DVB-S2技术指南：第二代卫星广播应用

需积分: 2 76 浏览量更新于2024-06-30 收藏 1.99MB PDF 举报

"ETSI TR 102 376-1 V1.2.1 (2015-11) DVB-S2应用指南是关于第二代数字视频广播系统DVB-S2的实施指南，主要关注卫星广播、交互式服务、新闻采集和其他宽带卫星应用。本技术报告详细阐述了DVB-S2的技术规范和实现建议，适用于广播、电视、视频等领域。" 在数字电视传输领域，DVB-S2标准是DVB（数字视频广播）组织推出的一种先进的卫星广播协议，旨在提高频谱效率和传输质量。这份应用指南针对DVB-S2系统提供了详尽的实践指导，帮助开发者和工程师理解并实现该系统的各项功能。 DVB-S2标准的核心特性包括： 1. **高级编码调制技术**：DVB-S2采用了更高效的信道编码方式，如低密度奇偶校验(LDPC)码，与传统的卷积码相比，能显著提高数据传输的错误纠正能力，从而提升接收质量。 2. **灵活的帧结构**：DVB-S2支持多种帧长度和码率，适应不同的传输需求。这使得系统能动态调整以应对不同的环境条件，例如信号强度的变化或带宽限制。 3. **多级星座映射**：采用多种星座图（QPSK、8PSK、16APSK和32APSK），允许根据信噪比动态选择最佳调制方式，以优化传输效率。 4. **前向纠错编码(FEC)**：DVB-S2引入了增强的前向纠错编码策略，配合智能接收技术，能在信号弱的情况下保持稳定的数据传输。 5. **卷积交织**：这种技术用于分散传输错误，使得连续的错误可以被单个纠错码字纠正，增强了系统抵抗连续错误的能力。 6. **高效功率分配**：DVB-S2允许在传输中进行智能功率分配，确保信号覆盖最大化，同时减少对其他卫星频道的干扰。 7. **增强型服务信息(ESI)**：提供了更强大的服务信息，帮助接收端识别和解析广播内容，支持交互式服务和个性化用户体验。 8. **兼容性**：DVB-S2设计时考虑了与前一代DVB-S系统的兼容，使得升级过程更加平滑，减少了用户设备的替换成本。这份指南不仅涵盖了技术细节，还可能包含实际部署中的注意事项、测试方法和性能评估标准，是工程师在设计、实现和优化DVB-S2系统时的重要参考资料。通过深入理解和应用这些技术，广播公司和网络运营商能够提供更高质量的电视服务，满足用户对高清视频、互动电视和高速数据服务的需求。

ETSI

ETSI TR 102 376

1 V1.2.1 (2015

11)

4.1.2 Commercial Requirements for Non-Broadcast Services

In general, DVB-CM stated that characteristics that are desirable exclusively for non-broadcast services should only be

included in the base specification if the burden of cost to the broadcast receiver is negligible. The specification should

be available for consideration as an alternative forward path for DVB-RCS Ku- and Ka-band systems and other data

systems currently using DVB-S. In the future non-broadcast two-way services will need to take advantage of such

techniques as adaptive modulation, adaptive coding and adaptive power systems. The services provided will include:

• Point-to-point services (e.g. IP-backbone).

• Point-to-multipoint services (e.g. VPN services).

• Two way mass market services (e.g. Internet access via satellite).

The above services are differentiated from broadcast services by the following requirements and characteristics:

• The possibility of targeting particular receivers with particular content within the common transport system. It

is therefore not necessary to be able to decode the entire data stream at a typical user terminal.

• The possibility of establishing different quality of service targets for services to different customers in

different areas.

• Receiver network volumes may not be as high as broadcast applications, but could benefit from inexpensive

silicon arising from broadcast applications.

• Satellite capacity is generally the most expensive part of a link, always more expensive compared to the

equipment behind it.

• Business users may be able to accept significantly larger receive antennas that residential users. In such cases

it would be desirable to use this to allow greater user data rates to be transmitted.

The technical specifications shall additionally take into account the following requirements:

• Non-broadcast services should be receivable on antennas down to typical consumer sizes.

• A wide range of system parameters shall be available to address applications across consumer to business

antenna sizes, and telecom to broadcast satellite powers.

• As in the case of broadcast applications, it should be possible to manufacture low cost receivers. If the impact

of advanced features such as adaptive coding and modulation that are not relevant to broadcast applications

is to raise broadcast receiver costs excessively, then these features could exist in an enhanced profile,

available as an option.

• The technology shall aim to optimize the use of the transponder (keeping all other technical parameters the

same, a minimum capacity increase of 100 % is targeted for the professional, non-broadcast market case

using adaptive technologies).

