Redes de datos móviles en Tercera Generación.

Presentación del tema: "Redes de datos móviles en Tercera Generación."— Transcripción de la presentación:

1 Redes de datos móviles en Tercera Generación.
Autor: Francisco Varela Departamento de Comunicaciones Universidad Central de Venezuela SEMINARIO WIRELESS.

2 Hacia la tercera generación en Redes de datos

3 Hacia la tercera generación en Redes de datos

4 Hacia la tercera generación en Redes de datos
PDC GSM 3G IS - 136 2G 95 A 2.5G EDGE W CDMA (UMTS) Migración 2 a 3 Generación GPRS HSCSD TD SCDMA 3GPP2 1xEV DO 2000 1xRTT B 3GPP da ra Hacia la tercera generación en Redes de datos

5 Hacia la tercera generación en Redes de datos

6 Definición de términos
CDMA Forward Channel o Downlink (Estación Base - Estación Móvil) CDMA Reverse Channel o Uplink (Estación Movil - Estación Base) Separación de Los canales En 800 MHz (tecnología Celular) Mhz En 1900 MHz (tecnología PCS) Mhz Canales en Forward link: Pilot, Sync, Paging y canal de Tráfico Forward Canales en el reverse Link: Canales de Tráfico: Acceso y reverso.

7 Asignación del espectro en Tercera Generación.

8 CDMA CDMA Tiempo 1.25 MHz Frecuencia 45 /80Mhz

9 Otros Esquemas de Acceso. Primera y Segunada Generación

10 Frecuency Hopping: Saltos de Frecuencia.
Time

11 DIAGRAMA EN BLOQUES DE CDMA
CDMA Carrier Voice Privacy BTS Code Vocoder External Interference Encoding & Interleaving BPF 9.6 Kbps 19.2 Kbps 1.2288 Mbps Voice 10 KHz 1.23 MHz Background Noise Walsh Code 20 ms Frames Other User Noise Voice Privacy Decorrelated Signal 20 ms Frames Vocoder Correlator Voice 10 KHz Decoding & DeInterleaving BPF Digital Filter Other Cell Interference 9.6 Kbps 19.2 Kbps 1.23 MHz Walsh Code BTS Code 1.2288 Mbps Composite Signal

12 El Concepto CDMA CDMA comienza con una señal de banda estrecha, mostrada aquí como la velocidad completa de datos de conversación de 9600 bps. esta señal se dispersa con el uso de códigos especializados a un ancho de banda de 1.23 MHz. La relación de la velocidad de los datos dispersos a la velocidad inicial de los datos se denomina ganancia de procesamiento. Cuando se recibe la señal el correlacionador recupera la señal deseada del ruido.

13 PROCESO DE EXPANSIÓN ESPECTRAL
Ganancia de Proceso (Processing Gain): = 20 dB Relación de la velocidad de los datos dispersos a la velocidad inicial PN: Codigo Pseudo ruido

14 PROCESO DE EXPANSIÓN ESPECTRAL
Ganancia de Proceso (Processing Gain): = 20 dB Relación de la velocidad de los datos dispersos a la velocidad inicial

15 Relaciones de densidad de energía de bit a ruido

16 Secuencias De Ensanchamiento (SPREAD SPECTRUM)
B C C B A CDMA Combina tres diferentes secuencias de ensanchamiento para crear canales únicos y robustos

17 Una estación movil recibe canal CDMA Forward desde un Sector de una Estación Base
The intent of this slide is to show the fundamental differences between a Frequency Division Analog technology, a Time Division Digital technology and a Code Division Digital technology. FDMA - Frequency Division Multiple Access FDMA is used for standard analog cellular. FDMA permitsonly one user per channel since it allows the user to usethe channel 100% of the time. So only the frequency and not the time "domain" are used to channelize. However, it hasthe advantage that all information is sent in "real time." Each user is assigned a discrete slice of the RF spectrum.For the AMPS air interface, this slice is 30 kHz wide. For NAMPS, the slice is 10 KHz wide. TDMA - Time Division Multiple Access The TDMA being referred to here is the IS-54 air interface.The key point to make about TDMA is that users are still assigned a discrete 30 kHz slice of RF spectrum (since thistechnique was designed to easily co-exist with AMPS), but three users must now share that RF channel on a time slot basis. Each of the three users alternate their use of theRF channel. FDMA is still employed, but these channels are now further sub-divided into "time", namely 3 time slots per FDMA channel and then the process repeats itself. For TDMA systems, the FDMA portions are usually referred to as "carriers" for the time slotted "channels". A user isassigned a particular time slot in a channel and can only send or receive information at those times. Other users will be using the other time slots. So information flow is not continuous for any user, but rather is sent and received in "bursts". The bursts are "glued" together at the receiving end and sound "continuous" because the process isvery fast. (Figure 2) GSM is also a TDMA technology, but it uses channels that are200KHz wide, and sub-divided into 8 time slots for eachchannel. This does not offer any spectrum efficiency over analog TACS, since you still have 8 users in 200KHz. (8 X25KHz = 200KHz) CDMA - Code Division Multiple Access There are several types of CDMA. The type cellular will use is called Direct Sequence (DS) CDMA. Notice that the channel, or again the "carrier", is very wide MHz. The traffic channels are created by assigning each user a seperate "code", and spreading each code over the entire carrier - both in time and in frequency. Therefore the example shows the users being "layered" on top of each other, but their"patterns" are different, which is what separates them. To understand the difference, imagine a room with several "pairs" of people in it. The pairs only want to talk and listen to themselves and have no interest in the others. If each pair only knows one language and uses it, and all the languages are different, they can all use the air in the room as a "carrier" for their voices and experience little interference from the other pairs. The analogy here is that the air in the room is a very wideband "carrier" and the languages are the "codes". If we incorporate language "filters", people speaking German will not hear those speaking Spanish, etc. We continue to add users until the overall "background noise" (interference from other users) limits us. By controlling the signal strength of all users to no more than necessary, while maintaining high quality conversations, we get many users per carrier. The maximum number of users or channels per carrier depends on the amount of activity that is going on on each carrier and is therefore not precise. It is a "soft overload" concept where an additional user (or pair in our analogy) can usually be accommodated if necessary, at the "cost" of a bit more interference to the other users. Pilot Sync Estación Móvil Estación Base Algunos de estos canales son canales de tráfico mientras otros de encabezamiento : UN conjunto de 64 códigos matemáticos son necesarios para diferenciar los 64 Forward Code Chanel Posibles . Estos códigos son llamadaos Walsh Codes

