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Design of next-generation cdma using orthogonal complementary codes and offset stacked spreading
(2007)
This article presents an innovative code-division multiple access system architecture that is based on orthogonal complementary spreading codes and time-frequency domain spreading. The architecture has several advantages compared to conventional CDMA systems. Specifically, it offers multiple-access-interference-free operation in AWGN channels, reduces co-channel interference significantly, and has the potential for higher capacity and spectral efficiency than conventional CDMA systems. This is accomplished by using an "offset stacked" spreading modulation technique followed by quadrature amplitude modulation, which optimizes performance in a fading environment. This new spreading modulation scheme also simplifies the rate matching algorithms relevant for multimedia services and IP-based applications.
NEXCODE is a project promoted by the European Space Agency aimed at research design development and demonstration of a receiver chain for telecomm and links in space missions including the presence of new short low-density parity-check codes for error correction. These codes have excellent performance from the error rate viewpoint but also put new challenges as regards synchronization issues and implementation. In this paper after a short review of the results obtained through numerical simulations we present an overview of the breadboard designed for practical testing and the test-plan proposed for the verification of the breadboard and the validation of the new codes and novel synchronization techniques under relevant operation conditions.
In this paper we integrate the ideas of network coding and relays into an existing practical network architecture used in a wireless network scenario. Specifically, we use the COPE architecture to test our ideas. Since previous works have focused on the communication aspect at the physical layer level, we attempt to take it one step further by including the MAC layer. Our idea is based on information theoretic concepts developed by Shannon in order to reliably apply network coding to increase the net throughput.