11/05/2026
BTS = RBS
BTS CONNECTIVITY
BTS means Base Transceiver Station.
It connects mobile users with the telecom network through antenna, RF equipment, transmission system, and core network.
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1. BASIC BTS CONNECTIVITY FLOW
====================================
Mobile Phone / UE
↓
Antenna
↓
RRU / RF Unit
↓
BBU / BTS Cabinet
↓
Router / Switch / Transmission Equipment
↓
Microwave / Fiber / IP Transport
↓
BSC / RNC / EPC / 5G Core
↓
Internet / Voice Network
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2. BTS MAIN CONNECTIVITY PARTS
====================================
1. Antenna System
- Sends and receives radio signal
- Covers mobile users in the area
- Connected with RRU by RF jumper or feeder cable
2. RRU / RF Unit
- Converts digital signal to RF signal
- Sends signal to antenna
- Receives signal from antenna
- Usually installed near antenna on tower
3. BBU / BTS Cabinet
- Main processing unit of BTS
- Handles user traffic
- Controls radio resources
- Connected with RRU by fiber cable
4. Transmission Equipment
- Sends BTS traffic to the main network
- Can be microwave, fiber, Ethernet, or IP router
5. Power System
- Rectifier
- Battery
- Generator
- DC power cable
- Grounding system
6. Alarm & Monitoring System
- Sends BTS alarms to NOC
- Helps monitor site health
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3. BTS CONNECTIVITY TYPES
====================================
A. Microwave Connectivity
BTS Site
↓
MW IDU / Router
↓
MW ODU
↓
MW Dish Antenna
↓ Air Link
MW Dish Antenna
↓
Hub Site / Main Site
↓
Core Network
Uses:
- Remote area backhaul
- Fast deployment
- Site-to-site connection
Common MW Bands:
- 6 GHz
- 7 GHz
- 13 GHz
- 15 GHz
- 18 GHz
- 23 GHz
- 70/80 GHz E-band
B. Fiber Connectivity
BTS
↓
Router / Switch
↓
Fiber Optical Cable
↓
Metro / IP Transport Network
↓
Core Network
Advantages:
- High capacity
- Low latency
- Very stable
- Best for 4G and 5G sites
C. Ethernet / IP Connectivity
BTS / eNodeB / gNodeB
↓
Router
↓
IP/MPLS Network
↓
Core Network
Used for:
- LTE
- 5G
- Modern telecom network
D. E1/T1 Legacy Connectivity
BTS
↓
E1 Cable
↓
BSC
Used mostly in old 2G network.
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4. BTS CONNECTIVITY BY TECHNOLOGY
====================================
2G Network:
Mobile Phone
↓
BTS
↓
BSC
↓
MSC
↓
PSTN / Core Network
3G Network:
Mobile Phone
↓
NodeB
↓
RNC
↓
MSC / SGSN
↓
Core Network
4G LTE Network:
Mobile Phone
↓
eNodeB
↓
IP Transport
↓
EPC
↓
Internet
5G Network:
Mobile Phone
↓
gNodeB
↓
IP / Fiber Transport
↓
5G Core
↓
Internet
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5. BTS SITE EQUIPMENT CONNECTION
====================================
Tower Top:
- Antenna
- RRU
- RF jumper
- RET cable
- AISG cable
- Grounding cable
Shelter / Cabinet:
- BBU
- Router
- Transmission equipment
- Rectifier
- Battery bank
- Alarm box
- DDF / ODF
- ACDB / DCDB
Transmission:
- Microwave IDU
- Microwave ODU
- Fiber ODF
- Switch / Router
- Ethernet cable
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6. BTS RF CONNECTION
====================================
BBU
↓ Fiber Cable / CPRI
RRU
↓ RF Jumper
Antenna
↓ Radio Signal
Mobile Phone
Important RF Items:
- Antenna azimuth
- Antenna tilt
- RRU power
- VSWR
- RSSI
- SINR
- RSRP
- RSRQ
- PCI
- Cell ID
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7. BTS BACKHAUL CONNECTION
====================================
Backhaul means the connection from BTS site to operator main network.
