CRAWDAD cister/rssi

Channel energy levels from Wi-Fi networks as seen from a 802.15.4 radio.

We use a sensor network composed of TelosB motes deployed in the library building to collect RF energy level samples (RSSI) on all 802.15.4 channels in the 2.4 GHz ISM Band. The building has several collocated Wi-Fi networks in normal operation. These networks produce interference for the 802.15.4 radios. Sensor nodes record RSSI values every 20 us, simultaneously on all channels, for 130 ms and then write the result to the respective files. This process is repeated every 8 seconds for around 4h.

date/time of measurement start: 2010-11-25

date/time of measurement end: 2010-11-25

collection environment: The data was collected in the library of the Faculty of Engineering at the University of Porto, Portugal. Over 300 MAC addresses were registered in the Wi-Fi networks during the measurement as indicated by complementary Kismet traces, not included in this set.

network configuration: The network consisted of 17 TelosB nodes connected to a laptop PC via USB. One node acted as master and broadcast scan commands on channel 26. Other nodes scanned one 802.15.4 channel (2.4 GHz) each for 130 ms at a time. Collocated 802.11b/g APs provide connectivity to library users with portable computing devices.

data collection methodology: All 16 nodes scan RSSI values (with the CC2420 radio chip on-board) at 20 us resolution, as the local memory permits, and then write to an associated data file (one per channel/node) on the laptop HDD.

limitation: Serial communication on the TelosB motes is remarkably slower than the rate at which it is possible to read RSSI via the CC2420 radio in the TelosB platform. Therefore, traces contain 130 ms of RSSI data every 8 seconds, to allow sufficient time for the nodes to complete the data dump process.

error :Two nodes apparently had misbehaving radios, which captured wrong RSSI values. They were originally intended to scan channels 7 and 13. This was detected beforehand and two other (well behaved) nodes were added to replace the data from the former ones (19 nodes, all in all). Original (wrong) traces are also included as a curiosity.

sanitization: The data does not contain any sensitive information that could raise any privacy concerns. Therefore, no sanitization is performed.

 Traceset

802.15.4

Channel energy levels from Wi-Fi networks as seen from a 802.15.4 radio.

• file: 15.4_RSSI.zip
• description: We use a sensor network composed of TelosB motes deployed in the library building to collect RF energy level samples (RSSI) on all 802.15.4 channels in the 2.4 GHz ISM Band. The building has several collocated Wi-Fi networks in normal operation. These networks produce interference for the 802.15.4 radios. Sensor nodes record RSSI values every 20 us, simultaneously on all channels, for 130 ms and then write the result to the respective files. This process is repeated every 8 seconds for around 4h.

• measurement purpose: Bit Error Characterization, MAC Protocol Development, Usage Characterization, Energy-efficient Wireless Network, Opportunistic Connectivity
• methodology: All 16 nodes record RSSI values (with the CC2420 radio chip on-board) at 20 us resolution, as the local memory permits, and then write to an associated data file (one per channel/node) on the laptop HDD. All nodes are time synchronized, via scan commands sent by master node on ch 26.

802.15.4 Trace

• 2010: Channel energy levels from Wi-Fi networks as seen from a 802.15.4 radio.
• configuration: 16 nodes were scanning on one 802.15.4 channel each, and one more node was working as the master node to synchronize the network, by sending a scan command on channel 26. Sensor nodes were positioned close to each other on the 2nd floor of the 4 level building and wired to a nearby (2-3 m away) laptop computer via USB. A Contiki OS script performed data collection on the nodes. 
• format: Consecutive RSSI values are recorded in separate files, one file for each channel/node. Each file has a header, containing the id and the channel of the node. Each 130 ms capture contains a header, which specifies scan beacon and sequence number. These two values do not always match, as the scanner node occasionally misses the scan beacon from the master, e.g. due to interference. To avoid repetitively using the minus sign in all values in the files, we use an implicit offset. In order to convert these values to dBm, please subtract 100, e.g., 44 in the file corresponds to -56 dBm.