• The target BER shall be at least as good as for broadcast applications.

• The system has to allow for power control technologies, adaptive modulation and adaptive coding.

ETSI

ETSI TR 102 376

1 V1.2.1 (2015

11)

4.1.3 Common Commercial Requirements

The primary goal of new broadband satellite systems is to deliver a significantly higher net data rate in a given

transponder bandwidth than the current DVB-S standard. Technical specifications for such a new standard should not

prevent operators from taking into account all issues covered by local, national, and international laws, especially those

related to security (protection of personal data, encryption of data and services). The new specification will cover

transmit-end functions only, but take into account the consequent cost of receive silicon. The market will determine

what features are actually implemented in receive silicon. For the protection of existing business, the current DVB-S

standard will not be modified, nor will changes to other standards cause any existing feature to become invalid. The

new specification will contain a range of options for coding that are appropriate to a wide range of applications. The

new specifications will be application neutral and media content independent. The specifications will be transmission

frequency neutral, or contain the elements allowing for an adaptation to the specifics of certain frequency ranges (e.g.

Ka Band). Specifications for broadcast and non-broadcast applications will be provided by the definition of a limited

number of profiles. The specification will not prevent the use of any kind of scrambling and security system at the

transport layer.

4.2 Application scenarios

The DVB-S2 system has been optimized for the following broadband satellite application scenarios.

• Broadcast Services (BS): digital multi-programme Television (TV)/High Definition Television (HDTV)

broadcasting services

DVB-S2 is intended to provide Direct-To-Home (DTH) services for consumer Integrated Receiver Decoder

(IRD), as well as collective antenna systems (Satellite Master Antenna Television - SMATV) and cable

television head-end stations (possibly with remodulation, see ETSI EN 300 429 [i.6]). DVB-S2 may be

considered a successor to the current DVB-S standard ETSI EN 300 421 [i.1], and may be introduced for new

services and allow for a long-term migration. BS services are transported in MPEG Transport Stream format.

VCM may be applied on multiple transport stream to achieve a differentiated error protection for different

services (TV, HDTV, audio, multimedia).

• Interactive Services (IS): interactive data services including internet access

DVB-S2 is intended to provide interactive services to consumer IRDs and to personal computers, where

DVB-S2's forward path supersedes the DVB-S standard ETSI EN 300 421 [i.1] for interactive systems. No

recommendation is included in the DVB-S and DVB-S2 standards as far as the return path is concerned.

Therefore, interactivity can be established either via terrestrial connection through telephone lines, or via

satellite. DVB offers a variety of return link specifications, such as for example DVB-RCS

(ETSI EN 301 790 [i.36]), DVB-RCP (ETSI ETS 300 801 [i.37]), DVB-RCG (ETSI EN 301 195 [i.38]),

DVB-RCC (ETSI ES 200 800 [i.39]). Data services are transported in (single or multiple) Transport Stream

format according to ETSI EN 301 192 [i.5] (e.g. using Multiprotocol Encapsulation), or in (single or multiple)

generic stream format. DVB-S2 can provide Constant Coding and Modulation (CCM), or Adaptive Coding

and Modulation (ACM), where each individual satellite receiving station controls the protection mode of the

traffic addressed to it.

• Digital TV Contribution and Satellite News Gathering (DTVC/DSNG)

Digital television contribution applications by satellite consist of point-to-point or point-to-multipoint

transmissions, connecting fixed or transportable uplink and receiving stations. They are not intended for

reception by the general public. According to Recommendation ITU-R SNG.770-1 [i.40], SNG is defined as

"Temporary and occasional transmission with short notice of television or sound for broadcasting purposes,

using highly portable or transportable uplink earth stations, etc.". Services are transported in single (or

multiple) MPEG Transport Stream format. DVB-S2 can provide Constant Coding and Modulation (CCM), or

Adaptive Coding and Modulation (ACM). In this latter case, a single satellite receiving station typically

controls the protection mode of the full multiplex.

ETSI

ETSI TR 102 376

1 V1.2.1 (2015

11)

• Data content distribution/trunking and other professional applications (PS)

These services are mainly point-to-point or point-to-multipoint, including interactive services to professional

head-ends, which re-distribute services over other media. Services may be transported in (single or multiple)

generic stream format. The system can provide Constant Coding and Modulation (CCM), Variable Coding and

Modulation (VCM) or Adaptive Coding and Modulation (ACM). In this latter case, a single satellite receiving

station typically controls the protection mode of the full TDM multiplex, or multiple receiving stations control

the protection mode of the traffic addressed to each one. In either case, interactive or non-interactive, the

present document is only concerned with the forward broadband channel.

