Mobile Ad-Hoc Networks (MANETs) are often characterized by high node mobility and rapid topology changes which in turn can cause high packet loss rates. In order to cope with this, MANETs typically rely on routing algorithms that try to efficiently distribute messages in the entire network. Such routing schemes introduce an overhead that limits the scalability of MANETs with respect to the number of nodes and/or mobility. Cooperative communication techniques have the potential to improve the efficiency of distributing messages and thus to increase the MANET scalability. In this paper, we propose an efficient cooperative broadcasting scheme based on distributed transmit diversity. To this end, we adapt Space-Time Block-Codes (STBCs), that were initially designed for a co-located setup in quasi-static environments, to a distributed setup with timevariant channels. We perform a comprehensive analysis based on bit error simulations to compare different STBC candidates and identify Linear-Scalable Dispersion Codes (LSDCs) to be a valuable option. For those, we propose an improvement of the inner-code for different channel models without the need for channel state information at the transmitter (CSIT). Besides, we validate the performance advantage of cooperative broadcasting by outage simulations in typical MANET scenarios.

Cooperative transmission is a promising approach to establish robust communication in Mobile Ad-Hoc Networks (MANETs). In low-complexity MANETs several transmitters (TX) can be aggregated to a virtual multiple input system. For such a setup, the impact of various timing and carrier frequency offsets (TO, CFO) has to be mitigated. We propose an effective, purely time-domain based equalizer structure that allows to establish cooperative transmission with a transmit diversity scheme in presence of aforementioned impairments and multipath channels. Exemplarily investigating the broadcast performance by outage simulations in a MANET scenario, we can demonstrate the benefits and indicate that the proposed structure is auspicious to improve the general scalability of MANETs.

Cooperative transmission, realized by aggregating several nodes to a virtual multiple input system, is an auspicious approach to establish a more robust and effective communication in MANETs. In such a setup, impairments, i. e. multiple timing and carrier frequency offsets (TO, CFO) will occur. While multi-carrier schemes, e. g. Orthogonal Frequency Division Multiplexing (OFDM), are well-known to mitigate the impact of multipath propagation and TO, multiple CFO causes inter-carrier-interference (ICI) which typically degrades the performance significantly. Within this paper, we propose an effective code and equalizer structure that allows to overcome this limitation. It mitigates the impact of multiple CFO that can be significantly larger than the subcarrier spacing with a reasonable computational effort. For that, we utilize inherent code properties of Linear-Scalable Dispersion Codes (LSDCs) and propose a communication system composed of an equalizer structure in combination with LSDCs that enables multi-carrier distributed cooperative transmission for practical MANETs with high node mobility. We demonstrate the benefits of cooperative transmission in comparison to classical non-cooperative multihop or concurrent transmission by outage simulations, which clearly indicate that our proposal can be of crucial importance for the overall MANET scalability. Lastly, we compare our OFDM system with a recently proposed time-domain equalization singlecarrier system and point out use cases, where the OFDM system can be more advantageous.