Polymorphic cellular network architecture

A nanoCell base station is disclosed for providing radio connectivity among one or more mobile stations, one or more base transceiver stations or one or more other nanoCell base stations. The nanoCell base station of the present invention has one or more transceivers. One of the transceivers provides a base station function, and one of the transceivers provides a mobile station function. A controller is present for managing the transceivers, and determining the communications connectivity paths between base station and mobile station functions.

DETAILED DESCRIPTION OF THE INVENTION FIG. 1 shows a polymorphic cellular network comprising a plurality of nanoCell base stations 21 , 22 , 24 , 24 base transceiver stations (BTS) 25 , 26 , with the attendant base station controller (BSC) 20 . As seen in the figure, a nanoCell base station 21 may communicate with one or more other nanoCell base stations 22 , 23 , 24 with one or more primary base stations 25 , 26 , i.e., macro cell BTS and with one or more mobile stations 27 , 28 . The communication path from a mobile station to a BTS may be made through one or more intercommunicating nanoCell base stations. As seen in FIG. 1 the presence of a number of nanoCell base stations in a given geographical location reduces and can also eliminate the need for additional macro cell stations. In addition, as seen in FIG. 1 the presence of the nanoCell base stations makes coverage in a given area significantly more uniform thereby reducing the number of dead spots and other areas of weak or spotty coverage. The nanoCell base stations 21 , as shown in FIG. 2 , function as relays 29 , collectors 30 , concentrators, or delay nodes 31 , as shown in FIG. 2 in order to provide efficient connectivity between mobile and base transceiver stations. The mobile stations may be any wireless communication device including but not limited to cellular telephone, computer, PDA etc. Two or more nanoCell base stations are each networked with one another in their respective areas of operation. In the event that the concentration of traffic is such that there is insufficient capacity between the nanoCell base station 21 and the macro cell BTS 25 , the use of in-band back haul in communication with any other nanoCell base station 22 with low traffic concentrations overcomes the lack of bandwidth between nanoCell base station 21 and the macro cell BTS 25 . A single nanoCell base station 21 , FIG. 3 , comprises one or more communication transceivers 32 and 33 , each sharing a common control function. The preferred embodiment comprises from two to four transceivers. It is reasonable to implement seven or more transceivers. A communication transceiver may function as a BTS, as a MS or as a relay. When functioning as a BTS 33 , the communication transceiver transmits on downlink channels 34 and receives on uplink channels 35 , as would a base station. When functioning as a MS 32 , the communication transceiver transmits on uplink channels 36 and receives on downlink channels 37 as would a MS. When functioning as a relay, the communication transceiver transmits and receives on independent channels, either of which may be uplink or downlink channels. In the case of the relay function, a channel would be configured as an uplink receiver and uplink transmitter, or conversely, as a downlink receiver and downlink transmitter. The nanoCell, when functioning as a collector in FIG. 4 , reroutes multiple individual channels without modifying the data stream of the incoming/outgoing channel. For a given channel defined by a center frequency (f), a channel identifier (c), a data rate (r), and power level (p), this channel is converted without modification of the data stream to a secondary frequency and channel number that is multiplexed with other individual channels. Power management of the secondary channel is then used to improve overall performance of all individual channels. As shown in FIG. 4 , to clarify, in a TDMA system, the collector function takes bursts related to an individual channel and re-multiplexes these into a new channel, possibly on a different carrier frequency, without modification of the burst structure. In this way, “f”, and “c” are changed without changing “r”. Inherent in this is the ability to readily control the power level of these multiplexed channels to more efficiently convey information. Similarly in a CDMA system, individual code channels are re-multiplexed onto a new channel with similar benefits. The nanoCell, when functioning as a concentrator in FIG. 5 , allows for data rate conversion and concentration of multiple independent channels into a new, higher rate channel. This implies that multiple lower rate channels may be combined into a higher rate channel, thus providing more efficient use of spectrum. This process is bidirectional in that it will also parse a concentrated high rate channel into its constituent lower rate independent channels. The nanoCell, when functioning as a relay in FIG. 6 , translates an individual channel between the incoming and outgoing channels without modification of the data stream or the multiplexing