This question was closed without grading. Reason: Answer found elsewhere
Mar 27, 2013 20:34
11 yrs ago
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English term
"extended CP" OFDM symbol
English to Polish
Tech/Engineering
Telecom(munications)
Metody dostępu do bezprz
OFDM (Orthogonal Frequency Division Multi-plexing) tego z tego co widzę się nie tłumaczy, ale co to jest to "extended CP"?
Kontekst:
Referring to FIG. 2, a time-domain diagram shows a "basic" dedicated basic ranging zone 201 defined for an
OFDM example system (the term "zone" is interchangeable herein with the term "interval" used in the figure), in accordance with some embodiments of the present invention. The duration of the dedicated basic ranging interval 201 consists of an interval of a special OFDM symbol 202 (denoted as "extended-CP" OFDM symbol) and a "dead interval" 204 that is a no-transmission interval equal to the maximum timing delay to be accommodated in the cell. The special OFDM symbol 202 has a duration equal to the sum of the duration of a special Fast Fourier Transform (FFT) window 209 and the duration of an extended cyclic prefix (CP) 203 wherein the CP represents the repeat of a portion of the signal as commonly known in OFDM. Hence, the special OFDM symbol is also referred to as an "extended-CP" OFDM symbol in FIG.2. The special Fast Fourier Transform (FFT) window 209 may be chosen conveniently to be the same as a "regular" OFDM symbol period in an example deployment of an OFDM system, or other designed value (discussed later). The duration of the extended CP 203 equals to the sum of the duration of a "regular" CP 205 and the maximum timing delay 206 to be accommodated. The maximum timing delay is chosen based on the possible timing differences among all possible subscriber locations. This value directly relates to the round-trip propagation delay and the cell size. Meanwhile, the duration of a "regular" CP 205 within the extended CP 203 is the same as the CP length defined for regular data transmissions if the invention is used for an OFDM system,. For other systems, the time duration of a regular CP is often chosen based on the excessive delay spread of the channels encountered in a deployment environment, which is also how the CP length is determined for OFDM systems. Lastly, as described above, the appended "dead" interval is chosen according to the maximal timing delay
Kontekst:
Referring to FIG. 2, a time-domain diagram shows a "basic" dedicated basic ranging zone 201 defined for an
OFDM example system (the term "zone" is interchangeable herein with the term "interval" used in the figure), in accordance with some embodiments of the present invention. The duration of the dedicated basic ranging interval 201 consists of an interval of a special OFDM symbol 202 (denoted as "extended-CP" OFDM symbol) and a "dead interval" 204 that is a no-transmission interval equal to the maximum timing delay to be accommodated in the cell. The special OFDM symbol 202 has a duration equal to the sum of the duration of a special Fast Fourier Transform (FFT) window 209 and the duration of an extended cyclic prefix (CP) 203 wherein the CP represents the repeat of a portion of the signal as commonly known in OFDM. Hence, the special OFDM symbol is also referred to as an "extended-CP" OFDM symbol in FIG.2. The special Fast Fourier Transform (FFT) window 209 may be chosen conveniently to be the same as a "regular" OFDM symbol period in an example deployment of an OFDM system, or other designed value (discussed later). The duration of the extended CP 203 equals to the sum of the duration of a "regular" CP 205 and the maximum timing delay 206 to be accommodated. The maximum timing delay is chosen based on the possible timing differences among all possible subscriber locations. This value directly relates to the round-trip propagation delay and the cell size. Meanwhile, the duration of a "regular" CP 205 within the extended CP 203 is the same as the CP length defined for regular data transmissions if the invention is used for an OFDM system,. For other systems, the time duration of a regular CP is often chosen based on the excessive delay spread of the channels encountered in a deployment environment, which is also how the CP length is determined for OFDM systems. Lastly, as described above, the appended "dead" interval is chosen according to the maximal timing delay
Discussion