1xBTS 1xBTS

Multiple Cells

A single BSC can serve several cells at once. Each cell is its own BTS — its own radio and its own process — and the BSC attaches to every one it is configured with. Add a cell by listing another BTS peer. The BSC enrolls it, brings up Abis, and starts carrying its traffic.

Add a cell

Each cell is one entry in the BSC’s bts_peers list (see Configuration Reference → bts_peers). Give each entry the address of the BTS’s operations endpoint and its Abis signaling and bearer addresses:

{
  "bts_peers": [
    {
      "oam_endpoint": "http://127.0.0.1:17024",
      "abis_addr": "127.0.0.1:5604",
      "bearer_bind_addr": "127.0.0.1:17022",
      "bearer_remote_addr": "127.0.0.1:17014"
    },
    {
      "id": "cell-2",
      "oam_endpoint": "http://127.0.0.1:27024",
      "abis_addr": "127.0.0.1:25604",
      "bearer_bind_addr": "127.0.0.1:27022",
      "bearer_remote_addr": "127.0.0.1:27014"
    }
  ]
}

Run one BTS for each entry, each with its own bts.json (its channel, sector, and radio) and its own SDR. The addresses on a peer entry must match the addresses that BTS listens on. On one host, give every BTS its own ports. Across hosts, point each entry at the right machine.

The optional id is a stable name you address the cell by in the web UI and management API — it stays the same whether or not the cell is currently up. Without it, the cell is addressed by its oam_endpoint. Ids and endpoints must be unique across peers.

Give each cell its own channel

Each cell must transmit on a different CDMA channel. 1xBTS runs every BTS from its own radio’s clock and has no shared time reference between them, so two cells cannot share one channel.

Same-channel cells are not supported yet. Placing two cells on the same channel with different pilot PN offsets only works when every BTS is locked to one common timebase (a GPS-disciplined oscillator). 1xBTS has no such shared timebase, so co-channel cells, cross-cell neighbor lists, and hand-off between cells are not available. Put each cell on its own channel.

Because the cells are on different frequencies, their pilot PN offsets do not need to differ — leaving pilot_offset at 0 on each is fine. Choose a distinct channel per cell with the Channel Planning guide.

Watch the cells

The Cells page in the web UI lists every cell you configured, addressed by its stable id. A cell that has not enrolled yet, or one whose BTS has gone away, shows as offline rather than disappearing — so a mis-wired or powered-down cell is visible instead of silent. In-service cells show their broadcast identity (pilot PN, channel, SID/NID) and mobile count.

Open a cell to see its radio metrics, run an IQ capture, or read its configuration — each of those is per cell and lives under that cell’s detail page.

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