Abstract:
Method and apparatus for providing a broadband, wireless network comprising residential communications gateway that accepts all incoming communications signals and securely broadcasts those signals throughout a residence. Each communications appliance within the residence is outfitted with a receiver that decodes the broadcast signals and couples the signals to the input terminals of the associated communications appliance. The system is completely “plug-and-play” such that a user can quickly and easily utilize the gateway for many communications appliances.

Description:
This application claims benefit of U.S. provisional patent applications 60/206,133, filed May 22, 2000, and 60/259,834, filed Jan. 5, 2001, both hereby incorporated herein by reference in their entirety. 
     The invention relates to wireless communications networks and, more particularly, the invention relates to broadband, wireless communications networks for residential and enterprise use. 
    
    
     BACKGROUND OF THE DISCLOSURE 
     Residences are presently coupled to many sources of audio/visual entertainment, communications, and computing signals, including, computer modems, cable television feeds, satellite television feeds, telephone, over-the-air television and so on. Each of these sources of signals enters a residence and is routed via cables to an associated communications appliance, i.e., the telephone signals are routed through the home on a twisted-pair cable to a telephone, the cable television signals are routed through the home on a coaxial cable to a cable set top box, and so on. As such, a residence will have many cables, wires and other communications connections throughout the home. Each time an appliance is to be moved from one location to another, the signal cabling must be rerouted. Such cutting and splicing leads to noisy connections and signal degradation that severely effects the fidelity of the signal. 
     To remedy this problem, wireless local area networks (LAN) have been developed that implement the Institute of Electrical and Electronic Engineers (IEEE) standard 802.11a. This standard defines a wireless LAN system that uses orthogonal frequency division multiplexing (e.g., 48 carriers carrying 64-QAM signals in a 20 MHz wide channel) and defines the control layer to utilize the media access control (MAC) protocol. A plurality of the carriers are used as pilot tones to achieve receiver synchronization. Multipath interference is controlled by having many carriers propagating a low data rate signal, e.g., 256 kbit. As such, the data rate for the system is limited within a given bandwidth. Conversely, higher data rates necessitate greater bandwidth. 
     Therefore, a need exists in the art for a broadband, wireless network that provides a user with a flexible environment for using and locating their communications appliances. 
     SUMMARY OF THE INVENTION 
     The present invention provides a residential communications gateway that accepts all incoming communications signals and securely broadcasts those signals throughout a residence. Each communications appliance within the residence is outfitted with a receiver that decodes the broadcast signals and couples the signals to the input terminals of the associated communications appliance. The system is completely “plug-and-play” such that a user can quickly and easily utilize the gateway for many communications appliances. 
     Each receiver is equipped with an antenna array and a multipath signal processor to ensure that each communications appliance received a robust, error free signal no matter where it is located in the home. The multipath signal processor comprises adaptive signal processing in both spatial and temporal domains to ensure that multipath signals are sufficiently suppressed to enable accurate decoding of the received signal. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The teachings of the present invention can be readily understood by considering the following detailed description in conjunction with the accompanying drawings, in which: 
     FIG. 1 depicts a block diagram of a wireless network system in accordance with the present invention; 
     FIG. 2 depicts a block diagram of a network gateway of FIG. 1; 
     FIG. 3 depicts a block diagram of a receiver of FIG. 1; 
     FIG. 4 depicts the frequency allocation for the wireless network system of FIG. 1; 
     FIG. 5 depicts a block diagram of one embodiment of a back channel transmitter; and 
     FIG. 6 depicts a block diagram of a specific embodiment of a receiver. 
     To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 depicts a block diagram of a broadband, wireless communication system  100  in accordance with the present invention. This system provides a broadband residential or small home office (SOHO) wireless network. The system  100  comprises a gateway  104  and a plurality of receiver nodes  120   n  (n is an integer). Each receiver node  120   n comprises a receiver  116   n  and a communications appliances  110 ,  112 ,  114 , and  118  coupled to the receiver  116   n . The gateway  104  receives a plurality of input signals from a plurality of sources  102  including a cable feed, a plain old telephone system (POTS) feed, a satellite television feed, over-the-air television antenna, and the like. The gateway  104  is also optionally coupled to a residential controller  108  that provides the ability to control various environmental aspects of a residence (e.g., lighting, heating, cooling and so on) through a wireless system. 
     As illustrated, FIG. 1 emphasizes that the entertainment DTH, cable, and terrestrial channel tuners are located within the gateway. Channel tuners are no longer associated with the entertainment appliance. Air and physical interface access control, payload mapper and demapper functions are executed within the logic blocks of the gateway. Network control functions also are executed within the logic of the gateway. 
     Conditional access control for DTH is handled within the traditional decoder module of the A/V appliance so that encrypted entertainment remains encrypted within the in-home network until de-encrypted at the specific subscribing appliance. The traditional interface between the logic block and the appliance is NRSS Level B for information flowing into the appliance and I 2 C for control going back into the in-home network. Cable pay per view (PPV) may be handled within the gateway. 
     The network itself, at 5.6 GHz, is comprised of three 100 MHz wide bands. These bands are channelized into fifty 6 MHz bands where each channel carries 40 Mbits/secs for a total capacity of 2 Gbits/sec. Control and Internet links can be multiplexed within the 6 MHz wide in-home bands as shown, for example, in Table I: 
     