18 Discriminación de Estaciones Bases
64 Canales Códigos The intent of this slide is to show the fundamental differences between a Frequency Division Analog technology, a Time Division Digital technology and a Code Division Digital technology. FDMA - Frequency Division Multiple Access FDMA is used for standard analog cellular. FDMA permitsonly one user per channel since it allows the user to usethe channel 100% of the time. So only the frequency and not the time "domain" are used to channelize. However, it hasthe advantage that all information is sent in "real time." Each user is assigned a discrete slice of the RF spectrum.For the AMPS air interface, this slice is 30 kHz wide. For NAMPS, the slice is 10 KHz wide. TDMA - Time Division Multiple Access The TDMA being referred to here is the IS-54 air interface.The key point to make about TDMA is that users are still assigned a discrete 30 kHz slice of RF spectrum (since thistechnique was designed to easily co-exist with AMPS), but three users must now share that RF channel on a time slot basis. Each of the three users alternate their use of theRF channel. FDMA is still employed, but these channels are now further sub-divided into "time", namely 3 time slots per FDMA channel and then the process repeats itself. For TDMA systems, the FDMA portions are usually referred to as "carriers" for the time slotted "channels". A user isassigned a particular time slot in a channel and can only send or receive information at those times. Other users will be using the other time slots. So information flow is not continuous for any user, but rather is sent and received in "bursts". The bursts are "glued" together at the receiving end and sound "continuous" because the process isvery fast. (Figure 2) GSM is also a TDMA technology, but it uses channels that are200KHz wide, and sub-divided into 8 time slots for eachchannel. This does not offer any spectrum efficiency over analog TACS, since you still have 8 users in 200KHz. (8 X25KHz = 200KHz) CDMA - Code Division Multiple Access There are several types of CDMA. The type cellular will use is called Direct Sequence (DS) CDMA. Notice that the channel, or again the "carrier", is very wide MHz. The traffic channels are created by assigning each user a seperate "code", and spreading each code over the entire carrier - both in time and in frequency. Therefore the example shows the users being "layered" on top of each other, but their"patterns" are different, which is what separates them. To understand the difference, imagine a room with several "pairs" of people in it. The pairs only want to talk and listen to themselves and have no interest in the others. If each pair only knows one language and uses it, and all the languages are different, they can all use the air in the room as a "carrier" for their voices and experience little interference from the other pairs. The analogy here is that the air in the room is a very wideband "carrier" and the languages are the "codes". If we incorporate language "filters", people speaking German will not hear those speaking Spanish, etc. We continue to add users until the overall "background noise" (interference from other users) limits us. By controlling the signal strength of all users to no more than necessary, while maintaining high quality conversations, we get many users per carrier. The maximum number of users or channels per carrier depends on the amount of activity that is going on on each carrier and is therefore not precise. It is a "soft overload" concept where an additional user (or pair in our analogy) can usually be accommodated if necessary, at the "cost" of a bit more interference to the other users. 64 Canales Códigos Estación Base 1 Estación Base 2 Una estación movil debe ser capaz de discriminar entre diferentes estaciones bases . Cada estación base está transmitiendo un canal de tráfico que contiene 64 códigos diferentes de canales forward.. Dos secuencias de dígitos binarios llamadas las secuencias de códicos cortos PN I y Q, los cuales son definidos con el propósito de identificar sectores de diferentes estaciones bases.

19 Discriminación de los canales códigos Reversos
The intent of this slide is to show the fundamental differences between a Frequency Division Analog technology, a Time Division Digital technology and a Code Division Digital technology. FDMA - Frequency Division Multiple Access FDMA is used for standard analog cellular. FDMA permitsonly one user per channel since it allows the user to usethe channel 100% of the time. So only the frequency and not the time "domain" are used to channelize. However, it hasthe advantage that all information is sent in "real time." Each user is assigned a discrete slice of the RF spectrum.For the AMPS air interface, this slice is 30 kHz wide. For NAMPS, the slice is 10 KHz wide. TDMA - Time Division Multiple Access The TDMA being referred to here is the IS-54 air interface.The key point to make about TDMA is that users are still assigned a discrete 30 kHz slice of RF spectrum (since thistechnique was designed to easily co-exist with AMPS), but three users must now share that RF channel on a time slot basis. Each of the three users alternate their use of theRF channel. FDMA is still employed, but these channels are now further sub-divided into "time", namely 3 time slots per FDMA channel and then the process repeats itself. For TDMA systems, the FDMA portions are usually referred to as "carriers" for the time slotted "channels". A user isassigned a particular time slot in a channel and can only send or receive information at those times. Other users will be using the other time slots. So information flow is not continuous for any user, but rather is sent and received in "bursts". The bursts are "glued" together at the receiving end and sound "continuous" because the process isvery fast. (Figure 2) GSM is also a TDMA technology, but it uses channels that are200KHz wide, and sub-divided into 8 time slots for eachchannel. This does not offer any spectrum efficiency over analog TACS, since you still have 8 users in 200KHz. (8 X25KHz = 200KHz) CDMA - Code Division Multiple Access There are several types of CDMA. The type cellular will use is called Direct Sequence (DS) CDMA. Notice that the channel, or again the "carrier", is very wide MHz. The traffic channels are created by assigning each user a seperate "code", and spreading each code over the entire carrier - both in time and in frequency. Therefore the example shows the users being "layered" on top of each other, but their"patterns" are different, which is what separates them. To understand the difference, imagine a room with several "pairs" of people in it. The pairs only want to talk and listen to themselves and have no interest in the others. If each pair only knows one language and uses it, and all the languages are different, they can all use the air in the room as a "carrier" for their voices and experience little interference from the other pairs. The analogy here is that the air in the room is a very wideband "carrier" and the languages are the "codes". If we incorporate language "filters", people speaking German will not hear those speaking Spanish, etc. We continue to add users until the overall "background noise" (interference from other users) limits us. By controlling the signal strength of all users to no more than necessary, while maintaining high quality conversations, we get many users per carrier. The maximum number of users or channels per carrier depends on the amount of activity that is going on on each carrier and is therefore not precise. It is a "soft overload" concept where an additional user (or pair in our analogy) can usually be accommodated if necessary, at the "cost" of a bit more interference to the other users. El sistema CDMA debe ser capaz de identificar cada estación movil que desea intentar comunicarse con una estación base. Un gran número de estaciones moviles estarán en el mercado. Una secuencia de binaria llamada la secuencia larga PN istá definida para identificar cada canal reverso diferentes estaciones bases.

