TelecomStudy18

Main differences between the third and second generation air interfaces are described. GSM and IS-95 (the standard for cdmaOne systems) are the second generation air interfaces considered here. Other second generation air interfaces are PDC in Japan and US-TDMA mainly in the Americas; these are based on TDMA (time division multiple access) and have more similarities with GSM than with IS-95. The second generation systems were built mainly to provide speech services in macro cells. To understand the background to the differences between second and third generation systems, we need to look at the new requirements of the third generation systems which are listed below:        ·          Bit rates up to 2 Mbps; ·          Variable bit rate to offer bandwidth on demand; ·          Multiplexing of services with different quality requirements on a single connection, e.g. speech, video and packet data; ·          Delay requirements from delay-sensitive real time traffic to flexibl

Bluetooth is a proprietary open wireless technology standard for exchanging data over short distances (using short-wavelength radio transmissions in the ISM band from 2400–2480 MHz) from fixed and mobile devices, creating personal area networks (PANs) with high levels of security. Created by telecoms vendor Ericsson in 1994,[1] it was originally conceived as a wireless alternative to RS-232 data cables. It can connect several devices, overcoming problems of synchronization. To understand any kind of communication technology, you should be able to answer to several basic questions about it. In other words, if you can answer the following questions, I would say you already have some general understanding on it. Is it wired communication? or Wireless communication ? If it is wireless communication, what kind of wave length (frequency) range it uses ? What is the typical range of communication? (How far it can go) ? What is the typical data rate you

Degrees, Minutes, Seconds to/from Decimal Degrees The form below allows you to convert Latitude and Longitude information between decimal format and degree/minute/second (DMS) format. This is useful when finding distances. Here's the basic equation: Decimal Degrees = Degrees + minutes/60 + seconds/3600 Decimal Lat Long Deg Min Sec Lat N S Long E W

All messages sent on the A-bis interface use the LAPD protocol that enables reliable transmission of information. LAPD provides two kinds of transfer modes: Unacknowledged info transfer with no guarantee that the information frame is successfully delivered to the addressee, and acknowledged information transfer, where each signal is acknowledged, and the system makes sure that the frame has reached the destination successfully. Only measurement reports use unacknowledged information transfer. Frame Structure and Data Links A flag, 01111110 (h'7E), delimits a frame. The one flag is enough between consecutive frames. The receiving entity looks for the flag 01111110 to synchronize on the start of a frame. TEI and SAPI are used to access the right entity and right function at the receiving end. SAPI is the address used to access different functions, such as TRXC, CF and Layer 2 management procedures, within one physical entity. The CF (Central Function

In the late 1980s, the groups involved in developing the GSM standard realized that within the given time-frame they could not complete the specifications for the entire range of GSM services and features as originally planned. Because of this, it was decided that GSM would be released in phases with phase 1 consisting of a limited set of services and features. Each new phase builds on the services offered by existing phases. Phase 1 Phase 1 contains the most common services including: ·          Voice telephony ·          International roaming ·          Basic fax/data services (up to 9.6 kbits/s) ·          Call forwarding ·          Call barring ·          Short Message Service (SMS) Phase 1 also incorporated features such as ciphering and Subscriber Identity Module (SIM) cards. Phase 1 specifications were then closed and cannot be modified. Phase 2 Additional features were introduced in GSM phase 2 including: ·          Advice of charge ·        

TGC FAULT No active TGC application exists in the Transceiver Group. PERMANENT FAULT A managed object is classified as being permanently faulty when fault situations have occurred, and have been cleared, a certain number of times within a certain period of time. Manual intervention is required to bring such equipment back into operation. LOCAL MODE The BTS equipment is in Local Mode or the BTS equipment has changed from Local to Remote Mode and a fault exists in the communication link between the BSC and the BTS. Communication between the BSC and the BTS is not possible. LMT INTERVENTION Local maintenance activities are being performed in the BTS. LOOP TEST FAILED Test of the traffic carrying capabilities of the TS has failed. BTS INTERNAL There is a fault internal to the BTS. MAINS FAILURE There is a fault in the power supply to the BTS or one or more items of equipment within the BTS. Battery backup (where available) is in use. Escalation may occur if

The Peak Data rate of LTE is about 400Mbps?     It’s in a simple way to calculate date rate in LTE. First: Assume That 20 MHz channel bandwidth, normal CP, 64QAM  and  4x4 MIMO technology are used. Second: Calculate the number of resource elements (RE) in a subframe with 20 MHz channel bandwidth: 12 subcarriers x 7 OFDMA symbols x 100 resource blocks x 2 slots= 16800 REs per subframe. Each RE can carry a modulation symbol. Third:  Assume 64 QAM modulation and no coding, one modulation symbol will carry 6 bits. The total bits in a subframe (1ms) over 20 MHz channel is 16800 modulation symbols x 6 bits / modulation symbol = 100800 bits. So the data rate is 100800 bits / 1 ms = 100.8 Mbps. Fourth:  with 4x4 MIMO, the Peak Data rate goes up to 100.8 Mbps x 4 = 403 Mbps.