What is URA and URA_PCH state?

URA or UTRAN Registration Area is a colection of cells that are used for fast moving UE’s in Connected mode when they are not transferring any data. In this case the UE is in CELL_PCH state. Everytime a fast moving UE in CELL_PCH state changes the cell, a CELL [...] Continue Reading…

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Difference Between HLR and VLR

HLR vs VLR

Home Location Register (HLR) and Visitors Location Register (VLR) are databases that contain the mobile subscriber information as per the GSM architecture. In general there is one central HLR per mobile network operator and one VLR per each Mobile Services Switching Centre (MSC) but this can vary according to [...] Continue Reading…

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Difference Between WiMAX and Wifi

WiMAX vs Wifi

WiMAX and Wi-Fi are both wireless technologies but Wi-Fi can only be operated in short ranges (Max 250 m) and WiMAX could be operated in long ranges (around 30 Km). WiMAX has fixed and mobile version which could be used for several applications with higher bandwidth (around 40 Mbps). [...] Continue Reading…

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Difference Between LTE and WiMAX

LTE vs WiMAX

LTE (3GPP Long Term Evolution) and WiMAX (Wireless Interoperability for Microwave Access) are high speed 4G wireless technologies. 3G growth ends at HSPA+ and mobile operators started deploying 4G networks to offer more bandwidth to mobile handsets. These 4G technologies give virtual LAN reality to mobile handsets [...] Continue Reading…

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Difference Between 3G and 4G Network Technology

3G vs 4G Network Technology | LTE and WiMAX | 3G vs 4G Speed, Frequencies and Features Compared | Battery Life more in 3G

3G and 4G are wireless communication technology classifications by certain standards and benchmarks. In the evolution of the mobile telephony the standards made for 3G and 4G network [...] Continue Reading…

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Difference Between 4G and LTE

4G vs LTE

4G, known as 4th generation of mobile communications, and LTE (Long Term Evolution) are 3GPP specifications for mobile broadband networks. Different eras of mobile communication are categorized into generations such as 1G, 2G, 3G, and 4G, where each generation has a number of technologies such as LTE. [...] Continue Reading…

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How does TMA – Tower Mounted Amplifier work?

A TMA – Tower Mounted Amplifier reduces system noise, improves uplink sensitivity and leads to longer UE battery life.

Sensitivity is the minimum input power needed to get a suitable signal-to-noise ratio (SNR) at the output of the receiver.  It is determined by receiver noise figure, thermo noise power and required [...] Continue Reading…

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UMTS Data Rates and Modulation

UMTS uses a 3.84 Mcps chip rate on a 5Mhz carrier (effectively only using 3.84Mhz with the remaining bandwidth acting as a guard to adjacent frequencies). Since the maximum modulation in UMTS is QPSK 1/2, that means 1 bit per symbol, making the maximum raw throughput for a 5Mhz [...] Continue Reading…

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KPI Introduction

1. CSSR (CALL SETUP SUCCESS RATE)
Definition: Rate of calls going until TCH successful assignment.

2. SCR (SUCCESSFULL CALL RATE)
Definition: Rate of calls going until normal release that is not interrupted by SDCCH DROP, neither by assignment failures, and neither by CALL DROP.

3. CALL DROP RATE (CDR)
Definition: Rate of all [...] Continue Reading…

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Definition RSCP, RSSI and Ec/Io

RSCP: The “Received Signal Code Power” (RSCP) is the collected RF energy after the correlation / descrambling process, usually given in dBm. Only this code power is of interest for the following receiver stages when judging on the quality of the reception.

Ec/Io: This is the ratio of the [...] Continue Reading…

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Explain Soft and Softer handover? Give some advantage and disadvantage for soft handover

In Soft Handover, the UE connection consists of at least two radio links established with cells belonging to different RBSs. In Softer handover, the UE connection consists of at least two radio links established with cells belonging to the same RBS.

It acts as macro diversity since UE is connected [...] Continue Reading…

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Capacity Management and Its functions – WCDMA

Capacity Management is responsible for the control of the load in the cell.
It consists of 3 main functions:
1. Dedicated Monitored Resource Handling: tracks utilization of critical resources of the system.
2. Admission Control: accepts/refuses admission requests based on the current load on the dedicated monitored resources and the characteristics of [...] Continue Reading…

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What is Pilot Pollution?

