Description
Network Control mode 2 (NC2) is a complementary control mode to NC1, defined in 3GPP specifications for the GSM/EDGE Radio Access Network. In NC2, the network (BSC) configures the mobile station with parameters detailing what to measure, such as specific neighbor cell ARFCNs and measurement quantities. However, unlike NC1, the MS does not autonomously decide when to send reports. Instead, it continuously performs the measurements and stores the results. The network explicitly requests a measurement report by sending a polling command to the MS. Upon receiving this request, the MS compiles a report containing the latest measurement data and sends it to the network. This provides the network with complete, on-demand visibility into the current radio conditions as perceived by the mobile.
The architectural flow involves an initial assignment phase where the BSC sends a measurement information message to configure the MS. Subsequently, the MS's physical and protocol layers perform the ongoing measurements. The BSC can then send a dedicated polling message, such as a Measurement Report request on the associated control channel. The MS responds with a Measurement Report message containing data for the serving cell and the list of configured neighbor cells. This mode places the reporting initiative entirely with the network, allowing it to gather measurement data at specific moments, for instance, just before a potential handover decision or for network optimization diagnostics.
NC2's operation is crucial for scenarios where the network requires a precise snapshot of radio conditions without relying on the MS's event triggers. It ensures the network receives comprehensive data when it needs it, but at the cost of additional downlink signaling (the poll) and guaranteed uplink signaling (the report). This makes it less efficient for constant mobility management than NC1 but more suitable for targeted data collection, testing, or situations where the network's centralized algorithm requires direct, unfiltered measurement samples to make a decision.
Purpose & Motivation
NC2 was developed to provide the network with direct, on-demand access to mobile station measurement data. Its primary purpose is to give network controllers precise control over the timing and content of radio environment information. This solves the problem of needing a complete set of current measurements for analytical or decision-making processes that cannot rely solely on event-triggered reports from modes like NC1.
The motivation for NC2 stems from network planning, optimization, and specific advanced handover algorithms. For example, a network operator might use NC2 to diagnose coverage issues by polling specific mobiles in a problematic area. It addresses the limitation of purely autonomous MS reporting, where the network only receives data when the MS deems it necessary, potentially missing subtle trends or specific data points required for network-tuning activities. NC2 ensures the network can always 'ask' for the current situation.
Historically introduced in Release 10, NC2 is part of the broader framework for flexible measurement control in GERAN. It represents the network-centric end of the control spectrum, contrasting with the MS-autonomous NC1. This dual-mode approach allowed GSM/EDGE networks to support a wide range of use cases, from high-efficiency routine mobility to detailed network-controlled diagnostics, ensuring the technology remained adaptable and manageable throughout its evolution.
Key Features
- Network-polled measurement reporting
- Mobile station performs continuous background measurements
- Network controls the exact timing of report generation
- Provides complete, on-demand snapshots of radio conditions
- Configured via measurement control messages from the BSC
- Used for diagnostics, optimization, and specific handover scenarios
Evolution Across Releases
Introduced as Network Control mode 2 in 3GPP TS 43.901. Defined the initial architecture where the BSC configures measurement parameters and subsequently polls the MS for reports. Established the model of network-initiated reporting for direct control over measurement data acquisition, complementing the autonomous reporting of NC1.
Defining Specifications
| Specification | Title |
|---|---|
| TS 43.901 | 3GPP TR 43.901 |