Rice Wireless

Permanent URI for this collection

https://hdl.handle.net/1911/21945

Formerly the Center for Multimedia Communications, Rice Wireless is part of the university's Electrical and Computer Engineering Department. More information about the group can be found at http://wireless.rice.edu/.

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Now showing 1 - 20 of 20

Application-Specific Accelerators for Communications
(Springer Science+Business Media, LLC, 2010-01-01) Sun, Yang; Amiri, Kiarash; Brogioli, Michael; Cavallaro, Joseph R.; Center for Multimedia Communication
For computation-intensive digital signal processing algorithms, complexity is exceeding the processing capabilities of general-purpose digital signal processors (DSPs). In some of these applications, DSP hardware accelerators have been widely used to off-load a variety of algorithms from the main DSP host, including FFT, FIR/IIR filters, multiple-input multiple-output (MIMO) detectors, and error correction codes (Viterbi, Turbo, LDPC) decoders. Given power and cost considerations, simply implementing these computationally complex parallel algorithms with high-speed general-purpose DSP processor is not very efficient. However, not all DSP algorithms are appropriate for off-loading to a hardware accelerator. First, these algorithms should have data-parallel computations and repeated operations that are amenable to hardware implementation. Second, these algorithms should have a deterministic dataflow graph that maps to parallel datapaths. The accelerators that we consider are mostly coarse grain to better deal with streaming data transfer for achieving both high performance and low power. In this chapter, we focus on some of the basic and advanced digital signal processing algorithms for communications and cover major examples of DSP accelerators for communications.
Architecture and Algorithm for a Stochastic Soft-output MIMO Detector
(IEEE, 2007-11-04) Amiri, Kiarash; Radosavljevic, Predrag; Cavallaro, Joseph R.; CMC
In this paper, we propose a novel architecture for a soft-output stochastic detector in multiple-input, multiple-output (MIMO) systems. The stochastic properties of this detector are studied and derived in this work, and several complexity reduction techniques are proposed to significantly reduce its cost from an architecture-implementation perspective. We also propose an efficient architecture to implement this detector. Finally, this detector is incorporated into an iterative detectiondecoding structure, and through simulations, it is shown that the overall frame error rate (FER) performance and complexity is of the same order as that of the conventional K-best sphere detector.
Architecture and Algorithm for a Stochastic Soft-output MIMO Detector
(IEEE, 2007-11-01) Amiri, Kiarash; Radosavljevic, Predrag; Cavallaro, Joseph R.; Center for Multimedia Communication
In this paper, we propose a novel architecture for a soft-output stochastic detector in multiple-input, multiple-output (MIMO) systems. The stochastic properties of this detector are studied and derived in this work, and several complexity reduction techniques are proposed to significantly reduce its cost from an architecture-implementation perspective. We also propose an efficient architecture to implement this detector. Finally, this detector is incorporated into an iterative detection-decoding structure, and through simulations, it is shown that the overall frame error rate (FER) performance and complexity is of the same order as that of the conventional K-best sphere detector.
Architectures for Cognitive Radio Testbeds and Demonstrators – An Overview
(IEEE, 2010-06-01) Gustafsson, Oscar; Amiri, Kiarash; Andersson, Dennis; Blad, Anton; Bonner, Christian; Cavallaro, Joseph R.; Declerck, Jeroen; Dejonghe, Antoine; Eliardsson, Patrik; Glasse, Miguel; Hayar, Aawatif; Hollevoet, Lieven; Hunter, Chris; Joshi, Madhura; Kaltenberger, Florian; Knopp, Raymond; Le, Khanh; Miljanic, Zoran; Murphy, Patrick; Naessens, Frederik; Nikaein, Navid; Nussbaum, Dominique; Pacalet, Renaud; Raghavan, Praveen; Sabharwal, Ashutosh; Sarode, Onkar; Spasojevic, Predrag; Sun, Yang; Tullberg, Hugo M.; Vander Aa, Tom; Van der Perre, Liesbet; Wetterwald, Michelle; Wu, Michael; Center for Multimedia Communication
Wireless communication standards are developed at an ever-increasing rate of pace, and significant amounts of effort is put into research for new communication methods and concepts. On the physical layer, such topics include MIMO, cooperative communication, and error control coding, whereas research on the medium access layer includes link control, network topology, and cognitive radio. At the same time, implementations are moving from traditional fixed hardware architectures towards software, allowing more efficient development. Today, field-programmable gate arrays (FPGAs) and regular desktop computers are fast enough to handle complete baseband processing chains, and there are several platforms, both open-source and commercial, providing such solutions. The aims of this paper is to give an overview of five of the available platforms and their characteristics, and compare the features and performance measures of the different systems.