20 Total de canales CDMA Walsh Code: Usuario Individual The intent of this slide is to show the fundamental differences between a Frequency Division Analog technology, a Time Division Digital technology and a Code Division Digital technology. FDMA - Frequency Division Multiple Access FDMA is used for standard analog cellular. FDMA permitsonly one user per channel since it allows the user to usethe channel 100% of the time. So only the frequency and not the time "domain" are used to channelize. However, it hasthe advantage that all information is sent in "real time." Each user is assigned a discrete slice of the RF spectrum.For the AMPS air interface, this slice is 30 kHz wide. For NAMPS, the slice is 10 KHz wide. TDMA - Time Division Multiple Access The TDMA being referred to here is the IS-54 air interface.The key point to make about TDMA is that users are still assigned a discrete 30 kHz slice of RF spectrum (since thistechnique was designed to easily co-exist with AMPS), but three users must now share that RF channel on a time slot basis. Each of the three users alternate their use of theRF channel. FDMA is still employed, but these channels are now further sub-divided into "time", namely 3 time slots per FDMA channel and then the process repeats itself. For TDMA systems, the FDMA portions are usually referred to as "carriers" for the time slotted "channels". A user isassigned a particular time slot in a channel and can only send or receive information at those times. Other users will be using the other time slots. So information flow is not continuous for any user, but rather is sent and received in "bursts". The bursts are "glued" together at the receiving end and sound "continuous" because the process isvery fast. (Figure 2) GSM is also a TDMA technology, but it uses channels that are200KHz wide, and sub-divided into 8 time slots for eachchannel. This does not offer any spectrum efficiency over analog TACS, since you still have 8 users in 200KHz. (8 X25KHz = 200KHz) CDMA - Code Division Multiple Access There are several types of CDMA. The type cellular will use is called Direct Sequence (DS) CDMA. Notice that the channel, or again the "carrier", is very wide MHz. The traffic channels are created by assigning each user a seperate "code", and spreading each code over the entire carrier - both in time and in frequency. Therefore the example shows the users being "layered" on top of each other, but their"patterns" are different, which is what separates them. To understand the difference, imagine a room with several "pairs" of people in it. The pairs only want to talk and listen to themselves and have no interest in the others. If each pair only knows one language and uses it, and all the languages are different, they can all use the air in the room as a "carrier" for their voices and experience little interference from the other pairs. The analogy here is that the air in the room is a very wideband "carrier" and the languages are the "codes". If we incorporate language "filters", people speaking German will not hear those speaking Spanish, etc. We continue to add users until the overall "background noise" (interference from other users) limits us. By controlling the signal strength of all users to no more than necessary, while maintaining high quality conversations, we get many users per carrier. The maximum number of users or channels per carrier depends on the amount of activity that is going on on each carrier and is therefore not precise. It is a "soft overload" concept where an additional user (or pair in our analogy) can usually be accommodated if necessary, at the "cost" of a bit more interference to the other users. PN SHORT CODE: Sector Estación Base PN LONG CODES: Cada teléfono Los tres códigos SPREAD SPECTRUM son usados de diferentes maneras para crear y asegurar la existencia de los enlaces entrantes y salientes.

21 Códigos CDMA PN SHORT y LONG
CDMA usa tres códigos de secuencias PN: dos cortos y uno largo The intent of this slide is to show the fundamental differences between a Frequency Division Analog technology, a Time Division Digital technology and a Code Division Digital technology. FDMA - Frequency Division Multiple Access FDMA is used for standard analog cellular. FDMA permitsonly one user per channel since it allows the user to usethe channel 100% of the time. So only the frequency and not the time "domain" are used to channelize. However, it hasthe advantage that all information is sent in "real time." Each user is assigned a discrete slice of the RF spectrum.For the AMPS air interface, this slice is 30 kHz wide. For NAMPS, the slice is 10 KHz wide. TDMA - Time Division Multiple Access The TDMA being referred to here is the IS-54 air interface.The key point to make about TDMA is that users are still assigned a discrete 30 kHz slice of RF spectrum (since thistechnique was designed to easily co-exist with AMPS), but three users must now share that RF channel on a time slot basis. Each of the three users alternate their use of theRF channel. FDMA is still employed, but these channels are now further sub-divided into "time", namely 3 time slots per FDMA channel and then the process repeats itself. For TDMA systems, the FDMA portions are usually referred to as "carriers" for the time slotted "channels". A user isassigned a particular time slot in a channel and can only send or receive information at those times. Other users will be using the other time slots. So information flow is not continuous for any user, but rather is sent and received in "bursts". The bursts are "glued" together at the receiving end and sound "continuous" because the process isvery fast. (Figure 2) GSM is also a TDMA technology, but it uses channels that are200KHz wide, and sub-divided into 8 time slots for eachchannel. This does not offer any spectrum efficiency over analog TACS, since you still have 8 users in 200KHz. (8 X25KHz = 200KHz) CDMA - Code Division Multiple Access There are several types of CDMA. The type cellular will use is called Direct Sequence (DS) CDMA. Notice that the channel, or again the "carrier", is very wide MHz. The traffic channels are created by assigning each user a seperate "code", and spreading each code over the entire carrier - both in time and in frequency. Therefore the example shows the users being "layered" on top of each other, but their"patterns" are different, which is what separates them. To understand the difference, imagine a room with several "pairs" of people in it. The pairs only want to talk and listen to themselves and have no interest in the others. If each pair only knows one language and uses it, and all the languages are different, they can all use the air in the room as a "carrier" for their voices and experience little interference from the other pairs. The analogy here is that the air in the room is a very wideband "carrier" and the languages are the "codes". If we incorporate language "filters", people speaking German will not hear those speaking Spanish, etc. We continue to add users until the overall "background noise" (interference from other users) limits us. By controlling the signal strength of all users to no more than necessary, while maintaining high quality conversations, we get many users per carrier. The maximum number of users or channels per carrier depends on the amount of activity that is going on on each carrier and is therefore not precise. It is a "soft overload" concept where an additional user (or pair in our analogy) can usually be accommodated if necessary, at the "cost" of a bit more interference to the other users. Los dos códigos cortos PN ( lllamados I y Q) están espandidos en cuadratura para diferenciar particiones (sectores/celdas) en la dirección entrante. Se crean mediante generadores de códigos PN de 15 bits. La cantidad de combinaciones generadas son 2^ más una cadena de ceros en la de mayor ceros generados . Su período es de ms

