Millimeter wave (mmWave) signals experience orders-of-magnitude more pathloss than the microwave signals currently used in most wireless applications and all cellular systems. MmWave systems must therefore leverage large antenna arrays, made possible by the decrease in wavelength, to combat pathloss with beamforming gain. Beamforming with multiple data streams, known as precoding, can be used to further improve mmWave spectral efficiency. Both beamforming and precoding are done digitally at baseband in traditional multi-antenna systems. The high cost and power consumption of mixed-signal devices in mmWave systems, however, make analog processing in the RF domain more attractive. This hardware limitation restricts the feasible set of precoders and combiners that can be applied by practical mmWave transceivers. In this paper, we consider transmit precoding and receiver combining in mmWave systems with large antenna arrays. We exploit the spatial structure of mmWave channels to formulate the precoding/combining problem as a sparse reconstruction problem. Using the principle of basis pursuit, we develop algorithms that accurately approximate optimal unconstrained precoders and combiners such that they can be implemented in low-cost RF hardware. We present numerical results on the performance of the proposed algorithms and show that they allow mmWave systems to approach their unconstrained performance limits, even when transceiver hardware constraints are considered.

Spatially Sparse Precoding in Millimeter Wave MIMO Systems

Driven by the visions of Internet of Things and 5G communications, recent years have seen a paradigm shift in mobile computing, from the centralized mobile cloud computing toward mobile edge computing (MEC). The main feature of MEC is to push mobile computing, network control and storage to the network edges (e.g., base stations and access points) so as to enable computation-intensive and latency-critical applications at the resource-limited mobile devices. MEC promises dramatic reduction in latency and mobile energy consumption, tackling the key challenges for materializing 5G vision. The promised gains of MEC have motivated extensive efforts in both academia and industry on developing the technology. A main thrust of MEC research is to seamlessly merge the two disciplines of wireless communications and mobile computing, resulting in a wide-range of new designs ranging from techniques for computation offloading to network architectures. This paper provides a comprehensive survey of the state-of-the-art MEC research with a focus on joint radio-and-computational resource management. We also discuss a set of issues, challenges, and future research directions for MEC research, including MEC system deployment, cache-enabled MEC, mobility management for MEC, green MEC, as well as privacy-aware MEC. Advancements in these directions will facilitate the transformation of MEC from theory to practice. Finally, we introduce recent standardization efforts on MEC as well as some typical MEC application scenarios.

A Survey on Mobile Edge Computing: The Communication Perspective

Millimeter-wave (mmW) frequencies between 30 and 300 GHz are a new frontier for cellular communication that offers the promise of orders of magnitude greater bandwidths combined with further gains via beamforming and spatial multiplexing from multielement antenna arrays. This paper surveys measurements and capacity studies to assess this technology with a focus on small cell deployments in urban environments. The conclusions are extremely encouraging; measurements in New York City at 28 and 73 GHz demonstrate that, even in an urban canyon environment, significant non-line-of-sight (NLOS) outdoor, street-level coverage is possible up to approximately 200 m from a potential low-power microcell or picocell base station. In addition, based on statistical channel models from these measurements, it is shown that mmW systems can offer more than an order of magnitude increase in capacity over current state-of-the-art 4G cellular networks at current cell densities. Cellular systems, however, will need to be significantly redesigned to fully achieve these gains. Specifically, the requirement of highly directional and adaptive transmissions, directional isolation between links, and significant possibilities of outage have strong implications on multiple access, channel structure, synchronization, and receiver design. To address these challenges, the paper discusses how various technologies including adaptive beamforming, multihop relaying, heterogeneous network architectures, and carrier aggregation can be leveraged in the mmW context.

Millimeter-Wave Cellular Wireless Networks: Potentials and Challenges

Driven by the visions of Internet of Things and 5G communications, recent years have seen a paradigm shift in mobile computing, from the centralized Mobile Cloud Computing towards Mobile Edge Computing (MEC). The main feature of MEC is to push mobile computing, network control and storage to the network edges (e.g., base stations and access points) so as to enable computation-intensive and latency-critical applications at the resource-limited mobile devices. MEC promises dramatic reduction in latency and mobile energy consumption, tackling the key challenges for materializing 5G vision. The promised gains of MEC have motivated extensive efforts in both academia and industry on developing the technology. A main thrust of MEC research is to seamlessly merge the two disciplines of wireless communications and mobile computing, resulting in a wide-range of new designs ranging from techniques for computation offloading to network architectures. This paper provides a comprehensive survey of the state-of-the-art MEC research with a focus on joint radio-and-computational resource management. We also present a research outlook consisting of a set of promising directions for MEC research, including MEC system deployment, cache-enabled MEC, mobility management for MEC, green MEC, as well as privacy-aware MEC. Advancements in these directions will facilitate the transformation of MEC from theory to practice. Finally, we introduce recent standardization efforts on MEC as well as some typical MEC application scenarios.