Cooperative Partial Detection Using MIMO Relays
(IEEE, 2011-10-01) Amiri, Kiarash; Wu, Michael; Cavallaro, Joseph R.; Lilleberg, Jorma; Center for Multimedia Communication
Using multiple-input multiple-output (MIMO) relays in cooperative communication improves the data rate and reliability of the communication. The MIMO transmission, however, requires considerable resources for the detection in the relay. In particular, if a full detect-and-forward (FDF) strategy is employed, the relay needs to spend considerable resources to perform the full MIMO detection. We propose a novel cooperative partial detection (CPD) strategy to partition the detection task between the relay and the destination. CPD modifies the tree traversal of the tree-based sphere detectors in a way where there is no need to visit all the levels of the tree and only a subset of the levels; thus, a subset of the transmitted streams are visited. The destination, then, combines the source signal and the partial relay signal to perform the final detection step and recover the transmitted vector. We study and compare the performance and complexity of FDF and CPD and show that by using the CPD approach, the relay can avoid the considerable overhead of MIMO detection while helping the source-destination link to improve its performance. More specifically, in the case of a 4X4 system, the relay complexity can be reduced by up to 80% of the conventional relaying scheme.
Design and Architecture of Spatial Multiplexing MIMO Decoders for FPGAs
(IEEE, 2008-10-01) Dick, Chris; Amiri, Kiarash; Cavallaro, Joseph R.; Rao, Raghu; Center for Multimedia Communication
Spatial multiplexing multiple-input-multiple-output (MIMO) communication systems have recently drawn significant attention as a means to achieve tremendous gains in wireless system capacity and link reliability. The optimal hard decision detection for MIMO wireless systems is the maximum likelihood (ML) detector. ML detection is attractive due to its superior performance (in terms of BER). However, direct implementation grows exponentially with the number of antennas and the modulation scheme, making its ASIC or FPGA implementation infeasible for all but low-density modulation schemes using a small number of antennas. Sphere decoding (SD) solves the ML detection problem in a computationally efficient manner. However, even with this complexity reduction, real-time implementation on a DSP processor is generally not feasible and high-performance parallel computing platforms such as FPGAs are increasingly being employed for this class of applications. The sphere detection problem affords many opportunities for algorithm and micro-architecture optimizations and tradeoffs. This paper provides an overview of techniques to simplify and minimize FPGA resource utilization of sphere detectors for high performance low-latency systems.
Flex-Sphere: An FPGA Configurable Sort-Free Sphere Detector For Multi-user MIMO Wireless Systems
(SDR Forum, 2008-10-01) Amiri, Kiarash; Dick, Chris; Rao, Raghu; Cavallaro, Joseph R.; Center for Multimedia Communication
Spatial division multiplexing (SDM) in MIMO technology significantly increases the spectral efficiency, and hence capacity, of a wireless communication system: it is a core component of the next generation wireless systems, e.g. WiMAX, 3GPP LTE and other OFDM-based communication schemes. Moreover, spatial division multiple access (SDMA) is one of the widely used techniques for sharing the wireless medium between different mobile devices. Sphere detection is a prominent method of simplifying the detection complexity in both SDM and SDMA systems while maintaining BER performance comparable with the optimum maximum-likelihood (ML) detection. There are several approaches for realizing sphere detectors, and the algorithmic landscape is rich with methods that enable the designer to make various tradeoffs between performance, e.g. throughput of the wireless channel, BER, and implementation complexity, e.g. silicon area for an ASIC implementation or FPGA resource envelope for an FPGA implementation. This paper describes the FPGA realization of a configurable and flexible sort-free sphere detector, Flex-Sphere, that supports 4;16;64-QAM modulations as well as a combination of 2;3 and 4 antenna/user configuration for uplink transmission. The detector provides a data rate of up to 849:9 Mbps. The algorithmic optimizations employed to produce an FPGA friendly realization are discussed.