22 Codigos CDMA PN SHORT y LONG
The intent of this slide is to show the fundamental differences between a Frequency Division Analog technology, a Time Division Digital technology and a Code Division Digital technology. FDMA - Frequency Division Multiple Access FDMA is used for standard analog cellular. FDMA permitsonly one user per channel since it allows the user to usethe channel 100% of the time. So only the frequency and not the time "domain" are used to channelize. However, it hasthe advantage that all information is sent in "real time." Each user is assigned a discrete slice of the RF spectrum.For the AMPS air interface, this slice is 30 kHz wide. For NAMPS, the slice is 10 KHz wide. TDMA - Time Division Multiple Access The TDMA being referred to here is the IS-54 air interface.The key point to make about TDMA is that users are still assigned a discrete 30 kHz slice of RF spectrum (since thistechnique was designed to easily co-exist with AMPS), but three users must now share that RF channel on a time slot basis. Each of the three users alternate their use of theRF channel. FDMA is still employed, but these channels are now further sub-divided into "time", namely 3 time slots per FDMA channel and then the process repeats itself. For TDMA systems, the FDMA portions are usually referred to as "carriers" for the time slotted "channels". A user isassigned a particular time slot in a channel and can only send or receive information at those times. Other users will be using the other time slots. So information flow is not continuous for any user, but rather is sent and received in "bursts". The bursts are "glued" together at the receiving end and sound "continuous" because the process isvery fast. (Figure 2) GSM is also a TDMA technology, but it uses channels that are200KHz wide, and sub-divided into 8 time slots for eachchannel. This does not offer any spectrum efficiency over analog TACS, since you still have 8 users in 200KHz. (8 X25KHz = 200KHz) CDMA - Code Division Multiple Access There are several types of CDMA. The type cellular will use is called Direct Sequence (DS) CDMA. Notice that the channel, or again the "carrier", is very wide MHz. The traffic channels are created by assigning each user a seperate "code", and spreading each code over the entire carrier - both in time and in frequency. Therefore the example shows the users being "layered" on top of each other, but their"patterns" are different, which is what separates them. To understand the difference, imagine a room with several "pairs" of people in it. The pairs only want to talk and listen to themselves and have no interest in the others. If each pair only knows one language and uses it, and all the languages are different, they can all use the air in the room as a "carrier" for their voices and experience little interference from the other pairs. The analogy here is that the air in the room is a very wideband "carrier" and the languages are the "codes". If we incorporate language "filters", people speaking German will not hear those speaking Spanish, etc. We continue to add users until the overall "background noise" (interference from other users) limits us. By controlling the signal strength of all users to no more than necessary, while maintaining high quality conversations, we get many users per carrier. The maximum number of users or channels per carrier depends on the amount of activity that is going on on each carrier and is therefore not precise. It is a "soft overload" concept where an additional user (or pair in our analogy) can usually be accommodated if necessary, at the "cost" of a bit more interference to the other users. El código largo es creado por un generador de 42 bits y es usado para ensanchar el espectro de la data con cierta aleatoriedad. La cantidad de cadenas generadas está alrededor de 4.4 trillones de combinaciones y su ciclo periódico es de aproximadamente 41 dias, 10 horas, 12 minutos y 19.4 segundos. Los tres códigos son sincronizados al comienzo de la puesta del sistema Los dos códigos cortos PN ( lllamados I y Q) están espandidos en cuadratura para diferenciar particiones (sectores/celdas) en la dirección entrante. Se crean mediante generadores de códigos PN de 15 bits. La cantidad de combinaciones generadas son 2^ más una cadena de ceros en la de mayor ceros generados . Su período es de ms