       
         
               
               
               
             
           
               
                 TABLE I 
               
               
                   
               
               
                   
                   
                 Maximum Available 
               
               
                   
                   
                 Bands--Adjacent 
               
               
                 Channel Function 
                 Channel Bandwidth 
                 Band Usage 
               
               
                   
               
             
             
               
                 Delivery of encrypted 
                 6 MHz 
                 50* 
               
               
                 entertainment from 
               
               
                 external broadband pipes to 
               
               
                 appliances at 40 Mbits/sec. 
               
               
                 In-home multimedia/data 
                 6 MHz 
                  4 per channel** 
               
               
                 channels at 10 Mbits/sec 
               
               
                 Internet Uplinks at 1 
                 6 MHz 
                 10 per channel** 
               
               
                 Mbit/sec 
               
               
                   
               
               
                 *Dedicated non-multiplexed bands.  
               
               
                 **Multiplexed within one 6 MHz band using a label protocol.  
               
             
          
         
       
     
     In a typical home configuration, assuming three DTH picture-in-picture/internet TV sets and two PCs plus DTH and xDSL Internet service subscriptions, the actual channel assignments for this typical network are shown below in Table II: 
     
       
         
               
               
               
             
           
               
                 TABLE II 
               
               
                   
               
               
                 Channel Function 
                 Bandwidth Required 
                 6 MHz Bands Used 
               
               
                   
               
             
             
               
                 Delivery of encrypted 
                 6 MHz 
                 6 
               
               
                 entertainment or internet 
               
               
                 to TVs ( 6@40  Mbits/sec) 
               
               
                 PC internet downlinks 
                 6 MHz 
                 1 
               
               
                 ( 2@10  Mbits/sec) 
               
               
                 PC internet uplinks ( 2 @ 1   
                 6 MHz 
                 1 
               
               
                 Mbits/sec) 
               
               
                   
               
             
          
         
       
     
