Click here for the enhanced PDF version of this article

The Smart Antenna Working Group of the SDR Forum is developing an application-programming interface (API) supporting interoperability and compatibility of various kinds of smart antenna systems operating in a software-defined radio (SDR) network following an open-architecture model. The smart antenna API consists of three components:

1. SAControl component is used for controlling the smart antenna system.

2. SAAlgorithmDevice component is used for executing various algorithms such as beamforming, direction-of-arrival (DOA) estimation, space-time coding (STC), channel estimation and spatial multiplexing.

3. SASynchronization component is used for calibration. This article introduces the smart antenna API, illustrating its use as a standard model and standard service in advanced wireless networks, and defining a roadmap for the API for additional standardization.

A smart antenna (SA) is an array of antennas that are used in conjunction with a signal-processing subsystem within a wireless base station, wireless gateway or mobile terminal device to significantly improve wireless system performance^[1]. These improvements are well known, and include increased communications capacity, enlarged cell coverage, and improved operations during handover. Smart antenna systems generally come in one of four basic types:

• Beamforming systems. These types of systems allow the antenna to adaptively adjust its beam pattern to receive and transmit from specific directions. Beamforming can be used to extend the communications range in a specific direction, or to allow more users to access a network through techniques such as spatial division multiple access (SDMA) that group users within different designated beams.

• Diversity combining systems. These systems mitigate the multipath fading effects inherent in many wireless networks by combining the signals from multiple spatially diverse antennas together to improve signal quality.

• Space-time equalization systems. These types of systems use temporal processing on the signals received from multiple spatially diverse antennas to correct frequency distortion in the received signal path.

• Multiple-input, multiple output (MIMO) systems. In the MIMO system, data is transmitted from one or more transmit antennas to one or more receiver antennas^[2]. If the antennas are sufficiently far apart, the signals traveling between the transmit and receive antennas will fluctuate or fade in an independent manner. As such, by encoding the transmit signals using either spatial multiplexing or a space-time diversity code, processing in the receiver can be used to extract the transmitted data. MIMO systems offer a significant increase in performance over more traditional single-input single-output communication links, which has led the IEEE 802 committee to design MIMO technology into the 802.16 standard^[3].

1 2 3 4 Next

RSS    Save to Del.icio.us  Digg This