Housing gateway (RG) is not only in the family all pronunciations, the video frequency and the data traffic central entrance and the control point, moreover in the future trade development foundation. But because has robustness, the security and the nimble memory system deficient, the housing gateway equipment development is slow. This article deep research has used the enlargement mode to dodge saves the solution to develop the housing gateway product the technology and the cost advantage, as well as trend of development.
The housing gateway is acts as the family network core in broadband access network (WAN) and between family local area network (LAN) a kind of equipment, supports between the interconnection electric appliance’s two-way communication and the data transmission, and may turn on the Internet. The housing gateway provides general high speed interconnection turning on the key equipment, may for the different broadband access way and many kinds of family networking solution, like HomePNA, HomeRF, wireless LAN or the IEEE1394 integration provides the platform and collection (convergence point). Similarly, the housing gateway or the service provider carry on the long-distance service disposition through the Internet to the local equipment the important means.
Promotes the housing gateway development to have many factors, including the following several points: 1. The emerging local networking emerges unceasingly; 2. Has the intelligence electronic control system’s family to increase unceasingly; 3. The network operator expands the new service unceasingly; 4. Internet application sustained growth; 5. International general standard making; 6. The wide band interconnection application promotes unceasingly; 7. The emerging rest and recreation way (including digital television) emerges.
Typical gateway construction
Because the wide band technology’s application relative line is quite new, and is developing unceasingly, therefore the housing gateway’s function unceasingly is also consummating. In addition, the housing gateway design must be able to satisfy in the future 5 to 10 year development change, this means that must the modulation, focus on future way design related software and the hardware. To understand the housing gateway well, first has must understand its core component: The housing gateway mainly by the processor, the memory, the digital modulation demodulator, the family networking chip set and the related software is composed, the memory and the non-volatile memory (dodges including volatility memory (RAM) saves).
The processor is the housing gateway’s core component, is responsible to process nearly all duties. The processor had decided the suitable operating system, may move characteristics and so on software, power loss and system stable degree. In addition, the processor overall system cost’s main determining factor, the processor is newer, is quicker, the function to be stronger, the housing gateway is also more expensive, also will be suitable for future application need. The existing some mainstream processor in fact is the network component and the CPU integration on the high performance-to-price ratio chip system-on-a-chip.
Is the same with the computer, the gateway also needs the memory the instruction which sends out to the user or the operator to carry on the memory and the operation. The memory available valid data are more, the gateway movement’s speed is quicker. The gateway usually uses RAM and dodges saves, RAM saves data volatile, once therefore the power source closure, RAM will lose the content which saves. On the contrary, even if breaks the lightning flash to save can also safeguard information and so on gateway’s operating system and special-purpose characteristic as well as user data and network data. Dodges saves is the capital stock “the protection god”, to provides reliable holds the long-time hardware and the software protection under the possible condition for the memory code and the data.
Because gateway support many kinds of modems, therefore has the strong disposition flexibility. These modem may for the direct broadcasting satellite, the fixed wireless wide band, the bidirectional electric cable network, as well as the power line local area network and the ISDN broadband access network provides the interconnection. In the housing gateway’s local network side, the chip set may provide the connection for the movement on the local network specific technology. Except that outside the different type’s wide band and the local network chip set, all gateways also contain the support equipment movement to need software’s computing resource.
On the housing gateway moves the software can improve between the family information equipment and the service joint operation. Although the software causes the user not to need to care about system unit’s complexity, but the housing gateway must have the extremely stable operating system, adjusts like resources and so on memory and processor use factor assignments, the operating system must small enough reduce the memory cost. In addition, the operating system must have the nimble modular software disposition, adapts the component construction demand which in the future will grow unceasingly, and will carry on the long-distance renewal and the promotion.
