(Global System for Mobile Communications Essays

(Global System for Mobile Communications Essays (Global System for Mobile Communications Essay (Global System for Mobile Communications Essay GSM Architecture of the GSM System GSM-elements interfaces System Architecture: Radio Subsystem Mobile Station (MS) Mobile Station (MS) Block Diagram of BTS with TRX Block Diagram of BTS Contd. Transmitter/Receiver Module – The TRX consists of a low-frequency part for digital signal processing and a high-frequency part for GMSK modulation and demodulation. The operations and maintenance (OM) module – connected directly to the BSC by means of a specifically assigned OM channel. That allows the OM module to process the commands from the BSC or the MSC directly into the BTS and to report the results – OM module provides a human-machine interface (HMI), which allows for local control of the BTS. BTS BSC Block Diagram of BSC BSC Contd†¦. Terminal Control Elements (TCEs) – Abis-Interface Terminal Control Elements Abis-TCEs are to set up LAPD connections toward the BTS peers, the transfer of signaling data, and last- but not lea st- the transparent transfer of payload. – A-Interface Terminal Control Elements The connection of a BSC to the MSC is established via the A-TCEs. A-TCEs is setting up and operating the SS7/SCCP connection toward the MSC. BSC Contd†¦. Database (DB) – maintenance status of the whole BSS, the quality of the radio resources and terrestrial resources, and so on are dynamically administrated – BSC database contains the complete BTS operations software for all attached BTSs and all BSS specific information,such as assigned frequencies. BSC Contd†¦. Central Module – One of the major tasks of the BSC is to decide when a handover should take place. The BSC may decide on intra-BTS handover and intraBSC handover without needing the MSC. In contrast, for all BSC external handovers, the BSC needs to involve the MSC. – Handover decision and power control are main tasks of the central module. Transcoding Rate and Adaptation Unit (TRAU) The task of the TRAU is to compress or decompress speech between the MS and the TRAU. – called regular pulse excitation–long term prediction (RPE-LTP) It is able to compress speech from 64 Kbps to 16 Kbps – Fullrate channel (net bit rate with fullrate is 13 Kbps) and to 8 Kbps in the case of a halfrate channel (net bit rate with halfrate is 6. Kbps) Possible Sites for TRAU System Architecture: Network and Switching Subsystem Home Location Register (HLR) Home Location Register manages the mobile subscribers database which stores – subscriber information – part of the mobile location information – International Mobile subscriber Identity – Mobile station ISDN Number It is the subscriber number commonly used – VLR address Vis itor Location Register (VLR) Dynamically stores subscriber information, needed to handle incoming/outgoing calls, which includes, – Mobile Station Roaming Number When a roaming mobile enters an MSC area. This MSC warns the associated VLR of this situation; the mobile enters a registration procedure through which it is assigned a mobile subscriber roaming number (MSRN) – Temporary Mobile Subscriber Identity, if applicable – The location area in which the mobile has been registered – Data related to supplementary service parameters MSC VLR MSC G-MSC The NSS hierarchy The NSS AUC/EIR Authentication Center(s) (AUC) – Providing the authentication key used for authorizing the subscriber access to the associated GSM PLMN. Equipment Identity Register(s) (EIR) – Handling Mobile Station Equipment Identity Equipment Identity Register(s) (EIR) White list: contains all the approved types of mobile stations Black list: contains those IMEIs known to be stolen or to be barred for technical reasons Gray list: allows tracing of the related mobile stations Numbering Arrangement in GSM International Mobile Subscriber Identification number (IMSI) It identifies a unique international universal number of a mobile subscriber, which consists of MCC+MNC+MSIN. ) MCC: country code, 460 2)MNC: network code, 00 or 01 3)MSIN: subscriber identification, H1H2H3H4 9XXXXXX, H1H2H3H4: subscriber registering place H1H2: assigned by the PT Administrative Bureau (operator )to different provinces, to each province H3H4: assigned by each province/city the IMSI of user will be written into the SIM card by specific device and software and be stored into the HLR with other user information. Numbering Arrangement in GSM Mobile Subscriber ISDN Number(MSISDN) It is the subscriber number commonly used. China uses the TDMA independent numbering plan: CC+NDC+ H1H2H3H4 +ABC CC: country code, 86 NDC: network code, 135- 139, 130 H1H2H3H4: HLR identification code ABCD: mobile subscriber number inside each HLR Numbering Arrangement in GSM International Mobile Equipment Identification code (IMEI) It will uniquely identify a mobile station. It is a decimal number of 15 digits. Its structure is: TAC+FAC+SNR+SP TAC=model ratification code, 6 digits FAC=factory assembling code, 2 digits SNR=sequence code, 6 digits SP=reserved, 1 digit Numbering Arrangement in GSM Mobile Subscriber Roaming Number (MSRN) The MSRN is temporarily distributed to the subscriber by the VLR according to the request by the HLR when this subscriber is called. The MSRN is released and can be assigned to other subscriber later. CC + NDC + 00 + M1M2M3 + ABC CC: country code, 86 NDC: mobile network code, 135- 139, 130 M1M2: same as the H2H3 of MSISDN ABC: 000 999 Numbering Arrangement in GSM Temporarily Mobile Subscriber Identification Number (TMSI) To insure the IMSI security, the VLR will assign an unique TMSI number for the accessed subscriber. It is used locally only and is a 4 GSM Mapping Example (DL) GSM Mapping Example (UL) Air Interface Protocols Air Interface Protocols Air Interface Protocols Block diagram of the base scenarios

