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20
User Cooperation Diversity -- Part I: System Description
- IEEE TRANS. COMMUN
, 1998
"... Mobile users' data rate and quality of service are limited by the fact that, within the duration of any given call, they experience severe variations in signal attenuation, thereby necessitating the use of some type of diversity. In this two-part paper, we propose a new form of spatial diver ..."
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Cited by 669 (22 self)
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Mobile users' data rate and quality of service are limited by the fact that, within the duration of any given call, they experience severe variations in signal attenuation, thereby necessitating the use of some type of diversity. In this two-part paper, we propose a new form of spatial diversity, in which diversity gains are achieved via the cooperation of mobile users. Part I describes the user cooperation strategy while Part II focuses on implementation issues and performance analysis. Results show that, even though the inter-user channel is noisy, cooperation leads not only to an increase in capacity for both users but also to a more robust system, where users' achievable rates are less susceptible to channel variations.
On the Theory of Space-Time Codes for PSK Modulation
- IEEE Trans. Inform. Theory
, 2000
"... The design of space--time codes to achieve full spatial diversity over fading channels has largely been addressed by handcrafting example codes using computer search methods and only for small numbers of antennas. The lack of more general designs is in part due to the fact that the diversity advanta ..."
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Cited by 103 (0 self)
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The design of space--time codes to achieve full spatial diversity over fading channels has largely been addressed by handcrafting example codes using computer search methods and only for small numbers of antennas. The lack of more general designs is in part due to the fact that the diversity advantage of a code is the minimum rank among the complex baseband differences between modulated codewords, which is difficult to relate to traditional code designs over finite fields and rings. In this paper, we present general binary design criteria for PSK-modulated space--time codes. For linear BPSK/QPSK codes, the rank of (binary projections of) the unmodulated codewords, as binary matrices over the binary field, is a sufficient design criterion: full binary rank guarantees full spatial diversity. This criterion accounts for much of what is currently known about PSK-modulated space-time codes. We develop new fundamental code constructions for both quasi-static and time-varying channels. These are perhaps the first general constructions---other than delay diversity schemes---that guarantee full spatial diversity for an arbitrary number of transmit antennas.
Downlink capacity of interference-limited MIMO systems with joint detection
- IEEE Trans. Wireless Commun
, 2004
"... The capacity of downlink cellular multiple-input multiple-output (MIMO) cellular systems, where co-channel interference is the dominant channel impairment, is investigated in this paper, mainly from a signal-processing perspective. Turbo space-time multiuser detection (ST MUD) is employed for intrac ..."
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Cited by 60 (7 self)
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The capacity of downlink cellular multiple-input multiple-output (MIMO) cellular systems, where co-channel interference is the dominant channel impairment, is investigated in this paper, mainly from a signal-processing perspective. Turbo space-time multiuser detection (ST MUD) is employed for intracell communications, and is shown to closely approach the ultimate capacity limits in Gaussian ambient noise for an isolated cell. Then it is combined with various multiuser detection methods for combating intercell interference. Among various multiuser detection techniques examined, linear minimum-mean-square-error (MMSE) MUD and successive interference cancellation are shown to be feasible and effective. Based on these two multiuser detection schemes, one of which may outperform the other for different settings, an adaptive detection scheme is developed, which together with a Turbo ST MUD structure offers substantial performance gain over the well known V-BLAST techniques with coding in this interference-limited cellular environment. The obtained multiuser capacity is excellent in high to medium signal-to-interference ratio scenario. Nonetheless, numerical results also indicate that a further increase in system complexity, using base-station cooperation, could lead to further significant increases of the system capacity. The asymptotic multicell MIMO capacity with linear MMSE MUD preprocessing is also derived, and this analysis agrees well with the simulation results.
Video streaming over the public internet: Multiple description codes and adaptive transport protocols
- In Proceedings ICIP
, 1999
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Broadcast Quality Video over IP
- in Communications, Special issue on QoS in the Internet
, 1999
"... Abstract—We consider the problem of designing systems for the transmission of video signals of the quality found in current television broadcasts, over high-speed segments of the public IP network. Our most important contribution is the definition of a network/coder interface for IP networks which g ..."