     Total 6 MHz band usage in this example is 8, leaving 42 free for near neighbor usage and other 5.6 GHz services. Two 6 MHz bands are dedicated to each TV to support regular high definition television (HDTV) viewing via a DTH service provider plus windows for HDTV PIP or Internet access, one 6 MHz band is dedicated to downloading the Internet to the two or three PCs and another lightly loaded channel is used for uploading from the PCs to the Internet. A bandwidth utilization example is summarized in FIG.  4 . 
     The modulated signals are transmitted from the gateway  104  to the receivers  116   n  through one or more antennas  106 . The transmitted signals are received and decoded at various locations throughout the residence. The receivers  116  can be up to 100 meters from the gateway  104 . Each receiver  116  decodes the relevant signals for the appliance that is attached to the receiver. For example, the receiver  116   1  decodes the signals that are applicable to the personal computer  110 , the receiver  116   2  decodes the signals that are applicable to the television (or home theatre system)  112 , and so on. The uplink uses a time division multiple access (TDMA) frame structure having timing synchronized to downlink timing markers. Uplinks and downlinks are time based synchronized in pairs. As such, the transmissions are packetized and each packet is addressed to a particular receiver node. Consequently, the gateway  104  can route signals to any receiver node  120  within the system  100 . 
     To facilitate the high data rates of the system, a 256/64 QAM modulation technology is used in the downlink. The occupied bandwidth is less than 6 MHz allowing a sufficiently large number of useable channels in the higher power portion of the 5 GHz band. With appropriate IF filtering, adjacent channel performance levels in excess of 40 dB can be achieved. A concatenated trellis code and block code structure is used to provide adequate Forward Error Correction or a Turbo Code method may also be employed based upon the outcome of further architectural refinements. 
     The QPSK modulation technology is used for the uplinks. This occupies a bandwidth of less than 6 MHz with a maximum data rate of 10 Mbits/sec. 
     The most difficult class of problems associated with this 5.6 GHz band is that of multipath. In this frequency band and in a home or SOHO environment, the multipath takes on a broad range of characteristics including frequency flat fading, frequency selective fading and high frequency Doppler distortion. To combat this set of problems a multiple antenna diversity technique is used in the form a spatial diversity equalizer/combiner. At least two antenna inputs at a receiver node are equalized and combined to reduce the effects of multipath encountered in the home or home/office environments. This approach achieves the maximum level of Quality of Service (QoS) that can be achieved without resorting to complex MAC protocols. 
     To avoid interference and allow maximum user capacity, a Carrier Sense Multiple Access Collision Detection, or CSMA/CD, channel access technique is employed. If contention is sensed, the next best available channel may be utilized by the system. Maximizing the overall available number of channels within the allowable spectrum eases the burden in a multidwelling unit application. A Forward Overhead Control Channel is embedded in the downlink data stream, which advises and controls uplink time slot allocation and channel bandwidth aggregation. Channel access is also controlled through this mechanism. 
     The uplink consists of a TDMA based 10 MB/s QPSK modulated data system in which burst demodulation must be employed to allow multiple users to access the hub unit as required. 
     Finally, power control of both uplink and downlink traffic channels, can be used to allow maximum utilization of spectrum in high capacity environments and mitigate some of the technical radio design challenges associated with wide dynamic signal range. Because more than one user is multiplexed on a single carrier the power control algorithm must accommodate the lowest recovered signal strength user as its minimum case. 
     FIG. 2 depicts a detailed block diagram of the gateway  104  comprising a gateway logic  240  and a radio section  238 . The radio section  238  comprises a plurality of tuner modules  202  (e.g., direct broadcast satellite (OBS), ultra-high frequency (UHF), very high frequency (VHF), and so on) and a transceiver  218 . The gateway logic  240  comprises a plurality of demodulators  204  (e.g., quadrature phase shift keying (QPSK), vestigial side band (VSB). standard television and the like), decoders  206 , a reconfigurable ATM adaptation layer  2   242 , a microprocessor  208 , a gateway firewall  210 , an encoder  2 l 2 , a modulator  214 , a demodulator  218  and a decoder  220 . The various sources of RF signals are coupled to the tuner modules  202 , which select particular signal channels for reception. Each appliance has a corresponding tuner module  202 . The tuner modules filter and down convert each of the selected channels. The channels are selected by a user or users via the back channel communication link from the receivers  116  to the gateway  104 . The back channel operation is discussed below. The demodulators  204  demodulate the down converted signals. The decoders  206 , then decode the signals including performing error correction to form baseband video The baseband video is coupled to the gateway firewall  210 . The tuner modules  202 , the demodulators  204 , and the decoders  206  are all controlled by the microprocessor  208 . 
