How to enable Samsung Galaxy S5/S4 for QXDM

Enable Developers option for USB debugging:
Go to Settings ->More->About Device and tap on the build number 3-5 times. It will notify that developer option is enabled.
Go back to Developers options and settings and Select USB debugging

Enables Modem Option on the Samsung Galaxy S5/S4:
Go to  Samsung Galaxy S5/S4 dialer and dial *#0808#. The USB Settings will opened.
Go to AP USB settings select the "RNDIS + DM + MODEM" and Click OK.

Connect the Samsung Galaxy S4/S5 to laptop and check the device manager. There must be a com port appear for your laptop. make note of the comm port and use it QPST and QXDM.

SRVCC - Subscribers VoLTE call will drop if out of VoLTE coverage?

SRVCC - Single Radio Voice Call Continuity

    Does the VoLTE call drop when out of VoLTE enabled cell coverage? Answer is Yes and a No. Potential solution is supporting SRVCC for call continuity with inter-RAT systems. SRVCC is adapted as standard but not something developed for VoLTE. SRVCC was designed to facilitate IMS Achored voice call continuity between LTE/HSPA network and GSM/UMTS/CDMA Networks.  This not as simple solution, since the voice call continuity is between Packet switch network and Circuit switched networks.

    Attach procedure is used to exchange the information about letting each other know SRVCC capability of UE and MME.  MSC-S, MME and UE needs to support SRVCC for the voice call continuity. Series of handover procedures carried out to move the voice leg from one RAT to another.

VoLTE - Voice over LTE - Must Know!

How will UE know that VoLTE is supported by the EPC network?

    During the NAS Attach procedure or NAS TAU procedure, in the Attach Accept and/or RAU Accept message, additional IE called "EPS Network Feature" will be included indicating "IMS Over PS session" is available. This triggers the UE to register with IMS network.

VoLTE Call Procedures - Call flow:

  In VoLTE call establishment procedure is achieved using a application server called Telephony Application Server(TAS).
Procedure includes:

• Establishment of Default EPS Bearer with  QCI = 5
• SIP Call Establishment Procedures
• Establishment of Dedicated EPS Bearer to support Media Bearer
• SIP Call Termination Procedures
• Termination of Dedicated EPS Bearer

LTE - Feature set in each 3GPP release

LTE is a flat IP architecture, bringing in higher data rates with improvements of radio access technologies. In addition to that it is way say good bye to circuit switched network by moving completely to packed switched network. This intern reduces both CAPEX and OPEX.

LTE is introduced in 3GPP release 8.

Release 8:

• All IP network
• New air interface
• Reduced latency
• Support for MIMO antennas
• Higher data rates: 300Mbps/75Mbps

Release 9:

• Introduction of small cells
• Self Organizing Networks (SON)
• evolved Multimedia Broadcast and Multicast service (eMBMS)
• Location Services

Release 10:

• 3Gbps/1.5Gbps data rates
• 8x8 downlink and 4x4 uplink MIMO antennas
• Carrier aggregation of 20 MHz channels to maximum 100 MHz channel
• Relay nodes to support Heterogeneous Networks (HetNet)

Release 11:

• Improvements to carrier aggregation
• New frequency bands
• Improvements to receivers
• Multipoint transmission and reception

Inter-frequency Hard Handover Events in Small Cells

During the hard handover procedure for inter-frequency, when the UE is moving away from HNB coverage area, HNB will receive the event 2D when quality of the currently used frequency is below the 2D threshold configured. When the event 2D is triggered, compressed mode scanning will be started.  If the UE moves further away and satisfy the event 2B condition when estimated quality of the currently used frequency is below the 2B threshold configured and estimated quality of the non-used frequency is above the configured threshold. Event 2B will trigger the handover procedure.
However if the Event 2D threshold is met and compressed mode measurement reporting is started but UE is moving towards the HNB coverage area and the estimated quality of the currently used frequency is better than the configured 2F threshold, UE will exit the compressed mode.

3G/UMTS Inter-frequency, Intra-frquency and Inter-RAT handover events

Intra-frequency Handover Events:

Event 1a: A Primary CPICH enters the Reporting Range (FDD only).
Event 1b: A Primary CPICH leaves the Reporting Range (FDD only).
Event 1c: A Non-active Primary CPICH becomes better than an active Primary CPICH (FDD only).
Event 1d: Change of best cell (FDD only).
Event 1e: A Primary CPICH becomes better than an absolute threshold (FDD only).
Event 1f: A Primary CPICH becomes worse than an absolute threshold (FDD only).
Event 1g: Change of best cell in TDD.
Event 1h: Timeslot ISCP below a certain threshold (TDD only).
Event 1i: Timeslot ISCP above a certain threshold (TDD only).
Event 1j: A Non-active E-DCH but active DCH Primary CPICH becomes better than an active E-DCH Primary CPICH (FDD only).

