Hairuo Zhuang - Academia.edu (original) (raw)

Papers by Hairuo Zhuang

IEEE Wireless Communications Letters

IEEE Transactions on Wireless Communications

The 57th IEEE Semiannual Vehicular Technology Conference, 2003. VTC 2003-Spring., 2003

1-Distributed antenna system (DAS) can reduce the access distance and so lower the required trans... more 1-Distributed antenna system (DAS) can reduce the access distance and so lower the required transmit power compared with the conventional multiple input multiple out (MIMO) system. This paper investigated the information-theoretic capacity of DAS based on the channel model considering path loss, log-normal shadowing fading and Rayleigh fading. We find that the location of the receiver affects the DAS capacity and the difference between capacity with water-filling power allocation and that with equal-power allocation is significant. Furthermore, simulation results show that DAS offers large capacity gains over the traditional MIMO system. I.

The 8th International Conference on Communication Systems, 2002. ICCS 2002., 2002

Multiple input/multiple output (MIMO) is a hot topic in wireless communication and has great adva... more Multiple input/multiple output (MIMO) is a hot topic in wireless communication and has great advantage in capacity. We investigate the influence of antenna topology on MIMO capacity and by comparing three topology schemes we find that selecting a proper antenna topology increases the capacity evidently. Three schemes under study are the traditional point-to-point concentrated antenna topology (CON), the multipoint-to-point distributed antenna topology (DIS) and the clustered antenna topology (CLUSTER). We explore their average capacity under different antenna number and power allocation methods. Simulation results show that DIS and CLUSTER excel the traditional concentrated MIMO structure in capacity. Keywords-MIMO capacity distributed antenna waterfilling equal-power allocation

14th IEEE Proceedings on Personal, Indoor and Mobile Radio Communications, 2003. PIMRC 2003., 2003

This paper proposes an iterative V-BLAST detection algorithm that improves the error performance ... more This paper proposes an iterative V-BLAST detection algorithm that improves the error performance over error propagation. Traditional detection algorithm cannot alleviate error propagation because the decision feedbacks from low-diversity substreams are used to decode high-diversity substreams. In our algorithm, we iteratively suppress the interference towards low-diversity substreams by using decisions from high-diversity substreams, and the system performance is highly improved over the traditional one, which is demonstrated via simulation results. Besides, existing algorithms combating error propagation operate in high complexity, while the complexity of our algorithm is proportional to the loop times, providing a tradeoff between performance and complexity.

14th IEEE Proceedings on Personal, Indoor and Mobile Radio Communications, 2003. PIMRC 2003., 2003

2008 IEEE International Conference on Acoustics, Speech and Signal Processing, 2008

For delay-tolerant data applications in a wireless system, using average throughput as a quality ... more For delay-tolerant data applications in a wireless system, using average throughput as a quality of service (QoS) measure results in more efficient resources allocation strategies compared to using instantaneous signal to interference and noise ratio (SINR). By adapting both power and rate in a multiuser multi-antenna system based on the channel conditions, the overall power consumption can be greatly reduced.

Vehicular Technology Conference. IEEE 55th Vehicular Technology Conference. VTC Spring 2002 (Cat. No.02CH37367), 2002

International Conference on Communication Technology Proceedings, 2003. ICCT 2003., 2003

IEEE Information Theory Workshop 2010 (ITW 2010), 2010

This paper considers the problem of routing packets across a multi-hop wireless network while ens... more This paper considers the problem of routing packets across a multi-hop wireless network while ensuring throughput optimality. One of the main challenges in the design of throughput optimal routing policies is identifying an appropriate Lyapunov function with negative expected drift. The only known throughput optimal routing policies in the literature, most notably backpressure routing, are constructed using simple node-based quadratic or exponential Lyapunov functions of the queue backlogs and as such exhibit poor delay performance under many network topologies and traffic conditions. By constructing a class of continuous, differentiable, and piece-wise quadratic Lyapunov functions, this paper provides a large class of throughput optimal routing policies. The nature of the proposed Lyapunov functions is such that, under a "sufficiently unbalanced" backlog state, the traffic must be routed away from nodes with significantly large backlogs (consistent with backpressure) in order to ensure a negative expected drift. In contrast, under all other backlog states, any non-idling policy can ensure a negative expected drift in the proposed Lyapunov function, providing tremendous flexibility in controlling routing decisions for most of the state-space.

