SHAREWAVE

ShareWave, Inc., provides highly integrated semiconductors and networking software for high-performance, multimedia, broadband gateways and wireless in-home networks. ShareWave's core product lines include wireless network controllers, wireless bridge controllers, residential gateway controllers, and associated networking services and protocols. ShareWave sells these products to leaders of the broadband, consumer electronics, computing, and networking industries. Founded in 1996 by a group of former Intel and venture capital executives, ShareWave is privately held with its headquarters in El Dorado Hills, California. ShareWave's goal is to provide consumers with the freedom of unrestricted access to the digital content they want, where and when they want it. A home network enabled by ShareWave technology provides the high performance required to support fast, secure, and robust wireless distribution of all digital content types—data, voice, audio, and video—to user-chosen locations throughout the house. ShareWave has announced customer partnership agreements with NETGEAR (a wholly owned subsidiary of Nortel Networks), Cisco, and Kyushu Matsushita Electric, who will all incorporate ShareWave technology into consumer home networking solutions.

Technology and Product Overview

ShareWave is focussed on easily extending access to broadband platforms (such as xDSL modems, cable modems, and cable set-tops) beyond their initial termination point in the home, while also enabling the deployment of low-cost client applications. ShareWave's technology is encapsulated in a set of ingredient products that are used by its OEM customers to develop home networking end products cited below. ShareWave's ingredient products are characterized by high performance, QoS-enabled delivery of multimedia content, ease of use, and superior price/performance. ShareWave's target consumer solutions, and respective product enablers, are described below.

• Wireless broadband bridges— ShareWave's Wireless Bridge Controller (SWB 2510) is used in bridging and routing products that attach externally to broadband modems to provide fast (11 Mbps and above) wireless connections to computers and other client access devices. This solution enables an easy extension of the broadband connection from where it initially enters the home to user-chosen locations throughout the home. Using industry standard connectivity options (e.g., Ethernet), wireless bridges enable the use and management of broadband content and services from anywhere in the home.

• Residential gateways— Broadband modems and set-tops will begin to add LAN routing to WAN access termination, becoming an early generation of the residential gateway. ShareWave's Residential Gateway Controller is a highly integrated, multi-interface chip that addresses the cost, performance, and interconnectivity requirements of emerging residential gateway platforms. It seamlessly enables the broadband connection to be shared across multiple physical layers, such as wireless, Ethernet, and phoneline, and across multiple connection technologies, such as USB and IEEE 1394. The SWG2710's highly integrated functions, interfaces, and programmability enable an optimized system architecture for current and future residential gateway products.

• PC wireless connectivity— ShareWave's wireless network controllers provide connectivity for desktop computers and laptops/mobile devices. These controllers enable low-cost PCI, USB, and PCMCIA cards that allow the client computer to be wirelessly connected to the broadband modems noted above. They also address traditional PC-to-PC networking products targeted at multi-PC households.

• Audio/video clients— ShareWave's series of high-performance semiconductors also enable new classes of consumer devices that allow ubiquitous consumption of multimedia content. Examples include wireless MP3 players, mobile web pads, personal video recorders, and digital audio and video jukeboxes.

A key element of ShareWave's technology portfolio is the Whitecap network protocol. It represents the "language" spoken by the high-performance, multimedia broadband in-home network. Whitecap's key features include dynamic TDMA, quality of service, and selectable error correction (FEC). Whitecap efficiently manages a network of heterogeneous devices and digital content: cable and xDSL modems, residential gateways, PCs, TVs, mobile pads, set-top boxes, digital audio and video jukeboxes, and other information appliances and servers. Whitecap can enable networks to handle bursty data communication among PCs and PC-like devices while simultaneously streaming full motion video to TVs and other entertainment devices and packet-based voice to Internet cordless phones. The next section of this guide will examine Whitecap in more detail.