For all these applications, DVB-S2 benefits from more recent developments in channel coding and modulation,

achieving typically a 30 % capacity increase over DVB-S ETSI EN 300 421 [i.1]. When used for point-to-point

applications like IP unicasting or DSNG, the gain of DVB-S2 is even greater. Adaptive Coding and Modulation (ACM)

functionality allows different modulation formats and error protection levels (i.e. coding rates) to be used and changed

on a frame-by-frame basis within the transmitted data stream. By means of a return channel, informing the transmitter

of the actual receiving condition, the transmission parameters may be optimized for each individual user, dependant on

path conditions.

Furthermore DVB-S2 is compatible with Moving Pictures Experts Group (MPEG-2 and MPEG-4) coded TV services

ISO/IEC 13818 [i.3], with a Transport Stream packet multiplex. Multiplex flexibility allows the use of the transmission

capacity for a variety of TV service configurations, including sound and data services. All service components are Time

Division Multiplexed (TDM) on a single digital carrier.

4.3 System architecture

4.3.0 Main features

To achieve the best performance, DVB-S2 is based on LDPC (Low Density Parity Check) codes, simple block codes

with very limited algebraic structure, discovered by R. Gallager in 1962 [i.9]. LDPC codes have an easily parallelizable

decoding algorithm which consists of simple operations such as addition, comparison and table look-up [i.20] and

[i.21]; moreover the degree of parallelism is "adjustable" which makes it easy to trade-off throughput and complexity

(see note 1).

NOTE 1: For the purpose of FEC technology selection during standardization, the maximum decoder complexity

was set to correspond to 14 mm

of silicon using a 0,13 μm technology, and the reference symbol rate

was 55 Mbaud.

Their key characteristics, allowing quasi-error free operation at only 0,6 to 1,2 dB from the modulation constrained

Shannon limit [i.10], are:

• the very large LDPC code block length (64 800 bits for the normal frame, and 16 200 bits for the short frame);

• the large number of decoding iterations (around 50 SISO iterations);

• the presence of a concatenated BCH outer code (without any interleaver), defined by the designers as a "cheap

insurance against unwanted error floors at high C/N ratios".

In comparison, the DVB-S and DVB-DSNG soft-decision Viterbi decoder takes decisions on blocks of only

100 symbols, without iterations, and the RS code over blocks of about 1 600 bits (interleaving factor 12), offering

already quite good performance (see figure 4), around 3 dB from the Shannon limit.

ETSI

TSI TR 102 376

1 V1.2.1 (2015

11)

Digital transmissions via satellite are affected by power and bandwidth limitations. Therefore DVB-S2 provides for

many transmission modes (FEC coding and modulations), giving different trade-offs between power and spectrum

efficiency. Code rates of 1/4, 1/3, 2/5, 1/2, 3/5, 2/3, 3/4, 4/5, 5/6, 8/9 and 9/10 are available depending on the selected

modulation and the system requirements. Coding rates 1/4, 1/3 and 2/5 have been introduced to operate, in combination

with QPSK, under exceptionally poor link conditions, where the signal level is below the noise level. Computer

simulations demonstrated the superiority of such modes over BPSK modulation combined with code rates 1/2, 2/3 and

4/5. The introduction of two FEC code block length (64 800 and 16 200) was dictated by two opposite needs: the C/N

performance improves for long block lengths, but the end-to-end modem latency increases as well. Therefore for

applications not critical for delays (such as for example broadcasting) the long frames are the best solution, while for

interactive applications a shorter frame may be more efficient when a short information packet has to be forwarded

immediately by the transmitting station. Four modulation modes can be selected for the transmitted payload (see

figure 1).

text

1100

1101

1111

1110

0000

0100

0101

0001

1001

1011

0011

0111

0110

0010

1010

1000

LSB

MSB

text

10001

10011

10111

10101

00000

10000

10010

00010

00011

00111

00110

10110

10100

00100

00101

00001

11000

01000

11001

01001

01101

11101

01100

11100

11110

01110

11111

01111

01011

11011

01010

11010

(d) 32APSK

Q=LSB

I=MSB

000

ρ=1

011

111

001

101

010

110

100

φ=π/4

(a) QPSK

(b) 8PSK

Figure 1: The four possible DVB-S2 constellations before physical layer scrambling

QPSK and 8PSK are typically proposed for broadcast applications, since they are virtually constant envelope

modulations and can be used in non-linear satellite transponders driven near saturation. For some specific broadcasting

applications (i.e. regional spot beams) and interactive application operating with multi-beam satellites, 16APSK

provides extra spectral efficiency with very limited linearity requirements if proper pre-distortion schemes are

employed. 32APSK modes, mainly targeted to professional applications, can also be used for broadcasting, but these

require a higher level of available C/N and the adoption of advanced pre-distortion methods in the up-link station to

minimize the effect of transponder non-linearity. Whilst these modes are not as power efficient as the other modes, the

data throughput is much greater. 16APSK and 32APSK constellations have been optimized to operate over a non-linear

transponder by placing the points on circles. Nevertheless their performances on a linear channel are comparable with

those of 16QAM and 32QAM respectively. All the modes are also appropriate for operation in quasi-linear satellite

channels, in multi-carrier Frequency Division Multiplex (FDM) type applications.