2012 50th Annual Allerton Conference on Communication, Control, and Computing (Allerton), 2012

IEEE Transactions on Information Theory, 2000

This paper considers the problem of routing packets across a multi-hop wireless network while ens... more This paper considers the problem of routing packets across a multi-hop wireless network while ensuring throughput optimality. One of the main challenges in the design of throughput optimal routing policies is identifying appropriate and universal Lyapunov functions with negative expected drift. The few well-known throughput optimal routing policies in the literature are constructed using simple quadratic or exponential Lyapunov functions of the queue backlogs and as such they do not use any metric of closeness to the destination. Consequently, these routing policies exhibit poor delay performance under many network topologies and traffic conditions. By considering a class of continuous, differentiable, and piece-wise quadratic Lyapunov functions, this paper provides a large class of throughput optimal routing policies. The proposed class of Lyapunov functions allow for the routing policies to control the traffic along short paths for a large portion of state-space while ensuring a negative expected drift, hence, enabling the design of routing policies with much improved delay performances. In particular, and in addition to recovering the throughput optimality of the well known backpressure routing policy, an opportunistic routing policy with congestion diversity is proved to be throughput optimal. I. INTRODUCTION Opportunistic routing for multi-hop wireless ad-hoc networks has seen recent research interest to overcome deficiencies of conventional routing [1]-[5]. Opportunistic routing mitigates the impact of poor wireless links by exploiting the broadcast nature of wireless transmissions and the path diversity. More precisely, the routing decisions are made in an online manner by choosing the next relay based on the actual transmission outcomes as well as a rank ordering of neighboring nodes. The authors in [5] provided a Markov decision theoretic formulation for opportunistic routing. In particular, it is shown that for any given packet and at any relaying epoch, the optimal routing decision, in the sense of minimum cost or hop-count, is to select the next relay node based on an index. This index is equal to the expected cost or hop-count of relaying the packet along the least costly or the shortest feasible path to the destination. Furthermore, this index is computable in a distributed manner and with low complexity using a time-invariant probabilistic description of wireless links and the time-invariant transmission costs or transmission times. As such, [5] provides a unifying framework for almost all versions of opportunistic

IEEE Transactions on Communications, 2003

Previous studies have shown that per-antenna rate and power control can greatly increase the data... more Previous studies have shown that per-antenna rate and power control can greatly increase the data throughput of vertical Bell Labs layered space-time (V-BLAST), while an extra transmit antenna selection can provide additional diversity advantage. In this letter, we combine the transmit antenna selection with power and rate control of each antenna. We derive a simple criterion for minimum bit-error rate (BER) or minimum total transmit power when the data throughput is constant over time. Zero-forcing and zero-forcing successive interference cancellation detections are considered. For practical implementation, we also present a fast algorithm that gives near-optimal performance with very low complexity. Simulation results show that the proposed closed-loop BLAST outperforms the open-loop V-BLAST significantly in terms of BER performance, especially when the antennas exhibit strong fading correlations. Index Terms-Multiple-input-multiple-output (MIMO), rate and power control, transmit antenna selection, vertical Bell Labs layered space-time (V-BLAST).

Electronics Letters, 2003

Electronics Letters, 2003

Spectral efficiency of distributed antenna system with random antenna layout ... Haimo Zhuang, Li... more Spectral efficiency of distributed antenna system with random antenna layout ... Haimo Zhuang, Lin Dai, Liang Xiao and Yan Yao ... The downlink capaciry potential of a distributed aniznna syslem (DAS) with rdndom antenna layout is investigated. A low COmplexity sub-...

