Showing papers on "Dirty paper coding published in 2007"

Transmitter Optimization for the Multi-Antenna Downlink With Per-Antenna Power Constraints

Abstract: This paper considers the transmitter optimization problem for a multiuser downlink channel with multiple transmit antennas at the base-station. In contrast to the conventional sum-power constraint on the transmit antennas, this paper adopts a more realistic per-antenna power constraint, because in practical implementations each antenna is equipped with its own power amplifier and is limited individually by the linearity of the amplifier. Assuming perfect channel knowledge at the transmitter, this paper investigates two different transmission schemes under the per-antenna power constraint: a minimum-power beamforming design for downlink channels with a single antenna at each remote user and a capacity-achieving transmitter design for downlink channels with multiple antennas at each remote user. It is shown that in both cases, the per-antenna downlink transmitter optimization problem may be transformed into a dual uplink problem with an uncertain noise. This generalizes previous uplink-downlink duality results and transforms the per-antenna transmitter optimization problem into an equivalent minimax optimization problem. Further, it is shown that various notions of uplink-downlink duality may be unified under a Lagrangian duality framework. This new interpretation of duality gives rise to efficient numerical optimization techniques for solving the downlink per-antenna transmitter optimization problem

High SNR Analysis for MIMO Broadcast Channels: Dirty Paper Coding Versus Linear Precoding

Abstract: In this correspondence, we compare the achievable throughput for the optimal strategy of dirty paper coding (DPC) to that achieved with suboptimal and lower complexity linear precoding techniques (zero-forcing and block diagonalization). Both strategies utilize all available spatial dimensions and therefore have the same multiplexing gain, but an absolute difference in terms of throughput does exist. The sum rate difference between the two strategies is analytically computed at asymptotically high SNR. Furthermore, the difference is not affected by asymmetric channel behavior when each user has a different average SNR. Weighted sum rate maximization is also considered. In the process, it is shown that allocating user powers in direct proportion to user weights asymptotically maximizes weighted sum rate.

Multiple Antenna Broadcast Channels With Shape Feedback and Limited Feedback

Abstract: In this paper, we consider two different models of partial channel state information at the base station transmitter (CSIT) for multiple antenna broadcast channels: 1) the shape feedback model where the normalized channel vector of each user is available at the base station and 2) the limited feedback model where each user quantizes its channel vector according to a rotated codebook that is optimal in the sense of mean squared error and feeds back the codeword index. This paper is focused on characterizing the sum rate performance of both zero-forcing dirty paper coding (ZFDPC) systems and channel inversion (CI) systems under the given two partial CSIT models. Intuitively speaking, a system with shape feedback loses the sum rate gain of adaptive power allocation. However, shape feedback still provides enough channel knowledge for ZFDPC and CI to approach their own optimal throughput in the high signal-to-noise ratio (SNR) regime. As for limited feedback, we derive sum rate bounds for both signaling schemes and link their throughput performance to some basic properties of the quantization codebook. Interestingly, we find that limited feedback employing a fixed codebook leads to a sum rate ceiling for both schemes for asymptotically high SNR.

Sum Capacity of Multiuser MIMO Broadcast Channels with Block Diagonalization

Abstract: The sum capacity of a Gaussian broadcast MIMO channel can be achieved with dirty paper coding (DPC). However, algorithms that approach the DPC sum capacity do not appear viable in the forseeable future, which motivates lower complexity interference suppression techniques. Block diagonalization (BD) is a linear preceding technique for downlink multiuser MIMO systems. With perfect channel knowledge at the transmitter, BD can eliminate other users' interference at each receiver. In this paper, we study the sum capacity of BD with and without receive antenna selection. We analytically compare BD without receive antenna selection to DPC for a set of given channels. It is shown that (1) if the user channels are orthogonal to each other, then BD achieves the same sum capacity as DPC; (2) if the user channels lie in the same subspace, then the gain of DPC over BD can be upper bounded by the minimum of the number of transmit and receive antennas. These observations also hold for BD with receive antenna selection. Further, we study the ergodic sum capacity of BD with and without receive antenna selection in a Rayleigh fading channel. Simulations show that BD can achieve a significant part of the total throughput of DPC. An upper bound on the ergodic sum capacity gain of DPC over BD is proposed for easy estimation of the gap between the sum capacity of DPC and BD without receive antenna selection.