Simply speaking, when the number of strong cells exceeds the active set size, there is “pilot pollution” in the area. Typically the active set size is 3, so if there are more than 3 strong cells then there is pilot pollution.

Definition of “strong cell”: pilots within the handover window [...] Continue Reading…

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What is the usage of Channelization code in downlink and uplink?

Uplink separation of physical data (DPDCH) and control channel (DPCCH) from same terminal.
Downlink separation of downlink connections to different users within one cell.

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What is Significance of Eb_No?

Eb_No is related to QOS of a service which in terms related to bit error rate.
Technically it is the minimum signal to noise needed by infrastructure equipment after despreading it signal. This is a value used to compare different infrastructure vendors. Eb_No changes with the service type.

For AMR 12.2 [...] Continue Reading…

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What is a typical CPICH power?

CPICH power typically takes about 8~10% of the total NodeB power. For a 20W (43dBm) NodeB, CPICH is around 2W (35.1 ~ 33dBm).
In urban areas where in-building coverage is taken care of by in-building installations, the CPICH may sometimes go as low as 5% because:
1) The coverage area is [...] Continue Reading…

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How much power usually a NodeB is allocated to control channels?

The power allocated to control channels may depend on equipment vendor recommendation. Typically no more than 20% of the total NodeB power is allocated to control channels, including CPICH. However, if HSDPA is deployed on the same carrier then the total power allocated to control channel may go up [...] Continue Reading…

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UTRA Network Functions

 

• Overall system access control
– System information broadcasting

• Radio channel ciphering
– Radio channel ciphering
– Radio channel deciphering

• Handover
– Radio environment survey
– Handover decision
– Macro-diversity control
– Handover control, execution, completion
– SRNS relocation
– Inter-system handover

• Radio resource management and control
– Radio bearer connection setup and release
– Reservation and release of physical [...] Continue Reading…

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UTRA W-CDMA Radio Interface

Channel bandwidth – 5MHz (10Mhz, 20Mhz)

Chip rate – 3.84Mchip/s

Frame length – 10ms

Channelisation spreading – variable spreading

Data modulation – QPSK(downlink), BPSK (uplink)

Spreading modulation – Balanced QPSK (downlink); Dual-channel QPSK (uplink)

Coherent detection – User dedicated time multiplexed pilot; Common pilot in downlink

Channel multiplexing in uplink – Control and pilot channel time [...] Continue Reading…

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UMTS Requirements (Radio Access)

• Maximum User Bit Rates
– Rural Outdoor: 144kb/s (goal 384kb/s), up to 500km/h
– Suburban Outdoor: 384kb/s (goal 512kb/s), up to 120km/h
– Indoor/Urban Outdoor: 2Mb/s, max speed 10km/h

• Flexibility
– Negotiation of bearer service attributes
– Parallel bearer services (service mix, multimedia)
– Circuit and packet switched bearers
– Scheduling of bearers
– Link adaptation [...] Continue Reading…

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RAKE Receiving in WCDMA

Radio wave propagation on radio channels is characterized by much reflection, diffraction and fading of signal energy. These are due to space obstacles, such as buildings and hills, which result in multipath propagation.

There’re Two effects of multipath propagation :
1. The code chip energies arrive at the receiver at distinguishable moments. [...] Continue Reading…

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The Global 3G Mobile Broadband Internet Access Connect Your Laptop on the Move in 75 Countries

Are you Abroad? On a Business Trip? Get “Wireless Internet on the Move,” the new 3G international mobile broadband Internet access, added to the global WiFi hotspots, dial-up and Toll Free MobilityPass network allow travelers to connect instantly and safely connect wirelessly everywhere around the world.

Ready to use with [...] Continue Reading…

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What is the main functions of Twin TMA – Tower Mounted Amplifier

The main functions of Twin TMA is to decrease the noise as well as enhances the BTS receiver sensitivity and bring advantages for BTS coverage as follows:

1. Balance Uplink and Downlink
2. Increase Uplink Rx Level and Extend BTS Reverse Coverage
3. Decrease System Noise
4. Reduce Drop Call and Improve Call [...] Continue Reading…

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CDMA Drive Test – 5 Important Parameters

1. TXPOWER
TXPOWER is the phone’s transmitter power. We know that power control is guaranteed call quality and address the CDMA community interference tolerance and one of the key means of mobile phone from the base station near, uplink quality good, the mobile phone transmitting power is smaller, because at [...] Continue Reading…

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