Electronics Letters, 2002

IEEE Wireless Communications Letters

IEEE Transactions on Wireless Communications

The 57th IEEE Semiannual Vehicular Technology Conference, 2003. VTC 2003-Spring., 2003

1-Distributed antenna system (DAS) can reduce the access distance and so lower the required trans... more 1-Distributed antenna system (DAS) can reduce the access distance and so lower the required transmit power compared with the conventional multiple input multiple out (MIMO) system. This paper investigated the information-theoretic capacity of DAS based on the channel model considering path loss, log-normal shadowing fading and Rayleigh fading. We find that the location of the receiver affects the DAS capacity and the difference between capacity with water-filling power allocation and that with equal-power allocation is significant. Furthermore, simulation results show that DAS offers large capacity gains over the traditional MIMO system. I.

The 8th International Conference on Communication Systems, 2002. ICCS 2002., 2002

Multiple input/multiple output (MIMO) is a hot topic in wireless communication and has great adva... more Multiple input/multiple output (MIMO) is a hot topic in wireless communication and has great advantage in capacity. We investigate the influence of antenna topology on MIMO capacity and by comparing three topology schemes we find that selecting a proper antenna topology increases the capacity evidently. Three schemes under study are the traditional point-to-point concentrated antenna topology (CON), the multipoint-to-point distributed antenna topology (DIS) and the clustered antenna topology (CLUSTER). We explore their average capacity under different antenna number and power allocation methods. Simulation results show that DIS and CLUSTER excel the traditional concentrated MIMO structure in capacity. Keywords-MIMO capacity distributed antenna waterfilling equal-power allocation

14th IEEE Proceedings on Personal, Indoor and Mobile Radio Communications, 2003. PIMRC 2003., 2003

This paper proposes an iterative V-BLAST detection algorithm that improves the error performance ... more This paper proposes an iterative V-BLAST detection algorithm that improves the error performance over error propagation. Traditional detection algorithm cannot alleviate error propagation because the decision feedbacks from low-diversity substreams are used to decode high-diversity substreams. In our algorithm, we iteratively suppress the interference towards low-diversity substreams by using decisions from high-diversity substreams, and the system performance is highly improved over the traditional one, which is demonstrated via simulation results. Besides, existing algorithms combating error propagation operate in high complexity, while the complexity of our algorithm is proportional to the loop times, providing a tradeoff between performance and complexity.

14th IEEE Proceedings on Personal, Indoor and Mobile Radio Communications, 2003. PIMRC 2003., 2003

2008 IEEE International Conference on Acoustics, Speech and Signal Processing, 2008

For delay-tolerant data applications in a wireless system, using average throughput as a quality ... more For delay-tolerant data applications in a wireless system, using average throughput as a quality of service (QoS) measure results in more efficient resources allocation strategies compared to using instantaneous signal to interference and noise ratio (SINR). By adapting both power and rate in a multiuser multi-antenna system based on the channel conditions, the overall power consumption can be greatly reduced.

Vehicular Technology Conference. IEEE 55th Vehicular Technology Conference. VTC Spring 2002 (Cat. No.02CH37367), 2002

International Conference on Communication Technology Proceedings, 2003. ICCT 2003., 2003

IEEE Information Theory Workshop 2010 (ITW 2010), 2010

This paper considers the problem of routing packets across a multi-hop wireless network while ens... more This paper considers the problem of routing packets across a multi-hop wireless network while ensuring throughput optimality. One of the main challenges in the design of throughput optimal routing policies is identifying an appropriate Lyapunov function with negative expected drift. The only known throughput optimal routing policies in the literature, most notably backpressure routing, are constructed using simple node-based quadratic or exponential Lyapunov functions of the queue backlogs and as such exhibit poor delay performance under many network topologies and traffic conditions. By constructing a class of continuous, differentiable, and piece-wise quadratic Lyapunov functions, this paper provides a large class of throughput optimal routing policies. The nature of the proposed Lyapunov functions is such that, under a "sufficiently unbalanced" backlog state, the traffic must be routed away from nodes with significantly large backlogs (consistent with backpressure) in order to ensure a negative expected drift. In contrast, under all other backlog states, any non-idling policy can ensure a negative expected drift in the proposed Lyapunov function, providing tremendous flexibility in controlling routing decisions for most of the state-space.

