Wired and wireless 802.11 Home Network

It is time to make full use of the coaxial cable network to achieve multimedia distribution in the room.

Introduction

Wireless Home network is becoming the first choice for data service distribution in the family. The price of 802.11b is comparable to that of Wired solutions, and interconnection between old and new families can be achieved without any connection. It is a natural choice for users who want to build networks in their homes. The enterprise market has a very high demand for 802.11b products, which leads to a further decline in prices and provides users with a common interface between the home network and the company network, this makes it more attractive as a home network technology.

At present, the main driving force of home networks is to share broadband connections among multiple computers. 802.11b can achieve the original data rate of 11 Mbps in the transmission distance between 300 and 500 feet, providing a good solution for the above requirements. With the introduction of new services to the home network, the 802.11g/a standards have solved the increasing capacity requirements, while 802.11e and 802.11i have solved the Quality of Service (QoS) and higher security requirements. However, as the capacity requirements of the home network keep increasing, the transmission range of wireless connections may limit the ability of cable TV operators to provide new services and applications with high bandwidth requirements, such as home video distribution.

IEEE 802.11 standard

Standard	Layer	Features
802.11b	PHY	Baseline, 2.4 GHz
802.11a	PHY	5 GHz OFDM modulation rate up to 54 Mbps
802.11e	MAC	QoS features
802.11 GB	PHY	Speed up to 54 Mbps in 2.4 GHz
802.11i	MAC	Higher security

The most advanced standard throughput of 802.11a/g is up to 54 Mbps, providing sufficient capacity for distributing multiple MPEG Video Streams in the home, but according to the above standard, the product connection distance and range may still be insufficient in many cases when working in the highest throughput mode. Why? Because the high-throughput mode of 802.11a/B/g is the most sensitive to path loss caused by obstacles such as walls, the Attenuation Caused by time-varying multiplexing is also the most sensitive. Therefore, we cannot guarantee reliable service delivery using the above operation mode.

In this article, we will introduce a new concept that enables cable TV operators to provide high-bandwidth services, especially video distribution, in their homes. We recommend that you use the home coaxial cable network as the backbone of the RF (FR) home network, and use 802.11 a/B/g as the transmission protocol on the coaxial cable network.

The carrier uses the home Coaxial Cable Network to increase the connection distance and range of the wireless network to provide reliable video distribution and other services in the home, it can achieve high-capacity coverage at each point, and gain all the advantages of 802.11b/a/g/e/I, including QoS, security, and low cost.

General concepts

We recommend that you use wireless (over the air) and coaxial cable networks to establish a home network based on the 802.11 transmission technology. the term "802.11" in this article refers to all standards based on 802.11, including all types of extensions 802.11b/a/g/e/I ). The network we imagine includes an access point (AP) with an antenna, used as a Wireless 802.11 Home Network, and also includes coaxial cable connections. The Network also includes two types of sites (STA): one is to connect to the network through a coaxial cable, and the other is to connect wirelessly. Remote antennas can also be attached to a node in the home coaxial cable network.

Each data packet generated on the AP can be transmitted through a wireless or coaxial cable. In this way, each packet can reach its destination through one of the three Signal paths. The first possible path is the direct wireless connection from the antenna to the AP. The second is to use a coaxial cable before the remote antenna, and then connect the station wirelessly; the third method is to use a coaxial cable. All wireless and coaxial cable transmission will adopt the same 2.4 GHz or 5 GHz band, but 2.4 GHz is more advantageous, the attenuation of 2.4 GHz transmitted via wireless and coaxial cables is not as high as that of 5 GHz ).

In most families, the transmission loss of 802.11b/g or 802.11a signals is 2.4 GHz or 5 GHz.) In the case of coaxial cables, the transmission loss is lower than that of wireless cables, this is especially true when considering wireless signal barriers such as walls. Therefore, coaxial cables avoid a large loss of wireless paths, and adopt a low loss of coaxial cable paths or coaxial cable/wireless hybrid paths, this expands the connection distance and coverage of the network. In a coaxial cable network, the connection quality between the AP and the site is particularly high, which enables reliable operations in the high-throughput mode of 802.11a/g (54 Mbps.