Housing gateway’s function
The housing gateway’s design decided that provides the service in the network operator. In the tradition, serves the charge which the provider only obtains merely turns on, but the housing gateway is helpful in the operator provides is suitable for the family traditional service and the value-added service. These services include:
1. Correspondence: Will provide the network for PC and the Internet equipment to turn on as well as to realize the family many equipment interconnection service provider to receive the market welcome. In addition, rises in value the telephone business, if will obtain the multiuser response based on the IP pronunciation and the single track multi-telephone channel connection service.
2. Safe: May substitute for the existing safety system based on the housing gateway’s safety system. Emerging advanced service, if system’s long-distance monitoring may realizes using the standard Internet browser or the mobile phone, this will integrate the existing core business and the safety service effectively, and provides a more widespread security measure for the user.
3. Household automation: Tie up the household automation and the existing domestic services, like this might attract many before was not interested to the household automation the user to pay attention to the housing gateway.
4. Unknown service: If will design can focus truly in future applies, then must consider in the future the possible demand, but these demands at present also not understood by housing gateway project engineer and the service provider. This can only be able to realize through the true modular construction, this kind of design must integrate nimbly may expand the hardware platform, as well as the support for the development serves newly, but promotes to the operating system and the application procedure robust filing system.
Housing gateway’s type
The housing gateway is between the Internet and the family intranet the route digit content face user’s equipment, at present mainly has the following several kind of gateways:
1. Based on computer’s family server: Is also called the family server based on computer’s gateway, theoretically is the easiest most and feasible one kind of housing gateway, because already had at present massive has installed and the handling ability computer, the digital modulation demodulator and the software platform, this is suitable completely for the disposition family networking service.
2. Digital video videocorder (DVR):DVR may install the software, this is helpful in the user and saves the television program by the digital form record. The television viewer may suspend the direct seeding television program using DVR, even can also go round the commercial advertizing. At present, DVR has been able to provide the wide band digital network connection, in the near future, DVR will become hopefully provides each kind of new service the gateway equipment.
3. Digital set-top box (STB): Digital STB was still expends in the electronic products market to develop the quickest one kind of digital equipment, digital STB for the content provider, serves the provider, the equipment producer and the semiconductor supplier provides one to have the potential market greatly. STB before is only one kind of pure receiving apparatus, but the present can process traditional the computation and the DVR function. To the correspondence company, uses integrates DVR STB to be very important, like this may cause its service and the platform distinguishes between other competitor.
4. Other types: The mechanical games and the multipurpose measurement equipment have provided one kind of rich imagination, the meaningful platform, and will develop to have the market potential housing gateway type. Looks like Microsoft and Sony these companies believed that the high speed game platform definitely may take in the future the digital family gateway or the concentrator.
Sharing memory component
All expectations hold the small space digital expense electronic products in the family gateway market to have a common spot, namely needs redundant reliable, the high performance, the low cost and the low power loss memory. At present, the memory has become the service to grow the quickest domain, not only this manifests in memory’s specification and quantity increases unceasingly seals getting smaller is actually small, moreover memory’s cost and the power loss also unceasingly drop. The housing gateway’s memory may divide into based on dodges the fast semiconductor’s solid state memory and the hard disk memory, these memories based on the different standard, and have the different contour and the specification.
It is well known, hard disk’s life is lower than expends the electronic products the mean lifetime. The hard disk inherent durability limited to the internal movable part, and the environmental factor influence which its locates, hard disk’s breakdown possible serious influence to serve provider’s commercial interest. According to some set-top box producer reflected, the PVR hard disk actuates the year failure rate may reach 2% to 8%, and has not cut this failure rate at present the efficient path. In addition, as a result of electronic installation’s cost reason, hardware design engineer therefore changes the solid state to dodge saves the component to meet the next generation housing gateway’s memory need. At present, including AMD, Intel, M-Systems, Toshiba and Tristar may provide the solid state to dodge saves the solution, the typical solid state dodges the capacity which saves to be possible to reach 1MB to 128GB.
NAND dodges saves dodges with NOR saves
NOR dodges saves dodges with NAND saves is dodges at present saves in the market the leading product, these two kind of technologies are characteristic and face the different target market. In next generation housing gateway design, when uses dodges saves, project engineer must the technology which may elect to each kind carry on the careful balance, chooses the most suitable product and the technology.