Limited Downlink Network Coordination in Cellular Networks

Abstract: We investigate the downlink throughput of cellular systems where groups of M antennas - either co-located or spatially distributed - transmit to a subset of a total population of K > M users in a coherent, coordinated fashion in order to mitigate intercell interference. We consider two types of coordination: the capacity-achieving technique based on dirty paper coding (DPC), and a simpler technique based on zero-forcing (ZF) beamforming with per-antenna power constraints. During a given frame, a scheduler chooses the subset of the K users in order to maximize the weighted sum rate, where the weights are based on the proportional-fair scheduling algorithm. We consider the weighted average sum throughput among K users per cell in a multi-cell network where coordination is limited to a neighborhood of M antennas. Consequently, the performance of both systems is limited by interference from antennas that are outside of the M coordinated antennas. Compared to a 12-sector baseline which uses the same number of antennas per cell site, the throughput of ZF and DPC achieve respective gains of 1.5 and 1.75.

Capacity Gain From Two-Transmitter and Two-Receiver Cooperation

Abstract: Capacity improvement from transmitter and receiver cooperation is investigated in a two-transmitter, two-receiver network with phase fading and full channel state information (CSI) available at all terminals. The transmitters cooperate by first exchanging messages over an orthogonal transmitter cooperation channel, then encoding jointly with dirty-paper coding. The receivers cooperate by using Wyner-Ziv compress-and-forward over an analogous orthogonal receiver cooperation channel. To account for the cost of cooperation, the allocation of network power and bandwidth among the data and cooperation channels is studied. It is shown that transmitter cooperation outperforms receiver cooperation and improves capacity over noncooperative transmission under most operating conditions when the cooperation channel is strong. However, a weak cooperation channel limits the transmitter cooperation rate; in this case, receiver cooperation is more advantageous. Transmitter-and-receiver cooperation offers sizable additional capacity gain over transmitter-only cooperation at low signal-to-noise ratio (SNR), whereas at high SNR transmitter cooperation alone captures most of the cooperative capacity improvement.

Precoding for Multiple Antenna Gaussian Broadcast Channels With Successive Zero-Forcing

Abstract: In this paper, we consider the multiuser Gaussian broadcast channel with multiple transmit antennas at the base station and multiple receive antennas at each user. Assuming full knowledge of the channel state information at the transmitter and the different receivers, a new transmission scheme that employs partial interference cancellation at the transmitter with dirty-paper encoding and decoding is proposed. The maximal achievable throughput of this system is characterized, and it is shown that given any ordered set of users the proposed scheme is asymptotically optimal in the high signal-to-noise ratio (SNR) regime. In addition, with optimal user ordering, the proposed scheme is shown to be optimal in the low-SNR regime. We also consider a linear transmission scheme which employs only partial interuser interference cancellation at the base station without dirty-paper coding. Given a transmit power constraint at the base station, the sum-rate capacity of this scheme is characterized and a suboptimal precoding algorithm is proposed. In several cases, it is shown that, for all values of the SNR, the achievable throughput of this scheme is strictly larger than a system which employs full interference cancellation at the base station (Spencer et al., 2004). In addition, it is shown that, in some cases, the linear transmission scheme can support simultaneously an increased number of users while achieving a larger system throughput.

On the Achievable Rate Regions for Interference Channels with Degraded Message Sets

Abstract: The interference channel with degraded message sets (IC-DMS) refers to a communication model in which two senders attempt to communicate with their respective receivers simultaneously through a common medium, and one of the senders has complete and a priori (non-causal) knowledge about the message being transmitted by the other. A coding scheme that collectively has advantages of cooperative coding, collaborative coding, and dirty paper coding, is developed for such a channel. With resorting to this coding scheme, achievable rate regions of the IC-DMS in both discrete memoryless and Gaussian cases are derived, which, in general, include several previously known rate regions. Numerical examples for the Gaussian case demonstrate that in the high-interference-gain regime, the derived achievable rate regions offer considerable improvements over these existing results.

On Achievable Rates for Interference Relay Channel with Interference Cancelation

Abstract: We consider two interfering source-destination pairs that are assisted by a common relay. The relay simultaneously helps both sources to improve communication rates. We provide coding strategies that combine dirty paper coding, beamforming and interference reduction techniques at the relay and give an achievable rate region for Gaussian interference relay channel. The region shows significant rate gain can be obtained by performing generalized dirty-paper coding at the relay.