structure. In this way, overall latency within the network is minimized. There is a finite limit to the number of concatenated relays that may exist at a given time due to two-way time delays and the cumulative effect of additive noise in each channel. For this reason, it is necessary to intersperse relays, concentrators and collectors to optimize communications performance. The nanoCell, when functioning as a delay in FIG. 7 , receives and holds data until such time that an appropriate outgoing channel is available. In this way, higher priority communications will receive preference for use of a nanoCell transceiver resource while a lower priority communication is temporarily delayed. The delay may be fixed or variable, and may encompass translation at any level, depending on the subsequently selected output channel. It is reasonable that a nanoCell with multiple transceiver channels may function as each of these simultaneously. In addition, a communications channel that is predominantly meant to traverse a FDD network from a BTS to a mobile station, that is, via a downlink channel, or conversely from a mobile station to a fixed site, that is, via an uplink channel, may be translated by two or more nanoCells 40 and 41 in a non-standard manner to make most efficient use of underused spectra, as shown in FIG. 8 . Such would be the case if the uplink portion of a FDD type network is underutilized due to the fact that uplink data rates tend to be much lower than downlink data rates. In this way, uplink and downlink spectra that are inherently balanced—same amount of spectrum in each direction—may be better utilized to transport asymmetrically loaded data traffic. The radio network of the present invention provides for capacity expansion through frequency reuse among a preponderance of intercommunicating nanoCell base stations. Communications and control channels are capable of being dynamically allocated from a set of allowed uplink and downlink frequencies, time slots and code channels. Communication paths are dynamically assigned to the appropriate base station based on traffic load, quality of service requirements and intercommunicating base station connectivity constraints. The control of a nanoCell enables the intercommunication among multiple nanoCells and base stations. This intercommunication allows linkage between adjacent nanoCells without the need to involve a primary base station. By doing so, information to be used in the autonomous network management function is efficiently distributed among nanoCells. This autonomous network routing is unique in that it allows the nanoCell to make autonomous routing decisions instead of a base station controller or mobile switching center, or similar network control functions. The intercommunicating network of nanoCell base stations dynamically determines efficient communication paths based on service prioritization, network loading and node availability as shown at reference numerals 51 and 53 in FIG. 9 . Subsequent communications can be routed via different paths in order to distribute traffic loading as shown at reference numerals 52 a and 52 b in FIG. 9 . Communications within a nanoCell network can be redistributed away from or toward a particular BTS in order to more efficiently accommodate mobile stations with varying quality of service requirements. In the case shown in FIG. 9, a mobile station would acquire BTS 1 (ACQ) and subsequently, a handover (HO) is performed within the infrastructure network to redistribute traffic loads. The auto-network configuration feature of the present invention allows self discovery within a network thus simplifying deployment. Initialization of a new node is similar to an MS registration within a new network. FIG. 10 shows the operation of in band backhaul by the present invention. Node 1 synchronizes to the beacon channel and establishes its local frequency and timing reference. Node 1 registers with the BTS as a mobile station (MS). Node 1 subsequently broadcasts as a BTS on an alternative beacon channel. Node 2 synchs to node 1 beacon channel and establishes the frequency and timing reference. Node 2 registers with node 1 as an MS. Node 2 subsequently broadcasts as a BTS on an alternative beacon channel. The user MS synchs to node 2 beacon channel and establishes its local frequency and timing reference. The user MS registers with node 2 . Once the user registers with node 2 , the user requests service and establishes a circuit or packet connection with node 2 . Node 2 , node 1 and BTS establish appropriate connections. The BTS establishes the connection with MSC for billing purposes. Extending this process of synchronization and channel allocation, a network topology may be derived as shown in FIG. 11 . In this figure, a hierarchical topology is derived through MS to BTS synchronization processes. NanoCell n 1 receives beacon channel f 1 and f 2 from BTS b 1 and b 2 , respectively, and synchronizes to each individually. NanoCell n 1 then selects beacon channel f 3 to transmit. In turn, nanoCells n 11 and n 12 receive frequencies f 1 , f 2 and f 3 , and synchronizes to each individually. Subsequently, n 11 and n 12 