- Teks
- Sejarah
W = 117"„ such that it is greater t
W = 117"„ such that it is greater than the fading rate f,, = 11To, by adding signal re-
dundancy. Error-correction coding can also provide mitigation: instead of provid-
ing more signal energy. a code reduces the required 551N, for a desired error
performance. For a given E1/NN, with coding present. the error floor out of the de-
modulator will not be lowered. but a lower error rate out of the decoder can be
achieved 114 Thus, with coding. one can get acceptable error performance and in
effect withstand a large error floor from the demodulator that might have other-
wise been unacceptable. To realize these coding benefits. errors out of the demod-
ulator should be uncorrelatcd (which will generally be the case in a fast-fading
environment), or an interleaver must be incorporated into the system design.
An interesting filtering technique can provide mitigation when fast-fading
distortion and frequency-selective distortion occur simultaneously. The frequency-
selective distortion can be mitigated by the use of an OFDM signal set. Fast fading.
however, will typically degrade conventional OFDM because the Doppler spreading
corrupts the onhogonality of the OFDM subcarriers. A polyphase filtering technique
1421 is used to provide time-domain shaping and partial-response coding (see Section
2.9) to reduce the spectral sidelobes of the signal set and thus help preserve its (Mho-
tonality. The process introduces known ISI and adjacent channel interference (AC).
which arc then removed by a post-processing equalizer and canceling filter [43].
15.5.3 Mitigation to Combat Lou in SNR
After implementing some mitigation technique to combat signal distortion due to
frequency-selective or fast fading. the next step is to use diversity methods to move
the system operating point from the error-performance curve labeled as "bad" in
Figure 15.17 to a curve that approaches AWGN performance. The term "diversity"
is used to denote the various methods available for providing the receiver with un-
correlated renditions of the signal of interest. Uncorrelated is the important feature
here. since it would not help the receiver to have additional copies of a signal if the
copies were all equally poor. Following are some of the ways in which diversity
methods can be implemented:
•
Time diversity can be provided by transmitting the signal on I. different time
slots with time separation of at least To Interleaving. when used along with
error-correction coding, is a form of lime diversity.
•
Frequency diversity can be provided by transmitting the signal on L different
carriers with frequency separation of at least fv. Bandwidth expansion is a
form of frequency diversity. The signal bandwidth IF is expanded so that it is
greater than ffo thus providing the receiver with several independently fading
signal replicas. This achieves frequency diversity of the order L= Wito. When-
dundancy. Error-correction coding can also provide mitigation: instead of provid-
ing more signal energy. a code reduces the required 551N, for a desired error
performance. For a given E1/NN, with coding present. the error floor out of the de-
modulator will not be lowered. but a lower error rate out of the decoder can be
achieved 114 Thus, with coding. one can get acceptable error performance and in
effect withstand a large error floor from the demodulator that might have other-
wise been unacceptable. To realize these coding benefits. errors out of the demod-
ulator should be uncorrelatcd (which will generally be the case in a fast-fading
environment), or an interleaver must be incorporated into the system design.
An interesting filtering technique can provide mitigation when fast-fading
distortion and frequency-selective distortion occur simultaneously. The frequency-
selective distortion can be mitigated by the use of an OFDM signal set. Fast fading.
however, will typically degrade conventional OFDM because the Doppler spreading
corrupts the onhogonality of the OFDM subcarriers. A polyphase filtering technique
1421 is used to provide time-domain shaping and partial-response coding (see Section
2.9) to reduce the spectral sidelobes of the signal set and thus help preserve its (Mho-
tonality. The process introduces known ISI and adjacent channel interference (AC).
which arc then removed by a post-processing equalizer and canceling filter [43].
15.5.3 Mitigation to Combat Lou in SNR
After implementing some mitigation technique to combat signal distortion due to
frequency-selective or fast fading. the next step is to use diversity methods to move
the system operating point from the error-performance curve labeled as "bad" in
Figure 15.17 to a curve that approaches AWGN performance. The term "diversity"
is used to denote the various methods available for providing the receiver with un-
correlated renditions of the signal of interest. Uncorrelated is the important feature
here. since it would not help the receiver to have additional copies of a signal if the
copies were all equally poor. Following are some of the ways in which diversity
methods can be implemented:
•
Time diversity can be provided by transmitting the signal on I. different time
slots with time separation of at least To Interleaving. when used along with
error-correction coding, is a form of lime diversity.
