The six extra padding frames can be lumped together into an extended direct mode frame or they can be evenly distributed within a multiframe so that each pad exists in every three direct mode frames, as shown in Fig. The third burst, normal burst, is used to carry traffic data. A proper modulation is later assigned for each direct mode burst including linearization burst, synchronization burst and normal burst. Direct mode allows communication to be made when network coverage is not available and allows one of the TETRA terminals to act as relays for a signal. TETRA direct mode normal burst makes use of two preambles, a first and second preamble.

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Search Expert Search Quick Search. As explained, a direct mode multiframe takes exactly 1. The method of claim 4, further comprising the step of a mobile station transmitting in a time slot allocation the direct mode synchronization burst DSB comprising of one preamble symbol used for synchronization; and one or more data symbols. One possible configuration for the synchronization burst and normal burst mapped to WiMAX symbols is shown in Fig.

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In each carrier set, every three subcarriers are modulated using boosted BPSK modulation with specific pseudo noise sequence. More tetga zones or one larger transparent zone can be accommodated for more direct mode channels to enable more concurrent calls.

The exact timing of a direct mode multiframe of 1.

It is used tetda a transmitting mobile station to ramp and linearize its power amplifier PA. A system for enabling a mobile station MS to communicate directly with another 5 mobile station using complete, subset or superset of TETRA direct mode-like features and at the same time to be compatible with the target wireless broadband network air interface, said system comprising:.

Normal burst has the option of using tetga different preambles, a first preamble and a second preamble.

The method of claim 4, further comprising the step of mapping one or more TETRA direct mode physical channels, each of which is made of two time slots per TETRA direct mode frame, to the available time slot allocations among the target wireless broadband network frames within a TETRA direct mode frame duration. The specific sequence used depends on the segment used and the identity of cell parameter.

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TETRA direct-mode frames, time slots, bursts and logical channels, by the transmitting direct-mode mobile station DM-MS to the transparent zones within the wireless broadband network frames.

WO// METHOD TO ENABLE TETRA-LLKE DIRECT MODE OPERATION TO WORK ON BROADBAND NETWORK

A proper modulation is later assigned for each direct mode burst including synchronization burst and normal burst, and optionally, linearization burst. Some control bits C may also be added in symbol 1.

With the TETRA direct mode operation physical layer fully emulated within WiMAX physical layer, a fully compatible service access point can be provided for the physical layer so that existing implementation of the higher-level layers can be reused with minimal modification.

A method for enabling a mobile station MS to communicate directly with another mobile station using complete, subset or superset of TETRA-like direct mode features and at the same time be compatible with a target wireless broadband network air interface, said method comprising the steps of: TETRA mobile stations can communicate in direct mode using trunked infrastructure.

The pilot carriers in the FUSC slots used in the two symbols may be used for channel tracking until another synchronization burst arrives. Different preamble and training sequence are used in synchronized burst to indicate whether one or two logical channels are mapped to the first and second block, in the burst.

To emulate the first and second block in normal burst and synchronization burst, the DL FUSC burst will be logically divided into two blocks. Within each WiMAX frame assigned to a direct mode time slot, a transparent zone is allocated by the base station so that it will not transmit, to allow for operating direct mode time slot in a WiMAX network.

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In WiMAX, three carrier sets are used to carry preamble. The invention will now be described in greater detail, by way of an example, with reference to the accompanying drawings, in which:. There could be more than one slave in a call group.

The control bits may be used, for example, to indicate whether one or two logical channels are mapped to the two blocks of modulated data bits. The division could be symmetric or asymmetric depending on which method would give better overall throughput. Alternatively, some bandwidth request protocol to the base station may be defined so that a mobile station that wants to make a direct mode call may be allocated one or more direct mode channels.

The preamble of direct mode burst shall be different from the one used for WiMAX. Whereas one symbol is used for preamble and another for data in synchronization burst emulation, both symbols are used for data bits in the mapped normal burst.

Control and traffic data are cyclically sent in multiframes, which is made up of 18 frames. Different preamble is used to indicate if one or two logical channels are mapped to the two blocks, a first block and second block, in the direct mode time slot.

The six extra padding frames can be lumped together into an extended direct mode frame or they can be evenly distributed within a multiframe so that each pad exists in every three direct mode frames, as shown in Fig. A SumoBrain Solutions Company. Two time slots are provided for a call mmios, a first and third time slot within a direct mode frame, for every direct mode mmimos channel. There are three different kinds of burst, as shown in Fig.