Patent Application
20080096483
To further clarify the features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:
In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings which form a part hereof, and in which are shown by way of illustration specific embodiments of the invention. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention.
Embodiments of the invention relate to a network amplifier that is designed to conserve power. Some of the signals used in communication networks, including RF networks such as cellular telephone networks, rely on various schemes to maximize the use of bandwidth. Embodiments of the invention selectively amplify a given signal according to some criteria. The following invention is described in terms of TDMA, but one of skill in the art can appreciate, with the benefit of the present disclosure, the applicability of the invention into other multiple access schemes.
Embodiments of the present invention relate to a network amplifier that is designed to receive a TDMA signal and conserve power while the TDMA signal is not broadcasting information. A TDMA signal transmitted to or from a handset is typically made up of a broadcasting timeslot sequentially followed by one or more non-broadcasting timeslots that can be used by other handsets operating in the same channel for transmitting information. The network amplifier includes a sensing circuit for analyzing the TDMA signal to determine whether a broadcasting timeslot or a non-broadcasting timeslot is being transmitted to or from the handset. When a broadcasting timeslot is detected, the sensing circuit instructs a power amplifier to amplify the TDMA signal. Conversely, when a non-broadcasting timeslots is detected, the sensing circuit instructs the power amplifier to power down so as to conserve power while amplification is not needed.
For purposes of the present invention, the following definitions are provided. The terms “cellular” and “cellular network” refer to a wireless telephone network that connects radio transmissions between a mobile phone and a system of multiple cell sites, each including an antenna and a base station, to a mobile telephone switching office, and ultimately to the public wireline telephone system. Cellular calls are transferred from base station to base station as a user travels from cell to cell. One of skill in the art can appreciate that embodiments of the invention can be applied to other wireless networks as well.
By way of example, the phrase “cell phone” refers to a wireless device that sends and receives messages using radiofrequency signals in the 800-900 megahertz (MHz) portion of the radiofrequency (RF) spectrum, and the phrase “PCS phone” (personal communication system phone) refers to a wireless device that uses radiofrequency signals in the 1850-1990 MHz portion of the RF spectrum. For purposes of simplicity, as used herein, the terms “cell phone” and “handset” are intended to cover both “cell phone” and “PCS phone”, as defined above, as well as other handheld devices. Likewise, as used herein, the phrase “cellular signal” refers to signals being transmitted both in the cell phone spectrum (i.e., 800-900 MHz) and in the PCS spectrum (i.e., 1850-1990 MHz). One of skill in the art can appreciate that embodiments of the invention are not limited to operation in these spectrums, but can be applied in other portions of the frequency spectrum as well.
“Cell site” and “base station” are used herein interchangeably. Cell site and base station are defined as the location where the wireless antenna and network communications equipment is placed. A cell site or base station typically includes a transmitter/receiver, antenna tower, transmission radios and radio controllers for maintaining communications with mobile handsets within a given range.
The word “uplink” refers to the transmission path of a signal being transmitted from a handset to a base station. The word “downlink” refers to the transmission path of a signal being transmitted from the base station to the handset. The phrases “uplink signal” and “downlink signal” are not limited to any particular type of data that may be transmitted between a handset and a base station, but instead are simply used to specify the direction in which a signal is being transmitted.
Referring now to
The network amplifier 102 amplifies the electrical signal and communicates the amplified signal to the handset 104 in one of two ways. First, the amplifier 102 may retransmit the electrical signal from a second antenna 112 as an amplified RF signal 114, which is received by an antenna 116 of the handset 104. Second, the amplifier 102 may communicate the electrical signal to the handset 104 via a wired connection 118. The handset 104 ultimately processes the signal and communicates the appropriate content to a user of handset 104.
Similarly, the handset 104 may communicate content to the network amplifier 102 by transmitting a signal from the antenna 116 or the wired connection 118. The network amplifier 102 amplifies the received signal and retransmits the signal using the antenna 110. The transmitted signal is received by the base station 106, which may perform a number of operations on the signal, as determined by the wireless service provider.
Many cellular networks utilize digital transmission techniques, such as time division multiple access (TDMA), for increasing the number of channels that can be provided by a cellular network. As will be appreciated by one of ordinary skill in the art, a TDMA channel allows several handset users to share the same frequency by allocating their signals different timeslots. The users transmit in rapid succession, one after the other, each using their own timeslot. In other words, a TDMA signal transmitted to and from a handset can be divided into broadcasting timeslots, when the handset is receiving or sending information, and non-broadcasting timeslots, when the handset is not receiving or sending information. Other handsets may use the non-broadcasting timeslots of a particular handset as their broadcasting timeslots.
TDMA is used in many different communication protocols including, for example, Global System for Mobile communications (GSM), Integrated Digital Enhanced Network (iDEN), Personal Digital Cellular (PDC), Digital AMPS (D-AMPS), and the like. The ratio of broadcasting timeslots to non-broadcasting timeslots varies for the different TDMA protocols. For example, an iDEN signal typically has one broadcasting timeslot followed by two non-broadcasting timeslots, while a GSM signal typically has one broadcasting timeslot followed by seven non-broadcasting timeslots.
