Functional Requirements Document (FRD) – PCI Locking

Feature: PCI Locking Management in zWAN SDWAN CPE
Version: 0.9

1. Objective

To enable users to lock the modem to specific Physical Cell Identity (PCI) values for 4G and 5G networks using the system’s graphical interface.
PCI locking helps maintain stable network behavior, reduce unwanted cell switching, and assist in diagnostics or controlled testing.

2. Functional Requirements

FR1: PCI Listing

• The system must provide a scan option to list available PCI entries for both 4G and 5G modes.
• Each listed PCI entry must display:
  • Carrier name
  • PCI value
  • Frequency (ARFCN)
  • Signal quality as a percentage
• The user must be able to click an Info icon for each PCI to view detailed information, including:
  • MCC, MNC, TAC, CellID, RSRP, RSRQ, Srxlev, Squal, Signal Quality
  • This information must be referred to before choosing a PCI for locking.

FR2: PCI Lock Configuration

• The system must allow users to:
  • Lock a single PCI for 4G
  • Lock a single PCI for 5G
• Required parameters:
  • For 4G: PCI and Frequency are mandatory
  • For 5G: PCI, Frequency, Subcarrier Spacing (SCS), and Band are mandatory
• PCI configuration must persist across modem and system reboots.
• If PCI locking is unsupported for the given hardware or mode, the system must notify the user.

FR3: Locking/Unlocking Operation

• The user must be able to:
  • Select and lock a PCI entry displayed by the system
  • Unlock PCI lock at any time through the system interface
• Locking and unlocking actions must take effect dynamically, or after modem restart, without requiring full system reboot.

FR4: Validation & Status

• The system must:
  • Show current carrier name (e.g., "Current Carrier: Airtel,JIO")
  • Indicate lock status for 4G and 5G separately
  • Allow locking only to PCI entries that match the current serving carrier
  • Example: If the current carrier is JIO, only JIO PCI entries must be eligible for locking.
  • Show validation errors if users attempt to lock to PCI entries not associated with the current carrier.

FR5: Persistence

• PCI Lock configuration must be stored and automatically reapplied after system or modem reboot.
• Re-locking must happen as soon as the modem reconnects to the network.

FR6: Status Display

• The system must display:
  • Current locked PCI (if any)
  • Corresponding Carrier
  • Frequency
  • Signal Quality
• Last scan timestamp must be shown
• Separate scan buttons for 4G and 5G must be available

FR7: Event Logging

• Minimal logging should be done internally for:
  • Lock and unlock actions
  • Scan initiation
  • Operation errors (e.g., invalid PCI or unsupported lock)

3. Out of Scope

• Locking multiple PCIs per RAT
• Dynamic PCI selection or switching logic
• Smart ranking or signal-based PCI suggestions
• Auto PCI locking based on operator (MCC/MNC) or region policies