First, NOR usually only uses in the code saving, therefore mainly applies in the simple digital equipment, if the low end honeycomb telephone or does not contain any gateway function simple electric cable modem. On the contrary, NAND usually already can apply in the digital equipment, like set-top box, MP3 player, digital camera, high-end honeycomb telephone and housing gateway’s code memory, can also apply in the data storage. However, cannot substitute for NOR, NAND without processing NAND to with guidance ROM which and the controller separates unifies, overcomes the NAND inherent data integrity flaw, or unifies with the special software, manages and corrects the data error.
In the performance, NOR most is suitable for the read data, but writes the data or the cleaning data speed is inferior to NAND, therefore NOR is not usually suitable for likely the housing gateway and needs the file processing function the equipment. In the above operation, the NAND performance is usually higher than NOR several magnitudes.
Through compares two kind of technical the physical constructions, is not difficult to discover why regarding the bare piece size which assigns, NAND may provide a higher density and the capacity, and has the very high performance-to-price ratio. NAND realizes the high-capacity key to lie in NAND the unit size only then NOR half. Even if compares the single stage unit NAND technology and multistage NOR, the conclusion is also so.
Through uses the simple technique of production, the producer may the capacity produce 8MB very much to the 128MB NAND product. Therefore, more and more producers are glad choose the NAND product to satisfy the BOM cost goal which the service provider proposed. However, must apply NAND reliable and in the stable request high housing gateway equipment, project engineer will face the arduous challenge.
Controls the NAND performance three kind of mechanisms
1. External hardware controller: Besides NAND bringing silicon chip, but also needs with actual to dodge saves the controller which the array unifies, thus provides the function which on the solid state silicon chip the hard disk can realize. This kind of NAND management system management system’s performance is high, but the corresponding cost is also high, its whole’s durability and the reliability are not ideal.
2. Management software: NAND dodges saves the management software system’s code to be complex, and usually moves on housing gateway’s main engine CPU. Although uses the management software to have the low cost superiority, but simultaneously also has the serious reliable problem. Because the operating system or dodges saves the capacity change each time to need to increase the extra cost, needs to design the new driver and the algorithm, thus has limited this solution promoted application.
3. Hardware and software union: The hardware and the software unify way, namely hardware inserting, in dodges saves on the silicon bare piece, with may choose the plan 1 to compare, the system expenses increase slightly. This kind of product does not need to separate only guides the ROM component then initialize the system based on the NAND product, therefore this kind of housing gateway’s modular structure has the cost benefit extremely. The composite structure method is the solution which housing gateway project engineer most is glad to use, this method has the very high reliability and the performance, and has the high cost advantage. Although its initial cost dodges primitive NAND saves the solution to be slightly higher than, but reduced the cost which in the general plan NAND the data and the reliable question possible extra to increase, therefore looked from the long-term angle, the mix design has the good cost benefit.
Chooses the appropriate storage capacity
Project engineer the storage capacity multi-great abilities which provides for the housing gateway is most appropriate? At present in the market presented many different capacities the memories, dodges including 1MB to 64MB saves, as well as over a thousand megabyte hard disk memories. In some need in the application which the massive media save, must use the hard disk memory, simultaneously uses to dodge saves takes the software code memory. At present in the market appears uses the design which 1MB, 2MB or 4MB dodge save, this kind as if to seize the market the 1-4MB memory’s design to bring any market to rise in value with difficulty, cut a produce market price slightly merely.
The genuine housing gateway must have enables ISP to provide the numerous service choices for the user the ability: Some services are present existing, but some services not yet may know. Must provide the sufficient space, the current design slightly dodges saves the capacity to be 8MB to 16MB, estimated that will achieve 32MB to 2003 to 64MB. But in fact, uses the single stage unit technology or multistage unit technology dodges 16MB dodges the cost which and 4MB to 32MB NAND saves to 8MB NOR saves quite.
