Telecommunications – Transmitter and receiver at same station
Reexamination Certificate
1999-05-28
2003-05-06
Appiah, Charles N. (Department: 2682)
Telecommunications
Transmitter and receiver at same station
C455S082000, C455S552100
Reexamination Certificate
active
06560443
ABSTRACT:
FIELD OF THE INVENTION
This invention relates, generally, to the field of telecommunications/mobile terminals, such as mobile phones and the like and, more particularly, it relates to an antennae sharing scheme for diversity antennae in a dual-radio hand-held terminal such as IP (Internet Protocol) based WLAN (Wireless Local Area Network)/BT (Bluetooth) hand-held terminal.
BACKGROUND OF THE INVENTION
Recently, a new technology has been developing which can expand the use of mobile phones in related hand-held mobile terminals using the same 2.4 GHz ISM (Industrial, Scientific and Medical) band as that employed by wireless LAN (WLAN) communication which conforms to the IEEE 802.11 standard such as for DSSS (Direct Sequence Spread Spectrum) radio communication, the contents of which are incorporated herein by reference. This new technology is referred to as Bluetooth (BT) which is a low-powered radio technology, having a range of approximately 10 cm to 10 m, but can be extended for greater distances through simply increasing the transmit power level. The frequency band of this new technology calls for an ISM radio band at 2.4 GHz, which is a license-free spectrum band, practically, available worldwide and which conforms to the wireless LAN (WLAN) radio ISM band conforming to IEEE 802.11 standard for DSSS radio communication. Employment of this low power/lower range ISM band to mobile phone technology would mean that cable hook-ups would no longer be required between laptop computers and cellular (or cell) phones to send E-mail, as one example. Further, business people would be able to surf the internet on their laptop, while their mobile phone is in their jacket pocket. That is, the mobile phone, as one example of a mobile terminal, will no longer have to be limited to a basic service set (BSS) link, which typically consists of a number of stations executing the same MAC (Medium Access Control) protocol in competing for access to the same shared medium. (The basic service set may be isolated or it may be connected to a backbone distribution system through an access point, the access point functioning as a bridge. The MAC protocol may be fully distributed or controlled by a central coordinated function housed in the access point. The basic service set generally corresponds to what is referred to as a cell in the literature. An extended service set (ESS) consists of two or more basic service sets interconnected by a distribution system. Such distribution system is, typically, a wired backbone LAN. The extended service set appears as a single logical LAN to the logical link control (LLC) level.
FIG. 5
of the drawings typifies a wireless LAN model conforming to the IEEE 802.11 standard.)
In a WLAN link-up, a single access transceiver can support a small group of co-located users within a range of less than one hundred to several hundred feet, typically. On the other hand, Bluetooth technology will enable users to connect their mobile computers, digital cellular phones, hand-held devices, network access points and other mobile devices by wireless short-range radio links, unimpeded by line-of-site restrictions using substantially less power. Bluetooth (BT) technology will increase the ease of wireless communication by the ordinary citizen, as well as the scope of wireless connectivity. Also, since BT is limited to short range communication, typically, under 10 meters, for example, 2-3 meters, it uses a considerably lower power level than that of WLAN. Namely, for a mobile phone, a WLAN DSSS radio operating in the 2.4 GHz ISM band having 30-50 meter range, for example, would typically require about 100 mW power level, whereas a BT ISM FHSS (Frequency Hopping Spread Spectrum) radio or, simply, a BT ISM spread spectrum radio would require about 1 mW power level. This technology enables portable electronic devices to connect and communicate wirelessly via short range, ad hoc networks.
In order to function on a worldwide basis, Bluetooth requires a radio frequency that is license-free and open to any radio. The 2.4 GHz ISM band satisfies these requirements, the 2.4 GHz band actually being 2.4-2.483 GHz radio band. When a Bluetooth radio is applied to a mobile phone, the user can leave the mobile phone clipped to his belt or in a pocket and walk around for the entire dial-up-connection. Also, because there are no line-of-site requirements for Bluetooth devices, it is well suited for wireless connectivity, such as between a mobile phone and a notebook computer. For example, with Bluetooth, a person could synchronize their phone with a PC without taking the phone out of their pocket or briefcase. Users would be able to automatically receive E-mail on their notebook or laptop computers by the digital cellular phones in their pockets or synchronize their primary PC with their hand-held computer without taking it out of their briefcase. The omni-directional capability of Bluetooth allows synchronization to start when the phone is brought into range of the PC. It allows for a gross data rate of 1 Mbit/S, with second generation plans to be increased to a ratio of 2 Mbit/second. It uses packets switching protocol based on a frequency hopping scheme (analogous to IEEE 802.11 standard). Also, because of its omnidirectionality, authentication and encryption is also included, for security reasons, as part of the base band protocol thereof. That is, authentication relies on utilizing a secret key (i.e., password or PIN), thereby assuring security.
In view of the attributes of this low power ISM radio band and its relevance to mobile terminals, such as hand-held mobile (cellular) phones and the like, the present inventors have considered how to facilitate both the 2.4 GHz ISM band WLAN DSSS radio and the low power/short range 2.4 GHz ISM BT radio to effect a practical and cost-effective dual mode mobile terminal, namely, an IP based dual mode WLAN/BT hand-held terminal. Filter, antennae and RF switch components of a WLAN IEEE 802.11 DSSS radio and BT dual mode terminal can be shared in a number of ways, the inventors determined. In its simplest form, such components are not shared, that is, both radios are implemented as separate and independent units. However, this is obviously not the optimal solution, both in terms of cost, as well as practicality. On the other hand, combining a low power short range 2.4 GHz ISM radio band device like a BT radio and a substantially higher power level WLAN device, like the 802.11 DSSS radio, into a small sized hand-held terminal, has several drawbacks, namely, interference, resulting from sharing of antennae, filters and other components. In fact, sharing a diversity antennae scheme, filters and antennae switches between two 2.4 GHz radios in a dual mode terminal has not been implemented earlier, as far as known. Therefore, such problems had not existed in such a form, earlier. Dual band mobile phones have somewhat similar problems, but, however, as the two radios in the dual band mobile phone employ different frequency bands, different approaches are used.
The present invention specifically addresses the issue of antennae sharing between two 2.4 GHz radios in a dual mode terminal such as would be effected in connection with an IP based dual mode WLAN/BT hand-held terminal. The present inventors are not aware of any earlier attempts at effecting antennae sharing in such a dual mode terminal. On the other hand, the inventors are aware of several earlier attempts at diversity antennae sharing, but, however, only with regard to a standard WLAN operation. One such known earlier scheme was disclosed by Lucent Technologies in EP 0 623 967 A1, dated Nov. 9, 1994, which describes dual antennae diversity system for wireless LAN consisting of two L-shaped PIFA antennae. In that disclosure, a single pole dual terminal switch (SPDT) is employed to effect switching between the two antenna members in a receive mode and for switching to only one of the two antenna members for operation of the apparatus in a transmit mode. However, that earlier disclosure did not address the issue o
Orava Pekko
Vaisanen Ari
Appiah Charles N.
Nokia Corporation
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