2012 50th Annual Allerton Conference on Communication, Control, and Computing (Allerton), 2012

IEEE Transactions on Information Theory, 2000

This paper considers the problem of routing packets across a multi-hop wireless network while ens... more This paper considers the problem of routing packets across a multi-hop wireless network while ensuring throughput optimality. One of the main challenges in the design of throughput optimal routing policies is identifying appropriate and universal Lyapunov functions with negative expected drift. The few well-known throughput optimal routing policies in the literature are constructed using simple quadratic or exponential Lyapunov functions of the queue backlogs and as such they do not use any metric of closeness to the destination. Consequently, these routing policies exhibit poor delay performance under many network topologies and traffic conditions. By considering a class of continuous, differentiable, and piece-wise quadratic Lyapunov functions, this paper provides a large class of throughput optimal routing policies. The proposed class of Lyapunov functions allow for the routing policies to control the traffic along short paths for a large portion of state-space while ensuring a negative expected drift, hence, enabling the design of routing policies with much improved delay performances. In particular, and in addition to recovering the throughput optimality of the well known backpressure routing policy, an opportunistic routing policy with congestion diversity is proved to be throughput optimal. I. INTRODUCTION Opportunistic routing for multi-hop wireless ad-hoc networks has seen recent research interest to overcome deficiencies of conventional routing [1]-[5]. Opportunistic routing mitigates the impact of poor wireless links by exploiting the broadcast nature of wireless transmissions and the path diversity. More precisely, the routing decisions are made in an online manner by choosing the next relay based on the actual transmission outcomes as well as a rank ordering of neighboring nodes. The authors in [5] provided a Markov decision theoretic formulation for opportunistic routing. In particular, it is shown that for any given packet and at any relaying epoch, the optimal routing decision, in the sense of minimum cost or hop-count, is to select the next relay node based on an index. This index is equal to the expected cost or hop-count of relaying the packet along the least costly or the shortest feasible path to the destination. Furthermore, this index is computable in a distributed manner and with low complexity using a time-invariant probabilistic description of wireless links and the time-invariant transmission costs or transmission times. As such, [5] provides a unifying framework for almost all versions of opportunistic

IEEE Transactions on Communications, 2003

Previous studies have shown that per-antenna rate and power control can greatly increase the data... more Previous studies have shown that per-antenna rate and power control can greatly increase the data throughput of vertical Bell Labs layered space-time (V-BLAST), while an extra transmit antenna selection can provide additional diversity advantage. In this letter, we combine the transmit antenna selection with power and rate control of each antenna. We derive a simple criterion for minimum bit-error rate (BER) or minimum total transmit power when the data throughput is constant over time. Zero-forcing and zero-forcing successive interference cancellation detections are considered. For practical implementation, we also present a fast algorithm that gives near-optimal performance with very low complexity. Simulation results show that the proposed closed-loop BLAST outperforms the open-loop V-BLAST significantly in terms of BER performance, especially when the antennas exhibit strong fading correlations. Index Terms-Multiple-input-multiple-output (MIMO), rate and power control, transmit antenna selection, vertical Bell Labs layered space-time (V-BLAST).

Electronics Letters, 2003

Electronics Letters, 2003

Spectral efficiency of distributed antenna system with random antenna layout ... Haimo Zhuang, Li... more Spectral efficiency of distributed antenna system with random antenna layout ... Haimo Zhuang, Lin Dai, Liang Xiao and Yan Yao ... The downlink capaciry potential of a distributed aniznna syslem (DAS) with rdndom antenna layout is investigated. A low COmplexity sub-...

Electronics Letters, 2002