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What's the difference between an industrial wireless... Terminal devices have different data access interfaces Wireless router provides one network interface of data access, terminal equipment need only with the network IP address as a gateway to the IP address of the terminal device must use specified or specify the IP address in the address period, and specify the IP address...

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VRRP function on industrial grade router VRRP is a selection protocol that dynamically assigns the responsibilities of a virtual router to one of the VRRP routers on the LAN. The VRRP router, which controls the virtual router's IP address, is called the master router and it forwards packets to these virtual IP addresses. Once the primary router is unavailable,...

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工业网关的功能组成 网关(Gateway)又称网间连接器、协议转换器。网关在网络层以上实现网络互连,是最复杂的网络互连设备,仅用于两个高层协议不同的网络互连。网关既可以用于广域网互连,也可以用于局域网互连。 网关是一种充当转换重任的计算机系统或设备。使用在不同的通信协议、数据格式或语言,甚至体系结构完全不同的两种系统之间,网关是一个翻译器。与网桥只是简单地传达信息不同,网关对收到的信息要重新打包,以适应目的系统的需求。 4G工业网关的基本功能是连接两个异构网络,这在工业物联网场景中尤为常见,因为传感器网络经常使用完全不同于普通网络层(长距离传输网络)的电信号和协议。   4G工业网关功能组成   网络层信号接口 它主要承担网络层信号的对接任务。与感知层信号接口相比,网络层信号接口一般简单得多,因为通常整个系统只需要一个标准的长途网络及其协议,因此相应的硬件接口和数据收发软件相对简单。然而,这并不是说它只能支持一种类型。在实际应用中,工业网关的制造商通常被设计为支持多种形式的长途网络,以实现产品的通用性。特定的表单可以是同时配置多个接口的方式,也可以以配置插件卡的形式设计产品,以便用户可以在离开工厂时选择要配置的不同配置。   传感层信号接口 主要负责传感器网络中各设备信号的对接工作。该模块包括用于不同电信号对接的硬件接口,以及相应的数据采集和指令发送软件。为了解决感知层的复杂性,工业网关厂商将根据各自的目标应用领域,装备感知层信号接口的硬件接口和协议组合。   就地数据库 在一些用于复杂数据处理流程或其他就地业务逻辑处理的场景中,处理后的数据还需要存储在网关本地数据库中。由于工业网关一般属于嵌入式计算设备,所以这类数据库也一般采用嵌入式数据库。嵌入式数据库功能简单,具有内存缓冲,提高了访问速度。   就地的业务逻辑 它主要处理与网关相关的传感器网络部分所连接的设备、传感器和执行器相关的本地系统的业务逻辑。不同网关的本地业务逻辑模块的丰富性和复杂性差异很大。如果工业网关中没有这样的功能模块,它通常被称为数据传输网关、协议转换器或通信管理器。有关就地业务逻辑的详细描述,请参见边缘计算。   数据处理 设备端数据处理主要解决数据不匹配问题。也就是说,服务器所需数据的范围、频率、完整性等等。数据处理的目的是对输入接口中的数据进行排序,将其转换为适合输出的数据形式,并将其推送到输出接口。输入端和输出端可以由设备端或服务器端播放,因此数据流是双向的,并且根据数据类型的不同而不同。   其他功能 除了上面的主要模块之外,网关还常常配置它的功能用户界面,要么使用按钮、命令行(通过Telnet或串口),要么使用图形界面(例如内置的WEB服务器,甚至面板)。如果网关具有适当的业务逻辑,它可能还需要工具来加载脚本文件、配置文件,等等,这些都是本地业务逻辑所需要的。 作为一种远程设备,4G工业网关的自我维护也非常重要。一般情况下,需要利用自己与服务器连接的优势,从服务器上自动下载自己的软件更新包并完成更新。还应通过远程登录完成部分设置和配置工作,以降低外派人员的现场维护成本,提高对用户需求的响应速度。

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Functional composition of 4G industrial gateway The basic function of the 4G industrial gateway is to connect the two heterogeneous networks, which is particularly common in the industrial Internet of things scenario, because the sensor network often USES completely different electrical signals and protocols from the common network layer (long distance transmission network).   4G...

