Algebra and Combinatorics seminar today

[Engström Alexander]

Algebra and Combinatorics seminar

Today: 15:15 - 17:00

Room U510 in the main building.

Speaker:

   Camilla Hollanti

Title:

   Algebraic Fast-Decodable Relay Codes for Distributed Communications

Abstract:

   The quality of wireless long distance communications can be significantly improved by using cooperative diversity techniques. Cooperating relays can be positioned between the source station and the destination to aid the transmission by either amplifying and forwarding (AF) or decoding and forwarding (DF) the signal. Spatially separated terminals will allow an increment in the diversity in a distributed manner. Depending on the application, a one-hop or multi-hop transmission is called for. Here, we consider multi-hop distributed space-time codes employing a half-duplex nonorthogonal AF (NAF) protocol.  It is known that the NAF protocol outperforms all other AF protocols since, as opposed to orthogonal protocols, it can keep transmitting also during the transmission of the relays. In addition, the AF protocols are less complex than the DF protocols. This type of low cost relay systems are called for in e.g. digital video broadcasting.

   In this talk, fast-decodable lattice code constructions are designed for the NAF multiple-input multiple-output channel. The constructions are based on different types of algebraic structures, e.g. quaternion division algebras. When satisfying certain properties, these algebras provide us with codes whose structure naturally reduces the decoding complexity. The complexity can be further reduced by shortening the block length, i.e., by considering rectangular codes called less than minimum delay codes.

After the seminar we go for beer and pizza!

Welcome!

Alexander, Camilla & Matthew