     The reconfigurable ATM adaptation layer  2   242  couples the gateway firewall  210  to an xDSL CPE stream to enable the system to be used to distribute voice, data, fax, multimedia content, and TCP/IP Internet services throughout a residence. The content from the xDSL stream can then be displayed by any one of the appliances in the network. 
     The gateway firewall  210  digitizes the decoded signals (if necessary) and provides firewall services. The firewall services ensure that unauthorized users cannot access the gateway from outside the residence without proper authority. Additionally, the gateway firewall  210  provides encryption to ensure that neighboring residences are not capable of viewing each other&#39;s programming. The firewall and encryption services are provided by using a well-known protocol such as the media access control (MAC) protocol. 
     The encrypted baseband video signals are coupled to an encoder  212 . The encoder  212  compresses the signal using, for example, run-length coding, or some other form of lossless encoding. The encoded signal is coupled to modulator  214 , where the signal is modulated onto a 5-6 GHz carrier. The modulation is an M-ary quadrature amplitude modulation (QAM). To transmit broadband signals such as HDTV, the modulation is selected to be 256-ary QAM. For lower bandwidth signals, the modulation index can be lowered to, for example, 64. 
     A transceiver  216  amplifies the modulated signal and couples the signal to a pair of antennas  106 . Specifically, the signal passes through a wide-band amplifier  222 , a bandpass filter  224 , a diplexer  228 , and a power splitter/combiner  226 . The diplexer  228  and band pass filter  224  may be fabricated as a single component. The diplexer  228  and power splitter  226  enables the transmitter and receiver to utilize the same antennas  106 . The transmitter portion of the transceiver  216 , for example, transmits a 1 Watt signal in the 5.75-5.85 GHz band (the UNII-band). Each of the transmitted signals carries 20-40 Mbps in a channel bandwidth of approximately 6 MHz. As such, many 6 MHz channels (one or more for each appliance) are transmitted in the UNII-band. 
     Additional antenna elements could be used with dynamic, beam forming circuitry such that the transmitted signal is “pointed” at the appliance that is to receive the signal being transmitted at any instant in time. Such antenna control provides multipath signal suppression at the receiver plus further enhancements of QoS without the complications of more complex MAC protocols. 
     The antennas  106  also receive control signals from various appliances within the residence. In one embodiment of the invention (not shown), only a single antenna is coupled to the back channel receiver  201  in the gateway  104 . In another embodiment, both antennas are coupled to the receiver  201  via a splitter/combiner  226  and diplexer  228 . Combining the antenna signals forms a spatial diversity combiner that suppresses multipath interference. An adaptive spatial diversity combiner that can be used in the gateway transceiver is described with reference to FIG.  2 . Because the back channel data rate is relatively low, the back channel modulation is generally BPSK, QPSK or 4-ary QAM, both of which are relatively easy to receive, even in a noisy environment. As such, diverse antennas are not generally necessary. 
     The received signals, known as back-channel signals, are coupled through a diplexer  228 , band pass filter  230 , amplifier  232 , mixer  236  and into a demodulator  218 . The transceiver  216  provides amplification and downconversion such that the output of the transceiver  216  is an IF signal with a relatively high signal-to-noise ratio (SNR). The back-channel signal is typically in the 5.125-5.325 GHz band (the UNLI-band) and transmitted from the network appliances using 100 mW. The back channel can support 10 Mbits/sec using burst mode QPSK modulation. The demodulator  218  extracts the modulation (a baseband signal) from the carrier signal and couples the baseband signal to the decoder  220 . The decoder  220  decodes the baseband signal. The back channel signal carries commands from the network appliances ( 120  of FIG. 1) to instruct the gateway  104  as to what signals to transmit to the appliances. The decoded signals are coupled to the microprocessor  208  for implementation. 
     FIG. 3 depicts a block diagram of a receiver  116  of FIG. 1 that uses a multipath processor  301  (referred to as a spatial diversity combiner) to combat multipath interference. Each antenna  106 A and  106 B is respectively coupled to tuners  300  and  302 . These tuners  300  and  302  select one of the 64 available channels. The tuners  300  and  302  filter and downconvert the received signal to near baseband. The near baseband signals are respectively coupled to the analog-to-digital (A/D) converters  304  and  306 . The digitized signals are applied to the timing recovery circuitry  308 . The timing recovery circuitry  308  ensures that the A/D converters  304  And  306  accurately sample the symbols in the near baseband signal. 