23 Generación del código Walsh
1 The intent of this slide is to show the fundamental differences between a Frequency Division Analog technology, a Time Division Digital technology and a Code Division Digital technology. FDMA - Frequency Division Multiple Access FDMA is used for standard analog cellular. FDMA permitsonly one user per channel since it allows the user to usethe channel 100% of the time. So only the frequency and not the time "domain" are used to channelize. However, it hasthe advantage that all information is sent in "real time." Each user is assigned a discrete slice of the RF spectrum.For the AMPS air interface, this slice is 30 kHz wide. For NAMPS, the slice is 10 KHz wide. TDMA - Time Division Multiple Access The TDMA being referred to here is the IS-54 air interface.The key point to make about TDMA is that users are still assigned a discrete 30 kHz slice of RF spectrum (since thistechnique was designed to easily co-exist with AMPS), but three users must now share that RF channel on a time slot basis. Each of the three users alternate their use of theRF channel. FDMA is still employed, but these channels are now further sub-divided into "time", namely 3 time slots per FDMA channel and then the process repeats itself. For TDMA systems, the FDMA portions are usually referred to as "carriers" for the time slotted "channels". A user isassigned a particular time slot in a channel and can only send or receive information at those times. Other users will be using the other time slots. So information flow is not continuous for any user, but rather is sent and received in "bursts". The bursts are "glued" together at the receiving end and sound "continuous" because the process isvery fast. (Figure 2) GSM is also a TDMA technology, but it uses channels that are200KHz wide, and sub-divided into 8 time slots for eachchannel. This does not offer any spectrum efficiency over analog TACS, since you still have 8 users in 200KHz. (8 X25KHz = 200KHz) CDMA - Code Division Multiple Access There are several types of CDMA. The type cellular will use is called Direct Sequence (DS) CDMA. Notice that the channel, or again the "carrier", is very wide MHz. The traffic channels are created by assigning each user a seperate "code", and spreading each code over the entire carrier - both in time and in frequency. Therefore the example shows the users being "layered" on top of each other, but their"patterns" are different, which is what separates them. To understand the difference, imagine a room with several "pairs" of people in it. The pairs only want to talk and listen to themselves and have no interest in the others. If each pair only knows one language and uses it, and all the languages are different, they can all use the air in the room as a "carrier" for their voices and experience little interference from the other pairs. The analogy here is that the air in the room is a very wideband "carrier" and the languages are the "codes". If we incorporate language "filters", people speaking German will not hear those speaking Spanish, etc. We continue to add users until the overall "background noise" (interference from other users) limits us. By controlling the signal strength of all users to no more than necessary, while maintaining high quality conversations, we get many users per carrier. The maximum number of users or channels per carrier depends on the amount of activity that is going on on each carrier and is therefore not precise. It is a "soft overload" concept where an additional user (or pair in our analogy) can usually be accommodated if necessary, at the "cost" of a bit more interference to the other users. 1

24 Generación del código Walsh
The intent of this slide is to show the fundamental differences between a Frequency Division Analog technology, a Time Division Digital technology and a Code Division Digital technology. FDMA - Frequency Division Multiple Access FDMA is used for standard analog cellular. FDMA permitsonly one user per channel since it allows the user to usethe channel 100% of the time. So only the frequency and not the time "domain" are used to channelize. However, it hasthe advantage that all information is sent in "real time." Each user is assigned a discrete slice of the RF spectrum.For the AMPS air interface, this slice is 30 kHz wide. For NAMPS, the slice is 10 KHz wide. TDMA - Time Division Multiple Access The TDMA being referred to here is the IS-54 air interface.The key point to make about TDMA is that users are still assigned a discrete 30 kHz slice of RF spectrum (since thistechnique was designed to easily co-exist with AMPS), but three users must now share that RF channel on a time slot basis. Each of the three users alternate their use of theRF channel. FDMA is still employed, but these channels are now further sub-divided into "time", namely 3 time slots per FDMA channel and then the process repeats itself. For TDMA systems, the FDMA portions are usually referred to as "carriers" for the time slotted "channels". A user isassigned a particular time slot in a channel and can only send or receive information at those times. Other users will be using the other time slots. So information flow is not continuous for any user, but rather is sent and received in "bursts". The bursts are "glued" together at the receiving end and sound "continuous" because the process isvery fast. (Figure 2) GSM is also a TDMA technology, but it uses channels that are200KHz wide, and sub-divided into 8 time slots for eachchannel. This does not offer any spectrum efficiency over analog TACS, since you still have 8 users in 200KHz. (8 X25KHz = 200KHz) CDMA - Code Division Multiple Access There are several types of CDMA. The type cellular will use is called Direct Sequence (DS) CDMA. Notice that the channel, or again the "carrier", is very wide MHz. The traffic channels are created by assigning each user a seperate "code", and spreading each code over the entire carrier - both in time and in frequency. Therefore the example shows the users being "layered" on top of each other, but their"patterns" are different, which is what separates them. To understand the difference, imagine a room with several "pairs" of people in it. The pairs only want to talk and listen to themselves and have no interest in the others. If each pair only knows one language and uses it, and all the languages are different, they can all use the air in the room as a "carrier" for their voices and experience little interference from the other pairs. The analogy here is that the air in the room is a very wideband "carrier" and the languages are the "codes". If we incorporate language "filters", people speaking German will not hear those speaking Spanish, etc. We continue to add users until the overall "background noise" (interference from other users) limits us. By controlling the signal strength of all users to no more than necessary, while maintaining high quality conversations, we get many users per carrier. The maximum number of users or channels per carrier depends on the amount of activity that is going on on each carrier and is therefore not precise. It is a "soft overload" concept where an additional user (or pair in our analogy) can usually be accommodated if necessary, at the "cost" of a bit more interference to the other users.

