 Portable work station-type data collection system |
| The objective of the present invention was, early on, to expand on the utility of relatively small, ... |
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| Method and apparatus for transbody transmission of power and information |
| The present invention capacitively transmits not only data but power through a user's body. In one ... |
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| Broadcast information delivering system |
| An object of the invention is to provide a broadcast information delivering system and a wireless ... |
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| Data card connector |
| According to the invention there is provided a data card connector comprising: a housing defining ... |
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| Keyboard with multiple input/output function |
| OF THE PREFERRED EMBODIMENT As shown in FIGS. 1 and 2, the keyboard device with multiple input/... |
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| Antenna array for point-to-point microwave radio system |
| FIG. 1 shows a point-to-point radio system 10 that may be used for communicating information over ... |
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| Location and tracking system |
| What is claimed is: 1. A mobile radio-frequency communication system, comprising: a network of at ... |
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| Bad frame indicator for radio telephone receivers |
| Accordingly, the present invention utilizes four-signal quality metrics to specify the bad frame ... |
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| System and method for application location register routing in a telecommunications network |
| Accordingly, a need has arisen for a solution to the application location register routing problem ... |
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Quality-based handover
| Details |
Inventors: Galyas, Johan Karoly Peter; Bodin, Stig Roland; Linden, Lars Kalle; Lindroth, Lars Magnus;
Assignee: Telefonaktiebolaget LM Ericsson (Stockholm, SE)
Primary Examiner: Nguyen; Lee
Assistant Examiner:
Attorney, Agent or Firm: Burns, Doane, Swecker & Mathis, L.L.P.
The present invention relates to the technique of handover in mobile telephony. A new Transcoder and Rate Adaptation Unit (100 FIG. 3) is introduced which provides two uplink (230, 250 respectively, FIG. 3) and two downlink (240, 260 respectively, FIG. 3) channels. The use of these two channels (230, 250 respectively, FIG. 3) on the uplink during handover provides for the use of distributed handover on the uplink. The result minimizes the audible interruption during handover by minimizing the loss of Traffic Channel frames to what is possible within the GSM standard. Additionally, interruption of the speech or background noise during these lost frames is masked by an error concealment algorithm, since the Transcoder and Rate Adaptation Unit (100 FIG. 3) still has information from the Base Transceiver Station responsible for transmission before the handover. |
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DETAILED DESCRIPTION The present invention uses the concept of a distributed handover to minimize interruption of the speech frames.
This is similar to the idea of "soft handover" as used in CDMA.
However, the present invention applies to a digital TDMA system such as the GSM system.
Instead of allocating a new TRAU to BTS-new in the handover, the present invention uses the same TRAU and the switching is done on the Abis side of the TRAU, at the full-rate of 16 kbit/s or the half-rate of 8 kbit/s in GSM, whether the TRAU is located at the Base Transceiver Station or anywhere more centrally, up to the Mobile Switching Center.
The actual rate is not important, the present invention applies equally well to different systems, regardless of the rate of transmission on the BTS side of the TRAU.
Although other systems exist using one TRAU for handover, they don't use the idea of the present invention, which is to have two uplink channels for a soft handover, wherein the best embodiment uses only one TRAU.
This new invention is applicable to both handovers between cells under the control of the same Base Station Controller, "intra-BSC" handovers, and handovers between cells under the control of different Base Station Controllers, "inter-BSC" handovers.
It is also applicable to "intra-cell" handovers from one channel to another within the same Base Transceiver Station.
It is also applicable to handovers with changed speech coding where the TRAU uses two different speech coders (e.
g.
bosh half-rate and full-rate), and both speech and data services will work with the present invention.
By keeping the same TRAU, the interruptions due to the switching of the uplink traffic can be more easily masked by the TRAU since the TRAU will have information stored from BTS-old about the speech frames being transmitted.
Since the uplink handover interruption with synchronous handover could be as short as 40-60 ms under ideal conditions, the TRAU will likely be generating partly muted speech from BTS-old, or perhaps comfort noise, based on the data received from BTS-old
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Cell Phones 
