TAC and CID from different? towers - weaker signal connects, stronger signal doesn't
Posted: Wed Oct 16, 2019 11:13 am
I'm having trouble getting a connection at my cabin where I want to mount an antenna. There is only one tower in range (EDIT - there may be more than one - see follow up below). I get a good connection 200 feet away, but both locations appear equal from an RF measurements perspective (RSSI, RSRP, RSRQ, SINR). If anything, the location that won't connect is better on these measurements. The puzzling part is I see one TAC and CID in one place but another 200 feet away.
First some details. I have two locations, one where I get a connection (called YES) and one where I don't (called NO). I want to get a connection at the NO location. I'm using the exact same device at both locations.
Physical Layout
Location YES is on the roof of my car on the side of the driveway slightly uphill of the cabin
(edited above, had this backwards when I first posted )
T-mobile tower and T-mobile SIM.
MC7455 Modem, We826-T2 router, stock antennas
Also tried with a Google Fi SIM and saw the same results. Was connecting to the same T-mobile tower with the Fi SIM.
Below is the output of at!lteinfo and at!gstatus? from both locations. Realized today I only copied part of the output from the NO location, hopefully I've got the important bits.
Location: YES
at!lteinfo
at!gstatus?
Locaiton NO (partial command output)
at!lteinfo
at!gstatus?
Note the difference in the TAC and CID. That is the confusing part. I'm not fully versed in TAC and CID values, but I thought they were unique to an antenna on a tower. Can't understand why they change. There was no place I ever saw an output of at!lteinfo that showed both. It was always only one or the other. One TAC/CID connected (AEFF / 01911916), one did not (AE80 / 019D0516). At the NO location, I only ever saw TAC: AE80 / CID 019D0516. At the YES location, I did sometimes see TAC: AE80 / CID 019D0516 at startup or after a reboot, with no connection. After a minute it would switch to TAC: AEFF / CID 01911916 and connect.
Questions
- why does it connect at one location but not the other despite what appears to be similar signal strength measures?
- what is the significance of TAC and CID
My long-term plan is to mount external antennas (preferably on the cabin) and I know that will improve things. Right now I'm just trying to understand why one location works but another doesn't.
First some details. I have two locations, one where I get a connection (called YES) and one where I don't (called NO). I want to get a connection at the NO location. I'm using the exact same device at both locations.
Physical Layout
- both locations are 2.62 miles from the tower
- YES and NO are along the same arc from the tower (same distance to the tower)
- distance between locations is 200ft
- altitude of antenna at each location is approximately equal (within +/- 5ft)
- tower is in valley below locations, about 1000ft lower in altitude
- only tower around, next nearest is over 5 miles and not LOS
- rural area, wooded mountains, leaves on the trees
- both locations have similar amount of trees along LOS to tower
Location YES is on the roof of my car on the side of the driveway slightly uphill of the cabin
(edited above, had this backwards when I first posted )
T-mobile tower and T-mobile SIM.
MC7455 Modem, We826-T2 router, stock antennas
Also tried with a Google Fi SIM and saw the same results. Was connecting to the same T-mobile tower with the Fi SIM.
Below is the output of at!lteinfo and at!gstatus? from both locations. Realized today I only copied part of the output from the NO location, hopefully I've got the important bits.
Location: YES
at!lteinfo
Code: Select all
!LTEINFO:
Serving: EARFCN MCC MNC TAC CID Bd D U SNR PCI RSRQ RSRP RSSI RXLV
5035 310 260 44799 01911916 12 2 2 1 133 -15.9 -103.4 -73.5 --
IntraFreq: PCI RSRQ RSRP RSSI RXLV
133 -15.9 -103.4 -73.5 --
166 -12.5 -104.7 -83.7 --
99 -17.6 -110.6 -83.7 --
InterFreq: EARFCN ThresholdLow ThresholdHi Priority PCI RSRQ RSRP RSSI RXLV
901 0 0 0 448 -18.1 -127.1 -100.0 0
GSM: ThreshL ThreshH Prio NCC ARFCN 1900 valid BSIC RSSI RXLV
WCDMA: UARFCN ThreshL ThreshH Prio PSC RSCP ECN0 RXLV
CDMA 1x: Chan BC Offset Phase Str
CDMA HRPD: Chan BC Offset Phase Str
Code: Select all
!GSTATUS:
Current Time: 1434 Temperature: 48
Reset Counter: 1 Mode: ONLINE
System mode: LTE PS state: Attached
LTE band: B12 LTE bw: 5 MHz
LTE Rx chan: 5035 LTE Tx chan: 23035
LTE CA state: ACTIVE LTE Scell band:B2
LTE Scell bw:10 MHz LTE Scell chan:901
EMM state: Registered Normal Service
RRC state: RRC Connected
IMS reg state: No Srv
PCC RxM RSSI: -75 RSRP (dBm): -103
PCC RxD RSSI: -76 RSRP (dBm): -108
SCC RxM RSSI: -92 RSRP (dBm): -127
SCC RxD RSSI: -91 RSRP (dBm): -127
Tx Power: 16 TAC: AEFF (44799)
RSRQ (dB): -11.9 Cell ID: 01911916 (26286358)
SINR (dB): 1.8
Locaiton NO (partial command output)
at!lteinfo
Code: Select all
!LTEINFO:
Serving: EARFCN MCC MNC TAC CID Bd D U SNR PCI RSRQ RSRP RSSI RXLV
5035 310 260 44672 019D0516 12 2 2 15 166 -13.2 -97.9 -70.7 26
at!gstatus?
Code: Select all
System mode: LTE PS state: Not Attached
LTE band: B12 LTE bw: 5 MHz
PCC RxM RSSI: -72 RSRP (dBm): -96
PCC RxD RSSI: -78 RSRP (dBm): -102
Tx Power: 0 TAC: AE80 (44672)
RSRQ (dB): -9.3 Cell ID: 019D0516 (27067670)
SINR (dB): 13.6
Note the difference in the TAC and CID. That is the confusing part. I'm not fully versed in TAC and CID values, but I thought they were unique to an antenna on a tower. Can't understand why they change. There was no place I ever saw an output of at!lteinfo that showed both. It was always only one or the other. One TAC/CID connected (AEFF / 01911916), one did not (AE80 / 019D0516). At the NO location, I only ever saw TAC: AE80 / CID 019D0516. At the YES location, I did sometimes see TAC: AE80 / CID 019D0516 at startup or after a reboot, with no connection. After a minute it would switch to TAC: AEFF / CID 01911916 and connect.
Questions
- why does it connect at one location but not the other despite what appears to be similar signal strength measures?
- what is the significance of TAC and CID
My long-term plan is to mount external antennas (preferably on the cabin) and I know that will improve things. Right now I'm just trying to understand why one location works but another doesn't.