LTE MAC standard is being defined by the 3GPP group. As the de-facto standards
body, all firms actively participating in the standardization process contribute/declare
their patents to the body. The patents contributed to the 3GPP body have to be
declared as relevant to (a) the standard and (b) the technical specification within
the standard by the contributing company. Step (a) of the declaration citing the
relevant standard for the patent is mandatory, failing which the contributing
company is not eligible for royalties. Part (b) involving citing the relevant
technical specification to which the patent is relevant is voluntary.
The patent contributions to any LTE standard are voluntary and are not screened
by the 3GPP body for their relevance to the technical subject. As a result,
akin to a gold rush, companies have a strong incentive to disclose as many patents
as they have relevant to as many technical specifications as possible. In summary,
contributions to a technical specification do not necessarily mean the patents
are relevant to the standard.
The gold rush phenomenon increases the information asymmetry between the patent
holder and a potential licensee. This information asymmetry creates challenges
for companies that sit down to negotiate expensive royalty arrangements subsequent
to the commercial roll out of the standard.
It is thus extremely important for a licensee to understand the essential patents
in any standard. A standard is an amalgamation of many technical specifications,
and one needs to understand the essential patents in each technical specification
of the standard.
Dolcera Centre for excellence in the electronics and communications domain has
identified this problem and as a neutral 3rd party is screening the contributions
to the 3GPP body to identify the ‘probably essential’ patents. The
Dolcera Centre for excellence is working on various technical specifications
to identify the ‘essential patents’ for that specification.
The process of identification followed by Dolcera team is as follows –
(a) identifying all patent contributions to a technical specification from the
3GPP database (b) screening all the patents for a technical specification for
its technical relevance to one of the embodiments of the standard (c) identifying
from all the relevant patents, the patents that are essential to a standard’s
implementation.
Step (a) has been done by the Dolcera team by collating the patent contributions
made to the 3GPP consortium. The step (b) of screening patents has been done
by Dolcera team of technical experts by reading through the patents. Dolcera
team has spent close to 15 to 20 minutes reading each patent document to determine
its relevance to a technical area. And finally step (c) that focuses on identifying
whether a technically relevant document is probably essential to the standard
or not, has been performed by spending close to an hour on each technically
relevant document. In this step the team has done a close comparison of the
claims of all relevant documents to the technical implementation steps disclosed
in the standard.
Dolcera team has for the purpose of this report gone through all the patent
contributions made under the Technical specifications 36.321 to determine the
patents that are technically relevant to MAC and more importantly to identify
the subset of patents that are ‘probably essential’ to the MAC implementation
under LTE.
Long Term Evolution (LTE)
Long Term Evolution (LTE) systems are designed with an objective of having
much higher data rates compared to 3G systems. This is a challenging proposition
as wireless networks are subject to interference, multipath and poor propagation
channel characteristics that limit data rates.
LTE - MAC
The MAC layer is the lowest sub-layer in the Layer 2 architecture of the LTE
radio protocol
stack. The connection to the physical layer below is through transport channels,
and the
connection to the RLC layer above is through logical channels. The MAC layer
therefore
performs multiplexing and demultiplexing between logical channels and transport
channels:
the MAC layer in the transmitting side constructs MAC PDUs, known as transport
blocks,
from MAC SDUs received through logical channels, and the MAC layer in the receiving
side
recovers MAC SDUs from MAC PDUs received through transport channels.
The following functions are supported by MAC sublayer:
• Mapping between logical channels and transport channels;
• Multiplexing of MAC SDUs from one or different logical channels onto
transport blocks (TB) to be delivered to the physical layer on transport channels;
• Demultiplexing of MAC SDUs from one or different logical channels from
transport blocks (TB) delivered from the physical layer on transport channels;
• Scheduling information reporting;
• Error correction through HARQ;
• Priority handling between UEs by means of dynamic scheduling;
• Priority handling between logical channels of one UE;
• Logical Channel prioritization;
• Transport format selection.
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