When an Event 1C is received, Handover procedure will be started in the NodeB.

Inter-frequency Handover Events:

Event 2a: Change of best frequency.
Event 2b: The estimated quality of the currently used frequency is below a certain threshold and the estimated quality of a non-used frequency is above a certain threshold.
Event 2c: The estimated quality of a non-used frequency is above a certain threshold.
Event 2d: The estimated quality of the currently used frequency is below a certain threshold.
Event 2e: The estimated quality of a non-used frequency is below a certain threshold.
Event 2f: The estimated quality of the currently used frequency is above a certain threshold.

Event 2B will trigger the inter-frequency handover procedure in the Node B. Event 2D will start the compressed mode scanning and Event 2F will stop the compressed mode.

Inter-RAT Handover Events:

Event 3a: The estimated quality of the currently used UTRAN frequency is below a certain threshold and the estimated quality of the other system is above a certain threshold.
Event 3b: The estimated quality of other system is below a certain threshold.
Event 3c: The estimated quality of other system is above a certain threshold.
Event 3d: Change of best cell in other system.

Event 3A will trigger the inter-frequency handover procedure in the Node B
 

UMTS: Traffic Volume Measurement (HSDPA, HSUPA)

Traffic Volume Measurement is used for purpose of Rate reallocation at UE. The monitored traffic volume corresponds to the amount of data in number of bytes that is available for transmission and re-transmission in RLC layer- Buffer Occupancy.
When an UE supporting Release 5 and below release is used then rate adaptation can be achieved. As the buffer occupancy goes lower than the threshold, Timer will be started. If the buffer occupancy goes above the threshold then it will stopped. If the timer expires then data rate will be adapted to lower rate for the UE.
Event 4a: Transport Channel Traffic Volume exceeds an absolute threshold.
Event 4b: Transport Channel Traffic Volume becomes smaller than an absolute threshold.

Traffic volume measurements may be configured by RRC to assist with dynamic radio bearer control. In general, RLC buffer payload, Average of RLC buffer payload or Variance of RLC buffer payload will be configured to report.

Traffic volume measurement reports can be triggered periodically and event triggered based on the reporting criteria specified in the measurement control message.

Traffic volume measurement information will be communicated in SIB11 and during the radio bearer setup stage.

Live wireshark/pcap collection and log rotation/round robin

Most of the live system requires PCAP/Wireshark log collection on the network interfaces. But logs needs to be rotated to avoid disk space consumption. Using simple script and tcpdump command, it is very easy to achieve this goal. tcpdump has an option to set the rotation of log files by specifying the number of log files and size of each log file. tcpdump command can be run in the background using these options. Writing a script to perform this task in the background is the best option.

Below is the Syntax:

tcpdump -nni <network interface> <filter if any> -s0 -w - | ( tcpdump -nn -r - -W <Number of files> -C <Size of each file> -w <Log file name> > <Logfile.output> 2> <Log.error> )


Below is the Example for keeping last 50 pcap files for eth0 interface, each file of size 20MB:
tcpdump -nni eth0 not arp and not port 22 -s0 -w - | ( tcpdump -nn -r - -W 50 -C 20  -w WS_ETH0.pcap > log.output 2> log.error ) 

How to resize or shrink the partition (LVM) in linux or VM

I wanted to shrink LVM partition in VM which has redhat linux and expand root partition because of  memory issue on root partition.  I have done searching excercise in the web and below are the results of the search and best pages that I have seen. However I was not able to reduce the LVM partition as all the procedures mentioned in the below did not recognize the LVM partition created in the redhat linux VM installation. Below procedures are pretty good in general and but does not work for LVM on VM. gparted, parted or steps mentioned below may work other partions. You can try got LVM, it may work for you. I have kept consolidated search result in one page.

http://gparted.sourceforge.net/download.php

http://www.thegeekstuff.com/2011/09/parted-command-examples/
http://gparted.sourceforge.net/screenshots.php#gparted-live-boot-menu
http://en.kioskea.net/faq/2036-how-to-resize-a-partition-using-gparted-on-linux

Back up all your important data before attempting this. Always assume that you can lose all your data when resizing partitions.

Shrink LVM without dataloss

This forum thread suggests the following procedure, in this example we shrink a partition from 10G to 9G:

First, we unmount.

# umount /dev/vg_blah/lv_blah

Check the file system.

# e2fsck -f /dev/vg_blah/lv_blah

Resize the file system.

# resize2fs /dev/vg_blah/lv_blah 9G

Reduce the size of the logical volume.

