Mission System Design Research Articles

Design of unequal error protection for MIMO-OFDM systems with hierarchical signal constellations

In multimedia communication systems, efficient trans- mission system design should incorporate the use of matching unequal error protection (UEP), since source coders exhibit unequal bit error sensitivity. In this paper, we present UEP schemes which exploit differences in bit error protection levels in orthogonal frequency division multiplexing (OFDM) systems over frequency selective fading channels. We introduce an UEP scheme which improves the link performance with multiple transmit and receive antennas. Especially, we propose a new receiver structure based on two stage Maximum Likelihood detection (MLD) schemes which can approach the performance of a full search MLD receiver with much reduced computational complexity. In the performance analysis, we derive a generalized pairwise error probability expression for the proposed UEP schemes. Simulation results show that the proposed schemes achieve a significant performance gain over the conventional equal error protection (EEP) scheme.

7.7.2 The Mission System Design Center: A Pilot of Formulation‐Phase Concurrent Engineering in Aerospace Design

AbstractIn this paper we describe pilots of a concurrent‐engineering, formulation‐phase design team demonstrated in spacecraft missions. This “Mission Team” operates within a design center called the Mission System Design Center, where design tools are linked via a central database and use large‐screen projection systems to engage the entire team in system‐level trade discussions. In these pilots, the Mission Team was able to manage complex trades, resolve conflicts, and rebalance requirements in the face of typical formulation phase issues. This team operates to periodically re‐evaluate requirements and resource allocations (e. g., mass, power, funds, datarate) in the face of both externally and internally imposed changes.