Carbon Copying Onto Dirty Paper

Abstract: A generalization of the problem of writing on dirty paper is considered in which one transmitter sends a common message to multiple receivers. Each receiver experiences on its link an additive interference (in addition to the additive noise), which is known noncausally to the transmitter but not to any of the receivers. Applications range from wireless multiple-antenna multicasting to robust dirty paper coding. We develop results for memoryless channels in Gaussian and binary special cases. In most cases, we observe that the availability of side information at the transmitter increases capacity relative to systems without such side information, and that the lack of side information at the receivers decreases capacity relative to systems with such side information. For the noiseless binary case, we establish the capacity when there are two receivers. When there are many receivers, we show that the transmitter side information provides a vanishingly small benefit. When the interference is large and independent across the users, we show that time sharing is optimal. For the Gaussian case, we present a coding scheme and establish its optimality in the high signal-to-interference-plus-noise limit when there are two receivers. When the interference power is large and independent across all the receivers, we show that time-sharing is again optimal. Connections to the problem of robust dirty paper coding are also discussed

On the Capacity of Interference Channels with a Cognitive Transmitter

Abstract: Outer and inner bounds are established on the capacity region of two-sender, two-receiver interference channels where one transmitter knows both messages. The transmitter with extra knowledge is referred to as being cognitive. One of the outer bounds is based on the Nair-EI Gamal outer bound for broadcast channels. The inner bound is based on strategies that generalize prior work to include rate-splitting, dirty-paper coding, and carbon-copying. The bounds are demonstrated for Gaussian channels.

Distributed MIMO receiver - Achievable rates and upper bounds

Abstract: In this paper we investigate the achievable rate of a system that includes a nomadic transmitter with several antennas, which is received by multiple agents, exhibiting independent channel gains and additive circular-symmetric complex Gaussian noise. In the nomadic regime, we assume that the agents do not have any decoding ability. These agents process their channel observations and forward them to the final destination through lossless links with a fixed capacity. We propose new achievable rates based on elementary compression and also on a Wyner-Ziv (CEO-like) processing, for both fast fading and block fading channels, as well as for general discrete channels. The simpler two agents scheme is solved, up to an implicit equation with a single variable. Limiting the nomadic transmitter to a circular-symmetric complex Gaussian signalling, new upper bounds are derived for both fast and block fading, based on the vector version of the entropy power inequality. These bounds are then compared to the achievable rates in several extreme scenarios. The asymptotic setting with numbers of agents and transmitter's antennas taken to infinity is analyzed. In addition, the upper bounds are analytically shown to be tight in several examples, while numerical calculations reveal a rather small gap in a finite $2\times2$ setting. The advantage of the Wyner-Ziv approach over elementary compression is shown where only the former can achieve the full diversity-multiplexing tradeoff. We also consider the non-nomadic setting, with agents that can decode. Here we give an achievable rate, over fast fading channel, which combines broadcast with dirty paper coding and the decentralized reception, which was introduced for the nomadic setting.

An Achievable Rate Region for Interference Channels with Conferencing

Abstract: In this paper, we propose an achievable rate region for discrete memoryless interference channels with conferencing at the transmitter side. We employ superposition block Markov encoding, combined with simultaneous superposition coding, dirty paper coding, and random binning to obtain the achievable rate region. We show that, under respective conditions, the proposed achievable region reduces to Han and Kobayashi's achievable region for interference channels, the capacity region for degraded relay channels, and the capacity region for the Gaussian vector broadcast channel. Numerical examples for the Gaussian case are given.

Successive Coding in Multiuser Information Theory

Abstract: In this correspondence, we show that solutions to the multiple description coding problem and the broadcast channel coding problem share a common encoding procedure: successive source encoding. We use this connection as the basis for establishing connections between the achievable multiple description rate region and Marton's region for broadcast channels. Specifically, we show that Marton's encoding scheme can be viewed as a multiple description coding procedure. We also explore the dual problem, namely, the relationship between successive channel decoding in multiple access communication and distributed source coding. By illuminating these connections to multiple description, we hope to motivate a solution to what remains a mostly unsolved problem

Writing on Dirty Paper with Resizing and its Application to Quasi-Static Fading Broadcast Channels

Abstract: This paper studies a variant of the classical problem of "writing on dirty paper" in which the sum of the input and the interference, or dirt, is multiplied by a random variable that models resizing, known to the decoder but not to the encoder. The achievable rate of Costa's dirty paper coding (DPC) scheme is calculated and compared to the case of the decoder's also knowing the dirt. In the ergodic case, the corresponding rate loss vanishes asymptotically in the limits of both high and low signal-to-noise ratio (SNR), and is small at all finite SNR for typical distributions like Rayleigh, Rician, and Nakagami. In the quasi-static case, the DPC scheme is lossless at all SNR in terms of outage probability. Quasi-static fading broadcast channels (BC) without transmit channel state information (CSI) are investigated as an application of the robustness properties. It is shown that the DPC scheme leads to an outage achievable rate region that strictly dominates that of time division.

