidirectional antennas. The APs also run the same base software (pebble Linux and madwifi driver) as the MobiSteer node.

data collection methodology: The APs operate in pseudo-ad hoc mode and continuously unicast 1000 byte UDP packets to the MobiSteer node at a constant rate of 300 packets/sec. The ad hoc mode is chosen instead of infrastructure mode so that the MobiSteer node can receive packets from any AP rather than only the specific AP it is associated to. This enables us to exclusively study the beam steering part of our algorithm. If and when the MobiSteer node receives any packet it records the tuple <location,timestamp, ap,="" channel,="" datarate,="" beam,="" snr="">. The default auto-rate algorithm in the card driver is used for rate adaptation. The data collection in the controlled experiments is done fairly conservatively to eliminate any source of error. In order to eliminate any possibility of missing packets due to beam steering delays (which is already negligible), only fixed beams are used for each drive and beams are switched only between drives. So a set of 9 drives on the same path gives us data on each of the 8 directional beam plus the omnidirectional beam. Each drive is done in a very slow speed (about 10 miles/hour). We have done 8 such sets of drives on different days and times in order to analyze the variability of the data. Recall that we are using one channel as all our deployed APs are in the same channel.

Traceset

sunysb/mobisteer/kismet

Traceset collected from a moving car equipped with a steerable directional antenna.

• files: apt.tar.gz, parking-lot.tar.gz
• description: This set of log files includes data traces that were collected from a moving car equipped with an electronically steerable directinal antenna. We drove the car in two different environments in Stony Brook University campus - Apartment Complex and Parking lot.
• measurement purpose: Network Performance Analysis
• methodology: We conducted our experiments to evaluate our beam steering algorithm. We use two specific controlled scenarios where we deploy our own APs. (a) a large empty parking lot in Stony Brook University campus without any neighboring buildings and large trees -- offering a virtually multipath-free environment with little, if any, external interference, (b) the graduate students' apartment complex in the same campus -- offering diametrically opposite environment, rich in both multipath and external 802.11 traffic. We use only one AP in the parking lot. It has been hard to use more than one AP gainfully in such a "clean" environ ment! However, we use five APs in the apartment complex. Here, the APs are carefully located so that at each point on our driving route, typically two APs are always heard and all points on the driving route are covered by at least one AP. This controlled set of experiments demonstrates the beam steering advantage by doing actual measurements of link-layer data transfer rate between the MobiSteer node and the APs. The APs are run on the same channel. Using just one channel in the experiments removes the channel variable from our experiments and lets us concentrate on only the beam steering aspect.

sunysb/mobisteer/kismet Traces

• apt: Traces collected from a moving car equipped with a steerable directional antenna in an apartment complex.
• configuration: This set of log files includes data traces that were collected from a moving car equipped with electronically steerable Phocus Array Antenna from Fidelity Comtech. We drove the car in an apartment complex in Stony Brook University campus. We had setup up 5 Accesspoints (802.11g) alongside the driving route. The APs were configured to send CBR traffic at 300 packets/second to the mobile node. Each file corresponds to the data collected at the mobile node using kismet tool during one complete drive along the route using one single beam pattern. We collected the data for 9 beam patterns (given below) by driving 9 times along the same route, each time with a different beam pattern. We have included the data collected on 12 different days. Beam-0 - Omni Directional beams (45deg beam width and 15dBi gain): Beam-1 - 0deg Beam-3 - 45deg Beam-5 - 90deg Beam-7 - 135deg Beam-9 - 180deg Beam-11 - 225deg Beam-13 - 270deg Beam-15 - 315deg
• format:

  Data format is as follows:

   

  Datarate field is interpreted as follows

  10 -- 1.0 Mbps

  20 -- 2.0 Mbps

  50 -- 5.5 Mbps

  110 -- 11.0 Mbps

  60 -- 6.0 Mbps

  120 -- 12.0 Mbps

  180 -- 18.0 Mbps

  360 -- 36.0 Mbps

  90 -- 9.0 Mbps

  240 -- 24.0 Mbps

  480 -- 48.0 Mbps

  540 -- 54.0 Mbps

• parking-lot: Traces collected from a moving car equipped with a steerable directional antenna in a parking lot.
• configuration: This set of log files includes data traces that were collected from a moving car equipped with electronically steerable Phocus Array Antenna from Fidelity Comtech. We drove the car in a parking lot in Stony Brook University campus. We only had one AP (802.11b) covering the entire area. The APs were configured to send CBR traffic at 300 packets/second to the mobile node. Each file corresponds to the data collected at the mobile node using kismet tool during one complete drive along the route using one single beam pattern. We collected the data for 9 beam patterns (given below) by driving 9 times along the same route, each time with a different beam pattern. Beam-0 - Omni Directional beams (45deg beam width and 15dBi gain): Beam-1 - 0deg Beam-3 - 45deg Beam-5 - 90deg Beam-7 - 135deg Beam-9 - 180deg Beam-11 - 225deg Beam-13 - 270deg Beam-15 - 315deg
• format:

  Data format is as follows:

   

  Datarate field is interpreted as follows

  10 -- 1.0 Mbps

  20 -- 2.0 Mbps

  50 -- 5.5 Mbps

  110 -- 11.0 Mbps

  60 -- 6.0 Mbps

  120 -- 12.0 Mbps

  180 -- 18.0 Mbps

  360 -- 36.0 Mbps

  90 -- 9.0 Mbps

  240 -- 24.0 Mbps

  480 -- 48.0 Mbps

  540 -- 54.0 Mbps