Why the Spanish Verb Estar Is Used With Muerto

Why the Spanish Verb Estar Is Used With Muerto Finding the reason why estar is used instead of ser in sentences like mi padre est muerto is probably to be found somewhere in the history of the Spanish language rather than in any logical application of the rules of grammar. To the native Spanish speaker, ser and estar are two separate verbs, seldom interchangeable. But because they can both be translated as to be, they have been the source of confusion over the years to English speakers learning Spanish as a second language. Estar vs. Ser If grammar were only a matter of following rules, one could make good arguments for using either ser or estar. Rather than list opposing arguments (which would probably serve more to confuse than anything else), here are two related rules that make a good case for using estar. First is that when a form of ser is followed by a past participle, it generally refers to the process of a verbs action taking place, while estar followed by a participle generally refers to a completed action. For example, in los coches fueron rotos por los estudiantes (the cars were broken by the students), fueron rotos passively refers to the action of the cars being broken. But in los coches estaban rotos (the cars were broken), the cars had previously been broken. Similarly, the use of estar generally suggests there has been a change. For example, tà º eres feliz (you are happy) suggests the person is by nature happy, while tà º ests feliz (you are happy) suggests that the persons happiness represents a change from a previous state. Following either of these guidelines for choosing the right to be would result in the use of a form of estar in a sentence such as Mi padre est muerto. One might also come up with arguments for using ser, and ser is often the choice incorrectly made by beginning Spanish students. But the fact is that estar is used with muerto, and it is also used with vivo (alive): Mi padre est muerto; mi madre est viva. (My father is dead; my mother is alive.) All logic aside, the indisputable rule that estar is the verb of choice with muerto is just something youll have to remember. Thats just the way it is. And after a while, estar is the verb that will sound right.

American Foreign Policy Essay Example | Topics and Well Written Essays - 500 words - 3

American Foreign Policy - Essay Example A global hegemony cannot be decided based on public opinion. What matters is international legitimacy which comes from global coalition of willing nations. This is something which US continues to gain ground in thus proving that it is not in a decline. The US has taken the international community as a whole. However, it is worth pointing out that some of this has taken place in a rather begrudging manner. Its position as the world’s super power will only start to decline when the allegiances to the nation break down. America still wields influence, leadership and persuasion in the international stage just as it did decades ago. One clear illustration of this strong influence is its ability to set international laws and at the same time be able to ignore them as it is accountable to no other state in the world. Military power has always been an integral part of hegemony (Jerel and Scott 2014, 60). This was quite evident during the World War period where nations which had the strongest military wielded so much global power in terms of political economy and relations. USSR and the USA were leading in this. Military power depends entirely on economic resources which are at the disposal of the state. It is something which the US has making it the nation with perhaps the most sophisticated military. The US is still moving in a path of progressive and democratic governance. It recognizes the freedom of the press, religion, association and expression. This has earned it legitimate allies that look at the nation as a role model. Despite the fact that it is no saint when it comes to these governance issues, it has a legitimate team of allies that allow dictating stability and global shifts in terms of relations. Arguments have been put across that the growth of economies in certain world countries like China is causing a decline in US influence in global policies. However, this is not true as the economic growth in other nations will