The PLUSS approach (Product Line Use case modeling for Systems and Software engineering) is a domain modeling method tailored towards the development of long lived software intensive systems. PLUSS provides means to maintain a common and complete use case model for a whole family of systems. In this paper, we describe how the commercial requirements management tool Telelogic DOORS and the UML modeling tool IBM-Rational Rose can be extended and used for managing system family models in accordance with the PLUSS approach.

Wireless asymmetric Internet access with a downlink peak bit rate of 10 to 30 Mb/s can be achieved by using the terrestrial digital video broadcasting system (DVB-T) as a supplemental downlink together with today's cellular systems. This paper is a study of dynamic radio resource management on a packet-by-packet basis for this broadband downlink. The dynamic single frequency networks (DSFN) scheme is evaluated. It exploits the macrodiversity capability of the OFDM modulation scheme. The transmitters are dynamically divided into groups of transmitters that send the same information at the same channel frequency simultaneously. The fairly shared spectrum efficiency (FSSE), in bits per second per Hertz per site, which is a combined measurement of maximum throughput and fairness, is evaluated for best-effort traffic. DSFN improves the FSSE by 100% to 370%, for a certain set of test cases, in comparison to the dynamic packet assignment (DPA) scheme, which combines packet scheduling with dynamic channel assignment (DCA).