In hindsight, I realize topics such as these can get extremely lengthy. How convenient is that? Have you ever even wondered how LTE works? Unfortunately for mobile users, which is all of us, researchers have uncovered several vulnerabilities in the LTE standard that could allow sophisticated hackers, or even government agencies, to spy, modify, and re-route cellular communication.
The Recent 4G LTE Network Vulnerabilities and Attacks
More specifically, researchers have demonstrated several attack vectors that allow them to intercept phone calls and text messages, spoof locations, re-route victims using DNS spoofing, knock devices offline, redirect data, modify data, and even send out fake emergency alerts. UE includes your mobile devices. Each base station serves a hexagonal, geographical area. There are more, components, but they are not essential for this discussion. There could be anywhere from 3 to 18 antennas on one tower.
When you make a phone call or request to a web server, these messages hit these antennas via radio waves. Antenna Array. The antenna array are connected to either copper or fiber-optic cables, which run down the tower into the network equipment at the bottom. Your data runs down this transmission medium. Copper and Fiber-Optic Media. The equipment is usually stored in a highly-protected base station or locker.
Inside, are tons of rack-mounted gear to route and transmit data, such as multi-model base stations, switches, routers, radio frequency amplifiers, and other mobile Carrier equipment. Cell Site Equipment. Cell sites also come with backup power supplies, including spare batteries and power generators that can keep the site running for an extra 24 hours just in case that particular region loses power for any reason.
After the UE determines which base station has the highest signal power, it establishes a connection with that base station. Connection takes place in 4 stages:.
So, if you move too far, another base station can go to work. There is a layer 1 — Physical, layer 2 — Data Link, and layer 3 — Network. They are just like the layers of the OSI model. OFDMA uses orthogonal sub-carriers, each spaced evenly at 15 khz.
Each phone call gets its own separate frequency.Effective date : Year of fee payment : 4. Methods, apparatuses and computer readable media are described that analyze and communicate signaling messages between a mobile wireless device and a wireless access network to realize a circuit switched fallback CSFB procedure when the mobile wireless device is initially in a radio resource control connected mode with the wireless network.
A set of information elements of a paging message is analyzed, and based on contents of the set of information elements and an internal state of the mobile wireless device, connections between the mobile wireless device and first and second wireless access networks are changed to realize the CSFB procedure. Provisional Application No. The described embodiments generally relate to methods and apparatuses for managing radio connections between mobile wireless devices and one or more wireless networks.
More particularly, the present embodiments describe signaling between a mobile wireless device and a wireless network to realize a circuit switched fallback CSFB procedure when the mobile wireless device is initially in a radio resource control RRC connected mode with the wireless network. Wireless networks continue to evolve as new communication technologies develop and standardize.
Wireless network operators can deploy new communication technologies in parallel with earlier generation communication technologies, and wireless networks can support multiple communication technologies simultaneously to provide smooth transitions through multiple generations of mobile wireless devices.
Mobile wireless devices can include hardware and software to support wireless connections to different types of wireless networks that use different wireless communication technologies. A wireless service provider can provide services to mobile wireless devices through overlapping wireless networks, and mobile wireless devices can connect to one or more of the overlapping wireless networks.
Mobile wireless devices can include a combination of hardware and software to connect to multiple wireless networks that use different wireless communication protocols. Representative mobile wireless devices can support circuit switched CS voice connections through a first wireless access network that uses a legacy wireless communications protocol, e. The mobile wireless device can operate in cooperation with the LTE wireless network and with the legacy wireless network to suspend a PS data connection with or disconnect from the LTE wireless network to originate or terminate a CS voice connection through the legacy wireless network, e.
While the mobile wireless device can use the LTE wireless network for PS data connections, when the mobile wireless device originates an outgoing voice connection or responds to an incoming voice connection, the mobile wireless device can transition from using the LTE wireless network to using a legacy wireless network that supports CS voice connections. When the CS voice connection completes, the mobile wireless device can subsequently return to the LTE wireless network for PS data connections.
The 3GPP standardized LTE wireless communication protocol specifies multiple options for CSFB procedures including messages and responses for when a mobile wireless device is in different connection states with the LTE wireless network. The LTE wireless communication protocol includes two possible connection states that can exist between the mobile wireless device and the LTE wireless network, namely a radio resource control RRC connected state and an RRC idle state.
