A fundamental problem that confronts peer-to-peer applications is to efficiently locate the node that stores a particular data item. This paper presents Chord, a distributed lookup protocol that addresses this problem. Chord provides support for just one operation: given a key, it maps the key onto a node. Data location can be easily implemented on top of Chord by associating a key with each data item, and storing the key/data item pair at the node to which the key maps. Chord adapts efficiently as nodes join and leave the system, and can answer queries even if the system is continuously changing. Results from theoretical analysis, simulations, and experiments show that Chord is scalable, with communication cost and the state maintained by each node scaling logarithmically with the number of Chord nodes.

Chord: A scalable peer-to-peer lookup service for internet applications

This paper presents the design and evaluation of Pastry, a scalable, distributed object location and routing substrate for wide-area peer-to-peer ap- plications. Pastry performs application-level routing and object location in a po- tentially very large overlay network of nodes connected via the Internet. It can be used to support a variety of peer-to-peer applications, including global data storage, data sharing, group communication and naming. Each node in the Pastry network has a unique identifier (nodeId). When presented with a message and a key, a Pastry node efficiently routes the message to the node with a nodeId that is numerically closest to the key, among all currently live Pastry nodes. Each Pastry node keeps track of its immediate neighbors in the nodeId space, and notifies applications of new node arrivals, node failures and recoveries. Pastry takes into account network locality; it seeks to minimize the distance messages travel, according to a to scalar proximity metric like the number of IP routing hops. Pastry is completely decentralized, scalable, and self-organizing; it automatically adapts to the arrival, departure and failure of nodes. Experimental results obtained with a prototype implementation on an emulated network of up to 100,000 nodes confirm Pastry's scalability and efficiency, its ability to self-organize and adapt to node failures, and its good network locality properties.

/pdf/pastry-scalable-decentralized-object-location-and-routing-1u2equbbbp.pdf

Pastry: Scalable, Decentralized Object Location, and Routing for Large-Scale Peer-to-Peer Systems

Hash tables - which map "keys" onto "values" - are an essential building block in modern software systems. We believe a similar functionality would be equally valuable to large distributed systems. In this paper, we introduce the concept of a Content-Addressable Network (CAN) as a distributed infrastructure that provides hash table-like functionality on Internet-like scales. The CAN is scalable, fault-tolerant and completely self-organizing, and we demonstrate its scalability, robustness and low-latency properties through simulation.

https://www.cs.sjtu.edu.cn/~gchen/course/acn/Reading/CAN.pdf

A scalable content-addressable network

A review of the geologic history of the Himalayan-Tibetan orogen suggests that at least 1400 km of north-south shortening has been absorbed by the orogen since the onset of the Indo-Asian collision at about 70 Ma. Significant crustal shortening, which leads to eventual construction of the Cenozoic Tibetan plateau, began more or less synchronously in the Eocene (50–40 Ma) in the Tethyan Himalaya in the south, and in the Kunlun Shan and the Qilian Shan some 1000–1400 km in the north. The Paleozoic and Mesozoic tectonic histories in the Himalayan-Tibetan orogen exerted a strong control over the Cenozoic strain history and strain distribution. The presence of widespread Triassic flysch complex in the Songpan-Ganzi-Hoh Xil and the Qiangtang terranes can be spatially correlated with Cenozoic volcanism and thrusting in central Tibet. The marked difference in seismic properties of the crust and the upper mantle between southern and central Tibet is a manifestation of both Mesozoic and Cenozoic tectonics. The form...

Geologic Evolution of the Himalayan-Tibetan Orogen

Reliability at massive scale is one of the biggest challenges we face at Amazon.com, one of the largest e-commerce operations in the world; even the slightest outage has significant financial consequences and impacts customer trust. The Amazon.com platform, which provides services for many web sites worldwide, is implemented on top of an infrastructure of tens of thousands of servers and network components located in many datacenters around the world. At this scale, small and large components fail continuously and the way persistent state is managed in the face of these failures drives the reliability and scalability of the software systems.This paper presents the design and implementation of Dynamo, a highly available key-value storage system that some of Amazon's core services use to provide an "always-on" experience. To achieve this level of availability, Dynamo sacrifices consistency under certain failure scenarios. It makes extensive use of object versioning and application-assisted conflict resolution in a manner that provides a novel interface for developers to use.

/pdf/dynamo-amazon-s-highly-available-key-value-store-2ozfk43ou4.pdf

Dynamo: amazon's highly available key-value store

The embodiment of the invention relates to the technical field of communication and discloses a base-station control method, device and system, wherein the base-station control method includes: determining whether any carrier wave of any section of a macro base station meets a first turn-off condition, if yes, then acquiring information of each micro base station which has an overlapping coverage relation with the carrier wave of the macro base station; determining whether the micro base stations meet a second turn-off condition according to the information of each micro base station, and if yes, notifying the micro base stations which meet the second turn-off condition to execute turn-off operation. Through the base-station control method, device and system, energy consumption of a whole network is reduced.

Base-station control method, device and system

Data transmission method

The invention provides an unlicensed transmission method and device, relates to the technical field of communication, and is used for avoiding the problem of mutual interference between DMRS and datain the uplink unlicensed transmission process. The method comprises the steps that a terminal receives time domain resource configuration and DMRS configuration of unlicensed transmission, the time domain resource configuration of unlicensed transmission is used for determining the configured time domain resource, and the DMRS configuration is used for determining the positions of a plurality of OFDM symbols used for bearing DMRS in the configured time domain resource; the terminal determines a time domain resource of the PUSCH according to the time domain resource configuration and DMRS configuration of unlicensed transmission, with the time domain resource of the PUSCH being a non-zero subset of the configured time domain resource, and the starting symbol of the time domain resource of the PUSCH being one OFDM symbol of a plurality of OFDM symbols for bearing DMRS in the configured time domain resource; and the terminal sends the PUSCH on the time domain resource of the PUSCH.

Unlicensed transmission method and device

Research on Crop Irrigation Schedules Under Deficit Irrigation—A Meta-analysis

In accordance to embodiments, methods, devices, and systems for determining initial transmissions in grant-free transmissions are disclosed. A UE receives a resource configuration for grant-free (GF) transmissions. The resource configuration comprises a periodicity parameter (P), a repetition number (K), and a sequence of redundancy version (RV) numbers corresponding to one or more RV types. The periodicity parameter defines a period having K transmission occasions (TOs), and each of the KTOs is associated with one RV number in the sequence of RV numbers. The UE performs an initial GF transmission of data in a TO of the K TOs in the period defined by the periodicity parameter. The TO is associated with an RV number corresponding to RV0.

Yan Chen

Papers

Base-station control method, device and system

Data transmission method

Unlicensed transmission method and device

Research on Crop Irrigation Schedules Under Deficit Irrigation—A Meta-analysis

Methods, devices and systems for initial grant-free transmission determination