     The samples are then coupled to separate spatial equalizers  310  and  312 . These equalizers are multi-tap feed forward equalizers (FFE) that delay their respective signals to achieve equal delays in the received signals. The most difficult class of problems associated with this 5.6 GHz band is that of multipath. In this frequency band and in a home or SOHO environment, the multipath takes on a broad range of characteristics including frequency flat fading, frequency selective fading and Doppler distortion. To combat this set of problems a multiple antenna diversity technique is used to form a spatial diversity equalizer/combiner. At least two antenna inputs are equalized and combined to reduce the effects of multipath encountered in the home or home/office environments. Once spatially equalized by equalizers  310  and  312 , the two signals are combined in combiner  314 . The output of the combiner  314  is coupled to a single circuit  316  comprising both a temporal equalizer and carrier loop recovery circuit. The equalizer/carrier recovery circuit  316  comprises a decision feedback equalizer (DFE) that removes intersymbol interference and a carrier recovery loop that extracts the carrier from the equalized symbols. The carrier is used to derotate the symbols for sampling using the symbol sampler  318 . Within the subtractor  320 , the symbol sample is compared to the unsampled symbol to produce a symbol error that is coupled to the tap control  322 . The tap control  322  uses the error signal to produce tap weight adjustments for the three equalizers: the two spatial equalizers  310  and  312  and the temporal equalizer  316 . To provide such multipath processing in the gateway, similar circuitry may be included in the transceiver of the gateway. 
     The sampled symbols are coupled to the appliance specific processor  324 . The processor  324  performs the necessary processing to convert the symbol stream into a signal that can be used by the appliance. For example, if the appliance is an NTSC television, the appliance specific processor  324  would convert the symbol stream into an NTSC signal. Receivers designed for other appliances convert the symbols into signals that are appropriate for those appliances. For example, an NTSC signal would be digitized and 3-D comb filtered in the gateway prior to encoding and transmission to a node in the system. An NTSC signal may be digitized in high definition (HD) or standard definition (SD). The receiver would convert the digital signal into a signal that is compatible with the television receiver. As such, the system can accommodate legacy television systems. 
     FIG. 5 depicts a back channel transmitter  500  for television appliance. The television set decoder  502  couples to the I 2 C bus  510  of the back channel transmitter  500 . The I 2 C bus  510  carries command and control signals to a logic block  504 . The logic block  504  contains a modulator/FEC encoder, payload mapper, MAC, transmit band selection and transmit control logic. The logic block  504  is coupled to the upconverter/modulator/frequency synthesizer block  506 . The logic block  504  sends a control signal and an 8 bit data signal to the block  506 . Block  506  modulates the command signal onto a carrier and upconverts the modulated signal to the back channel band. The signal is then coupled to one or more antennas  508 . This transmitter  500  receives, for example, channel turning commands from the television  502  and sends those commands to the gateway. The gateway then adjusts a tuner module to receive the specified channel. Content from that channel is then wirelessly sent to the television appliance for display. 
     FIG. 6 is a block diagram of an illustrative receiver  600  that is used to receive both a primary television signal and a picture-in-picture (PIP) signal from the wireless network. The PIP signal may be an HDTV signal. Also the PIP signal may be received by a separate device such as a hand-held wireless device. The receiver  600  comprises one or more antennas  602 A and  602 B, a pair of down converters  604 A and  604 B, a pair of low noise amplifiers (LNAs)  606 A and  606 B, a pair of tuners  608 A and  608 B, and a logic block  610 . The logic block  610  is coupled to a television set decoder  612 . 
     The antennas  602 A and  602 B receive signals from the wireless network. Although two antennas are shown, those skilled in the art should understand that each antenna  602 A and  602 B may be an array of antennas and a diversity combiner. The signals are coupled to the down converters  604 A and  604 B to select a particular channel in the 5.725-5.8256 Hz band. The selected channels (one for each down converter) are converted to a 725-825 MHz band. 
     The down converters  604 A and  604 B are each coupled to an LNA  606 A and  606 B that adjust the amplitude of the signal. The gain of each LNA  606 A and  606 B is controlled by a gain control signal from the logic block  610 . The amplified signals are each coupled to the tuners  608 A and  608 B. These tuners may be integrated circuit tuners similar to that disclosed in U.S. patent application Ser. No. 09/457,258, filed Dec. 8, 1999 and incorporated herein by reference. The tuners  608 A and  608 B are controlled by signals generated by the logic block  610 . 
     The logic block  610  receives 10 bit digital signals from the tuners  608 A and  608 B. The logic block  610  provides diversity combining (if the down converters and tuners select the same channel), demodulation, forward error correction, payload demapping, MAC functionality, band tuner control, de-encryption, and the like. The logic block  610  produces 8-bit signals in NRSS-B format that are coupled to the television set decoder  612 . The decoder  612  couples control signals to the logic block  610 . 
     The receiver  600  may select two different television programs from the wireless network such that one signal can be displayed on the television as a primary video signal and the second signal can be displayed on the PIP television. Alternatively, one of the signals may be an Internet channel so that for example, the PIP could display an Internet web site or sites or other information provided by the Internet. 
     Although various embodiments which incorporate the teachings of the present invention have been shown and described in detail herein, those skilled in the art can readily devise many other varied embodiments that still incorporate these teachings.