Whitecap Technical Overview

The Whitecap protocol was designed to enable home networks that address the consumer's need for performance, reliability, scalability, interoperability, security, upgradability, and ease of use. The Whitecap protocol was designed from the ground up to accommodate and transmit all multimedia content including control data, voice, audio, and video in a noisy home environment (Figure 8.8).

The Whitecap protocol is designed to work with leading-edge, wireless digital radio technology to deliver the highest network utilization. The network architecture, services, and packet structure in the Whitecap protocol have been streamlined to minimize overhead, enabling greater efficiency for multimedia transmission. The Whitecap protocol is designed to easily support various types of network devices, including either desktop or mobile PCs, as well as non-PC devices such as wireless bridges, residential gateways, Internet phones, and TV terminals.

Whitecap's key features enable high-performance, wireless multimedia transmission that meets the needs of today's home environment. These features include dynamic TDMA, quality of service (QoS), multicast addressing with shadow clients, privacy and security, co-location, multichannel and channel selection, remote automatic firmware updating, master device redundancy, and selectable error correction, as described in the sections that follow.

Dynamic TDMA

The Whitecap protocol is a connection-oriented network protocol that uses a dynamic time division multiple access (TDMA) mechanism. Network bandwidth is slotted and shared among the multiple streams of network traffic.

The Whitecap network assigns a master device that is responsible for transmitting periodic beacons to synchronize clients. The master also allocates bandwidth and polices traffic when devices transmit on the network. Each node that needs to transmit is assigned a particular slot within a network frame. Dynamic TDMA adjusts slots based on the bandwidth needs of each node on the network.

Dynamic TDMA provides several benefits, including:

• High network performance and efficiency (high usable network throughput)— Dynamic TDMA allows the Whitecap protocol to assign network nodes only the bandwidth they need. This minimizes wasted bandwidth and preserves overall bandwidth for other network nodes and applications. More usable throughput means higher performance for all home network applications (e.g., higher video quality, faster file transfer times).

• Eliminates unexpected delays and provides synchronization for multimedia content— Delays and unpredictable latency are unacceptable when transmitting isochronous content (video, audio, and voice). Dynamic TDMA avoids unpredictable and long delays by eliminating collisions and the capture effect caused by carrier sense multiple access (CSMA) mechanisms. In CSMA access, shared bandwidth is not governed and network nodes are allowed to transmit at the same time. When network` nodes realize they are transmitting simultaneously with other nodes, all nodes must back off and attempt to transmit later. This will result in unexpected and potentially long delays in multinode networks. Networks may also experience the "capture effect" where one node transmitting a long sequence of data can monopolize the entire bandwidth while other nodes must wait— particularly problematic for time-sensitive multimedia content.

  Whitecap protocol's dynamic TDMA architecture enables predictable latencies and provides the synchronization crucial for transmitting isochronous multimedia content (i.e., voice, audio, and video). The dynamic TDMA architecture provides the foundation and ability to support sophisticated QoS features to enable high-quality video, voice, and audio transmission simultaneously with batch data.

• Supports home network growth and expandability (adding more nodes)— As more and more nodes are added in a CSMA network, collisions become more frequent and the total usable throughput of the network degrades exponentially. Dynamic TDMA better supports additional nodes by eliminating collisions. Consequently, as network nodes are added, additional bandwidth is simply reallocated and the overall available throughput is gracefully maintained.

Quality of Service (QoS)

Guaranteed Bandwidth Reservation

The Whitecap protocol can reserve bandwidth for multimedia isochronous content that has extremely stringent bandwidth and latency requirements (e.g., MPEG video).

Priority Service

The Whitecap protocol provides a best-effort priority service. Priority services are applied to transmit traffic at each network node. High-priority traffic is differentiated from low-priority batch data (e.g., print jobs, file transfers) by decoding packet fields such as IP precedence bits and payload. Differentiated packets are separated and buffered into three queues of high, medium, and low priority. After differentiating network traffic, time-sensitive, high-priority traffic is transmitted first. Priority service is applied as packets are transmitted out of the three queues in a weighted fair queuing (WFQ) arbitration mechanism into the remaining bandwidth of each node's corresponding slot. WFQ arbitration transmits a higher ratio of higher-priority packets than lower-priority packets during the given slot time.