Downlink MIMO Systems Using Cooperation Among Base Stations in a Slow Fading Channel

Abstract: To increase the achievable sum rate of downlink MIMO (Multiple Input Multiple Output) systems, the cooperation among Base Stations (BS) is investigated in a slow fading channel. Three levels of BS coordination are considered: full coordination, partial coordination, and no coordination. This paper assumes that the downlink MIMO channel state information (CSI) is sent to the corresponding BS through a feedback link with some delay. In a fully coordinated system, the CSI at each BS needs to be collected at the central coordinator, and this process may result in significant additional delay. In this paper, the achievable throughput of each coordination level is evaluated and compared including the effects of the delay in CSI. A quasi-static fading is considered where the channel is static within one codeword, but it gradually changes over time based on the well-known Jake's model. Also, dirty paper coding (DPC) is applied, which is a transmission method shown to achieve the sum capacity of MIMO broadcast channels (BC). The results show that under certain delay conditions, the partially-coordinated system outperforms the fully-coordinated system. In addition, this paper presents a new partial-coordination method that provides higher throughput than the conventional partial-coordinated system.

Rate Regions for the Partially-Cooperative Relay Broadcast Channel with Non-causal Side Information

Abstract: In this work, we consider a partially cooperative relay broadcast channel (PC-RBC) controlled by random parameters. We provide rate regions for two different situations: (1) when side information (SI) Sn on the random parameters is non-causally known at both the source and the relay and, (2) when side information Sn is non-causally known at the source only. These achievable regions are derived for the general discrete memoryless case first and then extended to the case when the channel is degraded Gaussian and the SI is additive i.i.d. Gaussian. In this case, the source uses generalized dirty paper coding (GDPC), i.e., DPC combined with partial state cancellation, when only the source is informed, and DPC alone when both the source and the relay are informed. It appears that, even though it can not completely eliminate the effect of the SI (in contrast to the case of source and relay being informed), GDPC is particularly useful when only the source is informed.

Practical Vector Dirty Paper Coding for MIMO Gaussian Broadcast Channels

Abstract: Recently, the vector dirty paper coding (DPC) achievable rate region has been shown to be the capacity region of a multiple-input multiple-output Gaussian broadcast channel (MIMO GBC) With DPC, the multiuser interference noncausally known at the transmitter can be completely removed In this paper, we present a vector DPC structure for MIMO GBC It is a generalization of the single antenna superposition dirty paper coding for the scalar Gaussian dirty paper problem proposed by Bennatan et al In a theoretical random code setting, this construction is shown to be able to achieve the promised rate performance of the MIMO GBC We also implement it with existing vector quantizer and capacity-achieving channel coding Combined with iterative decoding, a design example validates the effectiveness of our methods

Writing on Dirty Paper with Resizing and its Application to Quasi-Static Fading Broadcast Channels

Abstract: This paper studies a variant of the classical problem of ``writing on dirty paper'' in which the sum of the input and the interference, or dirt, is multiplied by a random variable that models resizing, known to the decoder but not to the encoder. The achievable rate of Costa's dirty paper coding (DPC) scheme is calculated and compared to the case of the decoder's also knowing the dirt. In the ergodic case, the corresponding rate loss vanishes asymptotically in the limits of both high and low signal-to-noise ratio (SNR), and is small at all finite SNR for typical distributions like Rayleigh, Rician, and Nakagami. In the quasi-static case, the DPC scheme is lossless at all SNR in terms of outage probability. Quasi-static fading broadcast channels (BC) without transmit channel state information (CSI) are investigated as an application of the robustness properties. It is shown that the DPC scheme leads to an outage achievable rate region that strictly dominates that of time division.