•
Frequency diversity can be provided by transmitting the signal on L different
carriers with frequency separation of at least fv. Bandwidth expansion is a
form of frequency diversity. The signal bandwidth IF is expanded so that it is
greater than ffo thus providing the receiver with several independently fading
signal replicas. This achieves frequency diversity of the order L= Wito. When-
0/5000
W = 117"" sedemikian rupa sehingga itu lebih besar daripada f tingkat memudar,, = 11To, dengan menambahkan sinyal re - dundancy. Koreksi kesalahan coding juga dapat menyediakan mitigasi: bukan provid - ing lebih sinyal energi. Kode mengurangi 551N diperlukan, untuk kesalahan yang diinginkan kinerja. Untuk diberikan E1/NN, dengan coding hadir. lantai kesalahan dari de- Modulator tidak akan diturunkan. tetapi tingkat kesalahan yang lebih rendah dari decoder yang dapat dicapai dengan demikian 114, dengan coding. satu bisa mendapatkan kinerja kesalahan dapat diterima dan dalam Efek menahan kesalahan besar lantai dari demodulator yang mungkin memiliki lain- bijaksana telah tidak dapat diterima. Menyadari ini coding manfaat. kesalahan dari demod- ulator harus uncorrelatcd (yang umumnya akan terjadi di cepat-memudar lingkungan), atau interleaver harus dimasukkan ke dalam desain sistem.Teknik penyaringan yang menarik dapat memberikan mitigasi ketika cepat-memudar distorsi dan penyimpangan frekuensi-selektif terjadi secara bersamaan. Frekuensi- distorsi selektif dapat dikurangi dengan menggunakan set yang sinyal OFDM. Cepat memudar. Namun, akan biasanya menurunkan OFDM konvensional karena penyebaran Doppler merusak onhogonality OFDM subcarriers. Polyphase penyaringan teknik 1421 digunakan untuk menyediakan waktu-domain membentuk dan parsial-respon coding (Lihat bagian 2.9) untuk mengurangi sidelobes spektral set sinyal dan dengan demikian membantu melestarikan nya (Mho- nada suara. Proses memperkenalkan dikenal ISI dan gangguan saluran berdekatan (AC). busur yang kemudian dihapus oleh equaliser pasca-pengolahan dan membatalkan menyaring [43].15.5.3 mitigasi untuk memerangi Lou di SNRSetelah menerapkan beberapa teknik mitigasi untuk memerangi sinyal distorsi karena frekuensi-selektif atau cepat memudar. langkah berikutnya adalah untuk menggunakan keragaman metode untuk memindahkan sistem operasi titik dari kurva kesalahan performa yang dicap sebagai "buruk" dalam Gambar 15.17 untuk kurva yang mendekati AWGN kinerja. Istilah "keragaman" digunakan untuk menunjukkan berbagai metode yang tersedia untuk menyediakan penerima dengan un- penafsiran berkorelasi sinyal menarik. Tidak berkorelasi adalah fitur penting Sini. karena itu tidak akan membantu penerima untuk memiliki salinan tambahan sinyal jika salinan yang semua sama miskin. Berikut adalah beberapa cara di mana keragaman metode dapat dilaksanakan:• Waktu keragaman dapat disediakan oleh transmisi sinyal pada waktu yang berbeda I. slot dengan waktu pemisahan setidaknya untuk Interleaving. Ketika digunakan bersama dengan koreksi kesalahan coding, adalah bentuk keanekaragaman kapur.• Frekuensi keragaman dapat disediakan oleh transmisi sinyal pada L berbeda operator dengan frekuensi pemisahan di fv setidaknya. Bandwidth ekspansi bentuk frekuensi keragaman. Bandwidth sinyal jika diperluas sehingga lebih dari ffo sehingga memberikan penerima dengan beberapa independen memudar sinyal replika. Ini mencapai frekuensi keragaman urutan L = Wito. Ketika-
Sedang diterjemahkan, harap tunggu..
W = 117"„ such that it is greater than the fading rate f,, = 11To, by adding signal re-
dundancy. Error-correction coding can also provide mitigation: instead of provid-
ing more signal energy. a code reduces the required 551N, for a desired error
performance. For a given E1/NN, with coding present. the error floor out of the de-
modulator will not be lowered. but a lower error rate out of the decoder can be
achieved 114 Thus, with coding. one can get acceptable error performance and in
effect withstand a large error floor from the demodulator that might have other-
wise been unacceptable. To realize these coding benefits. errors out of the demod-
ulator should be uncorrelatcd (which will generally be the case in a fast-fading
environment), or an interleaver must be incorporated into the system design.
An interesting filtering technique can provide mitigation when fast-fading
distortion and frequency-selective distortion occur simultaneously. The frequency-
selective distortion can be mitigated by the use of an OFDM signal set. Fast fading.
however, will typically degrade conventional OFDM because the Doppler spreading
corrupts the onhogonality of the OFDM subcarriers. A polyphase filtering technique
1421 is used to provide time-domain shaping and partial-response coding (see Section
2.9) to reduce the spectral sidelobes of the signal set and thus help preserve its (Mho-
tonality. The process introduces known ISI and adjacent channel interference (AC).
which arc then removed by a post-processing equalizer and canceling filter [43].