The benefits of QoS include:

• Higher multimedia quality— Guaranteed bandwidth allows the support of high-bandwidth isochronous content such as MPEG-2 video. Priority services enhance the performance of multimedia applications by providing more bandwidth and better latency to multimedia content such as Internet video and audio.

• Simultaneous multimedia (video, voice, audio) and batch data (print jobs, file sharing) transmission— The ability to support simultaneous multimedia and batch data transmission without compromising multimedia quality is mandatory in a home network. Multimedia quality must be maintained when the home user is simultaneously printing a file to a remote printer or transferring a file from PC to PC.

  Whitecap protocol's guaranteed bandwidth reservation QoS preserves high-quality isochronous data transmission even in high-batch data traffic environments. By prioritizing network traffic and delivering time-sensitive traffic first, priority services allow low rate data (email, print jobs) to coexist with multimedia content without any degradation in the user experience.

• Preserves QoS of high-speed broadband Internet— Internet applications, services, and multimedia content distribution such as video on demand, VoIP, and streaming audio need end-to-end quality of service to operate properly. Internet QoS initiatives including Resource Reservation Setup Protocol (RSVP), the audiovisual data transmission standard H.323, Real-time Transport Protocol (RTP), and priority services implemented in head-end routers, provide high-quality distribution of content to the house. The network distributing content within the home must preserve QoS to utilize Internet content throughout the home in its intended form.

Multicast Addressing with Shadow Clients

Shadow clients in a Whitecap network allow the support of more multiple media streams. Viewing the same multimedia content at different locations is a common requirement for the home. Popular multicast protocols such as IP multicast and IGMP are being deployed by the Internet to deliver multiple media (audio, video, voice) streams to the home. Shadow clients reduce the required bandwidth to support sharing media streams by allowing traffic to be sent only once vs. individually to each client receiving the media stream. Shadow clients enable multicasting of multimedia content and data. A shadow client is a client that has been given permission from the master to decode and receive traffic destined for another client on the home network.

Privacy and Security

Privacy and security will become increasingly important as more and more wireless networks are deployed in the home. Unlike wired networks, wireless networks cannot be secured or contained physically. E-commerce over the Internet, copyrighted multimedia content (e.g., CDs, DVDs), and personal or financial information in the home require a high need for privacy. The Whitecap protocol employs several security mechanisms that prevent unauthorized access to data. Whitecap protocol privacy and security exists in three different layers of the network stack (Figure 8.9).

Physical Layer

Direct sequence spread spectrum (DSSS) radio transmission offers isolation at the physical layer. The implementation of DSSS is difficult to intercept and decode. Radios must also be tuned to the correct frequencies to receive data. The original data stream is essentially encoded through chipping and scrambling.

Data Link Layer

To avoid unauthorized access, the Whitecap protocol follows a strict authentication procedure before a connection is granted. Each Whitecap protocol network is identified by a unique 16-bit subnet ID. The subnet ID is a field in the Whitecap protocol header and is unique to a specific network. Packets with the incorrect subnet ID authentication are dropped and denied access to all devices on the network. The Whitecap protocol subnet ID provides reliable security by exercising security on a packet-by-packet basis. The Whitecap protocol data link layer provides an optional interface, ShareWave Encryption Protocol Interface (SEPI), to implement encryption schemes. SEPI allows traffic of different encryption types to exist on the same network by tracking encryption schemes on a stream-by-stream basis. Possible schemes for authentication/encryption include RC2, RC4, DES, and IDEA. This gives Whitecap protocol implementers the option to select an encryption scheme that is best for a given application.

Network Layer

The Whitecap protocol does not inhibit encryption or security mechanisms employed by higher-level network applications or protocols. For instance, encryption applied by the IP protocol (e.g., SSL) to IP data is preserved by the Whitecap protocol and decrypted by the IP protocol at the receiving end. Internet or Web transaction encrypted data will be transmitted through the Whitecap protocol and decrypted by the Web browser at the receiving end.