The following is an example of how to use 802.11 GB for data and video distribution in a typical home environment. In this example, there are two floors in the home: a TV and a digital set-top box (STB) in the living room on the first floor, and a laptop in the Home Office; one bedroom on the second floor has a TV Plus STB, and another room has a desktop computer. The digital STB in the living room on the first floor may include an integrated DOCSIS Cable Modem and a 802.11g AP with a maximum data rate of 54 Mbps. Two Computers in the family share the Internet and email broadband wireless connection. A layer-1 computer is connected to the STB/AP in 802.11g wireless mode. The location of the Second-layer computer may not receive the wireless signal generated by STB, so the remote antenna is connected to the antenna through a coaxial cable) to connect to the network. In this example, the function of connecting a L2 computer to a wireless network is an important advantage of a hybrid coaxial cable/wireless network.

The second important advantage is the high-capacity connection between two stbs in the House, which enables video signal distribution from one room to another. The distance between the two rooms is enough for 2 to 11 Mbps wireless connection to the Data Service Internet, email, etc ). However, video distribution requires a throughput of up to 54 Mbps, which requires a coaxial cable connection between two stbs. High-capacity connections between two stbs allow PVR to share the recorded materials, and access emails and the Internet through all stbs. STB with an AP can be used as the Home Media Center for storing videos and audios. Other low-level STB can access the above information through a coaxial cable network. All STB can also access data services and computer resources in the home, such as printers, scanners, and cameras.

The QoS function of 802.11e ensures the efficient use of the shared media and ensures the bandwidth allocation and maximum waiting time for services that require QoS. The CableHome function implemented by STB will facilitate management of the home network.

The combination of high-capacity coaxial cable channels and 802.11e ensures that operators can consistently deliver high-bandwidth services, such as video distribution, across coaxial cable networks.

Technical Considerations for hybrid coaxial cable/wireless

Although all components of the home coaxial cable network are designed for signals below 900 MHz, the 802.11 signal is robust enough to tolerate the attenuation of 2.4 GHz operations. In general, the home coaxial cable path degrades by 0.5 dB on each meter of cable, in general, the splitter may experience a attenuation of 20-30 dB at 2.4 GHz, which is measured between the splitter output and between the input and output), which is even lower than the requirement of a good wireless channel. The existing 802.11b/g system allows attenuation between the transmitter and receiver between 90 to 100 dB while maintaining the maximum throughput ), this attenuation margin enables hundreds of feet of coaxial cables and several splitters.

Multi-path will appear in the hybrid coaxial cable/wireless network, which is caused by no terminal connector cable. However, considering many reflection and Signal paths in a typical wireless environment, the design of the 802.11 device can reduce serious multi-path situations. It is unlikely that the signal is leaked to adjacent homes because additional cables and separation are used between different families. However, 802.11 still provides internal security features to solve security risks caused by signal leakage.

Comparison with other solutions

Cable operators already have various solutions for home multimedia distribution issues. Next we will compare the solution recommended in this article with other solutions.

1. Simulated Distribution

Analog distribution provides a simple solution for the distribution of home videos. Its obvious advantage is that the upgraded video signal can be decoded without the need to separate the converter box. However, this solution has great limitations in terms of functionality and quality. Data delivery, including remote data control, will require separated media and more components, and image quality may be poor due to micro-reflection issues in coaxial cable channels. The digital signal of 802.11 is much more robust to micro-reflection, so that the home coaxial cable network achieves always reliable Video Delivery and high-speed data transmission.

2. Purely 802.11 a/B/g/e Networks

Although this method can meet the needs of the entire home environment at the speed of supporting broadband connection sharing of data services in most cases, it is still not enough for multimedia distribution. The high-throughput operation mode is the most sensitive to wireless path loss and multi-path, and may not completely overwrite the mode that supports video distribution.

Wireless relay can be used to expand the network connection distance. Relay can indeed increase coverage, but will occupy more spectrum. However, if you do not plan well, you still cannot guarantee full coverage. This solution is more cost-effective than the hybrid coaxial cable/wireless solution recommended in this article.