25 Canales Códigos en la dirección Forward
Pilot: Código Walsh 0 Sync´: Código Walsh 32 Paging: Código Walsh 1 al 7 Traffic: el resto de los códigos Walsh The intent of this slide is to show the fundamental differences between a Frequency Division Analog technology, a Time Division Digital technology and a Code Division Digital technology. FDMA - Frequency Division Multiple Access FDMA is used for standard analog cellular. FDMA permitsonly one user per channel since it allows the user to usethe channel 100% of the time. So only the frequency and not the time "domain" are used to channelize. However, it hasthe advantage that all information is sent in "real time." Each user is assigned a discrete slice of the RF spectrum.For the AMPS air interface, this slice is 30 kHz wide. For NAMPS, the slice is 10 KHz wide. TDMA - Time Division Multiple Access The TDMA being referred to here is the IS-54 air interface.The key point to make about TDMA is that users are still assigned a discrete 30 kHz slice of RF spectrum (since thistechnique was designed to easily co-exist with AMPS), but three users must now share that RF channel on a time slot basis. Each of the three users alternate their use of theRF channel. FDMA is still employed, but these channels are now further sub-divided into "time", namely 3 time slots per FDMA channel and then the process repeats itself. For TDMA systems, the FDMA portions are usually referred to as "carriers" for the time slotted "channels". A user isassigned a particular time slot in a channel and can only send or receive information at those times. Other users will be using the other time slots. So information flow is not continuous for any user, but rather is sent and received in "bursts". The bursts are "glued" together at the receiving end and sound "continuous" because the process isvery fast. (Figure 2) GSM is also a TDMA technology, but it uses channels that are200KHz wide, and sub-divided into 8 time slots for eachchannel. This does not offer any spectrum efficiency over analog TACS, since you still have 8 users in 200KHz. (8 X25KHz = 200KHz) CDMA - Code Division Multiple Access There are several types of CDMA. The type cellular will use is called Direct Sequence (DS) CDMA. Notice that the channel, or again the "carrier", is very wide MHz. The traffic channels are created by assigning each user a seperate "code", and spreading each code over the entire carrier - both in time and in frequency. Therefore the example shows the users being "layered" on top of each other, but their"patterns" are different, which is what separates them. To understand the difference, imagine a room with several "pairs" of people in it. The pairs only want to talk and listen to themselves and have no interest in the others. If each pair only knows one language and uses it, and all the languages are different, they can all use the air in the room as a "carrier" for their voices and experience little interference from the other pairs. The analogy here is that the air in the room is a very wideband "carrier" and the languages are the "codes". If we incorporate language "filters", people speaking German will not hear those speaking Spanish, etc. We continue to add users until the overall "background noise" (interference from other users) limits us. By controlling the signal strength of all users to no more than necessary, while maintaining high quality conversations, we get many users per carrier. The maximum number of users or channels per carrier depends on the amount of activity that is going on on each carrier and is therefore not precise. It is a "soft overload" concept where an additional user (or pair in our analogy) can usually be accommodated if necessary, at the "cost" of a bit more interference to the other users.

26 Diagrama de bloques en la dirección Forward
MTSO VOCODER Walsh 0 Walsh 1 Walsh 32 Walsh 23 Walsh 44 Walsh 27 BSC PN SHORT  The intent of this slide is to show the fundamental differences between a Frequency Division Analog technology, a Time Division Digital technology and a Code Division Digital technology. FDMA - Frequency Division Multiple Access FDMA is used for standard analog cellular. FDMA permitsonly one user per channel since it allows the user to usethe channel 100% of the time. So only the frequency and not the time "domain" are used to channelize. However, it hasthe advantage that all information is sent in "real time." Each user is assigned a discrete slice of the RF spectrum.For the AMPS air interface, this slice is 30 kHz wide. For NAMPS, the slice is 10 KHz wide. TDMA - Time Division Multiple Access The TDMA being referred to here is the IS-54 air interface.The key point to make about TDMA is that users are still assigned a discrete 30 kHz slice of RF spectrum (since thistechnique was designed to easily co-exist with AMPS), but three users must now share that RF channel on a time slot basis. Each of the three users alternate their use of theRF channel. FDMA is still employed, but these channels are now further sub-divided into "time", namely 3 time slots per FDMA channel and then the process repeats itself. For TDMA systems, the FDMA portions are usually referred to as "carriers" for the time slotted "channels". A user isassigned a particular time slot in a channel and can only send or receive information at those times. Other users will be using the other time slots. So information flow is not continuous for any user, but rather is sent and received in "bursts". The bursts are "glued" together at the receiving end and sound "continuous" because the process isvery fast. (Figure 2) GSM is also a TDMA technology, but it uses channels that are200KHz wide, and sub-divided into 8 time slots for eachchannel. This does not offer any spectrum efficiency over analog TACS, since you still have 8 users in 200KHz. (8 X25KHz = 200KHz) CDMA - Code Division Multiple Access There are several types of CDMA. The type cellular will use is called Direct Sequence (DS) CDMA. Notice that the channel, or again the "carrier", is very wide MHz. The traffic channels are created by assigning each user a seperate "code", and spreading each code over the entire carrier - both in time and in frequency. Therefore the example shows the users being "layered" on top of each other, but their"patterns" are different, which is what separates them. To understand the difference, imagine a room with several "pairs" of people in it. The pairs only want to talk and listen to themselves and have no interest in the others. If each pair only knows one language and uses it, and all the languages are different, they can all use the air in the room as a "carrier" for their voices and experience little interference from the other pairs. The analogy here is that the air in the room is a very wideband "carrier" and the languages are the "codes". If we incorporate language "filters", people speaking German will not hear those speaking Spanish, etc. We continue to add users until the overall "background noise" (interference from other users) limits us. By controlling the signal strength of all users to no more than necessary, while maintaining high quality conversations, we get many users per carrier. The maximum number of users or channels per carrier depends on the amount of activity that is going on on each carrier and is therefore not precise. It is a "soft overload" concept where an additional user (or pair in our analogy) can usually be accommodated if necessary, at the "cost" of a bit more interference to the other users. BTS 1 sector