15.5.3 Mitigation to Combat Lou in SNR
After implementing some mitigation technique to combat signal distortion due to
frequency-selective or fast fading. the next step is to use diversity methods to move
the system operating point from the error-performance curve labeled as "bad" in
Figure 15.17 to a curve that approaches AWGN performance. The term "diversity"
is used to denote the various methods available for providing the receiver with un-
correlated renditions of the signal of interest. Uncorrelated is the important feature
here. since it would not help the receiver to have additional copies of a signal if the
copies were all equally poor. Following are some of the ways in which diversity
methods can be implemented:
•
Time diversity can be provided by transmitting the signal on I. different time
slots with time separation of at least To Interleaving. when used along with
error-correction coding, is a form of lime diversity.
•
Frequency diversity can be provided by transmitting the signal on L different
carriers with frequency separation of at least fv. Bandwidth expansion is a
form of frequency diversity. The signal bandwidth IF is expanded so that it is
greater than ffo thus providing the receiver with several independently fading
signal replicas. This achieves frequency diversity of the order L= Wito. When-
dundancy. Error-correction coding can also provide mitigation: instead of provid-
ing more signal energy. a code reduces the required 551N, for a desired error
performance. For a given E1/NN, with coding present. the error floor out of the de-
modulator will not be lowered. but a lower error rate out of the decoder can be
achieved 114 Thus, with coding. one can get acceptable error performance and in
effect withstand a large error floor from the demodulator that might have other-
wise been unacceptable. To realize these coding benefits. errors out of the demod-
ulator should be uncorrelatcd (which will generally be the case in a fast-fading
environment), or an interleaver must be incorporated into the system design.
An interesting filtering technique can provide mitigation when fast-fading
distortion and frequency-selective distortion occur simultaneously. The frequency-
selective distortion can be mitigated by the use of an OFDM signal set. Fast fading.
however, will typically degrade conventional OFDM because the Doppler spreading
corrupts the onhogonality of the OFDM subcarriers. A polyphase filtering technique
1421 is used to provide time-domain shaping and partial-response coding (see Section
2.9) to reduce the spectral sidelobes of the signal set and thus help preserve its (Mho-
tonality. The process introduces known ISI and adjacent channel interference (AC).
which arc then removed by a post-processing equalizer and canceling filter [43].
15.5.3 Mitigation to Combat Lou in SNR
After implementing some mitigation technique to combat signal distortion due to
frequency-selective or fast fading. the next step is to use diversity methods to move
the system operating point from the error-performance curve labeled as "bad" in
Figure 15.17 to a curve that approaches AWGN performance. The term "diversity"
is used to denote the various methods available for providing the receiver with un-
correlated renditions of the signal of interest. Uncorrelated is the important feature
here. since it would not help the receiver to have additional copies of a signal if the
copies were all equally poor. Following are some of the ways in which diversity
methods can be implemented:
•
Time diversity can be provided by transmitting the signal on I. different time
slots with time separation of at least To Interleaving. when used along with
error-correction coding, is a form of lime diversity.
•
Frequency diversity can be provided by transmitting the signal on L different
carriers with frequency separation of at least fv. Bandwidth expansion is a
form of frequency diversity. The signal bandwidth IF is expanded so that it is
greater than ffo thus providing the receiver with several independently fading
signal replicas. This achieves frequency diversity of the order L= Wito. When-
Sedang diterjemahkan, harap tunggu..
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- Czech J. Food Sci. Vol. 27, 2009, Specia
- dingin hujan
- Czech J. Food Sci. Vol. 27, 2009, Specia
- DACs are implemented with Σ-Δ converters
- kamu tak akan pergi dari hidup aku
- 2 ns, then using Equation (15.21), it ca
- sekolah pulang pagi
- siapa itu?
- Keywords: GMO detection; papaya; PCR; DN
- Yo no quiero un suegro
- Keywords: GMO detection; papaya; PCR; DN
- Dear' MrLogo dengan simbol huruf 4 tanda
- The delta modulator. often denoted .1 mo
- semoga tambah romantis dan hubungannya s
- tak kenal maka tak sayang
- Belakangan
- semoga tambah romantis dan hubungannya s
- ayah
- anda suka gambar apa
- Penyesalan
- semoga tambah romantis dan hubungannya s
- berjanji pada aku
- Terkadang,sendiri lebih baik
- kaisar
