The millimeter (mm)-wave small-world wireless NoC (mSWNoC) is an enabling interconnect architecture to design high performance and low power multicore chips. As the mSWNoC has an overall irregular topology, it is extremely important to design suitable deadlock-free routing mechanisms for it. In this paper we quantify the latency, energy dissipation, and thermal profiles of mSWNoC architectures by incorporating irregular network routing strategies. We demonstrate that the latency, energy dissipation, and thermal profile are affected by the adopted routing methodologies. In presence of the benchmarks considered, the variation in latency and energy dissipation is small. However, the network hotspot temperature can vary considerably depending on the exact routing strategy and the characteristics of the benchmark.

The millimeter-wave small-world wireless network-on-chip (mSWNoC) is an enabling interconnect architecture to design high-performance and low-power multicore chips. As the mSWNoC has an overall irregular topology, it is essential to design and optimize suitable deadlock-free routing mechanisms for it. In this paper, we quantify the latency, energy dissipation, and thermal profiles of mSWNoC architectures by incorporating irregular network routing strategies. We demonstrate that the latency, energy dissipation, and thermal profile are affected by the adopted routing methodologies. The overall system performance and thermal profile are governed by the traffic-dependent optimization of the routing methods. Our aim is to establish the energy-thermal-performance trade-offs for the mSWNoC depending on the exact routing strategy and the characteristics of the benchmarks considered.

An ultra-wideband low phase variation variable gain amplifier (VGA) in 0.18/am BiCMOS process with high linearity is presented in this paper. The proposed VGA uses novel current steering gain blocks to achieve gain steps with low phase variation. The VGA has a measured gain range of 6.3-8.1 dB over the entire frequency range of 12-40 GHz and shows a phase variation of 0.2-0.78 °/dB. The VGA achieves a simulated input P1dB of 0 dBm at 26 GHz while consuming only 20.5 mW from 1.5 V power supply and occupies an active area of just 0.05 mm2. The VGA shows 7.6 times better Figure of Merit as compared to current state-of-the-art VGAs.

The Network-on-chip (NoC) is an enabling technology to integrate large numbers of embedded cores on a single die. The existing methods of implementing a NoC with planar metal interconnects are deficient due to high latency and significant power consumption arising out of multihop links used in data exchange. To address these problems, we propose design of a hierarchical small-world wireless NoC architecture where the multihop wire interconnects are replaced with high-bandwidth and single-hop long-range wireless shortcuts operating in the millimeter (mm)-wave frequency range. The proposed mm-wave wireless NoC (mWNoC) outperforms the corresponding conventional wireline counterpart in terms of achievable bandwidth and is significantly more energy efficient. The performance improvement is achieved through efficient data routing and optimum placement of wireless hubs. Multiple wireless shortcuts operating simultaneously further enhance the performance, and provide an energy-efficient solution for design of communication infrastructures for multicore chips.

Massive levels of integration are making modern multicore chips all pervasive in several domains. High performance, robustness, and energy-efficiency are crucial for the widespread adoption of such platforms. Networks-on-Chip (NoCs) have emerged as communication backbones to enable a high degree of integration in multicore Systems-on-Chip (SoCs). Despite their advantages, an important performance limitation in traditional NoCs arises from planar metal interconnect-based multihop links with high latency and power consumption. This limitation can be addressed by drawing inspiration from the evolution of natural complex networks, which offer great performance-cost trade-offs. Analogous with many natural complex systems, future multicore chips are expected to be hierarchical and heterogeneous in nature as well. In this article we undertake a detailed performance evaluation for hierarchical small-world NoC architectures where the long-range communications links are established through the millimeter-wave wireless communication channels. Through architecture-space exploration in conjunction with novel power-efficient on-chip wireless link design, we demonstrate that it is possible to improve performance of conventional NoC architectures significantly without incurring high area overhead.