27 Canales de Códigos en la dirección Reversa
BSC Gen Código Largo MTSO The intent of this slide is to show the fundamental differences between a Frequency Division Analog technology, a Time Division Digital technology and a Code Division Digital technology. FDMA - Frequency Division Multiple Access FDMA is used for standard analog cellular. FDMA permitsonly one user per channel since it allows the user to usethe channel 100% of the time. So only the frequency and not the time "domain" are used to channelize. However, it hasthe advantage that all information is sent in "real time." Each user is assigned a discrete slice of the RF spectrum.For the AMPS air interface, this slice is 30 kHz wide. For NAMPS, the slice is 10 KHz wide. TDMA - Time Division Multiple Access The TDMA being referred to here is the IS-54 air interface.The key point to make about TDMA is that users are still assigned a discrete 30 kHz slice of RF spectrum (since thistechnique was designed to easily co-exist with AMPS), but three users must now share that RF channel on a time slot basis. Each of the three users alternate their use of theRF channel. FDMA is still employed, but these channels are now further sub-divided into "time", namely 3 time slots per FDMA channel and then the process repeats itself. For TDMA systems, the FDMA portions are usually referred to as "carriers" for the time slotted "channels". A user isassigned a particular time slot in a channel and can only send or receive information at those times. Other users will be using the other time slots. So information flow is not continuous for any user, but rather is sent and received in "bursts". The bursts are "glued" together at the receiving end and sound "continuous" because the process isvery fast. (Figure 2) GSM is also a TDMA technology, but it uses channels that are200KHz wide, and sub-divided into 8 time slots for eachchannel. This does not offer any spectrum efficiency over analog TACS, since you still have 8 users in 200KHz. (8 X25KHz = 200KHz) CDMA - Code Division Multiple Access There are several types of CDMA. The type cellular will use is called Direct Sequence (DS) CDMA. Notice that the channel, or again the "carrier", is very wide MHz. The traffic channels are created by assigning each user a seperate "code", and spreading each code over the entire carrier - both in time and in frequency. Therefore the example shows the users being "layered" on top of each other, but their"patterns" are different, which is what separates them. To understand the difference, imagine a room with several "pairs" of people in it. The pairs only want to talk and listen to themselves and have no interest in the others. If each pair only knows one language and uses it, and all the languages are different, they can all use the air in the room as a "carrier" for their voices and experience little interference from the other pairs. The analogy here is that the air in the room is a very wideband "carrier" and the languages are the "codes". If we incorporate language "filters", people speaking German will not hear those speaking Spanish, etc. We continue to add users until the overall "background noise" (interference from other users) limits us. By controlling the signal strength of all users to no more than necessary, while maintaining high quality conversations, we get many users per carrier. The maximum number of users or channels per carrier depends on the amount of activity that is going on on each carrier and is therefore not precise. It is a "soft overload" concept where an additional user (or pair in our analogy) can usually be accommodated if necessary, at the "cost" of a bit more interference to the other users. Sector Rx VOCODER Elemento de canal BTS 1 Sector Código largo

28 TIPOS DE CANALES Canales de tráfico - transportan la llamada telefónica real Canales accesorios Canal piloto- utilizado para obtener el sincronismo inicial del sistema y para identificar las instalaciones celulares. Canal de sincronismo- provee la identificación de la instalación celular, controla la potencia de transmisión del canal piloto, e indica la posición de la señal de cada instalación celular en la red de paquetes.

29 El Concepto CDMA2000 y WCDMA

30 Ensanchamiento de simbolos a chips
Las tramas de tráfico de bits de 20 ms pueden incluir información de voz desde el vocoder e informacion de señalización La Secuencia de conversion Bits - Simbolos -Chips.

31 Proceso de descompresión
En la dirección Forward las estaciones moviles correlacionan la señaL recibida con el patron walsh code (integrando la potencia sobre los 64 chips) En la direccion reversa La BTS compara la señal recibida con cada posible walsh code y selecciona el patron que produce el mayor grado de correlacion como la representacion de los seis simbolos que fueron enviados . Cuando todos los simbolos para una trama han sido recuperados y con la ayuda del codigo de detección de errores se determina si se elimina o no

32 Términos en CDMA 2000 CC: Configuración de canal: define un grupo de velocidades de datos derivados de su velocidad fundamental. Son asociados con velocidades de ensanchamiento específicas. Actualmente existen 12 configuaciones de canal definidas en el sistema CDMA Todas las CC se derivan de las configuraciones de canal ya sea de a) 9600 bps. b) bps. Por ejemplo CC7 y CC10 se basan en el canal a) y soportan velocidades de datos de hasta bps pero con diferentes codificadores.

33 Términos en CDMA 2000 Bit: Unidad de Información fundamental. (datos de entrada) Símbolo : Grupos de datos de bits basados en modulación. Ocurre después de la codificación. Chip : bit al final del ensanchamiento de la velocidad. SR : Velocidad de ensanchamiento: Define la velocidad de ensanchamiento en términos de Mbps. El sistema SR3 = 3*1,2288 o 3,6864 Mbps.

34 CDMA Forward Channels (SR3)
Bit: Unidad de Información fundamental. (datos de entrada) Símbolo : Grupos de datos de bits basados en modulación. Ocurre después de la codificación. Chip : bit al final del ensanchamiento de la velocidad. SR : Velocidad de ensanchamiento: Define la velocidad de ensanchamiento en términos de Mbps. El sistema SR3 = 3*1,2288 o 3,6864 Mbps.

35 Adquisicion del canal piloto. Walsh Code 0
Las estaciones moviles inicializan generando internamente las secuencias cortas PN I y Q correlacionandolas con la señal compuesta recibida. En menos de 15 segundos pueden chequear todas las posibilidades (37268). En la mejor Ec/Io la estacion la va almacenando en memoria se detiene en el mejor piloto e identifica el patron definiendo un 1 seguido de 15 ceros consecutivos. En estos momentos la estacion movil esta lista para extraer el sincronismo del canal del codigo walsh 32. La estacion movil obtiene su generador de codigo largo, junto con su reloj interno y con los valores contenidos y leidos en el canal de sincronismo

36 Tecnologías CDMA2000 y WCDMA

37 Walsh Code en CDMA2000 y WCDMA
Los operadores GSM que están ahora considerando a W-CDMA como su tecnología 3G podrían beneficiarse con este diagrama descriptivo de cdma. En lugar de emplear una canalización de frecuencia como la utilizada en las redes GSM, W-CDMA y cdma2000 utilizan acceso múltiple por dominio de código (CDMA). Ambos sistemas permiten que varios usuarios compartan el mismo espectro de frecuencia dado que los canales son ortogonales entre sí. Lo anterior es cierto solamente para el enlace de descenso, o enlace de avance. En ambos casos, el enlace de ascenso, o enlace inverso, no es ortogonal. En cdma2000, se emplea la codificación Walsh para la canalización del enlace de avance. W-CDMA emplea una técnica idéntica llamada codificación OVSF (factor de dispersión variable ortogonal). La señal de voz o datos de la banda base se codifica y entrelaza antes de la dispersión Walsh u OVSF. Entonces, la señal es transmitida por la estación base al móvil. El móvil revierte entonces el proceso al condensar y desentrelazar la señal codificada para producir la señal original de voz o datos de la banda base.