The CSFB procedures for each connection state can differ in the sequence of messages and responses communicated between the mobile wireless device and the LTE wireless network. In certain circumstances, the mobile wireless device and the LTE wireless network can become misaligned with respect to each other concerning the connection state that exists between them, e.
Following the standardized CSFB procedures, the LTE wireless network can send one or more messages to the mobile wireless device based on a first connection state, and the mobile wireless device can ignore the one or more messages from the LTE wireless network because it assumes a second different connection state. In such a scenario, the mobile wireless device can miss an incoming voice connection indicated by the LTE wireless network because of the misaligned connection states between the mobile wireless device and the LTE wireless network.
Thus, there exists a need for a method to support alternate CSFB procedures to establish mobile terminated voice connections when the mobile wireless device is in one connection state, e. The teachings described herein can be applied to mobile wireless devices that can operate in dual or more generally multiple wireless communication technology networks.
In particular, the teachings disclosed herein can pertain to mobile wireless devices that switch from using one wireless technology for a first connection e. More particularly, the present embodiments describe signaling between a mobile wireless device and a wireless network to realize a circuit switched fallback procedure when the mobile wireless device is initially in a radio resource control connected mode with the wireless network.
In an embodiment, a method to respond to paging messages by a mobile wireless device is described. The method includes at least the following steps executed by the mobile wireless device.However, while the UE is in idle state i. An operator defines a group of neighbor eNBs as a TA These grouping are performed at the initial deployment of the network. Each eNB is configured with its own TA. Why do we need TAs? If there is data traffic heading to a UE in idle state e. Here, this "waking up called paging " is performed TA-wide.
Let's say a UE is located in C neighborhood. Then, the network considers the UE is located in TA3. Then each eNB broadcasts the paging message over the radio link to wake up the UE.Is System Information Blocks part of Paging Procedures in LTE ?
A UE in idle state wakes up at certain periods to check for a paging message to see if there is any incoming data. If the UE finds it has been paged by an eNB, it turns back to active state to receive the data. Let's take a look at the format of TAs.
This format of assigning makes a TAI uniquely identified globally. If a UE in idle state has stayed in one location or moved within the TAs in the TAI list and has not notified the MME of its current location, the network cannot tell whether the UE is still in idle state, or is not able to communicate. Otherwise, the network believes the UE is not able to receive data and does not perform paging even when there is data traffic heading to the UE.
US20130331054A1 - Paging for csfb in lte connected mode - Google Patents
How multiple TA and s1-flex can be handled in this example. Don't you think it is coupled with MME pool.
Please correct me. All rights reserved. English Korean About Us. Samsung Cloud Native 5G Core. August 30, By Dr. Michelle M. Do tech netmanias. Download PDF File. Huge article, thanks. Thank you for visiting Netmanias! Please leave your comment if you have a question or suggestion.This includes In simple wordsThis represents the result and Score card of your Network.
Refer my another tutorial on SIP Registration for more details on same. The CSSR indicates the probability of successful calls initiated or received by the user. Here we count calls failed due to user behavior such Busynot reachable etc.
CST is overall length of time required to establish a circuit-switched call between users. CST is Time between the start of the call and the moment the phone of the called party starts ringing. ACD is the average length of an answered call made over the network. By Definition … A clear code is the identifier code of the reason to clear a call. This not only tells us about Internal Network Call failures but also Highlights failures happening out side in other Operator Networks as well.
This is complete list of cause codes which tell us exact reason why call failed. This shows congestion in Network where calls are not able to move ahead. The Most Important Metric of Mean Opinion Score is a measure of voice quality, MOS has been used in telephony for decades as a way to assess the human users opinion of call quality.
MOS is expressed in numeric from 1 to 51 being the worst and 5 the best. MOS is very very subjective, as it is based figures that result from what is perceived by people. Because of this, there are many factors that can affect the MOS score on VoIP system that would not be a factor on a regular phone line. These include High number of one way call will lead to very bad user experience. Paging Success Rate is just like any paging request which is used to trace down user sitting idle out there in Field.