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网关和路由器之间的区别 网关是充当转换代理的计算机系统或设备。网关是两个系统之间的转换器,它们使用不同的通信协议,数据格式或语言,甚至是完全不同的体系结构。与简单传达信息的网桥不同,网关重新打包它们收到的信息以满足预期系统的需要。那么网关和路由器之间的区别是什么? 网关和路由器之间的区别如下: 路由器的作用是连接不同的网络并传输信息。根据用途,可分为:接入,企业级,骨干级,太比特,多WAN和3G无线等。 网关 网关可以是路由器,交换机或PC。对于同一网段内的通信,不必涉及网关。只有当主机和非本地网段设备通信时,才需要将所有数据包发送到网关设备,然后通过网关设备转发或路由它们。 路由器是一个网络层系统。一般来说,市场上的路由器分为两类,一类是单协议路由器,另一类是多协议路由器。路由器可以转换数据格式,成为与协议不同的网络互连的必要设备。 网关与路由的关系可以表示为:网关是网络连接的基础,路由是网络连接的桥梁。 路由器使用静态或动态路由来确定网络之间的最短路径。静态路由需要管理员手动设置,动态路由USES协议以动态发现网络之间的路径并确定最短路径。通常,静态路由用于小型网络,动态路由用于大型复杂网络。 现在,路由器集成了网关功能,因此路由器也具有网关功能。 网关和路由器之间的区别 从网关和路由器的定义来看,如果只连接两个网络,则只需要一个网关。 假设只有两个网络:网络A和网络B. 为了使网络A和网络B能够通信,只使用网关连接两个网络,因为只有两个网络,并且不需要确定网络之间的最短路径。 如果需要连接多个网络,为了确保网络的可靠性,需要将网络结构设计为完整网络或部分网络。通过这种方式,网络之间的通信需要两个设备,网关和路由器。由于当前路由器集成了网关的功能,因此只能使用一个设备路由器。

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New 4G M2M Router

Category : 产品文章, 伊林思产品FAQ

E-lins H685t is a new 4G/LTE router with wifi,built on components that meet industrial requirements , with a low price but with unlimited features.The router can be mounted on a DIN rail with a separate bracket . It is powered by 12 VDC and has a rich support for different LTE bands, it can communicate via LTE at 800, 900 , 1800, 1900 , 2100 and 2600 MHz. Is not 4G on the spot then transferred router to 3G and then 2G. As for 4G so the router has a theoretical maximum speed of 100 Mbit / s download speed and 50 Mbit / s upload speed , but also for 3G offers the great performance by up to 42 Mbit / s download speed and 5.7 Mbit / s upload speed.

In order to reach these speeds , use of dual external antennas , three antennas included in the package , two for 4G and one for wifi. Because the router has an antenna plug of SMA type antenna can be replaced with more powerful antennas , which can be an advantage in such fixed installations.

Talking about Long Distance Wi-Fi

Category : 其他, 技术相关

Introduction
Since the development of the IEEE 802.11 radio standard (marketed under the Wi-Fi brand name), the technology has become markedly less expensive and achieved higher bit rates. Long range Wi-Fi especially in the 2.4 GHz band (as the shorter range higher bit rate 5.8 GHz bands become popular alternatives to wired LAN connections) have proliferated with specialist devices. While Wi-Fi hotspots are ubiquitous in urban areas, some rural areas use more powerful longer range transceivers as alternatives to cell (GSM, CDMA) or fixed wireless (Motorola Canopy and other 900 MHz) applications. The main drawbacks of 2.4 GHz vs. these lower-frequency options are:

poor signal penetration – 2.4 GHz connections are effectively limited to line of sight or soft obstacles
far less range – GSM or CDMA cell phones can connect reliably at > 16 km (9.9 mi) distances. The range of GSM, imposed by the parameters of Time division multiple access, is set at 35 km.
few service providers commercially support long distance Wi-Fi connections
Despite a lack of commercial service providers, applications for long range Wi-Fi have cropped up around the world. It has also been used in experimental trials in the developing world to link communities separated by difficult geography with few or no other connectivity options. Some benefits of using long range Wi-Fi for these applications include:

unlicensed spectrum – avoiding negotiations with incumbent telecom providers, governments or others
smaller, simpler, cheaper antennas – 2.4 GHz antennas are less than half the size of comparable strength 900 MHz antennas and require less lightning protection
availability of proven free software like OpenWrt, DD-WRT, Tomato that works even on old routers (WRT54G for instance) and makes modes like WDS, OLSR, etc., available to anyone. Including revenue sharing models for hotspots.
Nonprofit organizations operating widespread installations, such as forest services, also make extensive use of long-range Wi-Fi to augment or replace older communications technologies such as shortwave or microwave transceivers in licensed bands.