This paper investigates joint power and subcarrier allocation issues for cellular OFDM-relay networks. Two novel decentralized schemes, namely semi-distributed method and distributed method based on multihop equilibrium are proposed, which aims to exploit the radio resource management (RRM) function for relay nodes (RNs) and decrease the amount of feedback information for RN-MS links. In decentralized mechanism, the base station (BS) distributes resources to direct users and RNs roughly first with partial CSI feedback or without CSI feedback for RN-MS link, and then the RNs allocate resources for each relay user by striking an efficient balance for the multihop transmission. Simulation results show that the proposed decentralized methods can achieve good performances in terms of average throughput and fraction of satisfied users, especially for relay users with multihop equilibrium mechanism. Moreover, the semi-distributed method is better choice for future LTE-A system due to excellent tradeoff between performance and complexity.

The cooperative cellular relaying network is expected to achieve the higher capacity and enlarge the coverage. In this paper, a novel cost-aware handover decision algorithm (CHDA) for cooperative cellular relaying networks is proposed. Two cost functions, namely the triggering and priority decision cost functions are exploited, which involves the signal transmission quality, the handover signaling cost, the handover latency and the interference estimation. Simulation results show that the signaling overhead and the handover delay decrease significantly by utilizing the CHDA scheme. It is also proved that the CHDA strategy is an efficient method to achieve the tradeoff among the QoS requirements and the system overheads, which can remarkably enhance the system performance.

In this paper, three centralized packet scheduling schemes with fairness-oriented feature are proposed for OFDMA multihop relaying networks, namely Greedy polling with novel starvation restrained (SR-GP), enhanced proportional fairness with SR (SR-EPF) and novel subcarrier pairing with hop balance (HB-SP) scheduling algorithms. SR-GP can bring better fairness than traditional throughput-oriented algorithms by sacrificing a little complexity. SR-EPF with novel priority function can guarantee the quality-of-service (QoS) of the cell edge users. HB-SP can enhance the system throughput significantly by utilizing the relay link efficiently with multihop equilibrium. Simulation results of the throughput's deviation of different users indicate that HB-SP and SR-EPF are applicable to realtime services and SR-GP is suitable for non-realtime services. Generally, HB-SP algorithm is a good achievement for both capacity enhancement and resource fairness.

This paper presents a distributed power allocation (PA) algorithm for the downlink of relay enhanced cellular networks. The PA problem is built into a non-cooperative game where a utility function is formulated and maximized. The utility function is comprised of two parts considering the interests of the node B and the relay node respectively, which facilitates the distributed PA on the nodes. Since the relay user's data rate is constrained by the minimum capacity of the two hops, a novel pricing function is developed to avoid allocating excess power to the second hop when the capacity is inferior in the first hop. The proposed game theoretic approach is compared with the uniform power allocation and the pure iterative water-filling method. Simulation results show that within a few steps of iteration, the proposed scheme can not only achieve the highest system capacity, but also efficiently balance the capacities of relay users in the two hops.

This paper investigates the antenna selection and relay node selection issues for multi-antenna relay system. Based on the channel statistics, optimal selection criteria for antenna and relay node are derived respectively, aiming to maximize the ergodic capacity. We first discuss the statistical antenna selection in the single-relay scenario, and then the joint antenna and node selection in the multi-relay scenario is exploited. Simulation results show that the proposed statistical optimal selection provides significant selection gains. For the antenna selection in high signal-to-noise ratio regime, the achieved capacity based on the derived statistical criterion is close to that based on the instantaneous channel knowledge. In addition, the system can benefit from a moderate increase of relay number with node selection, compared to the transmission with all nodes used.

Relaying transmission is a candidate way to combat wireless channel fading and enlarge the coverage, and efficient radio resource allocation is essential to provide quality-of-service (QoS) for wireless networks. In this paper, an adaptive multiuser radio resource allocation model is proposed for the downlink of OFDM-relay system, which exploits performance gain in both frequency domain and time domain. According to the different transmission modes, two QoS-oriented scheduling algorithms based on the feedback of the channel state information (CSI) of two hops are investigated. One is enhanced proportional fairness (EPF) algorithm, and the other is improved priority (IPRI) algorithm. Both of them can achieve high system throughput and better resource fairness due to the adaptive allocation, especially in the QoS-guarantee aspect for cell edgy users compared with conventional scheduling schemes. The priority strategy is a novel scheme, because of considering resource fairness with artificial starve (AS) state in IPRI, which yields higher spectral efficiency and achieve better data rate requirements for the users.