FPGA Implementation of Dynamic Threshold Sphere Detection for MIMO Systems
(IEEE, 2006-11-01) Amiri, Kiarash; Cavallaro, Joseph R.; Center for Multimedia Communication
In this paper, we consider the FPGA implementation of a modified sphere detection algorithm. We analyze breadth-first and depth-first search in sphere detection, and compare the relative performance and complexity. Based on these comparisons, we propose a more efficient and less complex scheme, Dynamic Threshold Sphere Detection (DTSD), which can effectively increase the throughput and reduce the error rate. We, then, propose a novel architecture for this scheme, and discuss the complexity reduction techniques that we utilized. These techniques do not compromise the overall performance. Finally, the high throughput FPGA implementation results of this algorithm will be presented.
FPGA in Wireless Communications Applications
(Elsevier, Waltham, MA, 2012-07-12) Amiri, Kiarash; Duarte, Melissa; Cavallaro, Joseph R.; Dick, Chris; Rao, Raghu; Sabharwal, Ashutosh; Center for Multimedia Communication
In the past decade we have witnessed explosive growth in the wireless communications industry with over 4 billion subscribers worldwide. While first and second generation systems focused on voice communications, third generation networks (3GPP and 3GPP2) embraced code division multiple access (CDMA) and had a strong focus on enabling wireless data services. As we reflect on the rollout of 3G services, the reality is that first generation 3G systems did not entirely fulfill the promise of high-speed transmission, and the rates supported in practice were much lower than those claimed in the standards. Enhanced 3G systems were subsequently deployed to address the deficiencies. However, the data rate capabilities and network architecture of these systems were insufficient to address the insatiable consumer and business sector demand for the nomadic delivery of media and datacentric services to an increasingly rich set of mobile platforms.
FPGA Prototyping of A High Data Rate LTE Uplink Baseband Receiver
(IEEE, 2009-11-01) Wang, Guohui; Yin, Bei; Amiri, Kiarash; Sun, Yang; Wu, Michael; Cavallaro, Joseph R.; Center for Multimedia Communication
The Third Generation Partnership Project (3GPP) Long Term Evolution (LTE) standard is becoming the appropriate choice to pave the way for the next generation wireless and cellular standards. While the popular OFDM technique has been adopted and implemented in previous standards and also in the LTE downlink, it suffers from high peak-to-average-power ratio (PAPR). High PAPR requires more sophisticated power amplifiers (PAs) in the handsets and would result in lower efficiency PAs. In order to combat such effects, the LTE uplink choice of transmission is the novel Single Carrier Frequency Division Multiple Access (SC-FDMA) scheme which has lower PAPR due to its inherent signal structure. While reducing the PAPR, the SC-FDMA requires a more complicated detector structure in the base station for multi-antenna and multi-user scenarios. Since the multi-antenna and multi-user scenarios are critical parts of the LTE standard to deliver high performance and data rate, it is important to design novel architectures to ensure high reliability and data rate in the receiver. In this paper, we propose a flexible architecture of a high data rate LTE uplink receiver with multiple receive antennas and implemented a single FPGA prototype of this architecture. The architecture is verified on the WARPLab (a software defined radio platform based on Rice Wireless Open-access Research Platform) and tested in the real over-the-air indoor channel.
A High Throughput Configurable SDR Detector for Multi-user MIMO Wireless Systems
(Springer, 2011-02-01) Amiri, Kiarash; Cavallaro, Joseph R.; Dick, Chris; Rao, Raghu Mysore; Center for Multimedia Communication
Spatial division multiplexing (SDM) in MIMO technology significantly increases the spectral efficiency, and hence capacity, of a wireless communication system: it is a core component of the next generation wireless systems, e.g. WiMAX, 3GPP LTE and other OFDM-based communication schemes. Moreover, spatial division multiple access (SDMA) is one of the widely used techniques for sharing the wireless medium between different mobile devices. Sphere detection is a prominent method of simplifying the detection complexity in both SDM and SDMA systems while maintaining BER performance comparable with the optimum maximum-likelihood (ML) detection. On the other hand, with different standards supporting different system parameters, it is crucial for both base station and handset devices to be configurable and seamlessly switch between different modes without the need for separate dedicated hardware units. This challenge emphasizes the need for SDR designs that target the handset devices. In this paper, we propose the architecture and FPGA realization of a configurable sort-free sphere detector, Flex-Sphere, that supports 4, 16, 64-QAM modulations as well as a combination of 2, 3 and 4 antenna/user configuration for handsets. The detector provides a data rate of up to 857.1 Mbps that fits well within the requirements of any of the next generation wireless standards. The algorithmic optimizations employed to produce an FPGA friendly realization are discussed.