Backhaul Media:
- Microwave link
- Fiber optic
- IP radio
- Metro Ethernet
- Satellite link
- E1 transmission
Backhaul carries:
- Voice traffic
- Internet data
- SMS signaling
- Alarm traffic
- Operation and maintenance data
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8. MICROWAVE BACKHAUL CONNECTION
====================================
BTS Router
↓ Ethernet Cable
MW IDU
↓ IF Cable or Ethernet
MW ODU
↓ Waveguide / Direct Mount
MW Dish Antenna
↓ Wireless MW Signal
Remote MW Dish
↓
Hub Site Router
↓
Core Network
Important MW Parameters:
- RSL / RSSI
- Tx Power
- Frequency
- Bandwidth
- Modulation
- Capacity
- XPIC
- Availability
- Fade Margin
- BER
- Packet Loss
- Latency
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9. FIBER BACKHAUL CONNECTION
====================================
BTS Router
↓
SFP Module
↓
Fiber Patch Cord
↓
ODF
↓
Fiber Cable
↓
Metro Network
↓
Core Network
Important Fiber Parameters:
- Optical power Tx/Rx
- Fiber loss
- SFP type
- VLAN
- MTU
- Port speed
- Link status
- Packet loss
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10. POWER CONNECTIVITY
====================================
AC Power
↓
ACDB
↓
Rectifier
↓
-48V DC Output
↓
DCDB
↓
BTS / RRU / Router / MW Equipment
Backup:
Battery Bank
↓
BTS continues working during power failure
Important Power Items:
- Rectifier module
- Battery bank
- DC cable
- MCB
- Grounding
- Generator
- Solar system, if available
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11. ALARM CONNECTIVITY
====================================
Site Equipment
↓
External Alarm Cable
↓
BTS / Alarm Box
↓
Transmission Link
↓
NOC / OMC
Common BTS Alarms:
- Site down
- Link down
- VSWR high
- Door open
- Smoke alarm
- High temperature
- Low battery
- Rectifier fail
- AC fail
- Generator running
- Fiber LOS
- MW RSL low
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12. SYNCHRONIZATION CONNECTIVITY
====================================
BTS needs timing synchronization for proper network operation.
Timing Sources:
- GPS antenna
- SyncE
- PTP 1588v2
- BITS clock
Timing Problems:
- Call drop
- Handover issue
- Poor data performance
- Cell unavailable
- TDD interference in 4G/5G
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13. IMPORTANT CONNECTIVITY PARAMETERS
====================================
RSL:
Receive Signal Level for microwave link.
VSWR:
Shows antenna/feedline matching quality.
RSSI:
Received Signal Strength Indicator.
SINR:
Signal quality level.
Throughput:
Actual data capacity.
Latency:
Delay in network communication.
Packet Loss:
Data packets lost during transmission.
BER:
Bit Error Rate.
Availability:
Percentage of time link stays active.
VLAN:
Logical separation of traffic.
IP Address:
Used for management and traffic routing.
Gateway:
Next-hop network address.
MTU:
Maximum packet size.
QoS:
Traffic priority control.
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14. COMMON BTS CONNECTIVITY PROBLEMS
====================================
1. BTS Down
Possible causes:
- Power failure
- Transmission failure
- BBU fault
- Router issue
- Fiber cut
- Microwave link down
2. Low Throughput
Possible causes:
- Backhaul congestion
- Low MW capacity
- Poor RF quality
- Interference
- High users
- Wrong VLAN/QoS setup
3. Call Drop
Possible causes:
- Weak signal
- Bad handover
- Poor SINR
- VSWR high
- Transmission issue
4. Link Down
Possible causes:
- MW misalignment
- Fiber cut
- ODU fault
- IDU fault
- Router port down
- Power issue
5. High VSWR
Possible causes:
- Faulty jumper
- Water in connector
- Damaged antenna
- Loose connector
6. Synchronization Failure
Possible causes:
- GPS issue
- PTP issue
- SyncE failure
- Wrong clock source
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15. FIELD CHECKLIST FOR BTS CONNECTIVITY
====================================
Check Power:
- AC input available
- Rectifier working
- Battery voltage normal
- DC output normal
Check BTS:
- BBU power status
- Board status
- Alarm status
- Fiber connection to RRU
- Site ID and configuration
Check RRU:
- Power status
- Fiber link status
- RF connection
- Grounding
- Alarm status
Check Antenna:
- Azimuth
- Tilt
- Jumper connection
- RET connection
- VSWR
Check Transmission:
- MW RSL
- Fiber Rx/Tx power
- Ethernet port status
- VLAN configuration
- Ping test
- Throughput test
Check Alarm:
- External alarm cable
- OMC visibility
- Site alarm clear or active
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16. SIMPLE FIELD EXAMPLE
====================================
A mobile user makes a call:
Mobile Phone
↓
Antenna receives signal
↓
RRU converts RF signal
↓
BBU processes the call
↓
Router sends traffic
↓
Microwave or fiber carries traffic
↓
BSC/MSC/Core handles the call
↓
Call connects to another user
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17. SUMMARY
====================================
BTS connectivity means the full connection path from mobile user to telecom core network.
It includes:
- RF connectivity
- BBU to RRU connectivity
- Antenna connectivity
- Microwave or fiber backhaul
- IP routing
- Power connectivity
- Alarm monitoring
- Synchronization
A BTS site works properly only when RF, power, transmission, and core connectivity are all healthy.
