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This paper proposes a space division multiplexing aided opportunistic spectrum access (SDM-OSA) scheme for cognitive radio networks by exploiting the spatial signal processing ability provided by multiple antennas. With the scheme, cognitive transmission could be carried out using SDM even though there is no idle spectrum resource available. We make further discussion about antenna requirements for...
Transmitter precoding strategies are necessary to achieve the capacity promised in broadcast multiple input single output (MISO) systems. However, these schemes generally require perfect channel information at the transmitter. In this paper, we investigate the impact of Gaussian noise in the channel state information (CSI) of a linear zero forcing transmitter, operating in a fading MISO broadcast...
In this paper we present and analyze a computationally-efficient, adaptive precoder for partial FEXT cancellation in downstream VDSL. The precoder is based on error signal feedback. We present conditions on the channel matrix and on the precoder parameter, and prove that if the conditions are satisfied then the precoder converges in expectation to the partial precoder presented by Cendrillon et al...
Block diagonalization is a linear precoding technique which eliminates the multi-user interference at the transmitter side by creating parallel orthogonal single user links. In this technique, the transmit diversity order is fixed for each user and only power can be controlled to satisfy SINR requirements. This restricts the degrees of freedom available for resource allocation and limits the energy...
In this paper, our aim is to use a Kerdock codebook-based precoding scheme for a multi-user MIMO broadcast channel with channel state information at the base station and limited feedback. The main reason for applying a Kerdock code in place of optimal precoding is to reduce VLSI implementation complexity. The proposed scheme exploits the scheduling and precoding methods with a view to maximizing system...
In wireless cellular systems, cell edge users can only achieve far less capacity than cell center uses because of low receive signal power and strong inter-cell interference. Base station joint transmission has been proven to be an effective method to mitigate this effect. In this paper, we propose a novel precoding scheme for non-coherent joint transmission where both base stations and mobile stations...
A novel linear precoding scheme is proposed for the downlink of multiuser multiple input multiple output (MIMO) systems, that offers enhanced data throughput compared to conventional precoding. The proposed technique is based on the fact that part of the instantaneous multiple access interference (MAI) inherent in a multiuser MIMO system adds constructively to the useful signal. It utilises this concept...
In this paper, we investigate transmission methods for a multi-user multiple-input multiple-output (MIMO) network that utilizes base stations (BS) cooperation. To eliminate the interference between users, iterative zero forcing- (ZF) and iterative Tomlinson Harashima precoding-based (THP) schemes are proposed. In the iterative ZF-based scheme, all interference is cancelled by using the transmit-receive...
Focusing on the problem that the co-frequency interference of the downlink channels in multi-cell of multi-out multi-input (MIMO) systems, this paper used the adaptive network precoding based on the SJNR to reduce the inter-cell interference. First of all, the adaptive precoding design based on the SJNR criteria is given. In this design, each base station use independent precoding approach to suppress...
Cognitive Radio (CR) has attracted much attention for its ability allowing secondary users (SUs) to share the spectrum with licensed users (PUs). The precondition that PUs bear the coexistence of SUs is that the interference caused by SUs should be under a given threshold. Therefore the main challenge of CR is interference control or even interference cancellation. In this work we employ zero-forcing...
Interference among multiple base stations that co-exist in the same location limits the capacity of wireless networks. In this paper, we propose a method to design a spectrally efficient cooperative downlink transmission scheme employing precoding and beamforming for multi-user multiple-input-multiple-output (MIMO) systems. The algorithm eliminates the interference and achieves symbol error rate (SER)...
In this paper, we propose an improved precoding scheme using interference alignment on modulation signal for multi-user MIMO downlink transmission. The simulation shows that the new precoding scheme can significantly reduce interference and provide much better bit error rate performance than the conventional precoding schemes for multi-user MIMO.
Interference among multiple base stations that co-exist in the same location limits the capacity of wireless networks. In this paper, we propose a nonlinear multi-user MIMO cooperative downlink transmission scheme. The algorithm eliminates the interference and achieves symbol error rate (SER) fairness among different users. To eliminate the interference, Tomlinson Harashima precoding (THP) is used...
In this paper we consider user scheduling problem for linearly preceded multiuser multiple-input multiple-output (MIMO) downlink, where base station as well as the mobile receivers are equipped with multiple antennas. Optimal precoding involves dirty paper coding (DPC) technique, and it is highly nonlinear and complex. On the other hand, complete inter-user interference cancellation using linear zero-forcing...
A novel strategy codeword selection (called partial channel precoding) for channel state information (CSI) in a limited feedback scenario is proposed. Consider as an example the CSI codebook in the 3GPP LTE system of a 4times4 MIMO structure. Rather than using the traditional method of selecting the nearest codebook to the right singular vectors of the entire channel matrix, a partial match that aims...
Tomlinson-Harashima precoder (THP) is an efficient interference pre-canceler, however, the transmission power is increased over the symbol power due to the modulo operation. In this paper, we propose an improved THP that reduces the transmission power of the conventional THP by tilting a group of symbols by an angle toward minimizing the transmission power. The tilted angle can be either estimated...
User-specific, linear precoding is used extensively by almost all existing and emerging wireless MIMO standards [1], [2], [3], [4]. With user-specific, linear precoding, the data symbols to be transmitted to each user are passed through a linear transformation before being sent to the transmit antennas, and a different precoder is used for each user depending on his/her channel. For example, with...
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