Apparatus and method for removing interference in transmitting end of multi-antenna system

Abstract: An apparatus and method for removing interference in a transmitting end of a multi-antenna system are provided. The method includes receiving channel information for all Receive (Rx) antennas; calculating a beam-forming matrix that maximizes a Signal-to-Interference plus Noise Ratio (SINR) for each Rx antenna by using the received channel information; calculating an integer value which is in proportion to an interference signal for each Rx antenna by using the received channel information and the calculated beam-forming matrix, and performing Dirty Paper Coding (DPC) on a Transmit (Tx) signal by using the calculated integer value; and performing beam-forming by multiplying the Tx signal that has undergone the DPC by the calculated beam-forming matrix. Accordingly, a highest data rate for each user and a highest diversity can be obtained.

Cooperative Transmit Diversity Utilizing Superposition Modulation

Abstract: In this paper, the cooperative diversity with superposition modulation, which has been proposed as an instance of "dirty paper coding", is theoretically analyzed using the outage probability. We investigate the relationship between outage probability and transmission-rate corresponding to the parameter of superposition modulation. Moreover, we extend the modulation of this cooperative transmission system from one to two-dimensions and provide the system optimization

Data transmission method using dirty paper coding in MIMO system

Abstract: A data transmission method for multiple users having multiple receive antennas is provided The method includes selecting a receive antenna among the multiple receive antennas for each user, performing DPC (Dirty Paper Coding) from the multiple transmit antennas to the receive antenna and transmitting a transmission signal on which the DPC is performed Since DPC is implemented through a receive antenna selected among multiple receive antennas, complexity is not much increased although the DPC is applied to a MIMO system

Adaptive Orthogonal Beamforming for the Mimo Broadcast Channel

Abstract: This paper addresses both the user selection and the linear precoding design of a MIMO broadcast channel where the number of users is assumed to be greater than the number of transmit antennas. The optimization criterion considered is the sum-rate. A greedy algorithm tackling jointly the two issues is developed. It sequentially adds new users so as their beamformers build up an orthonormal basis which is optimized with the help of the channel knowledge assumed to be exhaustive. This solution benefits asymptotically (in the limit of a large number of users) from the full multiplexing and multiuser diversity gains alike the capacity achieving dirty paper coding. Moreover, it exhibits better results than existing schemes and offers some advantages resulting from the choice of an orthogonal structure.

Extended Uniform Channel Decomposition for MIMO Communications with Intersymbol Interference

Abstract: In this paper, a joint design of a unitary pre-coder and a decision feedback equalizer (DFE) is considered to decompose a multi-input multi-output (MIMO) intersymbol interference (ISI) channel into multiple scalar layers with identical mean square errors (MSEs), and consequently, achieve much improved error probability performance over the standard DFE without a precoder This design represents an extension of the existing uniform channel decomposition (UCD) scheme for frequency-flat MIMO channels Therefore, it is named extended UCD (EUCD) In contrast to the trivial extension of the UCD scheme which uses the orthogonal frequency division multiplexing (OFDM) to obtain multiple frequency flat channels and applies the standard UCD to each of them, the EUCD scheme uses a MIMO minimum-mean square error decision feedback equalizer (MMSE-DFE) to eliminate ISI and only needs one precoder for the entire broadband To eliminate error propagation, another form of the EUCD is also presented which uses the dirty paper coding (DPC) to cancel ISI at the transmitter The practical implementation aspect is also considered An example via numerical simulation validates the remarkable performance of the EUCD in terms of uncoded error probability

Maximum Weighted Sum Rate of Multi-Antenna Broadcast Channels

Abstract: Recently, researchers showed that dirty paper coding (DPC) is the optimal transmission strategy for multiple-input multiple-output broadcast channels (MIMO-BC). In this paper, we study how to determine the maximum weighted sum of DPC rates through solving the maximum weighted sum rate problem of the dual MIMO multiple access channel (MIMO-MAC) with a sum power constraint. We first simplify the maximum weighted sum rate problem such that enumerating all possible decoding orders in the dual MIMO-MAC is unnecessary. We then design an efficient algorithm based on conjugate gradient projection (CGP) to solve the maximum weighted sum rate problem. Our proposed CGP method utilizes the powerful concept of Hessian conjugacy. We also develop a rigorous algorithm to solve the projection problem. We show that CGP enjoys provable convergence, nice scalability, and great efficiency for large MIMO-BC systems.