3. HPNA and cable TV HPNA (HPNA over cable)

HPNA 2.0 is not successful in the market as a home network technology. Although its data rate is sufficient for high-speed data services, it still gives more popular wireless solutions a market share. Due to the location of telephone interfaces, the coverage of many families is incomplete, and many users intuitively feel that using telephone lines for home network connection is not as advantageous as wireless connection. In implementation, as the number of chip technologies and system vendors developing solutions based on 802.11 has increased significantly, the number of chip technologies and system vendors developing HPNA products has been decreasing. Due to lack of competition, this makes the technology less attractive.

For multimedia applications, HPNA 2.0 is not suitable at all. The actual data rate is not enough for video distribution, and the QoS mechanism in the specification is very small, resulting in low efficiency of using shared media, and cable TV operators cannot guarantee QoS to achieve service profit. The next-generation standard HPNA 3.0 may solve this problem, but there are other issues that make it difficult for HPNA 2.0 to become an attractive home network technology.

Just as we suggest using cables for wireless technology in this article, we also suggest using cables HPNA 2.0. However, unlike the 802.11g/a high data rate mode with QoS options, HPNA 2.0 cannot distribute multiple MPEG streams through coaxial cables because of its insufficient throughput and lack of QoS.

In addition, HPNA over cable also requires frequency conversion to avoid interfering with the uplink transmission of HPNA 2.0 from the cable and overlapping the upstream band of the cable ). This results in a non-standard factor in the solution, requiring components other than the phone line HPNA and additional standards for multi-vendor interoperability. Frequency conversion may be a problem for the standard HPNA component because HPNA 2.0 does not allow the above conversion. These problems, coupled with the small number of HPNA 2.0 chip technology vendors, make it almost a patent solution for a company.

In addition, in order to connect the coaxial cable and telephone network, at least one line in the home must be connected. Because many home coaxial cables and telephone interfaces are on the opposite sides of the room, the connection between the two networks is not as simple as wireless connection.

Finally, considering the popularity of wireless home networks, the AP still requires wireless support. The HPNA coaxial cable/telephone line solution cannot provide services for wireless handheld terminal devices, company computers with WLAN interfaces, and other devices not close to telephone or coaxial cable interfaces. Compared with the 802.11 coaxial cable/wireless solution, the solution that uses HPNA and 802.11 is a low-efficiency and redundant solution.

4. Dedicated coaxial cable transceiver ('homecna ')

Several companies have suggested a home network solution based on Coaxial Cables Using Non-standard transmission protocols. In fact, the delivery of multimedia optimization protocols through coaxial cables can provide better technical solutions, but compared with solutions based on existing standards, especially considering that 802.11b/a/g is very popular ), it is unlikely to be used. Developing new specialized standards and new components for cable home networks is a long way to go, and the cost is high. It is unlikely that many manufacturers will invest in this work. This method is far more advantageous than using 802.11b/a/g as the transmission protocol than relying on the existing tested standards, in particular, it depends on the existing 802.11 chip technology.

Even with the above method, in addition to the coaxial cable network technology, the STB still requires additional network technology to be connected to devices not close to the coaxial cable interface. This is a low-efficiency and expensive solution compared with the use of a single 802.11 interface in STB for transmission via wireless and coaxial cables.

Although the dedicated coaxial cable home network solution may claim to have a higher throughput of 802.11 Mbps and above than 100 currently, compared with 54 Mbps ), however, 802.11 has a dedicated Task Group to further increase its speed, so as to provide larger capacity for applications and services with high bandwidth requirements.

Summary

We introduced multimedia applications and services that use existing 802.11 standards and components to achieve high bandwidth requirements using a hybrid coaxial cable-Wireless Home Network. With a data rate of up to 54 Mbps, guaranteed QoS, and complete home coverage, cable TV operators can now obtain a solution, helps them reliably deliver and distribute services such as videos that require high capacity and QoS Assurance in the home environment ).

By adopting the existing 802.11 standard, the operator can ensure Component Availability and interoperability of multiple vendors, and can use 802.11 market competitiveness and high production to achieve low-cost, low-risk solutions.

802.11 is very popular in the family and enterprise fields. There are a large number of products based on 802.11, such as laptops with integrated wireless functions, PDAs supporting wireless functions, and 802.11 security cameras ), this promotes the widespread use of hybrid coaxial cable-Wireless 802.11 Home multimedia networks.