Conventionally, a network amplifier often consumes unnecessary power during the non-broadcasting timeslots. The power amplifiers located within a network amplifier often require a relatively high quiescent current in order to maintain linearity of the amplifier. The quiescent current is typically present within a conventional network amplifier both during broadcasting and non-broadcasting timeslots, thereby consuming a substantial amount of power even when there is no need for the network amplifier to amplify an incoming signal (i.e., during the non-broadcasting timeslots).
Referring now to
When a TDMA input signal is received by the network amplifier, the sensing circuit 204 analyzes the TDMA signal to determine whether the signal contains a broadcasting timeslot or a non-broadcasting timeslot. When the sensing circuit 204 detects a broadcasting timeslot, the sensing circuit 204 immediately sends a control signal 208 to the power amplifier 206 instructing the amplifier to turn on. When the power amplifier 206 is turned on, the amplifier amplifies the signal received at the input 210. Conversely, when the sensing circuit 204 detects a non-broadcasting timeslot, the sensing circuit 204 immediately sends a control signal 208 to the power amplifier 206 instructing the amplifier to turn off When the power amplifier 206 is turned off, the amplifier will not amplify the signal received at the input 210 and the amplifier will be placed in a state where power consumption is minimized. For example, when the power amplifier 206 is turned off, any quiescent current supplied to the amplifier is minimized or eliminated. The sensing circuit 204 and the power amplifier 206 are configured such that the power amplifier can be turned on and off in rapid succession and with minimal delay so that any adverse affect to the quality of the amplified TDMA signal is minimized or eliminated.
In one embodiment, the TDMA input signal received by the sensing circuit 204 is an uplink signal received from a handset. The TDMA input signal is analyzed and amplified, as described above, and is then transmitted via an antenna to a base station, as illustrated in
In another embodiment, the TDMA input signal is a downlink signal received from a base station. The TDMA input signal is analyzed and amplified, as described above, and is then transmitted via either an antenna or a wired connection to a handset, as illustrated in
The bidirectional cellular amplifier 302 is also configured to receive a TDMA signal from one or more handsets, amplify those signals, and retransmit the signals to a base station. The signals from the handsets may be received via either a wired or wireless connection. The signals are routed to a second power amplifier 314, which is also controlled by the sensing circuit 304. The sensing circuit 304 turns the power amplifier 314 on or off depending on whether the TDMA signal received from the handset presently includes a broadcasting or a non-broadcasting timeslot.
In order to allow the antenna 310 and the connection 312 between the handset and the network amplifier 302 to simultaneously transmit and receive TDMA signals, duplexers (DUP) 306 and 308 are provided, by way of example. A duplexer is an automatic electrical device that permits the use of the same antenna for concurrently transmitting and receiving. More generally, a duplexer is a three port device with one common port “A” and two independent ports “B” and “C”. Ideally, signals are passed from A to B and from C to A, but not between B and C. For example, the duplexer 308 receives an RF signal from a base station via the antenna 310 and routes the signal to the inputs of the power amplifier 316 and the sensing circuit 304. The duplexer 308 simultaneously receives a second electrical signal from the output of the power amplifier 314, and causes this signal to be transmitted as an RF signal via the antenna 310.
Although the network amplifier 302 is illustrated as having only a single sensing circuit 304, the network amplifier 302 may have multiple sensing circuits for each of the inputs it receives. For example, two sensing circuits may be provided, a first for analyzing the TDMA signal received from the handset and for controlling the power amplifier 314, and a second for analyzing the TDMA signal received from the base station and for controlling the power amplifier 316. Furthermore, if the broadcasting timeslots and the non-broadcasting timeslots of the TDMA signals received from the handset and from the base station are being transmitted simultaneously, the sensing circuit 304 may control both power amplifiers 314 and 316 by only analyzing one of the input signals 318 or 320.
The components of the sensing circuit 404 are designed such that the AC signal present during a broadcasting timeslot of a TDMA signal results in a DC voltage at the output of the diode detector 408 that exceeds the Vref voltage level. Therefore, the presence of a broadcasting timeslot causes the output 412 of the comparator 410 to instruct the power amplifier to turn on, and the presence of a non-broadcasting timeslots causes the output of the comparator 410 to instruct the power amplifier to turn off
As described previously, the link between the network amplifier 202 or 302 and the incoming TDMA signal may be wired or wireless. Where a wireless link is employed, the sensing circuit 404 may include additional functionality for handling the issues that are presented when receiving a wireless signal. For example, the sensing circuit 304 may include a filtering circuit for reducing noise levels within the received TDMA signal. If the filtering circuit creates a significant delay, the power amplifier 314, 316 may further include a delay circuit for delaying the TDMA signal in order to compensate for the delay in the sensing circuit 304 thus resulting in synchronization between the sensing circuit and the signals passing through the power amplifier, 314,316.
The sensing circuit 404 illustrated in
The method 500 then detects 504 the presence of the broadcasting timeslots within the TDMA signal. Referring once again to
A power amplifier is controlled 506 so that the power amplifier only amplifies the TDMA signal during the broadcasting timeslots and does not amplify the TDMA signal during the non-broadcasting timeslots. Therefore, power is conserved during the non-broadcasting timeslots. The TDMA signal produced by the power amplifier is then transmitted 508 from the network amplifier, either to a base station or to a handset.
The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. For example, the present invention is not limited to cellular telephones but can be applied in any situation where TDMA signals are being amplified, regardless of context. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.
