Gerhard Bauch

Network assisted inter-cell codeword cancellation for interference-limited LTE-A and beyond

Network assisted interference cancellation and suppression (NAICS) is being studied for 3GPP LTE-A to mitigate interference in multi-cell networks. To accomplish this goal, various interference mitigation techniques have been proposed. Contrary to conventional techniques, a rate splitting technique splits the interference in a way that part of the interference can be canceled at users through base station coordination. Rate splitting has been shown to have potential to achieve the channel capacity. This paper studies the benefits of the rate splitting scheme and proposes a new inter-cell codeword cancellation scheme for 3GPP LTE-A and beyond. Simulation results for interference-limited LTE-A scenarios show that the inter-cell codeword cancellation can be a very attractive interference coordination scheme due to its low complexity, low overhead and superior performance.

Interference map estimation using spatial interpolation of MDT reports in cognitive radio networks

An LTE-Advanced Radio Access Network (RAN) would be able to activate an additional component carrier in a Licensed Spectrum Access (LSA) channel, allowing the mobile network operator (MNO) to boost capacity and data rates. But such a dynamic spectrum access strategy requires an effective method for estimating the impact of the LTA-Advanced RAN operation on the primary user and minimizing it. LTE-Advanced provides a useful feature, namely the minimization of drive test (MDT) reporting system, wherein the network collects measurement data performed by the user equipment. Each report provides position and signal strength information. In this paper, we compare the performance of some spatial interpolation methods that would be used to reconstruct the interference map of an LTE-Advanced RAN based on the MDT reports. In this way, the MNO can determine if an LSA channel could be used without potential harm to the primary user operation just by checking the estimated interference map. Furthermore, the performance of different interpolation methods for establishment of interference map is analyzed, when the MDT reports containing errors in the values or locations of the reported measurements. Estimation accuracy is also evaluated respect to spatial correlation.

A mutual-information based power allocation algorithm for multi-layer rate splitting scheme in tri-sectored wireless networks

Cell-edge users inevitably suffer from strong interference from adjacent cells, and consequently their throughput will decrease. Recent investigations show that the Han-Kobayashi (HK) rate splitting scheme is the best known strategy to mitigate the interference for a two-user interference channel. However, its receiver is too complicated to implement in practical systems. This paper takes the multi-layer rate splitting (MLRS) scheme as an alternative and proposes a new mutual-information based power allocation algorithm for the MLRS scheme. Simulation results for the scenarios of two cell-edge users show that the proposed power allocation algorithm brings two advantages. First, it can reduce the complexity of receivers for the MLRS scheme. Second, it can achieve performance comparable to the simple HK scheme in a two-user fading interference channel and provide about 39% gains in terms of average throughput, compared with a fixed frequency reuse 2 scheme, in a realistic tri-sectored wireless network.

Responsive communications jamming against radio-controlled improvised explosive devices

Responsive communications jamming is an emerging technology for electronic-warfare applications. In contrast to state-of-the-art barrage jammers, which continuously jam entire frequency bands irrespective of current signal activities, responsive jammers regularly perform wideband scans of the radio spectrum and are thus able to react to observed signals. By this means, the available transmit energy can be focused on currently relevant spectral areas, which potentially leads to significantly improved jamming efficiencies. In this article, we provide a tutorial overview of this jamming technology with focus on vehicle- or convoy-protection jamming against radio-controlled improvised explosive devices (RCIEDs). Bringing in experience from our product development as well as from theoretical studies, we discuss various system design aspects of responsive anti-RCIED jammers and point out the main technological challenges. In particular, the issues of jam-duration optimization and time synchronization of multiple responsive jammers are discussed in some detail.

Inter-cell interference coordination via cooperative rate splitting and scheduling

The current coordinated multi-point transmission schemes require the transmission coordination to avoid the interference. This paper considers the benefit from the rate splitting method, which has been shown to improve the capacity of the interference channel by decoding part of the interference. In this paper, a coordinated multi-point transmission framework based on the cooperative rate splitting scheme is proposed in the Long Term Evolution Advanced system, where a user equipment pair selection algorithm and a cooperative proportional fair scheduling algorithm are newly developed. The simulation results have shown that the coordinated multi-point transmission with cooperative rate splitting can substantially improve the performance of the cell-edge user equipment without or with a slight performance loss at the average rate in a realistic network.

Interference mitigation with rate splitting in multi-cell wireless networks

Cell-edge users inevitably experience strong interference from adjacent cells, and consequently suffer from performance degradation. Currently, Han-Kobayashi (HK) rate splitting scheme is viewed as the best strategy to cancel the interference and improve the performance. As a special superposition coding scheme, the HK rate splitting scheme has been shown to potentially achieve the channel capacity. However, the way from theory to practice is not straightforward. Current investigations adapting the HK rate splitting scheme to practical applications only deal with the strongest interference and treat the other interferences as noise. In general, more than one strong interferer usually exists, which is targeted in this work. By applying a multi-layer rate splitting scheme for more than one strong interferer, a new ordered detection is proposed and a power allocation algorithm is derived associated with the detection order. Simulation results show that the multi-layer rate splitting scheme mitigates the interference from two different interferers and provides more than twice the gain in terms of average throughput compared with a reference scheme with a fixed frequency reuse factor of 3 in a realistic wireless network.

Interference mitigation via cooperative rate splitting and scheduling in tri-sectored OFDMA systems

In this paper, a downlink multi-cell orthogonal frequency division multiplexing access (OFDMA) system using the same carrier frequency is studied. The multi-cell interference degrades the performance severely. This paper analyzes the interference mitigation performance of the simple Han-Kobayashi rate splitting scheme in a realistic modeling of the multi-cell system. A cooperative rate splitting scheme is proposed and a closed form optimal power allocation solution is derived. Then, we propose a new scheduling strategy to further improve the performance. Simulation results show that the cooperative rate splitting strategy combined the new scheduling algorithm can get a substantial capacity gain.