Configuration

1xBTS uses a per-node config directory plus an optional radio-config override:

cargo run --release -p cdma-nib -- --config-dir config --radio-config config/radio_bladerf_micro2.json

The default config directory contains bts.json, bsc.json, msc.json, pcf.json, pdsn.json, hlr.json, smsc.json, and management.json.

Node Configuration

File	Role
`bts.json`	pilot/overhead parameters, downlink/uplink channel config, MCC/IMSI_11_12 digit-string defaults, BTS Abis signaling listener, local bearer address
`bsc.json`	traffic assignment, paging retry, traffic retry, BSC Abis signaling target, BSC bearer peer config
`msc.json`	A1 listen address, MSC management endpoint, voice policy, voice gateway endpoint, welcome SMS policy
`pcf.json`	packet-control client endpoint for the packet service
`pdsn.json`	packet gRPC listener plus packet transport mode (`tun`, `fou`, or `fou_tcp`) and tunnel endpoints
`hlr.json`	HLR gRPC listener and PostgreSQL DSN for subscriber and registration-binding data
`smsc.json`	SMSC gRPC listener and PostgreSQL DSN for SMS submissions and delivery attempts
`management.json`	management facade listener, tokio-console flag, IQ capture directory

1xbts-web uses MANAGEMENT_GRPC_ADDRESS for the facade endpoint and falls back to BSC_GRPC_ADDRESS for older local setups. MSC-owned call actions and SMS submission are served by the MSC management endpoint from msc.json; SMS coordination flows from MSC to BSC over A1 ADDS messages.

BTS Runtime

{
  "runtime": {
    "spreading_rate": "sr1",
    "chip_rate_hz": 1228800,
    "tx_sample_rate_hz": 4915200,
    "tx_center_frequency_hz": 881520000,
    "tx_digital_backoff": 0.5
  }
}

Downlink Channels

Channel	Walsh	Config
Pilot	W0	Gain
Sync	W32	1200 bps, interleaver params
Paging	W1	9600 bps, overhead messages (SPM, APM, ESPM, CCLM, NLM)

Extended System Parameters in bts.json carry the advertised MCC and IMSI_11_12 defaults as decimal digit strings, for example "mcc": "310" and "imsi_11_12": "55". The BTS encodes those strings into the C.S0005-E bit fields, and the BSC uses the same overhead values to reconstruct a complete class-0 registration IMSI when the mobile only sends the short IMSI fields on the access channel.

BSC / MSC / Packet Parameters

Section	Controls
`bsc.traffic_assignment`	supported forward/reverse RCs, preferred RC pairs, idle timeout
`bsc.paging_retry`	paging ACK timeout and retry count
`bts.abis` / `bsc.abis`	Abis TCP signaling bind/remote addresses; defaults wire the integrated runtime over localhost `127.0.0.1:5604`
`bts.bearer` / `bsc.bearer`	Abis UDP bearer bind/remote addresses; defaults wire BTS `127.0.0.1:17014` to BSC `127.0.0.1:17022`
`msc.voice`	supported SOs, answer/release timers, A2p bearer behavior, WAV fallback, MSC-owned voice gateway endpoint
`msc.welcome_sms`	first-registration/inactivity welcome SMS text, originating number, and threshold
`pcf.packet_grpc_endpoint`	BSC/PCF client endpoint for packet service RPCs; default `http://127.0.0.1:17021`
`pdsn.packet_grpc_listen_addr`	packet service gRPC listen address; default `127.0.0.1:17021`
`pdsn.packet`	packet transport mode and FOU/FOU-TCP endpoints
`hlr.grpc_listen_addr` / `smsc.grpc_listen_addr`	HLR/SMSC service gRPC listen addresses; defaults `127.0.0.1:17019` and `127.0.0.1:17020`
`hlr.postgres_dsn` / `smsc.postgres_dsn`	PostgreSQL connection strings

Access Channel

Parameter	Default
Channels per paging channel	1
Access rate	4800 bps
Frame duration	20 ms
ARQ ACK timeout	400 ms

Radio Configuration

Hardware-specific SDR parameters.

UHD (USRP B200/B210)

{
  "kind": "uhd",
  "device": "type=b200,num_recv_frames=1024,num_send_frames=1024",
  "channel": 0,
  "antenna": "TX/RX",
  "tx_gain_db": 65.0,
  "rx_antenna": "RX2",
  "rx_gain_db": 50.0,
  "rx_freq_hz": 836520000,
  "rx_sample_rate_hz": 4915200,
  "rx_bandwidth_hz": 5000000,
  "rx_sample_delay": 50
}

LimeSDR (Native)

{
  "kind": "lime",
  "device": "",
  "channel": 0,
  "tx_antenna": "BAND1",
  "tx_gain_db": 60,
  "rx_antenna": "LNAW",
  "rx_gain_db": 20,
  "rx_freq_hz": 836520000,
  "rx_sample_rate_hz": 4915200,
  "rx_bandwidth_hz": 5000000,
  "rx_sample_delay": 97
}

rx_sample_delay compensates for LimeSDR-specific timing offsets in the receive path.

bladeRF (Native)

{
  "kind": "blade_rf",
  "device": "",
  "channel": 0,
  "fpga_path": null,
  "tx_antenna": "TXA",
  "rx_antenna": "B_BALANCED",
  "tx_gain_db": 50,
  "rx_gain_db": 40,
  "rx_freq_hz": 836520000,
  "rx_sample_rate_hz": 4915200,
  "rx_bandwidth_hz": 2500000,
  "rx_reference_dbm": null,
  "rx_sample_delay": 0,
  "rx_batch_pcgs": 2,
  "num_buffers": 16,
  "buffer_size": 8192,
  "num_transfers": 8,
  "stream_timeout_ms": 3500
}

fpga_path: null uses libbladeRF’s host auto-load path, typically ~/.config/Nuand/bladeRF/hostedxA4.rbf. Set fpga_path to an explicit .rbf file if you do not want host auto-load. tx_antenna and rx_antenna select bladeRF RF ports; the current Micro 2.0 example uses TXA and B_BALANCED.

Environment Variables

Variable	Purpose
`CDMA_CONFIG_DIR`	Default config directory when `--config-dir` is omitted
`RUST_LOG`	Log level (`info`, `debug`, `trace`)

Next Steps

First Registration — Start the BTS and register a handset
Configuration Reference — Full parameter reference