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FP5

FLOWS Sintesi della relazione

Project ID: IST-2001-32125
Finanziato nell'ambito di: FP5-IST
Paese: United Kingdom

Simultaneous operation of multiple radio systems

A detailed consideration of the way that two or more wireless standards may be operated simultaneously suggests that the following combinations are possible:

Wholly parallel
Advantages
- Full transmission and reception at any instance from any standard
- No need for coordination between standards and their respective radio hardware
- No need for the convergence manager to manage the operation of the lower layers (signal from the lower layers to the convergence manager is still required for optimum operation.)

Disadvantages
- Interference issues between the wireless systems that probably cannot be resolved and may limit radio link performance
- Both standards would need full support and functionality
- Limited scope for sharable functions in the hardware (full set of system functions are needed for both standards)

Parallel with limitations
Advantages
- Mostly the same as the wholly parallel case (though limitation need to be specifically defined)

Disadvantages
- True simultaneous transmission from both standards may not be possible
- This may also apply to some combination of simultaneous transmission and reception
- The convergence manager would need to manage these situations to avoid the collisions (collisions could be treated as lost of corrupt packets.)

Interleaved transmit and receive slots
Advantages
- May solve some of the limitation of the example above
- Otherwise, no benefits which are obvious!
- This example is described in FLOWS deliverable D8.

Disadvantages
- Requires the more careful co-ordination and management of the transmit and receive frame slots
- Best suited to TDMA/TDD based standards so not possible with standards that use continuous transmissions such as UMTS FDD
- There may be an impact on other connections that are already in operation within the network
- The overall through-put will be constrained by the need to provide the necessary slot timing flexibility.

Operation of wholly uplink and wholly downlink on separate standards
Advantages
- Solves some issues concerning the managing of transmit and receive slot timing in previous cases.
- Fits neatly to some applications

Disadvantages
- Breaks the correct operation of most if not all existing standards
- Probably need a mechanism for providing a return channel via the other standard (for acknowledgements etc.)
- No scope for link or route diversity
- Interference between simultaneous transmission and reception may still be a problem

Rapid connection set-up and closure
Advantages
- Perform the switching on a rapid basis so that only one complete duplex connection (for one standard) is operational at any instance

Disadvantages
- There will be limits to how rapidly this could be achieved
- Significant throughput delays will be introduced
- It may not appear as simultaneous operation to the user
- No scope for link or route diversity

Use systems that are packet based
Advantages
- Only transmits when needed
- Continuous duplex connection are not needed
- Transmissions from each standard can contend for priority between themselves

Disadvantages
- Limits the choice of standards (GPRS etc)
- Packet and transmission collisions still need to be avoided and hence transmit and receive slot timings still need to be coordinated between the standards though this does not need to be performed on a regular TDMA basis.
- Has an impact for time bounded services (e.g. voice and video)

Conclusion:
Generally, constraints may need to be exercised on when transmissions can take place from one or both wireless systems. The network must therefore not expect that a particular standard will be able to transmit data or a packet at any instant. Delays may be introduced into the data flow so as to accommodate appropriate slot timings. Is it expected that these delays may be no longer than one or two frame periods.

Contatto

Dave EVANS, (Project leader)
Tel.: +44-1293-815537
Fax: +44-12-93815500
E-mail