T

====================================================
[範例]
CTV(Chinese Translation Version)，中文譯稱。一段中文或英文的簡短說明:-:知識分類。====================================================
TA(Timing Advance)，提前時序。MS發送所需提前的時間。TA = round trip propagation delay = BTS下傳信號到MS所需時間 + MS上傳信號到BTS所需時間。GSM為了滿足上行TS(時槽)比下行TS時間上準確落後三個TS，MS在接到下行TS時，必須在(3 x TS - TA)的時間提前發送上行TS，這樣才能抵銷(下行+上行)的傳遞延遲，正好趕上第三個TS的要求。

TA是BTS根據MS上行的burst來計算的，每秒更新兩次。

TA由0 to 63個bit symbol來表示，0表示MS與BTS間沒有delay, 63表示GSM系統所能容忍的最大delay。1個bit symbol約= 3.597 us，約等於1km距離，所以1個symbol表示MS與BTS相距500m(1km/2=500m)。63個symbol表示MS與BTS相距最大約34km，這也是GSM系統的距離極限。

GSM400的TA可以高達219個bit symbol。

MS timing offset:
delay of the received signal relative to the expected signal from an MS at zero distance under static channel conditions with zero timing advance. This is accurate to ± 1 symbol, and reported once per SACCH or after a RACH as. required (i.e. at the same rate as timing advance). For example, for an MS with a round trip propagation delay of P symbols, but with a timing advance of T symbols, the reported timing offset will be P‑T quantized to the nearest symbol. For GPRS the MS timing offset is not reported. :-:GSM實體層參數名稱。
說明：GSM TS = 3/5200 s ~ 0.577 ms；可參考AFA(Adaptive Frame Alignment)

Ref:
[-]元智大學賴薇如教授，GSM教材，960117版。
[-] 3GPP TS 05.10 V8.12.0 (2003-08), GSM/EDGE Radio Access Network; Digital cellular telecommunications system (Phase 2+); Radio subsystem synchronization (Release 1999)

TAI(Timing Advance Index)，提前時序指示。Timing Advance Index TAI used for GPRS, which determines the position of the subchannel on PTCCH (see 3GPP TS 05.02) used by the MS to send an access burst, from which the network can derive the timing advance.:-:GPRS實體層參數。
Ref:
[-] 3GPP TS 05.10 V8.12.0 (2003-08), GSM/EDGE Radio Access Network;
Digital cellular telecommunications system (Phase 2+); Radio subsystem synchronization (Release 1999)

TDMA(Time Division Multiple Access)，分時多工。1. A communications technique that uses a common channel (multipoint or broadcast) for communications among multiple users by allocating unique time slots to different users. Note: TDMA is used extensively in satellite systems, local area networks, physical security systems, and combat-net radio systems. 2. A multiple access technique whereby users share a transmission medium by being assigned and using (one at a time) for a limited number of time division multiplexed channels; implies that several transmitters use one channel for sending several bit streams. [47CFR]:-:一種資源分享的方式。

Ref:
[1] ATIS Telecom Glossary 2000: TDMA

TS(Time Slot)，時槽。TDMA技術的專用名稱，指每位用戶在使用上所能分配到的連續時間最小單位。
以GSM而言，TS = 156.25 bit symbol = 3/5200 s = 0.577 ms，依照功能，GSM的TS可分成5種burst:
- Normal Burst
- Frequency Correction Burst
- Syncronization Burst
- Access Burst
- Dummy Burst

070819r8版本