# lvreduce -L -1G /dev/vg_blah/lv_blah

Shrink the volume group if desired.

# vgreduce vg_blah /dev/sdxy

How to enable engineering/field test mode in blackberry

Blackberry has a very nice and interesting field test/Engineering mode.
While reading a blog I show that pressing ALT+CAP+H would display usefull  information about your mobile.
But you can enable the engineering mode from this screen using steps metioned in the blog:
http://www.zibri.org/2009/08/hidden-things-are-usually-best.html
Please make sure to follow steps very clearly. Read it twice!

UMTS Mobile Originated call flow sequence diagram (Mobile to Landline)

UMTS Handover event 2a, 2b, 2c, 2d, 2e, 2f explained

• Event 2a: Change of Best Frequency.
• Event 2b: The estimated quality of the currently used frequency is below a certain threshold and the estimated quality of a non-used frequency is above a certain threshold.
• Event 2c: The estimated quality of a non-used frequency is above a certain threshold.
• Event 2d: The estimated quality of the currently used frequency is below a certain threshold.
• Event 2e: The estimated quality of a non-used frequency is below a certain threshold.
• Event 2f: The estimated quality of the currently used frequency is above a certain threshold.

UMTS Call flow for Mobile to Mobile voice call

This call flow is mainly captured at the RNC.

What is IUFlex in UMTS

In the 3GPP Release 5 IUFlex is introduced. It provides an ability to connect RNC's to more than one MSC and/or SGSN. Major benefit would be load sharing between MSC's or SGSN's.

Features supported in 3GPP release 99, release 5, release 6, release 7, Release 8

I often forget what features are added or enhanced in the various 3GPP releases. Here is the list of supported features in the each of the 3GPP release which covers most of part of it.

Release '99

·        Bearer services

·        64 kbit/s circuit switch

·        384 kbit/s packet switched

·        Location services

·        Call services: compatible with Global System for Mobile Communications (GSM), based on Universal Subscriber Identity Module (USIM)

Release 4

·        Edge radio

·        Multimedia messaging

·        MExE (Mobile Execution Environment)

·        Improved location services

·        IP Multimedia Services (IMS)

 Release 5

·        IP Multimedia Subsystem (IMS)

·        IPv6, IP transport in UTRAN

·        Improvements in GERAN, MExE, etc.

·        HSDPA

 Release 6

·        WLAN integration

·        Multimedia broadcast and multicast

·        Improvements in IMS

·        HSUPA

·        Fractional DPCH

 Release 7

·        Enhanced L2

·        64 QAM , MIMO

·        Voice over HSPA

·        CPC - continuous packet connectivity

·        FRLC - Flexible RLC

 Release 8

·        DC-HSPA

·        HSUPA 16QAM

T3312 Periodic Routing Area Update Timer

Periodic RA update timer or  Periodic Routing Area Update Timer is T3312. T3312 is used to send RAU message periodically. Value of this timer is set based on the value received in the ATTACH ACCEPT and/or ROUTING AREA UPDATE ACCEPT message.

Normally, values are sent in the  Decihours. 1 Decihours =  6 mins.

How to change or add the SMSC number to apple iPhone

How to get the SMSC set in the iPhone?
In the iPhone keypad and type *#5005*7672# Press Call
How to erase the SMSC set in the iPhone?
In the iPhone keypad, type ##5005*7672# Press Call
How to modify the SMSC set in the iPhone?
In the iPhone keypad, type **5005*7672*+<SMSC># Press Call

T3212 Periodic Location Update Timer

Periodic Location update timer controls periodicity of the location update procedure triggered by Mobile(UE). The value T3212 shall be set to 0 if Peridic location updating procedure need to be disabled. The value can be set in multiples of 6 (6 mins) and default value is 60. When it is set to 60mins, T3212 is set to 10 because T3212 value is in dechours. 1 Decihour = 6mins

Rake receiver and Multipath signal propagation

Because of the natural obstacles, signals transmitted may take multiple paths and reach destination at different time. As the chip rate is 3.84Mcps leads to time duration 0.26MicroSecs. If the time difference between multipath signal is 0.26 Micro seconds then receiver can separate those signals and combine them.

Power Control

Open loop power control make rough estimate of path loss by means of a downlink beacon signal. This may not be accurate.
Closed loop power control is performed in the uplink; base station performs frequent estimates of the received Signal-to-Interference Ratio (SIR) and compares it to a target SIR. If the measured SIR is higher than the target SIR, the base station will command the mobile station to lower the power; if it is too low it will command the mobile station to increase its power.

Outer loop power control a procedure where target SIR is changed based on signal quality. Based on the quality of radio link measure in the uplink for each user data channel regulates the target SIR.