Prev

Next

E-Lins Industrial router applications Industrial-grade routers as Internet network layer communication equipment application in all walks of life, brought a lot of convenience for our industry. "E-Lins" introduce the application of industrial router scenario analysis.   1 The self-service terminal network   E-lins industrial router networking...

更多文章

Classification of 4G industrial routers There are many types of 4G industrial routers, which can be divided into different categories from different perspectives. Different types of 4G industrial routers can be used in different environments. The following sections classify the 4G industrial routers from different perspectives. According to the performance From...

更多文章

Dual SIM Router vs. Dual Radio Router Projects are looking to save their enterprises time and money ask us this very often: “When would I need to use dual SIMs, and in what situations should I consider dual radio dual sim router?” In order to make this clear, let’s take a quick look at the dual SIM and dual SIM dual radio module functionality. Dual...

更多文章

工业路由器NBMA网络转化为点到点的链路 当我们使用点到点子接口将NBMA网络转化为点到点的链路时,整个NBMA网络将产生过多的PVC部分互联或全互联的网状结构,但这将产生一定的负面影响,会使网络中产生大量的LSP泛洪流量。我们都知道,运行IS-IS的工业路由器当接收到一个LSP报文后,会将此LSP从除接收接口以外的所有启用了IS-IS协议的接口泛洪出去,以使网络中的其他工业路由器都可以接收到此LSP。但是这种泛洪机制对于存在大量部分互联或全互联的网络将产生过多冗余的LSP扩散。 所谓全互联或全网状网络拓扑,是指所有工业路由器都与其他工业级无线路由器向连接(通常是点到点子接口)。在这样的一个网络中,当一台路由器从某接口收到邻居泛洪过来的LSP后,由于它并不知道这个LSP是否已经被其他邻居工业4g路由器收到,所以会再从其他接口泛洪出去,即使其他工业级4g路由器的链路状态数据库中已经存在这个LSP。如果网络中有n个全网路由器的话,那么网络中的每台工业级LTE路由器都会扩散n-2条冗余的LSP,这样总共被泛洪的多余的LSP将为(n-1)x(n-2),条而这些LSP的扩散是多余。如果每台工业全网通路由器都刷新一条LSP的话,那么这个数量还将会成倍数的增长,导致了大量带宽资源的浪费。 为了解这种在全互联或高度互联的网络中出现的LSP泛洪的冗余现象,IS-IS提供了一种解决方案——IS-IS全通组,也称作Mesh组。IS-IS全通组在RFC2973中进行了定义。所谓全通组,就是假设所有工业3G路由器之间都是完全互联的,每个工业级全网通路由器都会直接收到其他全网通工业级路由器泛洪的原始的LSP的拷贝。 可以将全网工业路由器的接口加入到某个全通组中,一个全网通工业路由器上可以存在多个全通组,全通组内接口之间的LSP泛洪是受限制的,全通组之间的LSP泛洪是正常的操作,未加入全通组的工业级3G路由器接口与全通组之间也是正常的LSP泛洪操作。全网通路由器 ...

更多文章

工业路由器使用CSNP来保证链路状态数据库的完整性 在广播网络中,工业路由器使用CSNP来保证链路状态数据库的完整性,并且只有DIS才会发送工业全网通路由器CSNP报文,DIS发送CSNP报文的间隔为10s。CSNP报文中描述了DIS的链路状态数据库中所有工业级3G路由器LSP的摘要信息。当其他工业级路由器收到DIS发送的CSNP后,会使用CSNP中的LSP摘要信息与与本地的链路状态数据库中的LSP进行比较,进行比较的目的是确定本地链路状态数据库中的信息是否已经同步和完整。如果工业级4g路由器发现本地数据库中缺少某个LSP条目,那么它将使用PSNP向DIS请求这个缺少的LSP条目。这个PSNP报文中包含就是请求的LSP条目的摘要信息。当DIS收到其他全网路由器发送的PSNP报文后,将会发送一个完整的LSP报文,这个LSP就是其他工业无线路由器所缺少的LSP条目。在广播网络中,DIS使用周期性的CSNP报文向网络中发送同步链路状态数据库的信号,而其他工业4g路由器使用PSNP报文来请求缺少的LSP条目。 在IS-IS的点到点类型的网络中,链路状态数据库同步的操作与广播网络中略有不同,而且工业级全网通路由器发送CSNP与PSNP报文的方式和其作用也有一些差别。 在点到点网络中不存在DIS,工业3G路由器不会周期性的发送CSNP报文,CSNP报文只在链路链路被激活时发送一次,而且链路两端的工业级4g路由器都会发送CSNP报文以描述本地链路状态数据库中所有LSP的摘要信息。当工业路由器发送对端发送的CSNP中含有本地缺少的LSP信息时,也会使用PSNP报文向对端请求LSP。当对端收到PSNP报文后,将向请求方发送包含完整LSP信息的LSP报文,这点上与广播网络中的操作是相同的。但是在点到点链路上,收到LSP报文的工业4g路由器还会向对方再次发送一个PSNP报文以对之前收到的LSP进行确认。可以说,在点到点网络中的LSP交换是可靠的。这点与广播网络不同,在广播网络中工业级无线路由器不使用PSNP报文对收到的LSP进行确认,而是通过DIS周期性地发送CSNP报文以弥补广播网络中不可靠的LSP交换。 在点到点链路上,工业路由器使用PSNP对收到的LSP报文进行确认,所以在点到点链路上是可靠的泛洪机制。 IS-IS路由协议支持两种网络类型:广播链路和点到点链路。默认情况下,全网通工业级路由器IS-IS将广播网络和NBMA网络看作是广播类型。对于封装了PPP或HDCL等协议的链路看作是点到点类型。对于NBMA网络中的主接口和点到多点子接口,IS-IS将其看作是广播类型;对于NBMA网络中的点到点子接口,将其看作是点到点类型。IS-IS不像OSPF那样,提供了对NBMA网络(例如Frame-Relay、ATM)的专门支持。对于NBMA网络,全网通工业路由器IS-IS认为其网络拓扑是PVC全互联(mesh)的,就是把它看作广播网络。但如果实际网络拓扑中并不是PVC全互联的结构时,例如部分互联的结构和Hub-Spoke结构,推荐使用点到点类型网络,即使用点到点子接口,以免造成NBMA网络中的链路状态数据库同步出现问题。无线路由器