This article explores network densification as the key mechanism for wireless evolution over the next decade. Network densification includes densification over space (e.g, dense deployment of small cells) and frequency (utilizing larger portions of radio spectrum in diverse bands). Large-scale cost-effective spatial densification is facilitated by self-organizing networks and intercell interference management. Full benefits of network densification can be realized only if it is complemented by backhaul densification, and advanced receivers capable of interference cancellation.

Network densification: the dominant theme for wireless evolution into 5G

Methods and apparatus are presented for implementing an improved Control-Hold Mode that reduces the load of the reverse link and reduces the battery consumption of remote stations. While a remote station is in the improved Control-Hold Mode, the circuitry that monitors the forward packet data channels and the associated control channels are turned off. Since the forward packet data channels and their associated control channels are not monitored, the operations of the reverse channels can be gated off to predetermined duty cycles, or set on intermittent transmission modes, or shut down completely. Transitions from the Control-Hold Mode to the Active Mode can be initiated by the remote station or by a base station. When a transition is initiated by a remote station, the remote station transmits a signaling message to a serving base station (400) and then starts operating the feedback channels before actually receiving forward link signals (410).

An improved CONTROL - HOLD MODE in a remote station

Methods, systems, and devices for wireless communication are described. A wireless device may perform a listen before talk (LBT) procedure on a channel bandwidth using an energy detection (ED) threshold. The ED threshold being associated with a transmission bandwidth that is narrower than the channel bandwidth. The wireless device may also, responsive to a successful LBT procedure, transmit on the transmission bandwidth according to a frequency hopping pattern during a first channel occupancy time (COT). The frequency hopping pattern comprises a first resource allocation and a second resource allocation different from the first resource allocation.

Methods, apparatuses and systems for flexible channel access in shared spectrum

L'invention concerne un procede permettant de traiter des sous-paquets partages dans un systeme de communication. Ledit systeme, qui fournit des services vocaux et de donnees, permet a plusieurs stations abonnees de partager des donnees envoyees dans une unite d'un canal de trafic de reacheminement. Pour fournir l'information demandee par les stations abonnees afin d'etablir qu'une unite du canal de trafic de reacheminement est partagee, et pour decoder correctement les donnees, l'invention traite de differentes structures de canaux de controle. De plus, lesdites structures offrent une signalisation plus efficace de l'attribution de canaux de codes.

Procede de traitement de sous-paquets partages dans un systeme de communication

본 개시내용의 양상들은, 독립형/대역-내/가드-대역 배치에 대해 사용될 수 있는 협대역 동작을 위한 동기화 신호들의 설계를 위한 기법들을 제공한다. 기지국(BS)에 의해 수행될 수 있는 동작들에 대한 예시적인 방법이 제공된다. 예시적인 방법은 일반적으로, 하나 또는 그 초과의 서브프레임들 내의 제1 수의 심볼들에 걸친 제1 코드 시퀀스 및 제1 코드 시퀀스에 적용된 커버 코드를 이용하여 1차 동기화 신호(PSS)를 생성하는 단계, 하나 또는 그 초과의 서브프레임들 내의 제2 수의 심볼들에 걸친 제2 코드 시퀀스에 기반하여 2차 동기화 신호(SSS)를 생성하는 단계, 및 더 넓은 시스템 대역폭의 하나 또는 그 초과의 협대역 구역들 상에서 통신하는 제1 타입의 사용자 장비(UE)에 제1 및 제2 서브프레임들에서 PSS 및 SSS를 송신하는 단계를 포함한다.

협대역 동작을 위한 동기화 신호들의 설계

Methods and apparatuses are described in which an unlicensed spectrum is used for Long Term Evolution (LTE) communications. A first method includes performing clear channel assessment (CCA) to determine availability of an unlicensed spectrum, transmitting a request-to-send (RTS) signal to a set of user equipments (UEs) using the unlicensed spectrum when a determination is made that the unlicensed spectrum is available, and receiving, in the unlicensed spectrum, a common clear-to-send (CTS) signal and an individual CTS signal from one or more of the UEs in response to the RTS signal. A second method includes transmitting an RTS signal in an unlicensed spectrum or a V-RTS signal in a licensed spectrum, addressed to a set of UEs, and transmitting a CTS-to-self signal in the unlicensed spectrum along with the transmission of the V-RTS signal.

Yongbin Wei

Papers

An improved CONTROL - HOLD MODE in a remote station

Methods, apparatuses and systems for flexible channel access in shared spectrum

Procede de traitement de sous-paquets partages dans un systeme de communication

협대역 동작을 위한 동기화 신호들의 설계

Clear channel assessment for determining availability of non licensed spectrum for extending lte capacity