By selecting the modulation constellation and code rates, spectrum efficiencies from 0,5 to 4,5 bit/second/Hz are

available and can be chosen dependant on the capabilities and restrictions of the satellite transponder used.

ETSI

ETSI TR 102 376

1 V1.2.1 (2015

11)

DVB-S2 also features the presence of a Physical Layer (PL) scrambler that is X-oring the I-Q modulator symbols

(inclusive of the optional pilot symbols but excluding the PL header) with a complex binary randomization sequence of

length truncated to the current PLFRAME duration. The complex randomization sequence has an original period of

262 143 symbols and is the one used in the terrestrial UMTS standard. It provides good auto and cross-correlation

properties and allows to simply generate up to 262 142 distinct complex sequences. The main advantages of the

physical layer randomization presence in DVB-S2 are:

• capability to uniquely "sign" individual carriers present in a multi-carrier multi-channel transponder;

• randomization of periodic pilot symbols pattern when pilot is time interleaved in the carrier;

• randomization of other satellite or same satellite other beams interference. It should be remarked that in case of

interfering signals with lower baud rate than the useful carrier the physical layer descrambling present in the

DVB-S2 demodulator will make interferer appearing as wideband interference thus reducing their degradation

effect;

• the physical layer randomization also allows the application of repetition coding at the DVB-S2 modulator to

further increase the C/(N+I) operating range of the system.

DVB-S2 has three roll-off factor choices to determine spectrum shape. These are α = 0,35 as in DVB-S and two others,

namely α = 0,25, α = 0,20 for tighter bandwidth shape restriction.

DVB-S2 is suitable for use on different satellite transponder bandwidths and frequency bands. The symbol rate is

matched to given transponder characteristics, and, in the case of multiple carriers per transponder (FDM), to the

frequency plan adopted.

Two levels of framing structures have been designed:

• the first at physical level, carrying few highly-protected signalling bits;

• the second at base-band level, carrying a variety of signalling bits, to allow the maximum flexibility on the

input signal adaptation.

Physical Level framing

The first level of framing structure has been designed to provide robust synchronization and signalling at physical

layer [i.12]. Thus a receiver may synchronize (carrier and phase recovery, frame synchronization) and detect the

modulation and coding parameters before demodulation and FEC decoding. The DVB-S2 physical layer "train" is

composed of a regular sequence of periodic "wagons" (physical layer frames, PL Frame): within a wagon, the

modulation and coding scheme is homogeneous, but may change (Variable Coding and Modulation) in adjacent

wagons. The PL framing structure is application independent (Constant Coding and Modulation or Variable Coding and

Modulation).

Every PL Frame is composed of:

• a payload of 64 800 bits (normal FEC frame) or 16 200 bits (short FEC frame), generated by encoding the user

bits according to the selected FEC scheme; thus the payload corresponds to a code block of the concatenated

LDPC/BCH FEC;

• a PL Header, containing synchronization and signalling information: type of modulation and FEC rate, frame

length, presence/absence of pilot symbols to facilitate synchronization.

The PL-Header is always composed of 90 symbols (using a fixed Π/2 binary modulation), and the payload is always

composed of an integer multiple of 90 symbols (excluding pilot symbols). Since the PL Header is the first entity to be

decoded by the receiver, it could not be protected by the powerful LDPC/BCH FEC scheme. On the other hand, it had

to be perfectly decodable under the worst-case link conditions. Therefore designers selected a very low-rate 7/64 block

code, suitable for soft-decision correlation decoding, and minimized the number of signalling bits to reduce decoding

complexity and global efficiency loss. For example, assuming a 64 800 bit frame, the worst case efficiency of the PL

Frame is 99,3 % (excluding pilot symbols).

剩余117页未读，继续阅读

ataberman

粉丝: 4
资源: 22

DVB-S2技术指南：第二代卫星广播应用

ETSI TS 102 637-2 V1.2.1 (2011-03)

etsi tr 101 053-3

etsi en 301 489-1 v2.2.3(2019-11)是什么

DVB-S2X标准文档

etsi300132-1

etsi ts 102 361.1

etsi 5g网络mec部署、应用

ETSI EN 302 217

etsi en 303 396

最新资源