Abstract:
Separate power control for the forward voice channel and forward data channel is provided without using additional bandwidth or decreasing the amount of pilot signal provided from the mobile to the base station. Alternating voice and data power control commands or information are transmitted in the pilot channel by a mobile to a base station. In one embodiment, the power control portion of a first pilot channel segment is used to provide power control for the forward voice channel and then in the following pilot channel segment, the power control portion is used to provide power control for the forward data channel. In other embodiments, other than a 50/50 mix between voice and data power control is provided in the mobile's pilot channel. For example, forward voice channel power control commands may be transmitted two or more times for each transmission of forward data channel power control commands.
Abstract:
A back haul architecture effectively reduces the reactivation times for both forward-link and reverse-link data transmissions over CDMA wireless communications systems, by relying on packet-mode transmissions over the back haul between a frame selection/distribution (FSD) function and the appropriate base stations for both forward-link data and reverse-link data. In particular, for the forward direction, the FSD function transmits forward-link data only to one base station (i.e., the primary base station), which is solely responsible for controlling the forward-link air interface with the corresponding mobile unit. As such, the forward link always operates in simplex mode for data transmissions, independent of how many base stations are operating in soft handoff for the reverse link with the same mobile unit. For the reverse direction, each base station that receives frames of reverse-link data from the mobile unit, assigns a time tag to the frame, divides the frame into one or more data packets, assigns a different sequence number to each data packet, and transmits the data packets to the FSD function over the back haul, all without first synchronizing time with any other base station that is also operating in reverse-link soft hand-off with that mobile unit. The FSD function (or preferably the radio link protocol (RLP) function) is then responsible for selecting packets of reverse-link data for subsequent processing (e.g., transmission to the network end of the connection). By limiting forward-link data transmissions to simplex mode and using packet-mode transmissions for reverse-link data, the need to first synchronize timing between the various base stations is eliminated for both forward-link and reverse-link data transmissions. As a result, reactivation delays are greatly reduced.
Abstract:
Separate power control for the forward voice channel and forward data channel is provided without using additional bandwidth or decreasing the amount of pilot signal provided from the mobile to the base station. Alternating voice and data power control commands or information are transmitted in the pilot channel by a mobile to a base station. In one embodiment, the power control portion of a first pilot channel segment is used to provide power control for the forward voice channel and then in the following pilot channel segment, the power control portion is used to provide power control for the forward data channel. In other embodiments, other than a 50/50 mix between voice and data power control is provided in the mobile's pilot channel. For example, forward voice channel power control commands may be transmitted two or more times for each transmission of forward data channel power control commands.
Abstract:
The present invention is an apparatus and a method for sharing a communication channel among two or more base stations (32) connected to a base station controller (34) via a common transmission line (36) in a channelized format. The present invention allows each of the base stations to receive data transmitted over a shared communication channel from the base station controller, to determine whether the data transmitted from the base station controller is intended for that base station, and to insert its data into the communication channel without interfering with data transmitted by other base stations over the communication channel. In one embodiment, each of the base stations is configured to bridge onto the transmission facility such that signaling messages being transmitted over a signaling channel may be received by all of the base stations. The signaling messages has associated identifiers for specifying particular base stations to which the signaling messages are intended. In another embodiment, each of the base stations can insert its signaling message into the data stream over the signaling channel without interfering with signaling messages already in the data stream.
Abstract:
In a wireless communications system having a centralized interworking function (IWF) and geographically distributed base stations, a packet-oriented frame selection/distribution (FSD) function forwards forward-link user data intended for a particular mobile unit directly to a primary base station, which determines whether to transmit the forward user data to the mobile unit using a fundamental channel or a supplemental channel. If the data is to be transmitted using a fundamental channel, when the base station is operating in soft handoff, the forward user data is transmitted from the primary base station back to a circuit-oriented FSD function for forwarding to all of the base stations currently participating in the soft handoff, so that all of the base stations can transmit the forward-link user data to the mobile unit at the same time. If the data is to be transmitted using a supplemental channel, then the primary base station is able to assign a supplemental channel and transmit the forward user data to the mobile unit using the supplemental channel in simplex mode, independent of whether or not the mobile unit is otherwise operating in soft handoff. In this way, forward-link data transmissions can be performed without first having to coordinate either the timing or the data rate with any other base stations or with the FSD function. As such, the reactivation time needed to resume active forward-link data transmissions using a supplemental channel from the control hold state is less than the corresponding reactivation time under the prior art, which does require coordination of timing and data rate between all base stations in soft handoff.