Applications
Business
Provide coverage to a large office or business complex or campus.
Establish point-to-point link between large skyscrapers or other office buildings.
Bring Internet to remote construction sites or research labs.
Simplify networking technologies by coalescing around a small number of Internet related widely used technologies, limiting or eliminating legacy technologies such as shortwave radio so these can be dedicated to uses where they actually are needed.
Bring Internet to a home if regular cable/DSL cannot be hooked up at the location.
Bring Internet to a vacation home or cottage on a remote mountain or on a lake.
Bring Internet to a yacht or large seafaring vessel.
Share a neighborhood Wi-Fi network.
Nonprofit and Government
Connect widespread physical guard posts, e.g. for foresters, that guard a physical area, without any new wiring
In tourist regions, fill in cell dead zones with Wi-Fi coverage, and ensure connectivity for local tourist trade operators
Reduce costs of dedicated network infrastructure and improve security by applying modern encryption and authentication.
Military
Connect critical opinion leaders, infrastructure such as schools and police stations, in a network local authorities can maintain
Build resilient infrastructure with cheaper equipment that an impoverished war-torn region can afford, i.e. using commercial grade, rather than military-class network technology, which may then be left with the developed-world military
Reduce costs and simplify/protect supply chains by using cheaper simpler equipment that draws less fuel and battery power; In general these are high priorities for commercial technologies like Wi-Fi especially as they are used in mobile devices.
Scientific research
See also: Wireless sensor network
A long range seismic sensor network was used during the Andean Seismic Project in Peru. A multi-hop span with a total length of 320 kilometres was crossed with some segments around 30 to 50 kilometers. The goal was to connect to outlying stations to UCLA in order to receive seismic data in real time.
Large-scale deployments
The Technology and Infrastructure for Emerging Regions (TIER) project at University of California at Berkeley in collaboration with Intel, uses a modified Wi-Fi setup to create long-distance point-to-point links for several of its projects in the developing world. This technique, dubbed Wi-Fi over Long Distance (WiLD), is used to connect the Aravind Eye Hospital with several outlying clinics in Tamil Nadu state, India. Distances range from five to over fifteen kilometres (3–10 miles) with stations placed in line of sight of each other. These links allow specialists at the hospital to communicate with nurses and patients at the clinics through video conferencing. If the patient needs further examination or care, a hospital appointment can then be scheduled. Another network in Ghana links the University of Ghana, Legon campus to its remote campuses at the Korle bu Medical School and the City campus; a further extension will feature links up to 80 km (50 mi) apart.

The Tegola project of the University of Edinburgh is developing new technologies to bring high-speed, affordable broadband to rural areas beyond the reach of fibre. A 5-link ring connects Knoydart, the N. shore of Loch Hourne, and a remote community at Kilbeg to backhaul from the Gaelic College on Skye. All links pass over tidal waters; they range in length from 2.5 km to 19 km.

Increasing range in other ways
Further information: 802.11 non-standard equipment and Radio propagation
Specialized Wi-Fi channels
For more details on this topic, see List of WLAN channels.
In most standard Wi-Fi routers, the three standards, a, b and g, are enough. But in long-range Wi-Fi, special technologies are used to get the most out of a Wi-Fi connection. The 802.11-2007 standard adds 10 MHz and 5 MHz OFDM modes to the 802.11a standard, and extend the time of cyclic prefix protection from 0.8 µs to 3.2 µs, quadrupling the multipath distortion protection. Some commonly available 802.11a/g chipsets support the OFDM ‘half-clocking’ and ‘quarter-clocking’ that is in the 2007 standard, and 4.9 GHz and 5.0 GHz products are available with 10 MHz and 5 MHz channel bandwidths. It is likely that some 802.11n D.20 chipsets will also support ‘half-clocking’ for use in 10 MHz channel bandwidths, and at double the range of the 802.11n standard.

802.11n and MIMO
Preliminary 802.11n working became available in many routers in 2008. This technology can use multiple antennas to target one or more sources to increase speed. This is known as MIMO, Multiple Input Multiple Output. In tests, the speed increase was said to only occur over short distances rather than the long range needed for most point to point setups. On the other hand, using dual antennas with orthogonal polarities along with a 2×2 MIMO chipset effectively enable two independent carrier signals to be sent and received along the same long distance path.

Power increase or receiver sensitivity boosting

A rooftop 1 watt Wi-Fi amp, feeding a simple vertical antenna on the left.
Another way of adding range uses a power amplifier. Commonly known as “range extender amplifiers” these small devices usually supply around ½ watt of power to the antenna. Such amplifiers may give more than five times the range to an existing network. Every 6 dB gain doubles range. The alternative techniques of selecting a more sensitive WLAN adapter and more directive antenna should also be considered.