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Cited by 11 (0 self)
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Abstract—We consider the problem of designing systems for the transmission of video signals of the quality found in current television broadcasts, over high-speed segments of the public IP network. Our most important contribution is the definition of a network/coder interface for IP networks which gathers channel state information, and then sets parameters of the video coder to maximize the quality of the signal delivered to the receiver, while remaining fair to other data or video connections. This interface plays a role analogous to that of a Leaky Bucket controller, in that it specifies traffic shaping parameters which result in simultaneous good Quality-of-Service (QoS) for the source and good network performance. Since the network is not assumed to provide any form of QoS guarantee, fundamental to our construction is a hidden Markov model for the channel, based on which the interface solves a problem of optimal stochastic control, to decide how to configure the encoder. Other contributions are a) modifications to the standard Internet transport protocol, to make it suitable for the transport of delay-constrained traffic and to gather channel state information, and b) the design of an error-resilient video coder. Experimental studies reveal that the proposed system is able to stream video signals of the quality of current TV-broadcasts, among hosts in wide-area networks connected to the experimental vBNS backbone. Index Terms—Communication systems, computer networks, hidden Markov models, interactive TV, protocols, stochastic systems. I.
Unreliable and Resource-Constrained Decoding
, 2010
"... Traditional information theory and communication theory assume that decoders are noiseless and operate without transient or permanent faults. Decoders are also traditionally assumed to be unconstrained in physical resources like materiel, memory, and energy. This thesis studies how constraining reli ..."
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Cited by 8 (4 self)
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Traditional information theory and communication theory assume that decoders are noiseless and operate without transient or permanent faults. Decoders are also traditionally assumed to be unconstrained in physical resources like materiel, memory, and energy. This thesis studies how constraining reliability and resources in the decoder limits the performance of communication systems. Five communication problems are investigated. Broadly speaking these are communication using decoders that are wiring cost-limited, that are memory-limited, that are noisy, that fail catastrophically,
Low-Density Parity-Check Codes and their Rateless Relatives
"... This survey guides the reader through the extensive open literature that is covering the family of low-density parity-check (LDPC) codes and their rateless relatives. In doing so, we will identify the most important milestones that have occurred since their conception until the current era and eluci ..."
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Cited by 7 (1 self)
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This survey guides the reader through the extensive open literature that is covering the family of low-density parity-check (LDPC) codes and their rateless relatives. In doing so, we will identify the most important milestones that have occurred since their conception until the current era and elucidate the related design problems and their respective solutions.
Coding theory and algebraic combinatorics
, 2008
"... This chapter introduces and elaborates on the fruitful interplay of coding theory and algebraic combinatorics, with most of the focus on the interaction of codes with combinatorial designs, finite geometries, simple groups, sphere packings, kissing numbers, lattices, and association schemes. In part ..."
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Cited by 4 (3 self)
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This chapter introduces and elaborates on the fruitful interplay of coding theory and algebraic combinatorics, with most of the focus on the interaction of codes with combinatorial designs, finite geometries, simple groups, sphere packings, kissing numbers, lattices, and association schemes. In particular, special interest is devoted to the relationship between codes and combinatorial designs. We describe and recapitulate important results in the development of the state of the art. In addition, we give illustrative examples and constructions, and highlight recent advances. Finally, we provide a collection of significant open problems and challenges concerning future research.
A Survey on Progress and Standardization Trends in Wireless Communications. In: Journal of Communications 4(7
- In: Proceedings of the 28th IEEE conference on Global telecommunications (2009
, 2009
"... Abstract—Progress of digital wireless communications and recent trends in standardizations are reviewed, addressing the main features and driving factors of innovations. This progress is driven by research on information theory, inventions of communication technologies, and advances in semiconductor ..."
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Cited by 2 (0 self)
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Abstract—Progress of digital wireless communications and recent trends in standardizations are reviewed, addressing the main features and driving factors of innovations. This progress is driven by research on information theory, inventions of communication technologies, and advances in semiconductor technologies. Trends of technology integration and system integration are observed. It is also observed that innovations have been done in a concatenated manner; innovative systems and technologies are developed, influencing each other and causing further innovations. It is expected that wireless communications will keep playing important roles in the networked knowledge society in the 21st century.