select beacon channels f 4 and f 5 respectively to transmit. There is a mechanism such that if synchronization is established between two nodes, additional synchronization is dismissed. In the case of FIG. 11 , n 1 will not synchronize to n 1 via f 4 , nor will n 12 synchronize to n 1 via f 5 . If by some means, n 12 synchronizes to b 2 via f 2 before it synchronizes to n 1 via f 3 , then it is reasonable that n 1 will synchronize to n 12 via f 5 . Likewise, synchronization between n 1 and n 12 via f 4 or f 5 will depend on the order in which synchronization occurs. If any link is lost between any two nodes, re-selection of a new beacon channel occurs, and re-synchronization is used to establish new connectivity within the network. In this way, connectivity between nodes within a network structure may be autonomously established and maintained. One key aspect of the synchronization function is that it allows a nanoCell to establish the requisite accuracy in its internal frequency reference based upon the transmitted accuracy of adjacent nanoCells. Traditional means would use expensive devices such as rubidium or cesium standards, GPS receivers, or other more elaborate schemes (typical accuracy requirements are less than 0.05 parts per million—ppm—for a BTS control channel, while typical mobile stations will synchronize to a BTS and tune their internal references to within 0 . 10 ppm. The nanoCell will use a plurality of received control channel signals to calculate the best tuning control to statistically maintain an accuracy of 0.05 ppm FIG. 12 displays an example of a hierarchical infrastructure of the present invention. There is shown in this Figure, a BTS 60 and a plurality of nanoCell base stations 61 , 62 , 63 , 64 , 65 . The nanoCell base stations are in turn in communication with a plurality of mobile stations or other wireless apparatus 66 , 67 , 68 , 69 , 70 , 71 . In this example the communications channel may be General Packet Radio Service (GPRS), EDGE, or other recently defined communication systems such as Wideband CDMA (WCDMA) and cdma 2000 . In this example the backhaul speed between the BTS and the individual nanoCell base stations is on the order up to about 2 Mbps. Local backhaul between two nanoCell base stations is on the order of up to about 384 kbps or more. For the backhaul between a wireless device and a nanoCell base station the backhaul can be in the order of about 14.4 kbps and higher. When GPRS or EDGE is used the backhaul range is 114 to about 384 kbps. The preferred method of implementing a nanoCell base station is to use software defined radio methods. The software defined radio enables several improvements over traditional radios: short development cycle due to ability to reprogram the radio to meet different protocols, ability to upgrade radio with latest revisions of standards without the need to physically access unit, and ability to dynamically reconfigure radio to support different protocols as a function of load requirements, eg, high data rate concentrator hub running 384 kbps EDGE protocol to backhaul multiple 56 kbps GPRS channels for different users. The nanoCell base station is typically divided in its construction in view of the different types of operations that it performs. As seen in FIG. 13 the portion 81 of the nanoCell base station operates similar to that of a conventional mobile station. The mobile station portion 81 allocates frequency, time slot and code channel in a manner similar to the way a mobile station performs these functions. Control channel selection is based upon a survey conducted by the downlink receive function to detect and identify the best available downlink channel and channel selection is authorized through the configuration and control link. Synchronization, timing and frequency stabilization is attained through measurements made on this interface. The configuration and control of the nanoCell base station is managed over this interface wherein command and control messages are received on the downlink channel and provided to the control function 82 for further disposition. The nanoCell base station is also provided with a base station portion 83 that is similar in function to a base transceiver station. The base station portion allocates the frequency, the time slot and the code channel in the same manner as the base transceiver station would. This interface acts as the radio interface to mobile stations or other downstream nanoCell base stations. Control channel allocation is based on a survey conducted by the mobile station portion 81 as prioritized by an internal selection list and authorized through the configuration and control link. Configuration and control of the downstream nanoCell base stations is achieved by transmitting command and control messages to them. In order to minimize latency of direct transfers through the nanoCell base station, it is possible to connect the uplink receive path 84 directly with the uplink transmit path 85 and the downlink receive path 86 directly with the downlink transmit path 87 so long as an appropriate frequency, time slot or code channel conversion is accommodated. In another embodiment