These KPIs are Hope this information is useful for you. Please feel free to Mail me vikas. Skip to Content.CS Fallback. Basically LTE is a Packet only technology. It is well designed for data traffic. Then what about Voice call? There can be a couple of options to achieve voice call in LTE. One of the option is just to use packet based voice call e. Another option is to use multiple technology.
LTE Paging Mechanism
This technology that enables to redirect connection to other technology e. It may sound very simple and usefull First, UE should support multiple technologies and network side would be even more complicated. One of the simplest representation on network side would be as follows.
Now let's look into the interplay of the two networks to make the voice call possible. I think these interplay can be explained by adding just three lines as follows.
Is this everything make CS Fallback happen? Definately not. To make these two different protocol work together would not be that simple.
It is not the scope of this short section to describe the whole details of 'CS Fallback' protocol side. So just keep it mind that it would be pretty complicated process and try to google some of articles. These are not the full list of those situations, but can be most common situations triggers for CSCF.
User make voice call MO Call. For the details of 'Redirection' mechanism, refer to 'Redirection' section.There are a number of myths about paging.
Paging is not only used to bring a UE from Idle to connected mode. It is also used in RRC Connected mode. It is used for the following use cases. From the picture above. There are two types of paging with respect to which node will initiate paging i.
The range for paging cycle varies as 32, 64, and up to radio frames. The range of allowed values is the same as those used in SIB 2. Well, for paging to take place.
Call Setup delay
Operators set up paging cycle. Paging cycle is measured in Radio frames. Commonly used value for Paging cycles is Therefore, if an operator has setup default paging cycle as It means UE will wake up after every 1. After waking up. If it does not find paging information related to the UE it will go back to sleep. Within the radio frame, there are 10 subframes. UE does not remain awake in all 10 subframes.
Instead, it wakes up in a specific subframe either subframe 0, 4, 5 or 9 within a radio frame. In order to find out which paging frame the UE will wake up in. Once UE has computed the paging frame. It goes ahead and finds out in which subframe of the paging frame it will wake up. A UE does not need to wake up in all one 1 msec subframes within its Paging Frame. UE makes a use of the look-up table. The value of Ns is cell-specific so cells carrying low quantities of traffic can be configured with a value of one 1 to provide relatively low paging capacity, while cells carrying higher quantities of traffic can be configured with a value of 4 to provide relatively high paging capacity.
Subframes 5 and 0 were not selected for the lower capacity configurations likely to have smaller channel bandwidth because subframe 0 already includes Masters Information Block MIB and subframe 5 already includes System Information Block 1 SIB 1.
The high capacity configuration also uses subframes one 1 and 6. Special subframes tend to be PDCCH capacity limited so these subframes were not used for the lower capacity configurations. Given the value of the parameter. The following calculation reveals. So on and so forth, until it reaches closer to system frame number SFN and then it will start to loop back again. Continuing the example above. In order to find out which subframe UE will wake up in each subframe. Intercepting the two values from the table below.
UE will wake up in sub-frame 4 and 9 respectively during paging occasion.Paging is the mechanism in which Network tells UE saying "I have something for you". In most cases, this paging process happens while UE is in idle mode.
This means that UE has to monitor whether the networking is sending any paging message to it and it has to spend some energy battery to run this "Monitoring" process. If I have to run this "Monitoring" process continously even in the idle mode, isn't it too much waste of engergy? Yes, it is. Is there any way to prevent this kind of energy waste? There would be no way to prevent this envergy consumption completely if you can come out with any idea to prevent this completely, you don't need to read this any more.
What is it? There may be many different way to do this. What kind of contract it would be like? It is like "Hey. I will go sleep when you are not transmitting Paging and I will just wake up exactly at the time you are transmitting the paging message".
This way UE can save the battery while it is in sleep and can get the paging message as well. It means that UE is recieving some data from the network "discontinously".
Here we have an important question. How can UE knows the exact timing when the Network send the paging? The simplest solution for this would be to make another contract about "Paging transmission timing".
Overview on Paging Mechanism. Note : Each eNodeB can contain cells belonging to different tracking areas but each cell can only belong to one Tracking Area. Paging Parameters in SIB2. Now it's time to get into the official specification. Paging Occasion and Paging Frame. As you know, LTE has two timing units as many of other technology. Let's tackle the PF first.