38 Códigos de ensanchamientos Variables en CDMA 2000.
Existen hasta 256 códigos ortogonales generados y usados para mezclar los datos. Esto permite un máximo de hasta 256 canales de código. Para manejar el amplio rango de velocidades de datos disponibles, se emplea la dispersión de código Walsh de extensión variable. Entre mayor sea la velocidad de datos más corta es la extensión del código Walsh. Por ejemplo, para una velocidad de símbolo de 28.8 Kbps la extensión del código sería de 128 bits (factor de dispersión SF = 128)

39 Efectos de usar Códigos Variables.
SF = 2 SF = 4 SF = 8 1111 1 1 11-1-1 1 1-11-1 1-1 1-1-11

40 Dominio del Código

41 Dominio del código CDMA 2000

42 Codificadores de la voz.
• codificadores de la forma de onda: •codificadores en el dominio del tiempo •codificadores en el dominio de la frecuencia • vocoders • codificadores híbridos

43 Métodos para adaptar cuantificadores y predictores feedforward y feedbackwar
En la adaptación feedforward los niveles de reconstrucción y los coeficientes de predicción se calculan en el emisor, usando un bloque de voz. Después son cuantificados y transmitidos al receptor como información lateral. Tanto el emisor como el receptor usan estos valores cuantificados para hacer las predicciones y cuantificar el residuo. En la adaptación feedbackward los niveles de reconstrucción y los coeficientes de predicción se calculan a partir de la señal codificada. Puesto que la señal es conocida tanto por el emisor como por el receptor, no hay necesidad de transmitir información lateral, así el predictor y el cuantificador pueden actualizarse para cada muestra.

44 Codificación en frecuencia.
Codificación en subbandas

45 VOCODERS Los codificadores de la forma de la onda no tienen en cuenta la naturaleza de la señal a codificar. Sin embargo, si codificamos una señal de voz, podemos aprovechar sus características intrínsecas para que la codificación se realice de forma más eficiente.

46 VOCODERS Los vocoders intentan producir una señal que suene como la voz original, independientemente de si la forma de onda se parece o no. En el transmisor se analiza la voz y se extraen los parámetros del modelo y la excitación. Esta información se envía al receptor donde se sintetiza la voz. El resultado es que se produce voz inteligible a muy bajo bit-rate, pero tiene el problema de que no suena natural.

47 VOCODER por prediccion lineal
Es el tipo de vocoder más utilizado. Este vocoder utiliza el mismo modelo de producción que otros vocoders pero difiere en la determinación del modelo del tracto vocal. Supone que el tracto vocal se puede describir por un filtro todo polos de respuesta impulsiva infinita (filtro IIR),H(z). A este filtro se le conoce también como filtro LPC(Lineal Predictive Coding).

48 VOCODER por prediccion lineal
Se supone que cada muestra es una combinación lineal de las muestras anteriores. Los coeficientes del filtro se calculan para minimizar el error entre la muestra actual y su predicción.En este vocoder, se trabaja sobre bloques de 20 ms de voz. Se trabaja sobre lo que se conoce como modelo corto, las características de la voz se suponen que no varían con el tiempo en intervalos pequeños.

49 LPC-10 (FS-1015) Emisor: se divide en dos bloques, que tienen las siguientes funciones: •fase de análisis •codificación de parámetros La fase de análisis es la encargada de la extracción del "pitch" y del tipo de sonido (sonoro o sordo), así como de la extracción de los coeficientes de reflexión y la energía de la señal para cada una de las tramas en que dicha señal es dividida

50 Codificadores híbridos
En la codificación híbrida se combinan las técnicas de los codificadores de la forma de la onda con las de los vocoders con el propósito de obtener una alta calidad de voz a bajos bit-rates (inferiores a 8 Kb/s).En estos codificadores, las muestras de la señal de entrada se dividen en bloques de muestras (vectores) que son procesados como si fueran uno solo

51 CELP (FS-1016) CELP se basa en procedimientos de búsqueda de análisis-por-síntesis, cuantización de vectores con pesos (VQ) y predicción lineal (LP).

52 Codificación VSELP El codificador VSELP es el estándar en las comunicaciones celulares digitales en Estados Unidos. Permite el procesamiento de voz a un bit-rate de 7950 bps e incluso de 4.8 Kbps. Este algoritmo es una variación del CELP.

53 Detección de señales en términos geométricos
Provee una estructura general que hace fácil el análisis de muchos métodos de transmisión digital de datos. Proporciona una idea relacionado con los problemas de transmisión digital de datos. Provee una vía para generar esquemas stándares de modulación.

54 Modulación M- ary PSK. M -ario
M -ario es un termino derivado de la palabra binario. La M es solo un digito que representa el numero de condiciones posibles. Una M= 4 indica que con 2 bits son posibles cuatro condiciones de salida diferentes

55 Transmisión por desplazamiento de fase cuaternaria. (QPSK)
Es una técnica de codificación M -ario co M= 4. Debido a que hay cuatro fases de salidas diferentes, tiene que haber cuatro condiciones de entrada diferentes por lo que se utilizan grupos de 2 bits (dibits).

56 Transmisor QPSK Q I Datos de entrada Reloj de bits + BPF SenWct 90`
1 = 1volt 0 = -1volt

57 Diagrama fasorial QPSK
11 Tabla de Verdad Entrada binaria 00 Fase BPSK -135` 01 Fase BPSK -45` 10 Fase BPSK 135` 11 Fase BPSK 45` 10 01 00

58 Conclusiones. Preguntas