Multiplex communications – Communication over free space – Repeater
Reexamination Certificate
2002-05-31
2004-12-14
Dildine, R. Stephen (Department: 2133)
Multiplex communications
Communication over free space
Repeater
C370S328000
Reexamination Certificate
active
06831901
ABSTRACT:
BACKGROUND OF THE INVENTION
The wireless telecommunication industry continues to experience significant growth and consolidation. In the United States, market penetration is near 32% with approximately 86 million users nationwide. In 1999 the total number of subscribers increased 25% over the previous year, with the average Minutes of Use (MOU) also increasing by about 20% per user. If one considers growth in the digital market, in as short as three years, the digital subscriber base has grown to 49 million users, or approximately equal to the installed number of users of analog legacy systems. Even more interesting is an observation by Verizon Mobile that 70% of their busy hour traffic (an important system design parameter) is digital traffic, although only approximately 40% of the total number of their subscribers are digital users. The Verizon Mobile observation indicates the digital subscriber will drive the network design through its increasing usage, whereas the analog user is truly a passive “glovebox” subscriber. Similar growth has been witnessed in other countries, especially in Northern and Western Europe, where market penetration is even higher, approaching 80% in some areas, and digital service is almost exclusively used.
With the availability of Personal Communications Service (PCS) frequencies in the United States, and additional continuing auctions of spectrum outside of the traditional 800-900 MegaHertz (MHz) radio band, the past few years have also seen increased competition among service providers. For example, it has also been estimated that 88% of the U.S. population has three or more different wireless service providers from which to choose, 69% have five or more, and about 4% have as many as seven service providers in their local area.
In 1999 total wireless industry revenue increased to $43B, representing an approximate 21% gain over 1998. However, a larger revenue increase would have been expected given the increased subscriber count and usage statistics. It is clear that industry consolidation, the rush to build out a nationwide footprint by multiple competing service providers, and subsequent need to offer competitive pricing plans has had the effect of actually diminishing the dollar-per-minute price that customers are willing to pay for service.
These market realities have placed continuing pressure on system designers to provide system infrastructure at minimum cost. Radio tower construction companies continue to employ several business strategies to serve their target market. Their historical business strategy, is build-to-suit (i.e., at the specific request and location as specified by a wireless operator). But some have now taken speculation approach, where they build a tower where it may be allowed by local zoning and the work with the new service providers to use the already existing towers. The speculative build spawned by the recently adopted zoning by-law is actually encouraged by communities to mitigate the “unsightly ugliness” of cellular phone towers. Towns adopted the by-laws to control tower placement since Federal laws prohibit local zoning authorities to completely ban the deployment of wireless infrastructure in a community. Often the shared tower facility is zoned far removed from residential areas, in more commercialized areas of town, along heavily traveled roads, or in more sparsely populated rural sections. But providing such out of the way locations for towers often does not fully address each and every wireless operator's capacity or coverage need.
Each of the individual wireless operators compete for the household wireline replacement, and as their dollar-per-MOU is driven down due to competition in the “traditional” wireless space, the “at home” use is one of the last untapped markets. As the industry continues to consolidate, the wireless operator will look for new ways to offer enhanced services (coverage or products) to maintain and capture new revenue.
Considering the trends that have appeared over recent years, when given the opportunity to displace the household wireline phone with reliable wireless service, a wireless service operator may see their average MOUs increase by a factor of 2 to 4, thereby directly increasing their revenue potential 200 to 400%. In order to achieve this, the wireless operator desires to gain access throughout a community as easily as possible, in both areas where wireless facilities are an allowed use and in where they are not, and blanket the community with strong signal presence.
SUMMARY OF THE INVENTION
One aspect of the present invention is directed towards retransmission techniques. In an illustrative embodiment, a received signal includes data information that is transmitted to a following node in a communication system for eventual transmission of the data information over a wireless communication link. The data information is processed by hardware that produces overhead bits supporting a serial transmission of the data information over a communication medium to a following node. For example, the data information of the received signal and overhead bits can be combined or framed according to a serial transport protocol for transmission over the communication medium. This technique of mapping or framing the data information into a serial transport protocol is used to more efficiently transmit the data over the communication medium to a target receiver.
In a retransmission system, the received signal passes from receiving hardware, over a communication link, to transmission hardware. The received signal can consist of data from an analog to digital converter (ADC). The receiving hardware also has status information about the signal, the hardware that needs to pass over the link from receiver to transmitter.
One aspect of the retransmission system involves passing the digitized signal unmodified from receiver to transmitter. The retransmission system can provide fault detection, system status, and control features to control software that manages the link. For example, the transmitter can be notified when a retransmission link contains bad data, thus, preventing transmission of corrupted signals.
Three options can be considered in the design of control, status and fault detection. A first option passing only data over the retransmission link and using a separate software to software communication channel for status. A second option is to multiplex control and status data into a serial data stream, an “inband” approach. This approach can include state machines in the data channel to find and distinguish the overhead from the data and reduces the available data rate. A third option is to pass the control and status data over a “sideband.”
The SONET protocol can be used in a retransmission system since a number of commercial circuit cards include multiplexing capability at a sufficient data rate. This protocol used can include the sideband option. Specifically, SONET uses Path overhead to carry control and status information from one end of the link to another.
In one application, the signal is received in a digitized RF (Radio Frequency) format that reformatted and transmitted to a following node using a serial protocol such as SONET (Synchronous Optical Network). The original signal can be reconstructed at a downstream or receiver node using the data information. The overhead bits can be used to conform that the data is valid and provides information to manage retransmission in the network. Accordingly, one aspect of the present invention involves transmitting a digitized RF signal over SONET.
The received signal can be derived from an RF signal transmitted over a coaxial cable. More specifically, a band of frequencies of the RF signal on the coaxial cable can be down converted to produce an analog IF (Intermediate Frequency) signal that is thereafter converted using an analog-to-digital (A/D) converter. The A/D converter digitizes the IF bandwidth signal into digital words that are the data information transmitted over the serial stream. The overhead bits are added and the combin
Dildine R. Stephen
Hamilton Brook Smith & Reynolds P.C.
OpenCell Corporation
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