Abstract:
A single base station supports the non-diversity transmission of a first digital signal type and the diversity transmission of a second digital signal type. The base station includes primary channel boards for modulating and encoding a first digital signal type and secondary channel boards for modulating and encoding a second digital signal type. A first group of transmit radio modules accept the first digital signal type and the second digital signal type and provides a composite electromagnetic output signal. Each transmit radio module is associated with a different sector. A second group of transmit radio modules accept the second digital signal type from secondary channel boards and provide a diverse electromagnetic output signal for complementing the composite electromagnetic output signal.
Abstract:
A wideband code division multiple access (CDMA) communication system overlayed on an IS-95 network generates two or more digital bit streams from a group of wideband digital data streams, each digital bit stream spread to form a CDMA component signal. Each CDMA component signal is combined with a corresponding IS-95 digital bit stream to form a composite CDMA signal, allowing a base station to share transmitter subsystems between the wideband and IS-95 systems. For up to three carrier frequencies, up to three composite CDMA signals are employed. A digital bit stream for a group of summed user conversations in the IS-95 system modulates a respective RF carrier frequency to generate a low-power RF signal. The CDMA component signals of the wideband CDMA system are generated so each has a chip rate identical to the chip rate of the digital bit streams of the IS-95 system. The baseband digital data streams for all wideband user conversations are summed digitally for each targeted RF carrier frequency to produce the composite wideband digital signal for each targeted frequency. In one application, each composite wideband digital signal, each at the IS-95 chip rate, is then used to modulate a carrier frequency which is either the same, or has approximately the same frequency and phase as the carrier frequency used in the IS-95 system. Three low-power RF signals are produced in the wideband system, each having the same spectral characteristics as the corresponding low-power RF signals generated in the IS-95 system. These low-power RF signals at the same frequency are combined into a single signal provided to the amplifier and antenna subsystem of a base station transmitter. In another application, each composite digital signal is digitally combined with a respective IS-95 digital bit stream prior to modulation by respective RF carrier. Therefore, signal combining between the IS-95 and wideband CDMA portions of a base station system is accomplished either digitally or with RF signals prior to amplification, thereby allowing the IS-95 system and wideband CDMA system portions of the base station to share RF filters, amplifiers and antennas of the base station transmitters.
Abstract:
A back haul architecture enables efficient primary transfer (i.e., transfer of the designation of primary base station from one base station to another). A frame selection/distribution (FSD) function queues packets of forward-link data -- to which sequence numbers have been assigned --for packet-mode transmission over the back haul only to one base station -- the current primary base station -- where the packets are again queued for over-the-air transmission to the mobile unit. If and when it becomes appropriate to transfer the designation of primary base station to another base station, there may still be packets of data queued at the old primary base station awaiting transmission to the mobile unit. The old primary base station sends a message to the new primary base station indicating a particular sequence number that identifies the remaining packets of forward-link data queued at the old primary base station. The new primary base station then sends a message to the FSD function requesting transmission of those packets of forward-link data corresponding to the particular sequence number. The FSD function then transmits those requested packets of forward-link data to the new primary base station, which queues the requested packets for over-the-air transmission to the mobile unit. In this way, transmission of all of the forward-link data to the mobile unit is enabled without having to transmit the remaining queued packets of forward-link data from the old primary base station to the new primary base station over the back haul, thereby providing an efficient mechanism for primary transfer in wireless communications systems that support forward-link data transmissions only in simplex mode.