A High Throughput Configurable SDR Detector for Multi-user MIMO Wireless Systems
(Springer, 2009-04-08) Amiri, Kiarash; Cavallaro, Joseph R.; Dick, Chris; Rao, Raghu Mysore; CMC
Spatial division multiplexing (SDM) in MIMO technology significantly increases the spectral efficiency, and hence capacity, of a wireless communication system: it is a core component of the next generation wireless systems, e.g. WiMAX, 3GPP LTE and other OFDM-based communication schemes. Moreover, spatial division multiple access (SDMA) is one of the widely used techniques for sharing the wireless medium between different mobile devices. Sphere detection is a prominent method of simplifying the detection complexity in both SDM and SDMA systems while maintaining BER performance comparable with the optimum maximum-likelihood (ML) detection. On the other hand, with different standards supporting different system parameters, it is crucial for both base station and handset devices to be configurable and seamlessly switch between different modes without the need for separate dedicated hardware units. This challenge emphasizes the need for SDR designs that target the handset devices. In this paper, we propose the architecture and FPGA realization of a configurable sort-free sphere detector, Flex-Sphere, that supports 4, 16, 64-QAM modulations as well as a combination of 2, 3 and 4 antenna/user configuration for handsets. The detector provides a data rate of up to 857.1 Mbps that fits well within the requirements of any of the next generation wireless standards. The algorithmic optimizations employed to produce an FPGA friendly realization are discussed.
High-Level Design Tools for Complex DSP Applications
(Elsevier, Waltham, MA, 2012-07-12) Sun, Yang; Amiri, Kiarash; Wang, Guohui; Yin, Bei; Cavallaro, Joseph R.; Ly, Tai; Center for Multimedia Communication
High-level synthesis design methodology - High level synthesis (HLS) [1], also known as behavioral synthesis and algorithmic synthesis, is a design process in which a high level, functional description of a design is automatically compiled into a RTL implementation that meets certain user specified design constraints. The HLS design description is ‘high level’ compared to RTL in two aspects: design abstraction, and specification language.
Novel Sort-Free Detector with Modified Real-Valued Decomposition (M-RVD) Ordering in MIMO Systems
(IEEE, 2008-11-01) Amiri, Kiarash; Dick, Chris; Rao, Raghu; Cavallaro, Joseph R.; Center for Multimedia Communication
K-best MIMO detection technique is the prominent method of simplifying the detection complexity in MIMO systems while maintaining BER performance comparable with the optimum maximum-likelihood (ML) detection technique. However, sorting the candidate nodes in the tree search of the conventional K-best detection can take a significant number of cycles which would reduce the achievable data rate of the detector. In order to reduce this delay, and keep high performance at the same time, we propose using a novel sort-free based MIMO detector which avoids the demanding sorting step. Moreover, this detector utilizes a novel modified real-valued decomposition (M-RVD) ordering that, when compared to the conventional real valued decomposition scheme, can improve the BER performance at no extra computational cost. We show that our proposed detector can outperform the conventional K-best detector with a smaller combination of computation and latency requirements.
Partial Detection for Multiple Antenna Cooperation
(IEEE, 2009-03-01) Amiri, Kiarash; Cavallaro, Joseph R.; Center for Multimedia Communication
Multi-antenna relays can significantly increase the speed and reliability of wireless systems. However, because of the complexity of MIMO detection, there is considerable overhead in implementing a MIMO relay if the conventional detect-and-forward strategy is used. To address this challenge, we propose a novel cooperative partial detection (CPO) strategy that partitions the detection task between the relay and the destination. CPO leverages the structure of the tree-based c1ose-toML MIMO detectors, and modifies the tree traversal so that instead of visiting all the levels of the tree, only a subset of the levels, thus a subset of the transmitted streams, are visited. This novel approach reduces the tree levels, i.e. dimensions, in both the relay and the destination. Moreover, CPO provides a flexible method to control the level of partitioning between the relay and the destination, and thus, adjust the detection computational complexity in the relay and the destination. Monte-Carlo simulation results show that, under equal transmit power and complexity constraint in the destination, CPO achieves a better BER performance compared to the non-relay scenario, with limited computational overhead in the relay.