Broadcast- and MAC-Aware Coding Strategies for Multiple User Information Embedding

Abstract: Multiple user information embedding is concerned with embedding several messages into the same host signal. This paper presents several implementable dirty-paper-coding (DPC)-based schemes for multiple user information embedding, through emphasizing their tight relationship with conventional multiple user information theory. We first show that depending on the targeted application and on whether the different messages are asked to have different robustness and transparency requirements or not, multiple user information embedding parallels one of the well-known multiuser channels with state information available at the transmitter. The focus is on the Gaussian broadcast channel (GBC) and the Gaussian multiple access channel (GMAC). For each of these channels, two practically feasible transmission schemes are compared. The first approach consists in a straightforward-rather intuitive-superimposition of DPC schemes. The second consists in a joint design of these DPC schemes. This joint approach heavily relies on a recent work by Kim in which the authors extend the single-user Costa's DPC to the multiple user case. The results in this paper extend the practical implementations quantization index modulation (QIM), distortion-compensated QIM (DC-QIM), and scalar Costa scheme (SCS) that have been originally conceived for one user to the multiple user case. After presenting the key features of the joint design within the context of structured scalar codebooks, we broaden our view to discuss the framework of more general lattice-based (vector) codebooks and show that the gap to full performance can be bridged up using finite dimensional lattice codebooks. Performance evaluations, including bit error rates (BERs) and achievable rate region curves are provided for both methods, illustrating the improvements brought by a joint design

Cooperative Relaying with State Available at the Relay

Abstract: We consider a state-dependent full-duplex relay channel with the state of the channel non-causally available at only the relay. In the framework of cooperative wireless networks, some specific terminals can be equipped with cognition capabilities, i.e, the relay in our model. In the discrete memoryless (DM) case, we derive lower and upper bounds on channel capacity. The lower bound is obtained by a coding scheme at the relay that consists in a combination of codeword splitting, Gel'fand-Pinsker binning, and a decode-and-forward scheme. The upper bound is better than that obtained by assuming that the channel state is available at the source and the destination as well. For the Gaussian case, we also derive lower and upper bounds on channel capacity. The lower bound is obtained by a coding scheme which is based on a combination of codeword splitting and Generalized dirty paper coding. The upper bound is also better than that obtained by assuming that the channel state is available at the source, the relay, and the destination. The two bounds meet, and so give the capacity, in some special cases for the degraded Gaussian case.

The Capacity of Gaussian Multi-User Channels With State and Feedback

Abstract: This correspondence considers communication over two Gaussian channels with additive state interference and noiseless output feedback-the multiple access channel (MAC) and the augmented broadcast channel (ABC) (a special class of the physically degraded broadcast channel). The state interference is assumed to be available noncausally at the transmitters. Deterministic coding schemes for these two channels were suggested by Ozarow when there is no state present. Recently, Merhav and Weissman derived an optimal feedback coding scheme for the single-user Gaussian channel with additive state interference. Combining ideas from these two schemes, we extend Ozarow's coding algorithms to the state-dependent case, showing that the capacity regions of the MAC and the ABC are not affected, even though not all parts of the system have knowledge of the state. The proposed schemes attain a better error performance and reduce the coding complexity with respect to the standard random binning coding technique.

Lattice coding for the vector fading paper problem

Abstract: Dirty paper coding (DPC) is a promising preceding technique for canceling arbitrary interference known only at the transmitter. The interference-free rate is thus achieved. However, this result relies on the perfectly known channel coefficients at the transmitter when being applied to the fading channel. We thus consider the fading paper problem where only the channel statistics information is available at the transmitter. In general, the optimal transmission strategies to achieve the capacity of this channel is still unknown. We confine ourselves to the linear-assignment Gel'fand-Pinsker coding which has been proved to have good, sometimes even optimal, performance in the a variety of fast and slow fading channels. However, lack of structured codebook so far limited the practical applications of this coding. In this paper, we present a lattice-based coding structure for the vector fading paper channel. It can achieve the rate performance of the linear-assignment strategies previously proved by the random Gaussian codebook. Moreover, the lattice codebook has an algebraic structure and is possible to be implemented in practice. The results can be applied to the emerging fields such as fading multiple-input multiple-output (MIMO) Gaussian broadcast channels or fading MIMO cognitive channels.

Superposition Modulated Cooperative Diversity for Half-duplex Scenario

Abstract: In this paper, the cooperative diversity with superposition modulation, which has been proposed as an instance of “dirty paper coding”, is theoretically analyzed using the outage probability. However, the conventional system with superposition modulation cannot ideally perform dirty paper coding. Thus, we propose to apply constellation rotation technique and iterative processing to the superposition modulated system, which yields a performance close to the ideal one.