Radio Subsystem Research Articles

An architecture for self-test of a wireless communication system using sampled IQ modulation and boundary scan

An architecture for system-level self-test of a wireless communication transceiver integrates the functional (parametric) self-test of the radio frequency subsystem, and the structural self-test of the digital subsystem. The digital subsystem is tested using extensions of the IEEE 1149.1 boundary scan standard to verify connections within circuit boards and between boards. The RF subsystem is tested using a loopback connection between the RF transmitter and receiver. An RF parametric self-test is performed using a digitally modulated signal (as opposed to a sinusoidal tone) as the test stimulus, and using samples from the receiver digitizer as test data. This loopback test scheme imposes a relatively small overhead on the RF system design.

ATM-based TH-SSMA network for multimedia PCS

Personal communications services (PCS) promise to provide a variety of information exchanges among users with any type of mobility, at any time, in any place, through any available device. To achieve this ambitious goal, two of the major challenges in the system design are: (i) to provide a high-speed wireless subsystem with large capacity and acceptable quality-of-service (QoS) and (ii) to design a network architecture capable of supporting multimedia traffic and various kinds of user mobility. A time-hopping spread-spectrum wireless communication system called ultra-wide bandwidth (UWB) radio is used to provide communications that are low power, high data rate, fade resistant, and relatively shadow free in a dense multipath environment. Receiver-signal processing of UWB radio is described, and performance of such communications systems, in terms of multiple-access capability, is estimated under ideal multiple-access channel conditions. A UWB-signal propagation experiment is performed using the bandwidth in excess of 1 GHz in a typical modern office building in order to characterize the UWB-signal propagation channel. The experimental results demonstrate the feasibility of the UWB radio and its robustness in a dense multipath environment. A ATM network is used as the backbone network due to its high bandwidth, fast switching capability, flexibility, and well-developed infrastructure. To minimize the impact caused by user mobility on the system performance, a hierarchical network-control architecture is postulated. A wireless virtual circuit (WVC) concept is proposed to improve the transmission efficiency and simplify the network control in the wireless subsystem. The key advantage of this network architecture and WVC concept is that the handoff can be done locally most of the time, due to the localized behavior of PCS users.

Rosetta Radio Science Investigations: Gravity Investigations at Comet P/Wirtanen

AbstractThe Rosetta Radio Science Investigations (RSI) experiment was selected by the European Space Agency to be included in the International Rosetta Mission to comet P/Wirtanen (launch in 2003, arrival and operational phase at the comet 2011–2013). The RSI science objectives address fundamental aspects of cometary physics such as the mass and bulk density of the nucleus, the gravity field, non-gravitational forces, the size and shape, the internal structure, the composition and roughness of the nucleus surface, the abundance of large dust grains and the plasma content in the coma and the combined dust and gas mass flux on the orbiter. RSI will make use of the radio subsystem of the Rosetta spacecraft.

A bandwidth reservation protocol for speech/data integration in TDMA-based advanced mobile systems

The traffic performance of third-generation mobile systems is greatly influenced by the multiple access protocols used in the radio access subsystem. The paper introduces an access protocol, SIR (Service Integration Radio Access), which has the potential for accommodating the requirements of speech and bursty data traffic in an efficient way. SIR is evolved from a protocol (PRMA ++) studied in the framework of a TDMA-based version of the European Universal Mobile Telecommunication System (UMTS) and uses dedicated mechanisms for data bandwidth request collection and servicing.

A business cordless PABX telephone system on 800 MHz based on the DECT technology

In January 1988, The European Conference of Postal and Telecommunication administrations (CEPT) decided to base the standard for medium and long-term applications of advanced digital European cordless telecommunications (DECT) on a multicarrier/time-division-multiple-access/time-division-duplex (MC/TDMA/TDD) approach. The Ericsson DCT 900 MC/TDMA/TDD pico cellular cordless telephone system concept is presented. It is a DECT-like system with limited data services operating up to 8 MHz in the 860 to 870 MHz frequency band, but it can be implemented anywhere in the 800 to 900 MHz bands. A description of the DCT 900 system and the cordless radio subsystem is included. >

Measurement technique for the Giotto radio science experiment

The paper describes the technique used to record time delay and waveform measurements for the Giotto radio science experiment of ESA's mission to comet Halley. The data were taken by using either two-way measurements (during pre- and post-encounter) or one-way measurements (during encounter with comet Halley), the downlink of the radio signal of the Giotto spacecraft being received at 8.4 GHz by the 64 m tracking stations of NASA's Deep Space Network (DSN). The waveform measurements were obtained at a sampling frequency of 50 kHz with an open-loop receiver assembly at DSN station Canberra as recently used for the Voyager/Uranus fly-by. Performance and calibration data are given as relevant to the radio subsystems on the ground and aboard Giotto.

The final phases of the Viking mission to Mars

Of the four spacecraft that the Viking Project put into operation at Mars in the summer of 1976, one continues to acquire data periodically. The missions of the two orbiters were terminated by the depletion of their attitude-control gas: Orbiter 2 in July 1978 and Orbiter 1 in August 1980. Lander 2 was shut down in April 1980 because of degradation of its batteries. Lander 1 is programmed to continue acquiring a modest number of imaging, meteorology, and ranging data periodically until December 1994. During its final year Orbiter 1 continued to produce excellent data from its full complement of instruments—two cameras, two infrared instruments (thermal mapper and water vapor detector), and the radio subsystem. The major emphasis was on photography, with 10,000 images being acquired. These included two very large swaths of high-resolution contiguous coverage of the Martian surface and the completion of the moderate-resolution mapping of nearly the entire surface, as well as miscellaneous other observations. The majority of these images has not been processed and examined, but the others have revealed many previously unobserved features and have greatly enhanced the base for a geological understanding of the planet. The history of Viking mission operations is brought up to date.

Mariner Mars 1964 telemetry and command system

Mariner Mars 1964 spacecraft telecommunication system noting radio, telemetry and command subsystems