Higher gain antennas and adapter placement
Specially shaped directional antennas can increase the range of a Wi-Fi transmission without a drastic increase in transmission power. High gain antenna may be of many designs, but all allow transmitting a narrow signal beam over greater distance than a non-directional antenna, often nulling out nearby interference sources. A popular low-cost home made approach increases WiFi ranges by just placing standard USB WLAN hardware at the focal point of modified parabolic cookware. Such “WokFi” techniques typically yield gains more than 10 dB over the bare system; enough for line of sight (LOS) ranges of several kilometers and improvements in marginal locations. Although often low power, cheap USB WLAN adapters suit site auditing and location of local signal “sweet spots”. As USB leads incur none of the losses normally associated with costly microwave coax and SMA fittings, just extending a USB adapter (or AP, etc.) up to a window, or away from shielding metal work and vegetation, may dramatically improve the link.

Protocol hacking
The standard IEEE 802.11 protocol implementations can be modified to make them more suitable for long distance, point-to-point usage, at the risk of breaking interoperability with other Wi-Fi devices and suffering interference from transmitters located near the antenna. These approaches are used by the TIER project.

In addition to power levels, it is also important to know how the 802.11 protocol acknowledges each received frame. If the acknowledgement is not received, the frame is re-transmitted. By default, the maximum distance between transmitter and receiver is 1.6 km (1 mi). On longer distances the delay will force retransmissions. On standard firmware for some professional equipment such as the Cisco Aironet 1200, this parameter can be tuned for optimal throughput. OpenWrt, DD-WRT and all derivatives of it also enable such tweaking. In general, open source software is vastly superior to commercial firmware for all purposes involving protocol hacking, as the philosophy is to expose all radio chipset capabilities and let the user modify them. This strategy has been especially effective with low end routers such as the WRT54G which had excellent hardware features the commercial firmware did not support. As of 2011, many vendors still supported only a subset of chipset features that open source firmware unlocked, and most vendors actively encourage the use of open source firmware for protocol hacking, in part to avoid the difficulty of trying to support commercial firmware users attempting this.

Packet fragmentation can also be used to improve throughput in noisy/congested conditions. Although packet fragmentation is often thought of as something bad, and does indeed add a large overhead, reducing throughput, it is sometimes necessary. For example, in a congested situation, ping times of 30 byte packets can be excellent, while ping times of 1450 byte packets can be very poor with high packet loss. Dividing the packet in half, by setting the fragmentation threshold to 750, can vastly improve the throughput. The fragmentation threshold should be a division of the MTU, typically 1500, so should be 750, 500, 375, etc. However, excessive fragmentation can make the problem worse, since the increased overhead will increase congestion.

Obstacles to long-range Wi-Fi
Methods that increase the range of a Wi-Fi connection may also make it fragile and volatile, due to various factors including:

Landscape interference
Obstacles are among the biggest problems when setting up a long-range Wi-Fi. Trees and forests attenuate the microwave signal, and hills make it difficult to establish line-of-sight propagation.

In a city, buildings will impact integrity, speed and connectivity. Steel frames and Sheet metal in walls or roofs may partially or fully reflect radio signals, causing signal loss or multipath problems. Concrete or plaster walls absorb microwave signals significantly, reducing the total signal.

Tidal fading
When point-to-point wireless connections cross tidal estuaries or archipelagos, multipath interference from reflections over tidal water can be considerably destructive. The Tegola project uses a slow frequency-hopping technique to mitigate tidal fading.

2.4 GHz interference
Main article: Electromagnetic interference at 2.4 GHz
Microwave ovens in residences dominate the 2.4 GHz band and will cause “meal time perturbations” of the noise floor. There are many other sources of interference that aggregate into a formidable obstacle to enabling long range use in occupied areas. Residential wireless phones, baby monitors, wireless cameras, remote car starters, and Bluetooth products are all capable of transmitting in the 2.4 GHz band.

Due to the intended nature of the 2.4 GHz band, there are many users of this band, with potentially dozens of devices per household. By its very nature, “long range” connotes an antenna system which can see many of these devices, which when added together produce a very high noise floor, whereby no single signal is usable, but nonetheless are still received. The aim of a long range system is to produce a system which over-powers these signals and/or uses directional antennas to prevent the receiver “seeing” these devices, thereby reducing the noise floor.