of the nanoCell, a representative primary base station 90 is shown in FIG. 14 . The primary base station subsystem 91 provides the principle interface between the base station controller and the radio network. Synchronization, timing and frequency reference 92 is established within this subsystem. Commands from the base station controller interface are used to configure and control the primary base station to establish control channels frequency allocation and code channels. Control channel selection is based upon reported results from downstream nanoCell base stations and authorized through the base station controller interface. Data from this interface is modulated for transmission on the down link radio interface. Signals received on the uplink radio interface are demodulated and provided to the base station controlled interface. This is the primary base station radio interface to mobile stations and other downstream nanoCell base stations. Frequency, time slot and code channel allocation are base on commands received through the base station controller interface. The configuration and control of downstream nanoCell base stations is accomplished by transmitting command and control messages to them. The software defined radio modules are represented in FIG. 15 . The modules are over-the-air programmable and support multiple waveforms. The modules are preferably configurable as user nodes or as service backhaul and operate as a mobile station or a BTS. A steerable antenna array is used by the modules. The antenna preferably has high gain in the direction of adjacent nodes and enables interference avoidance. A preferred antenna is a beamforming antenna. The control processor controls network management and control management as well as the protocol stack and the inter-working function. In addition, the control processor also controls packet routing, equipment control, antenna pointing and monitors the health/status of the system. The control processor controls the equipment, manages the network as well as performs frequency stability management. The control processor also performs layer 3 protocol processing and has an intercommunication function. The control processor of the nanoCell base station typically contains the information required to control the interaction between the user and the network. The control processor in the system governs control and queuing, routing and the data links between the user and the BTS. FIG. 16 is the nanoCell RF Transceiver block diagram showing the relation of the receivers and transmitters in the nanoCell to the base band processor. As shown in this figure, the characteristics of the nanoCell base station preferably includes a radio frequency in the range of 824 to 3600 MHZ, as well as simultaneous Tx/Rx. The converter in this base station is preferably tunable over the entire frequency range as well as controlling selectivity filtering, isolation of the signal and output power amplifier (PA). The RF module provides up and down conversion and filtering of RF signals to support BTS and MS functions of the nanoCell base station. FIG. 17 shows one embodiment of the operation of the baseband processor of FIG. 15 . The purpose of the baseband processor is to provide digital modulation and demodulation functions within the nanoCell base station. FIG. 18 shows the preferred details of the structure of the baseband processor. The base band processor controls the transceiver, performs digital filtering and equalization performs layer 1 processing control and layer 2 control. The baseband processor can operate either by IF or the baseband sampling. The purpose of a steerable antenna array is to increase directivity or gain in the direction of a base transceiver station or an adjacent nanoCell, as shown in FIG. 19 . By increasing gain, the carrier to interference ratio—C/I—is increased, thus improving link performance. Greater C/I translates directly to increased data rate and frequency reuse distance. Because nanoCells are stationary, the complexity of steerable antenna arrays is significantly reduced making the overall unit less expensive to build. This is in comparison to a dynamically steered array that strives to maintain a beam pointed at a mobile station. The technical complexity and algorithmic complexity of that requirement makes a cost effective array cost prohibitive for a nanoCell. A less complex array used in a stationary nanoCell environment is significantly more cost effective. As seen in FIG. 19 adaptive beam steering homes in on the beacon frequency of adjacent nodes so gain is optimized for a high data rate. Directional beam linking of adjacent nodes is used to improve C/I and therefore provide higher data rates for backhaul. The omnidirectional pattern is presented to local end users to provide appropriate coverage and Quality of Service (QoS). One advantage of the present invention is that it reduces the frequency planning and topography analysis. In addition, it automatically compensates for interference and blockage. A phased array antenna is preferred for backhaul as they can have a simple steer-on-beacon algorithm which will support higher data rates.