The use of mobile communications networks has increased over the last decade. Operators of the mobile communications networks have increased the number of base stations in order to meet an increased request for service by users of the mobile communications networks. The operators of the mobile communications network wish to reduce the running costs of the base station. It is one option to implement the radio system as an antenna-embedded radio forming an active antenna array of the present disclosure. The antenna-embedded radio may be implemented on a chip, at least for some of the components of the antenna embedded radio. The antenna-embedded radio reduces the space needed to house the hardware components of the base station. Power consumption during normal operation of the active antenna array is reduced when implementing the active antenna array on a chip.
The mobile communications networks use protocols when relaying radio signals. Examples of first types of protocols used in the mobile communications system are the GSM protocol and a UMTS protocol but are not limited thereto.
New types of protocols for radio signals (or pertaining to radio signals) in mobile communication networks have been developed in order to meet an increased need of mobile communication and to provide higher data rates to handsets as well as an increased flexibility in adapting radio signals relayed by the active antenna array to specific needs of an individual site or cell of the mobile communications network.
Examples for a second (new) type of protocol pertaining to second protocol radio signals include the unified mobile telecommunication service protocol (UMTS), a third generation long term evolution (3GLTE) protocol, a freedom of mobile multi media access radio (FMRA) protocol, a wideband code division multiple access (WCDMA) protocol, and a Worldwide Interoperability for Microwave Access (WiMAX) protocol, but are not limited thereto.
Radio signals using the first protocol shall be referred to herein as first protocol radio signals. Radio signals using the second protocol shall be referred to herein as second protocol radio signals.
The operators of the mobile telecommunications networks are interested in supporting the first protocol radio signals and the second protocol radio signals. Therefore an interest exists to provide active and/or passive antenna arrays relaying both the first protocol radio signals and the second protocol radio signals.
The second protocol radio signals often require flexibility in beam shaping not often required with the first protocol radio signals.
In the prior art it was possible to provide an active antenna array for the second protocol radio signals and a further antenna array relaying the first protocol radio signals. Such an approach is rather expensive for the operators of the mobile communications network as two separate sets of the antenna arrays need to be setup and maintained.
Combined passive antenna arrays for the mobile communications networks are known relaying the first protocol radio signals and the second protocol radio signals concurrently. These combined antenna arrays of the prior art unfortunately do not provide the increased flexibility in terms of beam shaping as is often required with the second protocol radio signals.
FIG. 1 shows a passive antenna array 1a of the prior art. The passive antenna array 1a of the prior art is adapted to relay two different air interface standards (also referred to as a first protocol pertaining to a first protocol radio signal, for example GSM or UMTS but not limited thereto and a second protocol pertaining to a second protocol radio signal). The second protocol pertaining to the second protocol radio signal may be UMTS or LTE but is not limited thereto.
The first protocol radio signal comprises a general first protocol transmit signal 70Tx and a general first protocol receive signal 70Rx. The second protocol radio signal comprises a general second protocol transmit signal 75Tx and a general second protocol receive signal 75Rx. The general first protocol transmit signal 70Tx and the general first protocol receive signal are present between a first protocol base transceiver station (BTS) 10-1 and a duplexer 20. The general second protocol transmit signal 75Tx and the general second protocol receive signal 75Rx are present between a second protocol base transceiver station (BTS) 10-2 and the duplexer 20. The duplexer 20 combines the general first protocol transmit signal 70Tx and the general second protocol transmit signal 75Tx with a low combiner loss. The low combiner loss is much lower than a loss present with a 3 dB hybrid or Wilkinson combiner. It is a disadvantage of the duplexer 20 to require a roll-off band between the general first protocol transmit signal 70Tx and the general second protocol transmit signal 75Tx as well as between the general first protocol receive signal 70Rx and the general second protocol receive signal 75Rx. The duplexer 20 separates a general first protocol receive signal 70Rx and a general second protocol receive signal 75Rx such that the general first protocol receive signal 70Rx reaches the first protocol BTS 10-1 and the general second protocol receive signal 75Rx reaches the second protocol BTS 10-2.
The required roll-off of the prior art duplexer 20 represents a waste in bandwidth as the roll-off band is within a bandwidth of the first protocol radio signals and a bandwidth of the second protocol radio signals. Therefore it is expensive to use the duplexer 20 in terms of spectrum license fees, as the spectrum license fees also need to be paid for the roll-off band of the duplexer 20. The duplexer 20 is further inflexible with respect to frequency bandwidths for the first protocol radio signals and the second protocol radio signals. A bandwidth allocated to the first protocol radio signal and a bandwidth allocated to the second protocol radio signal are fixed different to the teachings of the present disclosure as will be explained below.
A coaxial feeder cable forwards the general first protocol transmit signal 70Tx and the general second protocol transmit signal 75Tx from a tower mounted amplifier (TMA) 80 to the antenna array 1a. The coaxial feeder cable further forwards a general first protocol receive signal 70Rx, and the second protocol receive signal 75Rx from the passive antenna array 1a to the TMA 80. The general first protocol transmit signal 70Tx is split into individual first protocol transmit signals 70Tx-1, 70Tx-2, . . . , 70Tx-N at a port 11 of the passive antenna array 1a reaching an individual one of the antenna elements Ant-1, Ant-2, . . . , Ant-N of the antenna array 1a. A corporate feed network is used for splitting the general first protocol transmit signal 70Tx into the individual first protocol transmit signals 70Tx-1, 70Tx-2, . . . , 70Tx-N. The corporate feed network is illustrated in FIG. 1 by the thick black lines within the body of the passive antenna array 1a. In FIG. 1 only 16 of the antenna elements Ant-1, ant-2, . . . , Ant-N are shown. The individual first protocol transmit signal 70Tx-1, 70Tx-2, . . . , 70Tx-N is only shown for the individual antenna elements Ant-1 and Ant-16 in FIG. 1 for the sake of clarity. The individual transmit signal 70Tx-1, 70Tx-2, . . . , 70Tx-N is typically present for each one of the antenna elements Ant-1, Ant-2, . . . , Ant-N.
The general second protocol transmit signal 75Tx is split into a plurality individual second protocol transmit signals 75Tx-1, 75Tx-2, . . . , 75Tx-N reaching the individual antenna element Ant-1, Ant-2, . . . , Ant-N of the antenna array 1a. The individual second protocol transmit signal 75Tx-1, 75Tx-2, . . . , 75Tx-N is only shown for the individual antenna elements Ant-1 and Ant-16 in FIG. 1 for the sake of clarity but may be present for more than two of the antenna elements Ant-1, Ant-2, . . . , Ant-N.