Multichannel Channel Selection

The Whitecap protocol allows operation across several independent, nonoverlapping channels. Each channel is capable of transmitting the full network bandwidth. Whitecap protocol channel selection can identify and switch network operation to the channel with the lowest packet error rate. Benefits of channel selection include network reliability and higher performance.

Network Reliability

Channel selection improves the interference immunity of the network. The Whitecap protocol can avoid interference (e.g., from cordless phones, microwaves) by monitoring channel conditions and selecting the channel with the least interference.

Higher Performance

Usable data throughput of the Whitecap protocol network is increased. Channel selection allows the Whitecap protocol to find the frequency channel that has the highest data throughput and the least interference. High usable throughput increases multimedia quality and speeds up batch data applications such as file sharing, print jobs, and Internet surfing.

Co-location

Co-location enables the deployment of Whitecap protocol networks in closely located homes and apartment complexes. Ideally, the distribution of wireless subnets should be nonoverlapping to avoid interference with each other. Realistically, closely located homes and dense apartment complexes may make overlapping subnets commonplace to wireless home networks. Co-location and channel selection features allow overlapping networks to operate without degrading performance.

Overlapping subnets first utilize channel selection to find and change network operation to an available open channel, allowing both overlapping networks to transmit at full bandwidth. In the scenario where there are more overlapping subnets than available channels, the Whitecap protocol co-location feature is enabled. The operation of nonoverlapping networks in the same channel is achieved by sharing the available channel bandwidth through appropriate negotiations between overlapping subnet masters.

Remote Automatic Firmware Updating

Remote automatic firmware updating allows users to install product enhancements and upgrades. Upgrades ensure scalability of the Whitecap protocol with new home networking applications and services. Packet types and the command protocol used to update network nodes are clearly defined in the Whitecap protocol so that updates are seamless to the end user. The update process is initiated when the master or client receives a new version of firmware. The master then identifies and updates all network nodes that do not have the latest firmware revision. The ability to update network protocols over the Internet benefits end users by significantly reducing device obsolescence.

Master Device Redundancy

The master device redundancy feature protects against the possibility of a master device failure bringing the whole network down. This feature eliminates a single point of failure and improves network reliability. Master device redundancy also allows users to power down master nodes in a Whitecap protocol network without disabling the entire network. Ease of use is improved because the user does not have to treat the master node differently from the clients.

Selectable Error Correction

Different network applications and content drive different requirements of delivery quality and error correction. For instance, every packet of a bank statement is mission-critical data and needs to be retransmitted until the data is received correctly. On the other hand, CD-quality audio would sound terrible if packets were retransmitted, causing unexpected delays. Video also cannot tolerate delays, but missing packets may cause poor image and viewing quality. The Whitecap protocol's selectable error correction offers several classes of delivery qualities to apply according to the type of media stream to deliver the highest possible performance and quality.

Auto Repeat reQuest (ARQ)

The Whitecap protocol supports selectable retransmissions or lossless streams with Auto Repeat reQuest (ARQ). ARQ does not guarantee latency of delivery; therefore, it is best applied to bulk and mission-critical data. The number of retransmissions is stream-dependent, as these parameters can be changed from a default value during stream initiation. ARQ is selectable to accommodate isochronous data and to interoperate with lossy upper network protocols such as UDP.

CRC and Forward Error Correction

Lossy streams are not retransmitted, but high-quality delivery is achieved through Forward Error Correction coding (FEC). FEC recovers data "on the fly" while other correction mechanisms, such as CRC, filter and drop corrupt data, requiring retransmission. Consequently, FEC actually increases the available usable throughput. CRC is reserved for data streams that require guaranteed reliability for every bit in the packet. FEC can be used by either lossy or lossless data; however, FEC is essential for video which is not retransmitted because even just a few dropped frames can cause poor image quality.