Physical Layer Algorithm and Hardware Verification of MIMO Relays Using Cooperative Partial Detection
(IEEE, 2010-03-01) Amiri, Kiarash; Wu, Michael; Duarte, Melissa; Cavallaro, Joseph R.; Center for Multimedia Communication
Cooperative communication with multi-antenna relays can significantly increase the reliability and speed. However, cooperative MIMO detection would impose considerable complexity overhead onto the relay if a full detect-and-forward (FDF) strategy is employed. In order to address this challenge, we propose a novel cooperative partial detection (CPD) strategy to partition the detection task between the relay and the destination. CPD utilizes the inherent structure of the tree-based sphere detectors, and modifies the tree traversal so that instead of visiting all the levels of the tree, only a subset of the levels, thus a subset of the transmitted streams, are visited. Based on this methodology, the destination combines the source signal and the partial relay signal to perform the detection step. We show, in both simulation and hardware verification on the WARP platform, that using the CPD approach, the relay can avoid the considerable overhead of MIMO detection while helping the source-destination link to improve its performance.
Reconfigurable Multi-Standard Uplink MIMO Receiver with Partial Interference Cancellation
(IEEE, 2012-06-01) Yin, Bei; Amiri, Kiarash; Cavallaro, Joseph R.; Guo, Yuanbin; Center for Multimedia Communication
As HSPA/HSPA+ and LTE/LTE-A evolve in parallel, the reconfigurability of a receiver to support multiple standards has become more and more important, especially for small cells. In this paper, we first suggest a reconfigurable multistandard uplink MIMO receiver based on a frequency domain equalizer. Then, to improve the performance, we propose two low-complexity partial iterative interference cancellation (IC) schemes to deal with the residual inter-chip and inter-antenna interference in HSPA/HSPA+ and the residual inter-symbol and inter-antenna interference in LTE/LTE-A. Compared with a receiver consisting of separate HSPA/HSPA+ and LTE/LTE-A uplink receivers, this reconfigurable receiver can save up to 66.9% complexity. Moreover, the two partial IC schemes have negligible performance loss compared with full IC scheme. They can achieve 2 dB gains in both standards with only 15.2% additional complexity to no IC scheme.
Reduced Complexity Soft MMSE MIMO Detector Architecture
(Wireless Innovation Forum, Inc., 2010-12-01) Amiri, Kiarash; Dick, Chris; Rao, Raghu; Cavallaro, Joseph R.; Center for Multimedia Communication
Computing the soft LLR values in MMSE receivers of MIMO systems requires a very large complexity. In this paper, we propose a reduced complexity soft MMSE detector for MIMO systems. We use different complexity reductions techniques and propose an architecture based on the new reduced-complexity method. We also compare the complexity and show more than 2x complexity reduction using this method. We present complexity/performance tradeoffs to demonstrate the efficacy of our techniques. More importantly, these techniques give the receivers the flexibility to choose how accurately they perform the detection based on the available resources.
WARP, a Modular Testbed for Configurable Wireless Network Research at Rice
(IEEE, 2007-03-01) Amiri, Kiarash; Sun, Yang; Murphy, Patrick; Hunter, Chris; Cavallaro, Joseph R.; Sabharwal, Ashutosh; Center for Multimedia Communication
Wireless Open-Access Research Platform (WARP), developed at CMC lab, Rice University, provides a scalable and configurable platform for wireless network research. Its programmability and flexibility makes it easy to prototype and implement various physical and network layer protocols and standards. In order to share algorithms and implementations developed at different research centers, an online open-access repository is used so that wireless network researchers can collaborate to initiate multi-disciplinary system designs.
WARP, a UnifiedWireless Network Testbed for Education and Research
(IEEE, 2007-06-01) Amiri, Kiarash; Sun, Yang; Murphy, Patrick; Hunter, Chris; Cavallaro, Joseph R.; Sabharwal, Ashutosh; Center for Multimedia Communication
In this paper, we introduce the Wireless Open-Access Research Platform (WARP) developed at CMC lab, Rice University. WARP provides a scalable and configurable platform mainly designed to prototype wireless communication algorithms for educational and research oriented applications. Its programmability and flexibility makes it easy to implement various physical and network layer protocols and standards. Moreover, the online open-access WARP repository is used to document and share different wireless architectures and cross-layer designs developed at educational and research centers. This repository is a fast and easy solution for students and researchers with a wide range of backgrounds in hardware implementation and algorithm development to collaborate and initiate multi-disciplinary system designs.

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