更多文章

twitter

TDD LTE and FDD LTE’s Advantages / disadvantages of for cellular communications

Category : 技术相关

Let’s talk something about TDD LTE and FDD LTE’s Advantages / disadvantages of for cellular communications.

As we know, the LTE mainly covers two types, which are TDD and FDD. There are a number of the advantages and disadvantages of TDD and FDD that are of particular interest to mobile or cellular telecommunications operators. These are naturally reflected into LTE.

COMPARISON OF TDD LTE AND FDD LTE DUPLEX FORMATS
PARAMETER TDD LTE FDD LTE
Channel reciprocity Channel propagation is the same in both directions which enables transmit and receive to use on set of parameters Channel characteristics different in both directions as a result of the use of different frequencies
Paired spectrum Does not require paired spectrum as both transmit and receive occur on the same channel Requires paired spectrum with sufficient frequency separation to allow simultaneous transmission and reception
Hardware cost Lower cost as no diplexer is needed to isolate the transmitter and receiver. As cost of the UEs is of major importance because of the vast numbers that are produced, this is a key aspect. Diplexer is needed and cost is higher.
UL / DL asymmetry It is possible to dynamically change the UL and DL capacity ratio to match demand UL / DL capacity determined by frequency allocation set out by the regulatory authorities. It is therefore not possible to make dynamic changes to match capacity. Regulatory changes would normally be required and capacity is normally allocated so that it is the same in either direction.
Guard period / guard band Guard period required to ensure uplink and downlink transmissions do not clash. Large guard period will limit capacity. Larger guard period normally required if distances are increased to accommodate larger propagation times. Guard band required to provide sufficient isolation between uplink and downlink. Large guard band does not impact capacity.
Cross slot interference Base stations need to be synchronised with respect to the uplink and downlink transmission times. If neighbouring base stations use different uplink and downlink assignments and share the same channel, then interference may occur between cells. Not applicable
Discontinuous transmission Discontinuous transmission is required to allow both uplink and downlink transmissions. This can degrade the performance of the RF power amplifier in the transmitter. Continuous transmission is required.

 

TDD LTE and FDD LTE

Category : 技术相关

As we know, the LTE mainly covers two types, which are TDD and FDD.  Let’s talk something about TDD LTE and FDD LTE’s Advantages / disadvantages of for cellular communications.

There are a number of the advantages and disadvantages of TDD and FDD that are of particular interest to mobile or cellular telecommunications operators. These are naturally reflected into LTE.

COMPARISON OF TDD LTE AND FDD LTE DUPLEX FORMATS
PARAMETER TDD LTE FDD LTE
Channel reciprocity Channel propagation is the same in both directions which enables transmit and receive to use on set of parameters Channel characteristics different in both directions as a result of the use of different frequencies
Paired spectrum Does not require paired spectrum as both transmit and receive occur on the same channel Requires paired spectrum with sufficient frequency separation to allow simultaneous transmission and reception
Hardware cost Lower cost as no diplexer is needed to isolate the transmitter and receiver. As cost of the UEs is of major importance because of the vast numbers that are produced, this is a key aspect. Diplexer is needed and cost is higher.
UL / DL asymmetry It is possible to dynamically change the UL and DL capacity ratio to match demand UL / DL capacity determined by frequency allocation set out by the regulatory authorities. It is therefore not possible to make dynamic changes to match capacity. Regulatory changes would normally be required and capacity is normally allocated so that it is the same in either direction.
Guard period / guard band Guard period required to ensure uplink and downlink transmissions do not clash. Large guard period will limit capacity. Larger guard period normally required if distances are increased to accommodate larger propagation times. Guard band required to provide sufficient isolation between uplink and downlink. Large guard band does not impact capacity.
Cross slot interference Base stations need to be synchronised with respect to the uplink and downlink transmission times. If neighbouring base stations use different uplink and downlink assignments and share the same channel, then interference may occur between cells. Not applicable
Discontinuous transmission Discontinuous transmission is required to allow both uplink and downlink transmissions. This can degrade the performance of the RF power amplifier in the transmitter. Continuous transmission is required.