Femtocells
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Femtocells, or Home NodeB’s (HNB), are small, low-cost cellular access points designed to provide improved mobile network coverage within buildings such as private homes and small-scale enterprises.
For mobile devices, femtocells operate like base stations, but at much lower power levels. Femtocells are connected to the operator’s core network via a DSL or cable broadband connection. They are available on the market for a wide range of cellular standards including WCDMA/HSPA, CDMA2000®, WiMAX™ and in the future also Long Term Evolution (LTE.)
Femtocells operate in an environment of macro base stations. To enable smooth integration into and operation within an existing network, femtocell manufacturers and chipset vendors alike need to manage interference scenarios, implement standard- and customer-specific requirements and ensure high product quality at the lowest possible costs.
Femtocells are designed to provide improved mobile network coverage within buildings.
T&M solution
During a product development cycle, each stage has different test and measurement requirements.
In R&D, new technologies such as WiMAX™ and LTE require more advanced test and verification methods for higher-order modulation, MIMO and diversity testing. These very demanding test and measurement tasks can be addressed with the
When it comes to manufacturing, cost efficiency and fast yet accurate test solutions are the driving factors. Since a femtocell can be seen as a small base station with reduced output power, in general all tests typically used for macro base stations also apply to an HNB.
Due to the demand for efficient manufacturing tests, in practice only a subset of the paramenters as proposed in the WCDMA base station conformance specification 3GPP TS 25.141 for example, are tested to ensure short test times.
One of the test parameters typically relevant in production is the transmitter modulation quality. This parameter is determined by error vector magnitude (EVM) measurements, adjacent channel leakage ratio (ACLR) and the maximum output power level to ensure that the femtocell transmitter fulfills the coverage requirements. Beside these standard RF parameters, the bit error rate / block error rate (BER/BLER) is tested to verify the sensitivity of a WCDMA receiver.
A typical test setup is shown below, where the RF frontend is calibrated and verified by a signal generator and a signal and spectrum analyzer. An external PC controls the setup via GPIB or LAN interface. In order to ensure a fast calibration and verification process of the device under test (DUT), measurement times are a critical factor.
Manufacturing setup for calibration, verification and BER/BLER measurements on a femtocell DUT
The
Rohde & Schwarz instruments are based on scalable multi-standard platforms, which support all major standards in one box, including WCDMA, HSPA, HSPA+, LTE, CDMA2000® and WiMAX™.
Key features and benefits of test and measurement solutions from Rohde & Schwarz:
- Low cost of ownership
- Low test cost due to high measuring speed
- Flexible and future-ready instruments due to multi-standard upgradeability
- Realtime signal generation
- Multisegment waveform mode
- High-performance RF instrument
- High output power
- Supports the R&S®NRP-Zx power sensors
- Fast switching and measurement times
- High throughput for efficient production
- Internal electrical attenuator
- Supports the R&S®NRP-Zx power sensors
- Outstanding RF properties
